Replacement options for 305 engine?

Ok, I finally got most of the issues with the current 305 engine in my 1991 Roadmaster figured out.
But it is kinda slow and drinks gas like crazy. I know that eventually the engine will need to be replaced. I really do not want to drop in another 305.

I know the 350 is slightly better in terms of gas consumption and has quite a bit more power. I am wondering what else would fit? I really do not want to make any major modifications to the frame since I do not really have those skills (yet?).

I am mainly looking for some ideas as to what I could swap in once the current engine needs the next round of major work. Or maybe some options for easy upgrades to get a bit more power/better mpg out of the 305. Although considering the 200k on the current engine that might not be the best way to go.

A TBI 350 is a very easy drop in and no wiring changes.Change the PCM and thats it.Can use
your existing TBI by swapping the injectors with the ones in the 350.
Jim

s1l1sc wrote:

Ok, I finally got most of the issues with the current 305 engine in my 1991 Roadmaster figured out.
But it is kinda slow and drinks gas like crazy. I know that eventually the engine will need to be replaced. I really do not want to drop in another 305

Well a TBI owner thats aware of their antiquated inefficient engine,.and is willing to pursue other options, how refreshing.
The possibilities are endless,. a huge thread could develop here, probably not from the tbi crowd as they tend to cling to their tbi's like linus blankets,and are very sensitive about their lack of horsepower etc,
The LS series engines are getting very popular, a nice mild cammed 4.8/5.3 and 4l60/4l80e inho would be the best option probably could be achieved for 2000-2500. I would bypass the LT series engines, they are far superior to TBI but are inferior to LS engines and i,m not insecure or overly sensitive or sentimental to cling to the LT engines.
Outside the box options are always fun,.
4.3 turbo has been done, mileage and power too,
There's enough room for a 4bt swap,.not the fast way, but definitely good for 30mpg
The turbo 4 cyl ecotec motors are making awesome power and would certainly raise a few eyebrows under the hood of a big wagon,.

Questions that need to be answered tho,.

Whats your budget?
How are your mechanical skills,.
Are you willing to invest the money in your car.

Day dreams are still free,..


Nick

This is 1-2 years off, I just spent 3k to get everything fixed. (yeah, should have known better...)

Budget wise I am thinking 2-5k, possibly not on the current car. I have seen rolling shells for $750 where someone pulled the LT1 for other uses and is selling the rolling wagon shell cause they don't need it. Most recent one i saw was for a 1994 model.

Mechanical Skills are mediocre. As long as I do not need to fabricate metal or weld I can probably do it though.

I am always keeping my eyes open for other options - if gas spikes again I might pick up an unwanted LT1 for cheap ;-)

if you have a tbi engine your an idiot.

seriously though i wouldn't bother looking for upgrades for your high mileage 305. not really worth the money or time, most 305s don't yield great performance results. I'm in the same boat with my 200k tbi 350;its still running just fine and as much as I'd like to, i don't think mods would be a great thing to do to such an engine.

easiest swap to do would be to stick with a tbi like jim mentioned. i have heard an LT1 swap isn't exactly easy as far as the wiring goes. i could be wrong. I've seen complete LT1 engines for sale near me for around 1000 bucks including the trans, wiring harness and PCM. i would assume a complete setup like that wouldn't be to big of a deal to swap in.

I believe to fit a LT1 engine into a '91-'93 model you have to cut the frame to make things fit... Which pretty much eliminates that option in my mind.

Yeah, I ended up fixing a little oil leak here, a worn out part there, sensors, seals, etc, etc - next thing I know I had spend 3k to get the engine fixed... Not really the smartest move on my part. On the other hand this was over 6 months with new issues showing up each time something else had been fixed.

s1l1sc wrote:

I believe to fit a LT1 engine into a '91-'93 model you have to cut the frame to make things fit... Which pretty much eliminates that option in my mind.

Yeah, I ended up fixing a little oil leak here, a worn out part there, sensors, seals, etc, etc - next thing I know I had spend 3k to get the engine fixed... Not really the smartest move on my part. On the other hand this was over 6 months with new issues showing up each time something else had been fixed.

that idiot remark wasn't towards you or anyone else btw. thats just me joking/ being an idiot lol

really though?! i had no idea about frame modifications to fit an lt1 into a pre lt1 car... that pretty much crosses that one off the list for me aswell. what about a vortec 350 out of a later '90s truck? those things make good power and likely better mpg then your our tbi's

No worries... Still feel a bit like an idiot for buying that car - should have waited a bit for a nicer one. Oh well, when wagon fever strikes... :-)

s1l1sc wrote:

I believe to fit a LT1 engine into a '91-'93 model you have to cut the frame to make things fit... Which pretty much eliminates that option in my mind

Is there something in the water????

um,. just exactly what needs to be cut to fit the LT1 to the 91-93 frame?? I,d like to know about this as i have a 92 based car thats sopposedly getting a swap sometime.

Nick

Just what I remember from my research - let me find the link

here is one source:
"Crossmember and exhaust are easy, it's the notching of the frame for the A/C compressor and all of the wiring that makes it difficult."
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The LQ4 or LQ9 is the engine of choice for swaps at this time. If you get one from a truck with the complete FEAD and transmission, the only mod to install the engine is the AC bracket, adapter engine mounts, trans crossmember, electric fans, and wiring mods for speedo, etc. You use the engine harness, computer, and reprogram for gearing and tire size. Look in the ISSF, engine performance, LS swap basics. You can even cam the engine before installation, but it would require reprogramming the computer for the cam. The LQ4 is a low compression LQ9, and uses regular gas. The LQ9 uses premium gas. Both of them are 6.0 liters.

After 05 I think they came with aluminum heads, prior they are iron engines.

You can find the LQ9 in 02-07 Escalades, Sierras, and Silverados. 347hp 380lb/ft

I do not know which trucks have the LQ4, but it has 300 - 325hp 360 – 370lb/ft.

Either of them would be a good boost in HP, and make a nice mod.

I am driving my LO5 until I get the cash to do the LQ9 swap with a cam. I would consider the LQ4 if the price was right.

Fred,I believe the 07 to 11 LQ-9 caddy engine has 403 horsepower and 380 lb feet of torque.
Both of these engines have very conservative ratings and almost aways dyno with considerably
higher horsepower/torque.I am holding out for a below 100,000 mile aluminum head LQ9 and
hopefully a matching transmission.
Jim

The 07-09 is an L92 and is a 6.2 liter with VVT.

being a tbi owner theres always room for improvements,but theres always one thing that holds me back is the fk'n emissions,here they check to make sure the lite come on/ off etc or if its on all the time dont bother to bring it in, over the years to it seems they tighten up on the numbers ,i bet its to try to get rid of the old stuff off the streets, plus here they up'd the exempt sticker from 20 to 25 yrs old on the cars b4 u can get one,my girls made it 20 yrs so far, ive made it 20 more yrs older, i have no problem they'll make it another 5 yrs and beyond but ill be in my 60's,would i feel like doing something like that then?and everything thats newish now and available now by then will be beat to death and hard to find maybe.. i guess time will tell,lets see if we make it pass dec 12 lol and if obama hasnt completely put this country in the toilet etc, hell lets see if we even have jobs by then...
for now tbi's work fine for me,if need be just upgrade to a 350 and call it a day...being a old school gear head ,hate thinking that way

Well said Wayne although Obama is a much bigger threat than Dec12th is.Nothing wwrong with a
good running TBI but I still want a LS conversion down the road someday.
Jim

Flasheroo wrote:

Well said Wayne although Obama is a much bigger threat than Dec12th is.Nothing wwrong with a
good running TBI but I still want a LS conversion down the road someday.
Jim

+2 I am dying to get ahold of a LQ/LS set up for the wagon. That and back it up with a 4L80E. Thing would be a TOWMONSTER

Thanks guys, this gives me a few ideas.
How many of these conversions have been done? Mainly LQ4 / LQ9?

Also, has anyone done a diesel swap? Would love to do that along with a larger fuel tank for a real road trip monster, but thinking the coast might be a bit much.

s1l1sc wrote:

Thanks guys, this gives me a few ideas.
How many of these conversions have been done? Mainly LQ4 / LQ9?

Also, has anyone done a diesel swap? Would love to do that along with a larger fuel tank for a real road trip monster, but thinking the coast might be a bit much.

convert to diesel in 3...2...1,..

Sven, a member (Convert 2 Diesel) up north has done a couple of conversions on our wagons.
Once he hears diesel he will be here quickly and ready to talk diesel with you.A twin turbo
DuraMax would be my pick just for the bottomless pit of torque.
Jim

If you go to diesel, you need the GM9 2.56 rear. It will use the torque better, and give you good speed on the highway.

s1l1sc wrote:

Thanks guys, this gives me a few ideas.
How many of these conversions have been done? Mainly LQ4 / LQ9?

Also, has anyone done a diesel swap? Would love to do that along with a larger fuel tank for a real road trip monster, but thinking the coast might be a bit much.

The conversion cost can be as little as 3 grand, using J/Y bits or as high as 5 or 6 if you do it properly. I did a write up on the conversion back a couple of years ago that you might find helpful:

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Did a step by step on that other board but it would appear that it was a victim of the crash. PM me if you want more information. Sure the guys here are tired of listening to me on the topic of diesels

"If you go to diesel, you need the GM9 2.56 rear. It will use the torque better, and give you good speed on the highway."

Fred:

Actually the 3.23 (tow pack gears) are more closely matched to the torque curve of these engines. The 6.2/6.5 engines really don't like anything below about 1,600 RPMs. My best mileage figures were at 65MPH with the engine turning about 1,850. With the 2.56s, you'd have to be traveling over 80 MPH to hit that figure.

Bill

Bill whats your fuel mileage on a trip like?Bet its a lot of fun with all that grunt!
Jim

Ok, Thanks bill, I'll take a look.

Flasheroo wrote:

Bill whats your fuel mileage on a trip like?Bet its a lot of fun with all that grunt!
Jim

Jim:

In US gals, the best I ever achieved was 35 MPG (41 MPG IMP). That was with summer fuel and at a steady speed of 65 MPH. Made some mods to help with towing and lost about 2 MPG. Would consistantly get 33 MPG (38 MPG IMP) after the mods in the summer. In winter they lace the fuel with kerosine and by the middle of February I would lose another 2 MPG.

Performance wise it was great between 1,600 and 2,200 RPMS. Below and above that the torque fell off pretty abruptly. The engines are governed for 3,500 RPMS but overall performance was between an L05 and a LT1. A puffer really helps smooth out that torque curve on these engines but never could find the room for one under the hood.

Bill

Is it the new duramax that has the turbo mounted in the V/between the heads?What about the
possibility of a turbo installed behind the axle like STS is doing on gas engines?With a turbo there would be quite a boost in performance and mileage?
Jim

The Dmax will work. Have done all the dimensions. Actually works better than the 6.5. Issue is one would have to go with a 4l80/6L80 instead of the Alison. Just no room for the Ally. With the torque of the Dmax, you had better have a good tranny guy.

The van version of the 6.5 turbo had the center mount puffer but the down pipe is a problem. This was also used in the Hummer and is the standard configuration used by American General for their 6500 "Optimizer". If I do another one, this is the configuration I would go with. Think I have the downpipe problem licked but would have to get into the job to be sure. Would actually save the dual exhaust.

Have resigned myself to getting a Lux truck to haul the trailer and use the Caddy as my daily. If I do it, my main design consideration will be for highway mileage, with abilty to occassionally haul the RV short distances if need be. Thus the 6.5. No need for 600HP and 500 ft. lbs. of torque, just to drive at 70 MPH on the freeway. The Dmax would be cool but really can't justify the extra 4 or 5 grand just to say I had a Dmax in a Cadillac. My name ain't Obama.

Regardless, unless the price of diesel starts getting reasonable again, the LT1 will do just fine for now. Would take almost 200,000 miles to justify even the 6.5.

Bill

As little as I drive now I would never recover the conversion cost.Getting 35 mpg in one of these
wagons would be incredible.Having 500 to 600 pound feet of torque just off idle would indeed
make my transmission guy a very happy fellow too.
Jim

I would love the DMax conversion... maybe if the engine could be found at a reasonable price? Pull it from something smacked hard in the back?

I am planning on converting my wagon into a road trip vehicle - thinking of adding a winch, police bull bars and pop-up tent/camper top. Mainly for vacation trips (camping) and some off-road duty for garvel roads and such where I want the front protected from branches and bushes.

I am also planning on using the car for ski trips, so the winch should help if I do get it stuck.

It will also be used as a tow car, so the extra torque should be good for that.

The car is too rough in my mind to spend the money required to make it a nice daily driver, so I am looking for another one in better shape. But as a road trip vehicle/equipement hauler it should work well.

Sven,there are much better choices out there for what you want to accomplish.Maybe a retired
military ambulance would be easier to convert and be a better ski trip vehicle too.Drive to the
slopes and sleep in your camper instead of paying the rediculous rates they charge.Dont know if
its even allowed.Sure would be neat to see one of our wagons converted into something like
what you are talking about.
Jim

Jim,

I have the wagon, might as well work with it :-)

What I have in mind for the roof tent is similar to this:
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There are larger versions as well that fold up on both sides for a larger space:
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I am not 100% sure which route to go yet, but with the space in front of the vista roof the larger one should fit.

This should prove an interesting project.Only way I am sleeping up there is if they come with a
little elevator to carry my big butt up there.I was thinking with the right tires and the winch
you could do some light offroading as long as its dry.Use to camp that way all the time when I
was much younger.Even tryed motorcycle camping once,just once.Take plenty of pics please!
Jim

Assuming I find the time and money for it soon - for right now I am pretty much just kicking the tires...