94 Caprice Wagon fuel economy project, stock LT1--46 MPG so far

This project started when we wanted a second car in addition to our 2000 Chevy Metro (which has also been modified and currently averages about 77 MPG, with tanks as high as 90 MPG).  We were looking for a vehicle with 7+ seats for carpooling that could also tow/haul moderate to heavy loads if necessary.

So in August 2013 we bought a 1994 Chevy Caprice station wagon with 83,000 miles (it currently has about 99,000 miles).   Since purchasing it, we have slowly but surely been modifying it, with the most recent mods (about three weeks ago) being a complete drivetrain swap (a manual transmission replacing the stock automatic, a higher geared rear end, and a kill switch).  It probably would have been more interesting to start a running build thread, but I just didn't have the time to devote to keeping it updated.

I have also tried to be as frugal as possible with this project.  I have less than $4000 total in the car, including the purchase price and all modifications.

Since the drivetrain swap, we've had two fill ups.  The first was a very mixed tank, with some highway, some in-town driving, and some short trips and idling for tuning and test runs.  It calculated out to 39.2 MPG.  The second fill up was basically a highway trip from one side of Virginia to another and then back again, which ended up being 46.3 MPG.

I have a feeling, based on these fill-ups and what my MPG gauge tells me, that we'll end up averaging 38-40 MPG with highs approaching 50 MPG from here on.  Before the drivetrain swap and kill switch, we were averaging 25 MPG overall with highway trips around 31-32 MPG (which really wasn't bad at all for an automatic).

Now for the most important part...the mods.  I've included both a "Cliffs Notes" summary, as well as a more detailed description, below.  More pics are available here: https://imgur.com/a/XCbgI



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Mods Summary

Aero mods
-Roof rack delete
-Rear wiper delete
-Moon disc wheel covers
-Side skirts
-Rear fender skirts
-Front air dam that is wider and lower than stock
-Rear kammback extension
-Full grill block and front gap sealing
-Shorter and narrower front tires for less frontal area and lower ride height
-Slightly lower rear springs to match lowered front
-Power antenna override switch, to allow CD listening with antenna down

Drivetrain
-Manual steering conversion, using manual steering box from an S10 pickup
-Lightweight, 23% underdrive crank pulley (made by "ASP")
-A/C compressor override switch, to allow use of any HVAC setting without running the compressor
-Engine tuning, using "Tuner CAT" program (mainly moderate tweaks to AFR and ignition timing)
-Before the manual swap, I created an optional "manumatic" mode that allowed complete manual control of the automatic transmission (see below)
-Manual transmission swap--NV3500 transmission from 1996 Chevy 1/2 ton truck
-"GM 7.625 inch 10-bolt" rear axle from a Caprice sedan, with 2.14 gears installed
-Lightweight 9.5" aluminum brake drums from an early 80's GM car (weighing 8 lbs. each vs. 25 lbs. stock)
-Kill switch (interrupting the distributor sensor feed)
-Auxiliary brake vacuum reservoir and electric vacuum pump, to allow for indefinite engine off coasting
-16" aluminum wheels from a Jeep Grand Cherokee, installed using spacers/adapters
-Bridgestone "Ecopia" low rolling resistance tires; 215/65R16 front (27") and 235/70R16 rear (29")
-Compact spare tire from Jeep Grand Cherokee (in place of stock full size spare)

Instrumentation
-"UTCOMP" trip/MPG computer

Fluids
-Amsoil full synthetic in engine, transmission, and axle
-Ethanol free premium gas

Other (non-eco) mods
-Installed a child seat tether
-Installed locking seat belts from a Chevy Trailblazer in the middle row, in order to make child seats easier to install
-Monroe "Severe Service" heavy duty shock absorbers

Planned future mods
-smaller and/or skinnier front tires, when they need replacing; I'm thinking either 215/55R16 or 205/65R15 (both are about 25.5")
-lower rear springs to go with the shorter front tires
-A/C delete(?); the A/C doesn't do much with a lot of engine off coasting anyway
-"Clear" window tint, to reduce summer interior heat
-Power vent windows; I've got motors (form a Nissan minivan) that I think will work, but I just haven't had the time to do it yet
-Set up the car for interchangeable rear axles, using quick disconnects on the brake lines and cables; one axle will be an "economy" axle (the one that's in the car now) and one will be a "towing axle"
-The towing axle will be a "GM 9.5 inch 14-bolt" rear with 3.73 gears and heavy duty 11x2.75 "truck" drum brakes, from a commercial chassis Cadillac Fleetwood; I already have this axle in my shop
-The "towing" setup will also include heavy-duty rear springs, a rear sway bar (from a Ford Crown Victoria), 235/70R16 tires on all four corners, and a full size spare
-Heavy duty "J55" front suspension/brakes, also from the commercial chassis Fleetwood; this will stay in the car all the time, since it won't really affect fuel economy

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Mods Details

When we first bought the car, it was in good mechanical condition with hardly any rust (having spent most of its life in Georgia), but the engine did have some oil leaks.  They ended up being fairly easy to fix--just a waterpump shaft seal and an oil filter adapter seal.  The best part is that the previous owner's mechanic told her that the leaks would cost $1700 to fix, so she adjusted the sale price accordingly (cheap!).

The first thing I did, after fixing the leaks and doing a tune up (fluids, oil filter, fuel filter, spark plugs, wire, O2 sensors, etc.) was to install a gauge.  Being a 1994 model, an OBDII unit like a Scangauge wasn't an option.  I ended up buying a "UTCOMP" on eBay, and I have been very pleased with it.  It works a lot like an MPGuino, in that you have to tap into the VSS and FI signals, but it has a much friendlier interface, more features, and the capability to wire in a lot more sensors (I also wired in a temp sensor for the automatic transmission, for example).  The gauge has been very accurate for as long as we have owned the car.

The car did need a new crank pulley/harmonic balancer, and since it needed to be replaced anyway, I spent a few extra dollars and bought an underdrive pulley.  I never did A/B testing with it, but it probably made a slight difference, particularly with the A/C running.

The next step was to start the aero mods.  Most of this was pretty straightforward.  I got a good deal on 15" wheel covers on eBay; the grill block is black "Gorilla tape," with home insulation strips for gap sealing; the front air dam was made using lawn edging material; the side skirts are made from plastic guttering; and the wheel skirts are coroplast pieces that are held on with screws going into homemade brackets.  The most complicated part was the kammback.  The kammback on our Metro was pretty simple--I just attached it solidly to the rear door, since the door is one piece with a metal frame around the rear window.  On the Caprice, though, the window and tailgate operate separately, and the window does not have a metal frame.  What I did was to make a lightweight metal frame with hinges that attach to the roof above the rear glass and arms that come down and attach to the car near the bottom of the rear glass using wingnuts.  The kammback itself is made from coroplast and is attached to the metal frame.  The sides of the kammback that meet the sides of the car have rare earth magnets in them to keep them in contact with the car.  This allows the entire kammback to be detached at the wingnuts and swing upwards on the hinges, allowing the rear glass to open.  It works very well and has proven to be durable after several years.

Buying the "Tuner CAT" tuning program was also an excellent investment.  I have used it for everything from adjusting the speedometer after tire and gear changes, to tweaking ignition timing and AFR, to making the cooling fans turn on sooner, to modifying shift points and TCC engagement, to giving the car a "manumatic mode."  This car uses the same "LT1" engine that was also used in the Corvette, Camaro, and Firebird.  The Firebird had a "performance mode" button that, when selected, caused the transmission to shift differently (later, mostly, for a more "sporty" feel).  Even though the other cars with the LT1 did not have that feature, the programming still exists in the PCM.  So I put one of the Firebird "Transmission Perform" buttons in the wagon, wired it to the engine computer, and then reprogrammed the "performance mode" tables so that the transmission would go to and stay in whichever gear the shift lever was moved to.  I then wired up another button, and placed it on the end of the shifter, which would ground the TCC solenoid and lock the torque converter clutch.  Between the two, I could shift into any gear I wanted, and lock the TCC whenever I wanted to, giving me complete control over the transmission.  Once I got the hang of it, this "manumatic mode" gained me several MPG, particularly in city driving.  The best part is that the "manumatic mode" was completely optional--if one got into the car, started it up, and drove, it would work like any other automatic.  It would only go into "manumatic mode" if the "Transmission Perform" button was selected.  My wife really liked that feature.

Another thing I did fairly early on was to convert it to manual steering.  I did some research and discovered that a manual steering gearbox from an S10 pickup bolts right into a Caprice.  So I found a box, swapped it in, and replaced the PS pump with an idler pulley (just like the tensioner pulley).  I simply bolted it into one of the bolt holes from the pump, and it worked great with the stock serpentine belt.

I knew that when the tires needed to be replaced I would be looking for LRR replacements.  However, there are very few LRR 15" options, especially in the taller sizes.  So I figured out that 1999 to mid 2000's Jeep Grand Cherokees have the same bolt pattern as the Caprice, just with a different offset and hub center bore, and come in 16" and 17" sizes.  So I got a set of aluminum 16" wheels for really cheap from a local U-pull yard, and got a set of adapters/spacers for the wheels.  I then settled on the tires and sizes I listed above, and bought them used on eBay.  We put so few miles on this car that we really don't need new tires for it, and used tires have lower rolling resistance anyway.  Switching to the LRR tires was another mod that made a big difference--about 2 MPG across the board.  Running different sizes front and back gives the best of both worlds--taller tires in the rear for lower rpms, and shorter, narrower tires in the front for less weight and better aerodynamics.  I plan to go with even shorter front tires the next time they need to be replaced.

Once all of the mods I have described so far were completed, I didn't do anything more for a while.  I began collecting parts for the drivetrain swap, but even once I had collected everything I needed, I didn't do anything for about a year and a half.  Life kind of got in the way--we had another baby, bought a house, and I had other projects to work on.  I had figured that a manual transmission with a kill switch would make a pretty substantial difference.  I just didn't have the time to do it.  

But I finally did it this Memorial Day weekend.    I had gotten the transmission, clutch, flywheel, hydraulics, pedal, etc. from a 1996 Chevy 1/2 ton pickup.  I went to our local U-pull's "all you can carry sale" and got everything for $65.  I also was fortunate in that the particular truck I pulled everything from had just had a new clutch and hydraulics put in before it was wrecked.  I got inspiration and guidance to do the swap from this thread, which has a lot of details: 1992 Olds Custom Cruiser project - Chevy Impala SS Forum.  The only things I'll add to it is that the crossmember was a lot easier for me because I was starting with a 1994 model; all I had to do was  elongate one of the holes in the center of the crossmember.  I also used the clutch pedal from the truck.  I had to modify it a little bit, but it went in fairly easily.  It doesn't look as nice, since it sits closer to the driver than the brake pedal, but it works very well.

I knew that I wanted the highest rear gearing that I could get, particularly since the overdrive of the NV3500 manual is slightly lower than the overdrive of the 4l60E automatic.  However, the highest gears that are available for the 8.5" 10 bolt rear that came in the car are 2.41 ratio (stock ratio was 2.56).  With the 7.5/7.625" 10 bolt, the highest is 2.14.  So I found a 7.625" axle from a Caprice sedan (with less than 100,000 miles), found a set of 2.14 gears (which, surprisingly, were not too difficult to find or too expensive, given their rarity), and had a local shop install them for me.  The axle was $150, the gears were $85, the bearing/install kit was $60, and the labor was $150--so $445 total.  It was the single most expensive part of the project, but still not too bad and, after I saw the difference it made, definitely worth it.  The car now turns slightly less than 1000 RPM at 55 MPH.

To go with the 2.14 axle, I thought I might as well go all the way and put a set of aluminum brake drums on it.  I found a set from an 80's GM car, and had a local machine shop enlarge the center bore and bolt pattern to fit the Caprice sedan axle (all of the other dimensions were perfect).  These drums saved 17 pounds per wheel, for a total of 34 pounds of rotational mass deleted.

The only problem with running a "lightweight" axle like this with really high gearing is that you practically eliminate your ability to tow a trailer.  My solution to this problem will be to set up the car for easily interchangeable rear axles.  Once I install the brake quick disconnects, it should only take me about an hour and a half to swap axles.  The "heavy duty" 14 bolt 3.73 Cadillac axle (which has only 50,000 miles and only cost me $175) is basically like what you would find in a 3/4 ton pickup--so I'll have the best of both worlds.  In fact, when the 14 bolt rear axle is combined with the "J55" heavy duty front suspension, which I also plan to swap in, the car should be able safely to tow significantly more weight than stock.  In towing mode, I'll have higher capacity brakes (front and rear), axles, bearings (front and rear), ball joints, springs, and sway control than stock, and (in my opinion) a more reliable transmission.

Last but not least, the single most significant MPG mod I've done to this car is the kill switch--which of course was only possible after the manual transmission swap.  This car, being pretty heavy and fairly aerodynamic, will coast for a long, long time.  It also uses a fairly large amount of fuel at idle (approximately .45 GPH, compared with .12 GPH in the Metro).  These two characteristics together mean that a kill switch will have a BIG impact.  I put a switch in the manual shifter, ran the wires to a relay, and initially used the switch to interrupt the fuel injector power supply.  This is what I did in our Metro, and it works very well.  However, in the Caprice, interrupting the FI power supply did cut the engine off, but if I held the button for more than a second or two, it would create an error in the PCM that would not allow the injectors to fire again unless the key was turned to "off" and then back to "run."  I had originally thought that it might be setting a "silent" check engine code, but when I ran a scan no codes were set.  So I wired the switch instead to interrupt the power supply for the sensors in the distributor, which serve as an engine RPM signal for the PCM (among other things).  When those sensors are tuned off, the PCM thinks the engine is turning 0 RPM and cuts both spark and fuel, killing the engine.  It works very well, without causing any other errors or issues.

To allow for long coasts with the engine off, I wanted to still be able to have brake vacuum.  In the Metro, an auxiliary vacuum canister doubled my vacuum capacity, but that was not nearly enough for this Caprice.  So I decided to go with an auxiliary vacuum pump as well.  You can buy vacuum pump kits online, but they're very expensive.  Instead, I got an electric pump from a late-model VW diesel in a junkyard, and purchased only the relay and vacuum switch from one of the kits online.  The pump is the most expensive part of the kits, so doing it that way made it pretty economical.  I've included a picture of the vacuum pump setup under the hood.  It sits where the cruise control module used to be before I deleted it.  

There are a lot more details that I could share, but I've already probably written too much.  I hope y'all have found it interesting.  Please let me know if you have any questions or feedback!

I'm not sure any of us here really care about MPG, but congrats on doing it!

Did you keep the LT1 and just choke it with big gears, or did you swap in a ricer engine?

Sorry I didn't read it top to bottom….

As the title says, it still has the stock LT1. So I guess I "choked it with big gears."

Although with the interchangeable rear ends, it will have either 2.14 OR 3.73 gears--so maximum economy OR maximum power. I didn't want to have to compromise either.

Your Kamm effect parts may not contribute to your gas mileage.

I am surprised that you did not put rear view cameras on the car, and remove the rear view mirrors. Maybe even replace the doors with 95-96 doors and use the 94 window trim. That would probably do more than the Kamm addition. The only way you can tell if the Kamm addition actually makes a difference is to put it in a wind tunnel and measure the drag coefficient with and without it.

Fred,

Those are all good points. I have thought about doing a side mirror delete, but there are two reasons I haven't so far. First, I'm not sure that having just cameras would pass inspection in VA. I'm pretty sure that you need to have at least one externally mounted mirror. And second, replacing the doors and buying cameras would cost a lot of money--and I'm cheap.

Having the opportunity to do some wind tunnel testing would be fantastic. Short of that, I could "tuft test" the Kammback to see how much detached flow and turbulence there is, but I'm satisfied with it without doing that. The car was getting 32 MPG highway very consistently while it still had the automatic, which it did not do before the aero mods. I'm guessing that the Kammback made at least a 5% increase in fuel economy. That would be pretty consistent with ABA testing on Kammbacks that the folks on the Ecomodder forum have done. The Kammback on our Metro had a similar effect.

A T56 swap might be a great idea for you,.keep the 3.73's all the time,.
it would raise the rpm at 55 mph by a little,. but 31" tires would fix that,. although the tread designs might not be good for LRR,

Interesting project,.i subscribe to eco modder forum,.some of the innovations make for good reading,.

Personally,. the reduction in creature comforts, does not appeal to me,.i drove vehicles with armstrong steering and 552 air conditioning,and plastic seats,.

removing the front bumper and making a roll pan i think would make a difference too,.

I think also the 14 bolt 9.5 rear end is too big and not necessary,.

If you are concerned with braking power,. then a wagon rear axle with disc brakes, would tow and stop anything you could safely tow with a 4500 pound tow vehicle,.
and a simple home made 13" front rotor conversion with 4 piston calipers will definitely stop anything you have,.

Put the wagon an a diet,. interior comforts aren't a priority for you, and the weight reduction is good for economy,.

If i ever pass you on the highway at 80 mph with the a/c full on,.i will be sure to lower my 5% tinted windows and wave!,.. but i will expect you to buy lunch whenever you arrive, after having saved so much money on fuel consumption we can both eat exceptionally well,.

Tip of the cap to you sir on your accomplishments. You are indeed focused. If this world goes full on "Mad Max" you will have it made. Might even make mayor of Bartertown.

phantom 309 wrote:

A T56 swap might be a great idea for you,.keep the 3.73's all the time,.
it would raise the rpm at 55 mph by a little,. but 31" tires would fix that,. although the tread designs might not be good for LRR,

I thought for a long time about which transmission to use--T56, NV3500, or NV4500.  The NV4500 is overkill, really heavy, more expensive, and would take a lot of floor pan/crossmember modifications to fit.

The 5 speed NV3500 actually has a wider range of gearing than the 6 speed T56 (5.51:1 vs. 5.32:1 overall).  My NV3500, 2.14's, and 29" tires is basically the same as a T56, 2.93's, and 27" tires--except with a slightly lower first gear.  My NV3500 with 3.73's and 29" tires is the same as a T56, 27" tires...and 5.08's!

Also, the spacing between the gears on the NV3500 is wider in the lower gears and closer in the higher gears, which is what you want for economy.  The T56 is the opposite--closer spaced lower gears and wider spaced overdrives.  The T56 is also heavier.

However, the price difference is what really made it a no brainer.  I got the entire NV3500 swap for less than $100, and it probably ended up being about $300 overall.  There's no way I could put a T56 in for anything close to that.

phantom 309 wrote:

Personally,. the reduction in creature comforts, does not appeal to me,.i drove vehicles with armstrong steering and 552 air conditioning,and plastic seats,.

I hear you on the creature comforts.    One of the things I did not list above was that I hope to make an "ice cooler A/C" that I can use in either one of our cars.  Like this: http://www.instructables.com/id/Portable-12V-Air-Conditioner---Cheap-and-easy!/

Supposedly they really do work, are cheap to build, and don't have any parasitic losses (like the factory A/C).  One of these units would also allow me to delete the factory A/C, cutting almost 50 pounds, relocate the alternator to where the A/C compressor currently is, and run a belt from just the crank pulley to the alternator (reducing parasitic losses).

But my ultimate motivation for this project is not saving money, but rather reducing my carbon footprint.  So from that viewpoint, I'm willing to sacrifice a few creature comforts for efficiency.

phantom 309 wrote:

I think also the 14 bolt 9.5 rear end is too big and not necessary,.

If you are concerned with braking power,. then a wagon rear axle with disc brakes, would tow and stop anything you could safely tow with a 4500 pound tow vehicle,.
and a simple home made 13" front rotor conversion with 4 piston calipers will definitely stop anything you have,.

You're right--the 14 bolt is probably overkill.  But it definitely wins in the "cool factor" department.  

In all seriousness, the rear disc conversion and front rotor conversion you describe would be really neat, but a lot more expensive than what I plan to do.  I got the entire commercial Fleetwood suspension (rear axle and both front knee assemblies) for less than $400.  Besides the beefier brakes, the Fleetwood suspension also has the advantage of bigger bearings front and rear, and well as heavier duty ball joints.

I've considered getting a "custom built" registration in VA, once the Fleetwood parts are in the car, and register it with the 7200 lb. GVWR that the Fleetwood had.  I could easily justify a 7000-8000 pound tow rating with the commercial suspension and gearing.

phantom 309 wrote:

Put the wagon an a diet,. interior comforts aren't a priority for you, and the weight reduction is good for economy,.

If i ever pass you on the highway at 80 mph with the a/c full on,.i will be sure to lower my 5% tinted windows and  wave!,.. but i will expect you to buy lunch whenever you arrive, after having saved so much money on fuel consumption we can both eat exceptionally well,.

Between the transmission swap, axle swap, aluminum drums, lighter wheels, and compact spare, the car probably weighs over 150 lbs. less than it did from the factory already.  There isn't too much "low hanging fruit" left (easy and inexpensive to do) when it comes to weight reduction.  I'm not convinced that weight makes too much of a difference with MPG, anyway, unless you're talking about 500-1000 lbs. or more.  I think that aerodynamics and parasitic losses are much more important overall.

And I'd be happy to buy you lunch if we ever run into each other on the road.   I've been hoping to make it to Wagonfest one of these years, just for the fun of it...

Andebe wrote:

Tip of the cap to you sir on your accomplishments. You are indeed focused. If this world goes full on "Mad Max" you will have it made. Might even make mayor of Bartertown.

Thanks! Though if this world ever "goes full on 'Mad Max'" I'll probably just get pancaked on the highway somewhere...

Weight makes a big difference in rolling resistance with the balloon tires. At a given tire pressure the heavier car has a larger contact patch, and subsequently more rolling friction with the road.

Be careful, in some states it is illegal to "freewheel" (drive with the engine off).

funkhoss wrote:

phantom 309 wrote:

A T56 swap might be a great idea for you,.keep the 3.73's all the time,.
it would raise the rpm at 55 mph by a little,. but 31" tires would fix that,. although the tread designs might not be good for LRR,

I thought for a long time about which transmission to use--T56, NV3500, or NV4500.  The NV4500 is overkill, really heavy, more expensive, and would take a lot of floor pan/crossmember modifications to fit.

The 5 speed NV3500 actually has a wider range of gearing than the 6 speed T56 (5.51:1 vs. 5.32:1 overall).  My NV3500, 2.14's, and 29" tires is basically the same as a T56, 2.93's, and 27" tires--except with a slightly lower first gear.  My NV3500 with 3.73's and 29" tires is the same as a T56, 27" tires...and 5.08's!

well i think that kinda reinforces my point,. overcoming inertia with lower gearing is beneficial,. now we have oem 8 spd transmissions vs 4 spd transmissions,.to keep the motors in their efficient power bands today,.

funkhoss wrote:

Also, the spacing between the gears on the NV3500 is wider in the lower gears and closer in the higher gears, which is what you want for economy.  The T56 is the opposite--closer spaced lower gears and wider spaced overdrives.  The T56 is also heavier.

thats something i didn't know,. i thought the T56 was pretty light,.not sure i agree with your theory of wider spaced gears to overcome inertia,.

funkhoss wrote:

However, the price difference is what really made it a no brainer.  I got the entire NV3500 swap for less than $100, and it probably ended up being about $300 overall.  There's no way I could put a T56 in for anything close to that.

 i will agree on that,.

phantom 309 wrote:

Personally,. the reduction in creature comforts, does not appeal to me,.i drove vehicles with armstrong steering and 552 air conditioning,and plastic seats,.

funkhoss wrote:

Supposedly they really do work, are cheap to build, and don't have any parasitic losses (like the factory A/C).  One of these units would also allow me to delete the factory A/C, cutting almost 50 pounds, relocate the alternator to where the A/C compressor currently is, and run a belt from just the crank pulley to the alternator (reducing parasitic losses).

v=belts vs serpentine,.serpentine is proven to be less parasitic,.
not sure i believe 50 lbs ,..  
Kudo's on the wanting to reduce your carbon footprint,,...just buying a vehicle that will last 30 yrs or more with care is a good start,..
we need people like you to make up for people like me,..

phantom 309 wrote:

I think also the 14 bolt 9.5 rear end is too big and not necessary,.

If you are concerned with braking power,. then a wagon rear axle with disc brakes, would tow and stop anything you could safely tow with a 4500 pound tow vehicle,.
and a simple home made 13" front rotor conversion with 4 piston calipers will definitely stop anything you have,.

funkhoss wrote:

You're right--the 14 bolt is probably overkill.  But it definitely wins in the "cool factor" department.  

cool factor strays from carbon foot print morality,. but definitely something i relate too,. even tho i think a wagon with an 8 bolt axle would be tres un cool,. bordering more on hillbilly un ingenuity,. but again ,. just my opinion,.

funkhoss wrote:

In all seriousness, the rear disc conversion and front rotor conversion you describe would be really neat, but a lot more expensive than what I plan to do.  I got the entire commercial Fleetwood suspension (rear axle and both front knee assemblies) for less than $400.  Besides the beefier brakes, the Fleetwood suspension also has the advantage of bigger bearings front and rear, and well as heavier duty ball joints.

you'll have to explain those advantages,.bigger ball joints and bigger bearings,mean nothing in economy tables,. in the weight/duty cycle etc that you are exploring,. its over kill again,.

phantom 309 wrote:

Put the wagon an a diet,. interior comforts aren't a priority for you, and the weight reduction is good for economy,.

If i ever pass you on the highway at 80 mph with the a/c full on,.i will be sure to lower my 5% tinted windows and  wave!,.. but i will expect you to buy lunch whenever you arrive, after having saved so much money on fuel consumption we can both eat exceptionally well,.

funkhoss wrote:

Between the transmission swap, axle swap, aluminum drums, lighter wheels, and compact spare, the car probably weighs over 150 lbs. less than it did from the factory already.  There isn't too much "low hanging fruit" left (easy and inexpensive to do) when it comes to weight reduction.  I'm not convinced that weight makes too much of a difference with MPG, anyway, unless you're talking about 500-1000 lbs. or more.  I think that aerodynamics and parasitic losses are much more important overall.

you're probably right about aerodynamics,.150 lbs is minimal, yet a 9.5 rear axle weighs how much?,. which reinforces my point about straying from your goal with a large, unwieldy, over rated, parasitic, rear end like the 14 bolt , 3/4 ton rear end you described,.
If you like,. and as your carbon footprint is forefront in your goals,. i can give you a comprehensive list of parts and pieces to remove for weight reduction, also taking into consideration your lack of needs for creature comforts,.
I would also add that an A body wagon might be more beneficial to your goals than a b-body,.

funkhoss wrote:

And I'd be happy to buy you lunch if we ever run into each other on the road.   I've been hoping to make it to Wagonfest one of these years, just for the fun of it...

excellent ,. thankyou,. even tho,. i might be waiting a considerable time for you to catch up,. and exhausted and hot and sweat as you may be at the time you finally arrive,. i would be happy let you pay.

Fred Kiehl wrote:

Your Kamm effect parts may not contribute to your gas mileage.

I am surprised that you did not put rear view cameras on the car, and remove the rear view mirrors. Maybe even replace the doors with 95-96 doors and use the 94 window trim. That would probably do more than the Kamm addition. The only way you can tell if the Kamm addition actually makes a difference is to put it in a wind tunnel and measure the drag coefficient with and without it.

I vaguely remember reading the "bubble" caprice was one of very few cars whose rearview mirrors improved Cd.

phantom 309 wrote:

well i think that kinda reinforces my point,. overcoming inertia with lower gearing is beneficial,. now we have oem 8 spd transmissions vs 4 spd transmissions,.to keep the motors in their efficient power bands today,.

not sure i agree with your theory of wider spaced gears to overcome inertia,.

It actually makes perfect sense.  I spend very little time in gears 1-3, and about 85-95% of my driving is in gears 4 and 5.  I want those two gears to be closer together, to maintain efficiency.  Gears 4 and 5 are closer to each other in the NV3500 than gears 5 and 6 are in the T56.

For performance driving and racing, you spend most of your time in the lower gears, and don't use the overdrive(s).  In that context, you want the lower gears to be closer to each other, in order to keep the engine in its power band--which is exactly how the T56 is set up.

Economic driving is more about efficiently managing inertia than it is about overcoming it.

phantom 309 wrote:

v=belts vs serpentine,.serpentine is proven to be less parasitic,.

Sorry I wasn't clear.  If I deleted the A/C and relocated the alternator, I would still use a sock-style poly-rib belt.  It would just go directly from the crank to the alternator and back, so there'd be only one pulley for the engine to spin instead of 4.

phantom 309 wrote:

cool factor strays from carbon foot print morality,. but definitely something i relate too,. even tho i think a wagon with an 8 bolt axle would be tres un cool,. bordering more on hillbilly un ingenuity,. but again ,. just my opinion,.

The Fleetwood axle is five lug, not eight.  It has all of the same mounting dimensions as any other B/D sedan axle (axle flanges, overall width, mounting brackets, spring perches, etc.).

phantom 309 wrote:

you'll have to explain those advantages,.bigger ball joints and bigger bearings,mean nothing in economy tables,. in the weight/duty cycle etc that you are exploring,. its over kill again,.


you're probably right about aerodynamics,.150 lbs is minimal, yet a 9.5 rear axle weighs how much?,. which reinforces my point about straying from your goal with a large, unwieldy, over rated, parasitic, rear end like the 14 bolt , 3/4 ton rear end you described,.

The idea is that we will have, in essence, two different vehicles, for two different functions.  "Economy mode" will have the functionality and capacity of a minivan, except be much more efficient.  "Towing mode" will have the functionality and capacity of a 3/4 ton Suburban, except be much more efficient.  

I think the Fleetwood J55 front end parts will have a negligible effect on economy (maybe 30 lbs heavier overall?), but will improve durability and strength.  And the main advantage of the Fleewood brakes is not increased stopping power, but rather better heat dissipation.

We'd eventually like to do some small farming, and have the ability to tow a livestock trailer, dump trailer, flatbed equipment hauler, etc.  That's why I want to have the "towing mode" when we need it.

phantom 309 wrote:

If you like,. and as your carbon footprint is forefront in your goals,. i can give you a comprehensive list of parts and pieces to remove for weight reduction, also taking into consideration your lack of needs for creature comforts,.

That would be fantastic!

phantom 309 wrote:

excellent ,. thankyou,. even tho,. i might be waiting a considerable time for you to catch up,. and exhausted and hot and sweat as you may be at the time you finally arrive,. i would be happy let you pay.

Two things you're forgetting.  (1)  It's only hot in the summer.  (2)  Hypermiling is FUN!!  

Interesting stuff, Best MPG I've gotten with an L05, 3.23 and 235/75R15s on heavy 9C1/N97 wheels is about 20 MPG, I blame my issue with the thermostat and EGR for those numbers, and that's driving with traffic and a sticky odometer that when running is accurate.

I didn't properly read what you wrote, i scanned,. sorry,.

I had/have no idea the fleetwood rear end is a 14 bolt with car axles,.??
Would you please take a picture of this, and explain what years it came in etc,.?

Which would be good if you are planning to carry heavy weight, rather than pull it,.

There is a write up you may be interested in for increased front braking power, is reasonably cheap too,.
It involves cutting down the b-body front rotor into a hub, and using astro van rotors,.
cheap bigger brakes

To help my friend/neighbour i pulled hay wagons in from the field last year with my orange wagon,. 16 bales at 1000lbs a piece or so plus the wagon,.our wagons have a 1/2 ton truck rear end in them,.my son drove our old 3/4 ton 4x4 pulling 2 at a time,.
the limiting factor with the wagon was traction to get rolling,.i put 4 80 lb bags of molasses feed in the back,. the wagon has 3:73's,. top speed on the haul was maybe 15 miles an hour tho,..hay fields are lumpy,.
perhaps a 12v cummins and a 10 spd roadranger might be perfect for you?

the 14 bolt came in the Commercial chassis, hearses, limos and such. It's just a 9.5 semi floater with the car lug pattern. GM did the same thing with the 454SS. Also, fun fact, I'm told the alloy wheels that came on those cars that looked like the base Fleetwood wheels were heavy duty and marked "Limo only" on the inside.

phantom 309 wrote:

I had/have no idea the fleetwood rear end is a 14 bolt with car axles,.??
Would you please take a picture of this, and explain what years it came in etc,.?

MalibuSSwagon wrote:

the 14 bolt came in the Commercial chassis, hearses, limos and such. It's just a 9.5 semi floater with the car lug pattern. GM did the same thing with the 454SS. Also, fun fact, I'm told the alloy wheels that came on those cars that looked like the base Fleetwood wheels were heavy duty and marked "Limo only" on the inside.

That is correct.  The Cadillac 14-bolt axle came only in 1991-1996 commercial chassis vehicles--hearses, limos, and also armored vehicles.  1991-1993 had either 3.08 or 3.73 gears, and 1994-1996 had 2.93 or 3.42 gears (just like regular production Fleetwoods).  In my experience from trying to find one, the 2.93 and 3.08 axles are more common than the 3.42 and 3.73 axles.  I also know that some had the G80 option and some didn't; I don't know whether it was a "Gov-Lock" like a truck or a clutch-style Posi.  Mine is an open 3.73 from a 1993 hearse.

Mechanically, the Cadillac 14 bolt is just like the truck 14 bolt 9.5" semi floaters--same housing, carrier, gears, axles, axle tubes, bearings and brakes (brakes are 11x2.75 vs. the 11x2 on our wagons).  The only differences are that (1) they are built to the same width as a standard B/D sedan axle, (2) they are five lug instead of 6 or 8, and (3) they have all of the  mounting brackets needed for a B/D sedan.

I'm not at home right now, but here's an eBay auction for one where you can see some pictures: http://www.ebay.com/itm/14-Bolt-9-5-5-lug-car-rear-end-axle-Dana-60-size-and-stronger-than-12-Bolt-car-/161860233016?fits=Make%3ACadillac&hash=item25af9f2738:g:AfcAAOSwl9BWIUmZ&vxp=mtr

The commercial chassis Cadillacs also came with, in addition to the 14 bolt rear, the J55 front brakes/suspension.  In comparison with the standard B/D front end, the J55 had heavier duty knuckles/spindles, larger inner bearings (outer are the same), thicker rotors (diameter is the same), larger calipers to match the thicker rotors, 5/8" lower ball joints, different outer tie rods, and no ABS.  Dimensionally, these parts are the same and will interchange into a standard B/D body.

The 14 bolt rear and J55 front gave the Cadillac commercial chassis a GVWR of 7200 lbs.--3500 lbs. front and 3700 lbs. rear.

phantom 309 wrote:

There is a write up you may be interested in for increased front braking power, is reasonably cheap too,.
It involves cutting down the b-body front rotor into a hub, and using astro van rotors,.
cheap bigger brakes

Thanks.  I've seen that write up--the J55 rotors are very similar to the rotors in that write up, in terms of thickness.  If you use the J55 knuckles, lower control arms, and outer tie rods with them, they bolt in with no modifications AND have heavier duty bearings and ball joints than stock.  I've got all these parts ready to go in my storage shed.  

phantom 309 wrote:

To help my friend/neighbour i pulled hay wagons in from the field last year with my orange wagon,. 16 bales at 1000lbs a piece or so plus the wagon,.our wagons have a 1/2 ton truck rear end in them,.my son drove our old 3/4 ton 4x4 pulling 2 at a time,.

16,000 lbs. plus is impressive.    Being hay wagons, though, there was no tongue weight involved.  Towing 16,000 lbs. is something else entirely.

phantom 309 wrote:

the limiting factor with the wagon was traction to get rolling,.

Even with the little bit of towing I've done with the car so far (3000-3500 lbs on a few occasions) I've found traction off road to be challenging too.  I plan to move the 29" LRR tires to the front and put 29" A/T tires on the rear when I set up the wagon in "towing mode."

phantom 309 wrote:

perhaps a 12v cummins and a 10 spd roadranger might be perfect for you?

Conversion to diesel would be awesome!  I'd want to wait for the LT1 to die first, though, which might take a while...

Is it honestly "miles per gallon" if the engine is shut off?
I applaud the effort, but I'm scratching my head over the idea of spending 4K modifying a 4500# car for the sake of fuel mileage when there are plenty of used cars you could buy for less than $4k that already do that well and could be modified to do even better.
In my driveway, I have a variety of vehicles (tools) that do different jobs......My strategy is more of a "gallons (or dollars) per week" thing and my 8 mpg 94 crewcab dually is the vehicle that uses the fewest gallons per week because I hyper-mile with it by leaving it parked in the driveway....If I need to tow something heavy, it is instantly available....I had a Chevy Metro for when I worked 35 miles out from the house, but am now willing to spend some gas money for more comfort....

AzDon wrote:

I applaud the effort, but I'm scratching my head over the idea of spending 4K modifying a 4500# car for the sake of fuel mileage when there are plenty of used cars you could buy for less than $4k that already do that well and  could be modified to do even better.

Did you read my initial post carefully?

I know of no other car that seats seven people that can get the sort of mileage we're getting now.  We carpool with people pretty regularly, and use most of those seats.  That's the main reason we bought the car.

Is there some other car with seven seats that I'm unaware of that gets 40 MPG or more?  What other car with seven seats could possibly be modified to do better than 46 MPG?

That's not to mention the towing capacity (which we use as well).  Most minivans can't tow 5,000 lbs...or get anything close to 40 MPG.

AzDon wrote:

In my driveway, I have a variety of vehicles (tools) that do different jobs......My strategy is more of a "gallons (or dollars) per week" thing and my 8 mpg 94 crewcab dually is the vehicle that uses the fewest gallons per week because I hyper-mile with it by leaving it parked in the driveway....If I need to tow something heavy, it is instantly available....I had a Chevy Metro for when I worked 35 miles out from the house, but am now willing to spend some gas money for more comfort....

I agree wholeheartedly.  Our main car is a Chevy Metro which averages almost 80 MPG.  And we use it for at least 80% of our driving.  The wagon stays parked most of the time.

How does that not make sense?  

If you really pencil this whole project out, does the fuel savings even get close to the cost of the mods? Just curious.

Wife and I penciled out the lifetime of a couple vehicles and the fuel expense itself was not a very big penalty with a larger vehicle vs a 35 mpg sedan, so we bought the twin turbo!

Deadmanonduty wrote:

If you really pencil this whole project out, does the fuel savings even get close to the cost of the mods?  Just curious.  

50,000 miles @ 20 MPG (typical for most) @ $2.00 per gallon = $5,000

50,000 miles @ 40 MPG @ $2.00 per gallon = $2,500

Savings = $2,500

______________________________

100,000 miles @ 20 MPG @ $2.00 per gallon = $10,000

100,000 miles @ 40 MPG @ $2.00 per gallon = $5,000

Savings = $5,000

______________________________

Mods cost about $1,000.  (That does not include towing parts, since they are not needed if fuel economy is the bottom line.  Even if they are included, the total is less than $2,000.) The mods will pay for themselves after 20,000 miles.

So, yes--from a financial viewpoint, definitely worth it.

My primary motivation is ecological, though.  The money savings are just a fringe benefit.  

I see. Glad its working out for you!

How long do you estimate to reach the 50,000 miles?

4? 5? years?

5 years would save you roughly $42 a month,.

As much as i usually appreciate what turns the others guys crank,.. for me and my family,. i couldn't imagine dogging along with no power steering, and no a/c,. windows up to save fuel etc,.
I can understand the attraction of meeting a mileage challenge everyday,. but it honestly doesn't appeal to me, much like base jumping, sky diving, deep sea exploration, mountain climbing,
tri-athalons etc,. all activities that turn the other guys crank and involve sometimes some physical hardship and discomfort,.

Having said all that i do enjoy being tightly strapped in a 5 point harness and thrashing some overpowered, hard braking gas guzzling race car that can exert some G forces going around the track,. with no a/c etc,. pretty the diametrical opposite of what you enjoy,.
Thats what makes the world an interesting place,..

Run a full tank for us with no engine cut off and let us know what the actual mileage is. I'm interested to see what the difference is.

Very cool effort and echo Jay's comment of about engine on all the time. I live in FL where it's flat so I can't turn of my motor and cars get 150+ inside so that AC needs to run....

The Humidity alone in Wisconsin makes AC a necessity for 6 months a year, muchless in a warmer state.

I agree with Phantom, I want to beat the tar out of the beastly LT1 every chance I get and hear the straight pipes rattle! But to each his own.

Yeah, I get that you were choosing an aerodynamic envelope that can contain seven people as a starting point......We all make modifications to our vehicles to reflect our personalities, goals, and concerns....To make a statement about ourselves and to perform the way we want them to....
Where I live it's 120 degrees today...Upgrades to my vehicles incorporate a strategy of eliminating (some say wasting) heat, because to me, heat is the enemy. People that live in cold places sometimes have a hard time understanding this....
I'll probably never understand the need to hypermile and probably only want to pay my share of the gas (not the modifications) if I carpooled with you....
The point of my original post was to highlight the idea that using the best possible tool (vehicle) for a particular duty and having a variety of "tools" available can keep fuel costs reasonable....
Just because I don't see myself pursuing a high mpg strategy and expressing why doesn't mean that I don't respect or applaud your efforts to save some gas...... We may be a tough crowd here, but I think most of us respect your efforts to save gas and appreciate the opportunity to converse and learn a few things....

Deadmanonduty wrote:

If you really pencil this whole project out, does the fuel savings even get close to the cost of the mods?  Just curious.  

Wife and I penciled out the lifetime of a couple vehicles and the fuel expense itself was not a very big penalty with a larger vehicle vs a 35 mpg sedan, so we bought the twin turbo!  

A lot of folks making the carbon footprint "statement" drive a Prius, Chevy Volt, or Nissan Leaf......
When the initial cost of the vehicle, cost of plug in electricity, and cost and frequency of replacement batteries is factored in, I believe that the true cost per mile is much higher for these vehicles.... Since I only buy completely depreciated vehicles in economically restorable condition, I'll probably never own a hybrid...

You all have asked some really good questions, and I promise I'll answer them.  However...I first want to examine some of the implicit assumptions behind several of the remarks that have been made so far.  I'll takes these two as representative examples:

AzDon wrote:

Is it honestly "miles per gallon" if the engine is shut off?

jayoldschool wrote:

Run a full tank for us with no engine cut off and let us know what the actual mileage is.  I'm interested to see what the difference is.

Let me ask a question: would you continue to pedal when coasting on a bicycle?

From an objective viewpoint, continuing to run an internal combustion engine when it's not needed is much the same as continuing to pedal while coasting on a bike.  The reason that we've never really thought of it that way (besides being culturally conditioned to think that needless idling is "normal") is because for most of the history of the automobile, fuel was very cheap, very plentiful, and we didn't know about the ecological consequences of burning a lot of it.  

More recent history, however, shows that automobile manufacturers have finally understood the absurdity of unnecessary idling.  In almost every "hybrid" vehicle on the road, when you lift your foot off of the accelerator (below a certain speed), the engine will shut off and the vehicle will be allowed to coast until the throttle is reapplied.  This is very different from Deceleration Fuel Cut Off (DFCO) which the engines on most non-hybrid fuel injected vehicles do under similar circumstances, as the engine is disconnected from the drive train (i.e., is no linger spinning) and will not turn "on" again until the throttle is reapplied, even if the vehicle comes to a stop.

In other words, most hybrid cars do from the factory, using a computer and electronic controls, what I have modified my cars to do when I use a kill switch and the clutch pedal (i.e., "bump starting").  

Do hybrid cars not get "actual mileage"?

If I wired my car so that the engine shut off and restarting was controlled by a computer, instead of by me, would that somehow be more "legitimate"?

I ask you to ponder these questions carefully.  I would be very interested in having a thoughtful discussion about this with you all.

But with that said, I'll address some of the questions that have been raised...

________________________________________

First, the lack of power steering has been mentioned a few times now.  To me, having the engine continuously turning a pump when it's only needed less than 5% of the time doesn't make much sense.  I would think a "performance minded" person would see it the same way--it's wasted horsepower.

I will say that with the narrow, LRR tires pumped up to 44 psi, it is truly is not hard at all to steer.  My wife drives the car almost as much as I do, and she doesn't have any problems with it.  

________________________________________

Second, what has become a "hot" topic...the A/C.     I honestly, truly do understand the objections that have been raised.  Not everyone who carpools with us shares our passion for efficiency, so interior temps are a very real consideration for us, too.  It's not like we enjoy to sweat profusely, after all.

I mentioned earlier that I hope to make some sort of portable/removable electric A/C unit that I can put in the car when needed.  I also hope that some good quality window tint will help to reduce interior temps, too.  In other words, I hope that I can make the car comfortable despite the fact that the engine is off much of the time, and I think it will be doable.  I just haven't gotten there yet.

And I still maintain that for most of the USA, A/C is only needed for a few months of the year.

________________________________________

Third...the mileage without engine off coasting (if you must know).  

When the car still had the automatic and 2.56's, and pretty much everything else was the same as it is now, it would do 31-32 MPG highway pretty consistently.  Based on what my MPG gauge said then, and what it says now, the car would probably get at least 35 MPG on a pure highway trip.  It's not 46 MPG, but it's still pretty doggone impressive.

When it comes to city mileage...even if I ran a "pure city" tank without using the switch, the result would be practically meaningless.  City mileage is very dependent on driving technique, particularly with a manual transmission.

With me driving, it would probably be around 25 MPG or maybe a little more.  With someone else behind the wheel...who knows?

At any rate, it would be much better than the 15-17 MPG city these cars do in stock form.  

________________________________________

Fourth, another thought on the monetary savings.  Look at it this way: after 20,000 miles, it's like having every fill-up 50% off.  

________________________________________

Finally, something along these lines has been expressed a few times...

AzDon wrote:

Just because I don't see myself pursuing a high mpg strategy and expressing why doesn't mean that I don't respect or applaud your efforts to save some gas...... We may be a tough crowd here, but I think most of us respect your efforts to save gas and appreciate the opportunity to converse and learn a few things....

I agree, and I sincerely appreciate the discussion so far.  I learned a long time ago that not everyone sees the world the same way that I do--and I don't expect them to, either.  I have been a "lurker" on this forum for a few years now, and I've enjoyed reading the discussions from time to time.  It's nice now to be able to participate a little.

I can appreciate a well-built performance car, even though I'd never own one.  And I'm glad that you can appreciate what we've achieved with our wagon, even if you'd never in a million years do something similar.

AzDon wrote:

A lot of folks making the carbon footprint "statement" drive a Prius, Chevy Volt, or Nissan Leaf......
When the initial cost of the vehicle, cost of plug in electricity, and cost and frequency of replacement batteries is factored in, I believe that the true cost per mile is much higher for these vehicles.... Since I only buy completely depreciated vehicles in economically restorable condition, I'll probably never own a hybrid...

Agreed.  I'd never own a hybrid or electric vehicle.  They're too expensive to buy new, and too expensive to maintain and repair.

And from an environmental standpoint, I'm not convinced they're really any better.  The handling and disposal of all those depleted batteries is an ecological disaster waiting to happen. And for "plug in" vehicles, if your electricity is generated by coal-fired plants, you're just exchanging one fossil fuel for another...

Exactly, on the electric cars….You are basically driving a coal burning car in the big picture.

Again, I REALLY appreciate that this thread didn't derail and get into an argument. Its all great info we are speaking of, and it is interesting the way people look at things differently.


The next topic to consider is if removing the Cats and pollution control is worth the fuel savings? Its gonna stink up the world, but its going in the +mpg category…..

Have you ever given thought to swapping in a smaller engine, not sure what, but I'm sure something smaller could sip less fuel. Look at Fords Ecoboost, that 3.5L is easy on fuel til you spool up the turbos! (gosh I love ours, it hauls azz)

engine swap,. i think with the manual transmission a well tuned ecotec 2.2 turbo would be more than sufficient,.

Woah...just caught up on this.  Very cool.  

Random side note....I also like how you still have the factory window washer tag.  I wish someone would do a repro of that and yours would be a great example to scan since it's still flat.  Most I find are curled up and so brittle they shatter if you try and flatten them.

Sorry...random I know with all the cool MPG science magic going on here.  

 Chris

Deadmanonduty wrote:

The next topic to consider is if removing the Cats and pollution control is worth the fuel savings?  Its gonna stink up the world, but its going in the +mpg category…..

I'm not so sure that deleting the catalytic converters would help in any significant way.  In fact, it may actually make things worse.

I usually keep the engine between 700 and 1000 RPM. At that speed, "free flow" is not an issue.  The back pressure might actually help in developing torque in that range.

Deleting EGR might help if I drove "normally," but with the way I drive it probably cycles very little, if at all.  When I'm driving, I'm either accelerating under load, or the engine is off.

And I don't think deleting the AIR pump would do anything except remove a few pounds.

Deadmanonduty wrote:

Have you ever given thought to swapping in a smaller engine, not sure what, but I'm sure something smaller could sip less fuel.  Look at Fords Ecoboost, that 3.5L is easy on fuel til you spool up the turbos!  (gosh I love ours, it hauls azz)  

phantom 309 wrote:

engine swap,. i think with the manual transmission a well tuned ecotec 2.2 turbo would be more than sufficient,.

I have thought about doing an engine swap--in fact, I have a 4.3L L99 V8 (with only 40,000 miles) sitting in my shed right now.  It would bolt/plug in without any modifications.

I don't think I'm going to swap it, though.  If I didn't use the kill switch, it might make a difference, since it uses less fuel at idle.  But I never idle, and I can keep the LT1 in roughly the same BSFC range as the L99 by just shifting sooner and keeping the RPM lower.

A smaller, more modern gas engine might make some improvement, but I doubt it would be huge.  The time and expense to swap it would be considerable.  

If I do any major engine mods, it will probably be one of two things.  Either I'll convert it to run on wood gas using the LT1, or do a (bio) diesel swap.  A 6.2 would be the easiest, but one of the new 2.8L Duramax engines would be both more powerful and more efficient.  I'll have to wait a while until they're available cheaply in junkyards, though.

I don't have any plans for either option any time soon.

brokecello wrote:

Random side note....I also like how you still have the factory window washer tag.  I wish someone would do a repro of that and yours would be a great example to scan since it's still flat.  Most I find are curled up and so brittle they shatter if you try and flatten them.

I'd be happy to mail it to you if I can get it off without tearing it.  I have no use for it--as you've probably guessed by now, "collector value" is not a top priority for me.  And with it gone, the car will be .0001% lighter, for .000001% better MPG...  

Try an older Cummins. My buddy swaps the smaller versions into some cars, I forget it its a small cummins or possibly a small mercedes diesel. The cars make 50-60 mpg and they beat them and make no effort to get milage.

the smaller cummins is a 4 bt,. they are not cheap these days,.

They aren't, but these guys buy the cars up after they are scrapped or whatever and they end up with the whole car, but they rip the engine out and junk the cars. They are getting harder to find tho, I know he said that. He was planning on putting one in a newer Toyota Tacoma!

I'm curious about the about the lower side molding mods. I'd like some more specific info on what material that you bought, and how it was attached. Some close up pics with the doors open might help. For the most rear section by the tank, where/how did you attach it?

lakeffect wrote:

I'm curious about the about the lower side molding mods. I'd like some more specific info on what material that you bought, and how it was attached. Some close up pics with the doors open might help. For the most rear section by the tank, where/how did you attach it?

I can't take pictures right now--I'm away from the car and won't be home again until Saturday.

I can tell you how I made them, though.  They're constructed from plastic guttering that I bought from Lowes.  I cut off the front, curved part of the gutter, so that I was left with a long, right angle plastic piece.  I drilled holes in both the plastic piece and the bottom of the car, so that I could attach it with screws.  I then added a soft weather-sealing strip to fill the "gap" between the top of the piece and the bottom of the doors.  Finally, I painted everything black and attached it to the car.  

The pieces behind the wheel are attached the same way, except I didn't need the weather seal.  I just drilled holes and attached them to the bottom of the fender with screws.  For the rear section, I did have to use two pieces (instead of just one long piece), cut at a slight angle and then fitted together, in order to follow the contour of the rear fender.

have you done any sort of before and after tests with the kamback thingy,.?
i always thought the wagon had a particularly slippery shape,. and to my eye, the kambak thingy looks like it leaves a big hole behind the car as far as airflow ,. knowutimeen?
do you think the idea of louvers on the hood to let the pressure and heat out would make any difference?

funkhoss wrote:

brokecello wrote:

Random side note....I also like how you still have the factory window washer tag.  I wish someone would do a repro of that and yours would be a great example to scan since it's still flat.  Most I find are curled up and so brittle they shatter if you try and flatten them.

I'd be happy to mail it to you if I can get it off without tearing it.  I have no use for it--as you've probably guessed by now, "collector value" is not a top priority for me.  And with it gone, the car will be .0001% lighter, for .000001% better MPG...  

Shoo..if you are serious...I just PMd you my address! Let me know what I owe ya!

Chris

phantom 309 wrote:

Do you think the idea of louvers on the hood to let the pressure and heat out would make any difference?

How about removing the thick weatherstripping seal at the back of the hood to release the air instead of making holes?
I always thought that the seal's main purpose was more to keep oily air off the windshield and help divert it under the car instead.

A belly pan will help, too.  It'll need to be multi-piece, but it's certainly doable on these cars.

lakeffect wrote:

phantom 309 wrote:

Do you think the idea of louvers on the hood to let the pressure and heat out would make any difference?

How about removing the thick weatherstripping  seal at the back of the hood to release the air  instead of making holes?
I always thought that the seal's main purpose was more  to keep oily air off the windshield and  help divert it under the car instead.

And to keep engine fumes from getting sucked into the fresh air intake for the HVAC.  lol Not that it really helps any.

All the new eco-boxes are sealed off tight underneath. Lots ever have are deflectors to deflect air off the suspension and such.

Sorry to be slow in responding. I've been on the road away from home and had several busy days with work.

Some questions about aerodynamics...this is the part of the car that I haven't messed with for a few years now. In doing the aero mods that I've done so far, I picked ones that are known to be effective and relatively simple to do.

I have not done any back-to-back testing with the Kammback on and off. I think the easiest way to do it would be to find a hill somewhere that I can do coast down tests, A-B-A-B-A. Start at the same spot at the top of the hill each time, put it in neutral, let off the brake, and measure how far it rolls. The hard part would be finding the time to do it.

The idea with the Kammback is that it allows for more attached airflow before the airflow de-attaches and creates turbulence. I'm no aerodynamics expert, but it's a well-proven principle that has been tested and found effective numerous times by the folks on Ecomodder.com. It certainly made a big improvement on our Metro, and I tried to replicate the same shape and angles on the Caprice that I used on the Metro.

Tweaking the airflow into and through the engine compartment is something that would take a lot of trial and error to get right (and there may not be that much gain to be had anyway, at least without overheating the engine). Right now, I have the entire grill covered, and all the gaps around it and the hood/headlights sealed, so the only air that's entering the engine compartment is what comes up behind the bumper and through the radiator. I've had no problems with overheating, despite the fact that the grill is completely sealed. In fact, when it still had the automatic, the transmission almost never saw 200 degrees, even while towing 3000 lbs. in the summertime. It only got over 200 degrees when I was moving 10 mph or less and doing a lot of backing or slow maneuvering. And the engine gauge never goes beyond the "middle" of the range.

Perhaps letting some air escape from the back of the hood would help, instead of keeping everything under the car. Or, that extra pressure and flow coming out from the hood might create turbulence on top of the car that's not present now. Who knows?

I've thought about doing a belly pan from the transmission crossmember to the rear of the car, and even took measurements and bought the coroplast to do it at one point. However, I don't think it would create much improvement, given the bigger front air dam and side skirts I put on, and how low the car already sits. And I'd be concerned about heat build up, rust, and ripping it while passing over uneven ground or other obstructions. It would also make servicing more of a pain and leaks harder to detect.

The absolute best belly pan would be one that runs the entire length of the car underneath, including the engine compartment. That probably would make a significant difference--but it would almost certainly cause the engine to overheat, too.

Any thoughts on how I could put a belly pan under the engine without causing overheating?

Remember, Heat naturally rises, so forcing it out through the bottom is not natural..... Having said that, a full wraparound skirting around the engine compartment (including an air dam) and continuing back is generally believed to create a vacuum in the engine compartment that draws air through any air intakes ahead of the air dam. Directional side fender vents can also help hot air escape. The cowl area ahead of the windshield is pressurized, so not a good spot for outflow.....
As a longtime hotrodder and trucker, I've always been skeptical of add-on aerodynamics, not believing that their aerodynamic value surpasses their weight penalty. This is why I believe that aerodynamic design of the vehicle itself is important.....Every time I see a big truck going down the road with a fully-deployed box kite on the back, I wonder if there is provable fuel saving, or if that company is simply a marketing victim (sucker).

AzDon wrote:

As a longtime hotrodder and trucker, I've always been skeptical of add-on aerodynamics, not believing that their aerodynamic value surpasses their weight penalty. This is why I believe that aerodynamic design of the vehicle itself is important.....Every time I see a big truck going down the road with a fully-deployed box kite on the back, I wonder if there is provable fuel saving, or if that company is simply a marketing victim (sucker).

You should do some reading over at Ecomodder.com if you get the chance. There are lost of folks on that site who have done objective, quantified tests of aerodynamic modifications, and yes--they do make a significant, measurable difference.

With our Metro, the aero mods we did increased our mileage by at least 10-15% across the board. You can see the difference very clearly in our fillup records.

With the wagon, we did the mods soon enough after purchasing the car that we didn't have a "baseline" to compare with once the mods were done.

VWs and many imports have full or partial pans under the engines. The VW diesels in the 2000s have full pans that go back to the firewall. Try one out, it will be cheap and easy to make one out of sheet aluminum.