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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Hi all. I am bring back to life a 91 Formula, 350 tpi, Ttop car. This car has sat for 20 years. After getting into this car I am having to rebuild the motor and trans. Car was parked because the trans went out. Good thing with this car is everything is there. I am however thinking about getting rid of the smog system as I don't have emission testing here. I also think it would make the engine bay a little cleaner.
I'm doing the same thing, although mine only sat for about 11 years.
Make sure you have someone watching the pulleys when you go to crank it for the first time, my smog pump was fully seized when I got mine started and I had to shut it off real fast. I followed https://www.thirdgen.org/serpentine/ to delete the pump and reroute the belt, but the 96.8" belt was too short for my '89 L98 and I needed a 99" belt to get the tensioner close to the stock position.
Appreciate the tip. Everything spun freely. I pulled the driver side valve cover just to make sure everything looked OK. Glad I did before firing because there is too much sludge for anyone's liking. I have never seen anything like it.
motor is now pulled and being tore down.
So questions for the experts...
-What would the best build using the stock tpi intake? How far can I take it?
-What part or parts of the egr system do I need to keep so I don't get codes?
I also Am not sure what a couple sensors are but don't have pictures right now. Will get those and post.
Just throw that away and pickup an L31 Vortec. That's hot garbage.
Keep the EGR. It helps with emissions and fuel economy. Zero reason to delete it.
You can take it as far as you want but you'll want tuning. Either get a chip from Tuned Performance (member here), get the equipment to burn chips, or get other-than-stock management. Depending on how far you want to go, you may need/want management that can do full sequential. It will allow more fuel and better economy not to mention better idle quality.
BIGGEST QUESTION to be answered - what's your budget? Next question - what's your use case? You looking for a cruiser with more or less stock power levels or are you wanting 1000 HP so you can slap down some Hellcat?
The only reason to keep that engine would be for originality. If that is not a concern, then there a many better choses in the scrap yards or a crate engine. One of the modern self tuning injection systems would make your life much simpler as well. I know you mentioned keeping the TPI but that is a huge limitation.
If it was me I would probably rebuild the L98. Great running engine when everything is right, and you wont have to mod or tune anything, everything will bolt back in place as original. And I like seeing cars original. If you want more power that is fine to go some other engine option, but keep in mind this will probably lead to the rest of the drivetrain making another dent in your pocketbook. The used third gen market is chock full of people selling their abandoned, half finished projects that got too expensive and/or complicated.
Just throw that away and pickup an L31 Vortec. That's hot garbage.
Keep the EGR. It helps with emissions and fuel economy. Zero reason to delete it.
You can take it as far as you want but you'll want tuning. Either get a chip from Tuned Performance (member here), get the equipment to burn chips, or get other-than-stock management. Depending on how far you want to go, you may need/want management that can do full sequential. It will allow more fuel and better economy not to mention better idle quality.
BIGGEST QUESTION to be answered - what's your budget? Next question - what's your use case? You looking for a cruiser with more or less stock power levels or are you wanting 1000 HP so you can slap down some Hellcat?
GD
What parts of the EGR system do I need to keep? I was hoping to get rid of the tubes on the exhaust manifold and try to clean the engine bay.
I'm mainly trying to get a little more power if I can. I understand i'll need tuning but how far will a new chip allow me to go? What info will the tuner need to get a chip burned?
I am trying to keep it as original as possible. I was reading the originality page and if I read it correctly there were 44 91 formuala 350 t-top cars built.
The AIR pipes on the manifold aren't part of the EGR system. That's smog pump air injection. Only used for the older catalysts that need their injection. Modern 3 way cats don't.
The injection system on these cars is bank fired and the computer fires all injectors at the same time. The ECU does not know or care which cylinder is firing and it does not time injection events for intake valve opening - it does not have enough information to do this with only the 8 point trigger in the distributor. It adjusts fuel and timing globally and fuel that ends up behind a closed valve just sits there and waits for the valve to open. Not exactly ideal for atomization but such is life with bank injection (as opposed to full sequential injection). None of the factory computers from this era are capable of full sequential.
If you want more power - Exhaust (headers, y-pipe), Camshaft, and Heads. With tuning of course. The emissions equipment will not detract from performance. I would, however, remove the smog pump and AIR tubes in favor of a 3 way cats. That junk is really in the way.
GD
Last edited by GeneralDisorder; Feb 15, 2021 at 07:13 PM.
