Truck Y pipe on a 93 TBI?

Hi fellas,

I've been looking around at helping out the poor TBI a bit. I'm going to keep this guy single pipe, but I'd like to smooth the airflow a bit.

Jegs sells this: http://www.jegs.com/i/JBA/578/2831SY/10002/-1?ymm=4294829834+4294829791+4294829307

Truck Y pipe for the 88-93 CK trucks. Looks like it'll flow better than the factory right turn pipes. I'll have to put a custom catalytic on there (That was in the plan anyway) but I do get a new hole to mount the wideband so that'll be nice.

So, will it pretty much bolt up or will I be better served just using the flowmaster Y collector deal and fabbing the downpipes myself?

Not looking for many ponies, just enjoying maximizing the little TBI. Damn thing runs like a sewing machine so I'm not swapping it yet!

Thanks!

Try Harris TBI Performance. A ton of great info there. He also burns custom chips as well.

That's where I got the idea for the Y pipe replacement! Made a sizeable difference after tuning for his truck.

If I get really stuck I'll call him for help, but so far the moates kit has been great for chip burning, and I've been able to tune the car to like it's new 14lb fuel regulator spring. Slowly I'm tweaking things here and there. Working on the timing tables now. Very far retarded compared to the trucks. It's liking the overall bump. Working on fuel economy now. Last trip netted 18.5-18.7 mpg highway with the 3.23 gears cruising at 70-75, so I'm fairly pleased so far!

Thanks!

Seemed like the right fuel pump was high on his list of improvements,if I remember correctly.

I did the fuel pump when I was trying to troubleshoot my starting troubles. I don't remember which one I did, but it should be able to feed this guy at 14psi. (Turned out my regulator diaphragm in the throttle body was leaking, causing hard starts)

Lots of good advice on the site. Keeps it simple.

I just gotta remember that it's not a race car. It weighs 4500lbs+, lol

Why not use the bigger 9C1 Y pipe that will bolt right on?

Are those available anywhere? I honestly had not thought to look!

I just spent the last 4 hours changing the starter on this roady. Given that GM made it so much fun to change on the 91-93 cars, I don't think I'll be putting a larger set of pipes coming down from the manifolds! Yeesh! I'm glad I changed to a gear reduction starter from the original, but it'll probably still be too big to change easily in the future.

Thanks for the advice tho!

It is not all that difficult to put duals with headers on the car, except that the automatic level would require relocation with one from a 94-96 that mounts behind the driver's side front fender, and weld a bump in the trans crossmember. You need the lines as well. I ended up needing a patch chord for the O2 sensor, but that was an easy fix. I used the pigtail from a defunct O2 sensor, and crimped it to an original connector from a JY harness. I also put a tab with a clip on a trans bolt to keep the wire away from the header. The headers will not have the port for the EGR system, so I eliminated EGR (take the vacuum hose off, and plug/cap the line). You should get about 20-25 HP.

Fred Kiehl wrote:

It is not all that difficult to put duals with headers on the car, except that the automatic level would require relocation with one from a 94-96 that mounts behind the driver's side front fender, and weld a bump in the trans crossmember. You need the lines as well. I ended up needing a patch chord for the O2 sensor, but that was an easy fix. I used the pigtail from a defunct O2 sensor, and crimped it to an original connector from a JY harness. I also put a tab with a clip on a trans bolt to keep the wire away from the header. The headers will not have the port for the EGR system, so I eliminated EGR (take the vacuum hose off, and plug/cap the line). You should get about 20-25 HP.

20-25? Sounds like a lot for an unmodified car otherwise!

I've never liked headers on street cars tho. Admittedly I've never run shorties on anything, but I've had a rash of cars with long tubes and they make everything a pain.

Damnit, now you've got me considering the shorties...

The 93 9C1 has an LO5 with the larger Y pipe, and a slightly different cam, bigger injectors, a modified computer, and it makes 25 more HP than the standard LO5. Headers and duals will do more than the Y pipe, so you could come out close to the 20-25 HP.

Just make sure you keep anything that will melt, either shielded, or wrap the headers. They can really melt things. I wrapped all my wiring, rubber lines and the oil pressure sensor within inches of the headers.

A couple of points; make sure the trans is in 1st gear when installing the left pipe, you can mount exhaust hangers at the drive shaft hoop, and the hangers for the right pipe can be used on a left pipe, including the one that sits on the cross member in front of the axle. The holes are already there, and you can just bolt them in. If you are going to the rear bumper, use heat wrap on the pipe, so you do not damage the tank.

Also pretty sure you can use an LT1 car cross member to get that notch for duals.

The Lt1 runs one pipe right next to the transmission. You must also flatten the top of the pipe along the trans. If you run the pipe as a mirror image you need to make the hump in the original crossmember. You can weld a half pipe (tapered and ends closed) on the top, cut the bottom up to the inside of the original top, then weld covers on the open ends of the tube. The bottom should be about 6-8 inches wide. The height of the piece should be tapered from about 1 1/2 inches down to about 3/4 of an inch so it does not hit the body. I used a 16-18 inch piece of another trans crossmember to make the hump. The Lt1 crossmember is substantially heavier. It also needs to be fitted with new holes in your frame rails. I believe the hump in the original TBI trans crossmember is easier, and it also weighs a lot less. It is a rectangular tube vs. two stampings spot welded together. Just remember to mark where you are going to run your second pipe.

BTW, if you got the computer from a 93 9C1, you could probably get away with running the L99 cam, with the 9C1 injectors, and duals.

My '91 sedan...the converter was plugged badly. It 'fell' off and a piece of tubing fit right in its place. Found out the factory 26 yr old muffler was badly plugged and rusty, too. Replaced that with a Thrush welded and replaced the pipe from con to muffler with a Walker piece. Car didn't have a resonator on it so I put one on from a Hellcat Charger to calm the noise in the car. These mods, along with a couple airbox mods, basic ignition tune-up and a fuel injector service (at my GM dealer workplace) netted me a best MPG of 26.5 on a trip to and from the cabin (260 miles round trip). Now, this is a sedan with 2.56 gears. Your results may vary.

The heat shield on the cat just fell off yesterday, the rest might follow soon! The resonator had that big an effect?

Wrap them with header wrap, so the cabin does not give you a hot foot.