350 tbi -vs- lt1

[gaboi68]

Hello, AF pros...i just have one question..I have a 91 9ci with a stock 350. what immediate mods will i need to make it out do or come close to the HP of a of that monster(LT1)

[kdrolt]

LT1 in a Bcar was rated at 260 fwhp during 1994-1996. The LO5 in your 91 was rated at 195 fwhp. You can get to 215-220 fwhp by doing CAI and a good exhaust (either duals or improved big single) and keeping the stock tune in the ECM chip. Retuning the ECM would gain a little more from the combination, say 230-235 fwhp depending on the skill of the tuner. And all of this assumes the stock engine in your 91 is in good shape and still puts out 195 fwhp @ 4500 rpm during WOT.

To go the next +40 hp beyond the above you will need a bigger cam, an LT1 fuel pump (plug-n-play), and revised ECM tuning.

OR you could get away with keeping the stock 9C1 cam, and using L31 Vortec heads and a compatible Vortec intake manifold and get to the same power level, but you would still need the fuel pump swap and the ECM chip retune.

Let me warn you now that ECM retuning is the largest obstacle in getting a TBI engine to make LT1 power. It's not that hard to do but there is a learning curve involved. And a lot of reading here:

http://www.thirdgen.org/techboard/diy-prom/

The other option is to remove the LO5 and swap-in an LT1 drivetrain + PCM. Several people have done it.

None of the above paths are really that easy.

The easiest alternative path might be to disconnect/remove the TBI and replace it with a carb. The go with carb, duals, cam, headers etc..... and you can get all the power your wallet can stand, while at the same time losing all the manners of a well-tuned and fairly economical TBI/EFI engine.