InfernalVortex

My 355 has developed a head gasket problem... Due to my situation and budget restraints (around ~$1500) and goals, the only thing that is making sense to me with my car right now is an LT1 swap. I've got a ~300hp Vortec headed flat tappet cam, 1 pc RMS 355 bolted to an LT1 T56. Im tired of the carb. I want aluminum heads to cut some weight. And the LT1 gets all of those done at the same time. Ideally I may be able to get the car down into the low 3200s with full interior this way.

This is an autocross car, so raw power is not a huge concern. From what I understand the F/Y-body LT1s make around 280hp, while the B-body LT1's make around 260. I can live with 280, but 260 is a little disappointing.

But I've got 2 concerns:

1. Since I would LIKE to put a cc503 or a hotcam in it, Im going to need to be able to tune it. From what I understand, due to the costs of tuning the OBDII LT1s, I should be looking at 94-95 LT1's. Is this the same for B-body LT1's? Is this correct? It seems like last I checked the costs were astronomical to get the tuning software for the OBDII LT1 setups. I may put this off until later and run it stock for a while, but I want to make sure Im barking up the right tree here.

2. If I go with a B-body LT1, the aluminum heads are only $200-$350ish on ebay. That would necessitate a cam change to get the power to where Im satisfied, but the B-body LT1's are everywhere around here for $500 with harness and computer. Are there any significant external differences between teh F and B body LT1s? Different years for OBDII cutoffs? Inability to work with a T56? Anything weird like that? This is a viable option to me, but it's a hassle to work with something that is less ideal to start. Just wanted to make sure it's a workable option. I do know about the baby LT1...

Anything else I should be concerneda bout?

Essentially, if you guys were going to do it, on a budget, what would you get?

This is my car:

Injuneer

The iron head B-Body engine makes less HP, but has better low end torque, due to the cam - it's designed to get the 4,000+ # mass moving. The iron heads actually flow better than the LT1 heads, but you give up some compression and ignition timing.

Doesn't matter whether the LT1 was originally in an OBD-I car or an OBD-II car. Either can be controlled by an OBD-I PCM. The knock sensor screwed into the block has to match the OBD-I PCM.

There are no external differences on OBD-I/OBD-2/B-Body/F-Body/Y-Body with regard to block/heads/intake and what trans they will bolt to. The accessory brackets and the exhaust manifolds will be different B-Body vs. F-Body vs. Y-Body. Also subtle differences in the knock sensors (as mentioned), damper hub.

Some info on various versions of the LT1. Just make sure the engine out of the B-Body is not a 265ci L99:

Rebuilding the Chevrolet LT1 Engine, Doug Anderson, Automotive Rebuilder, September 1999

InfernalVortex

Every other sensor is the same? Is the wiring harness the same as well? Is there an easy way to identify the difference between the two PCMs? Thirdgens had something like nearly a dozen different ones, so I dont know which were available or desirable with the 4th gen cars, but thankfully GM pared down the drivetrain options so I presume it should be a little easier...

Yeah I already came across a baby LT1 on craigs... Thanks for the link, that's super helpful!

Injuneer

There is one ECM for 93 (one wiring harness), one PCM for 94/95 (each has a unique wiring harness) and one PCM for 96/97 F-Bodies (one wiring harness). I don't know the distribution for the B- and Y- Bodies, but I do know that the Y-Body complicated things by incorporating OBD-1.5 into the 94.

93 F-Body controls only the engine, and the auto trans lockup. 94 and up control engine and transmission, both manual (skip shift, reverse lockout) and automatic.

I'm assuming you would want to avoid the 93 because of the fact you can't flash program the ECM (burn a new chip). There are significant differences on the 93 - speed-density (no MAF), batch fire injectors, no knock module, different IAC motor connection.

93-95 F-Body use the same single knock sensor (4 Kohm) and 96/97 use the same knock sensor (100Kohm). 96/97 added the crank position sensor (not required to run the engine, just for misfire detection) and an EVAP vacuum detection switch (not required in OBD-1.

There are different water pump configurations used on each "-Body" (F/Y/B)

A can't comment on whether every sensor is the same on every variation of the F-, B- and Y-Bodies.

Shoebox has additional info on the F-Body:

http://shbox.com/1/4th_gen_f-body_ye...onversions.pdf

http://shbox.com/1/lt1_water_pumps.jpg