adreed24

I have a 1990 Trans Am GTA. When I got it from the dealership, they told me that the 5.7 liter, 350 cu. in. V8 (Tuned Port Injected) engine was the same engine that was put in the 1990 Chevy Corvette.

Is this true?

Thanks in advance!
adreed24

Abird4u2nv1

iTrader: (-1)

The same other than vette had aluminum angle plug heads.

yjischoking

iTrader: (3)

wasn't the vette 4-bolt main? f-body is 2-bolt?

Quick_Trans_Am

iTrader: (2)

Along with the aluminum heads, I believe that the Corvette also had a different cam than the L98 for the FBody.

LuBu_Z28

Is the B2L engine the same as the L98?

Abird4u2nv1

iTrader: (-1)

Correct me if I'm wrong, but I think B2L is the RPO code for the L98 engine.

sofakingdom

iTrader: (1)

B2L is not an engine. Likewise, you couldn't go to the dealer and order RPO L98.

B2L is the package that installed the L98 into one of these cars. It included the engine itself as well as other things deemed necessary or appropriate to support it; for example, an oil cooler.

The L98 in the F cars was very similar to, but not the same as, the version used in the Vette. The single biggest difference is the heads. F cars got cast-iron ones, but the Vettes got aluminum ones. The aluminum ones had smaller chambers, which give higher compression, which is necessary to obtain equivalent performance since aluminum "loses" more heat by conduction out of the cylinder. And, since the aluminum ones lack the exhaust crossover passage, the EGR was plumbed externally.

Other than that, there is very little difference. 2-bolt vs 4-bolt is a very very very minor thing, with zero effect on HP output or reliability in the application at hand (The factory's implementation of 4-bolt main caps is more suited to trucks.... although it could be argued that TPI is too.) Power output was within a few HP of the same, depending on years. The Pontiac cars always had a little less power than any of the others with TPI, because of the inferior air intake that the lower hood line required.

There is no difference between a TPI motor in a GTA and the same motor (305 or 350) in any other Firebird variant of the same year. And there's no difference between the Firebird and Camaro motors except for the air intake, AFAIK.

LuBu_Z28

Thanks for the info, I appriciate it.

MikeDwhoROCZImports

iTrader: (1)

Bringing this back from the dead...but...

What about pistons? Aren't the pistons on the Vette L98's different than those on the Camaro L98? And the cams are the same?

I have a shortblock L98 out of a Vette that I'm putting in my Camaro with factory Cast Iron thirdgen L98 heads and, in my research, noted a thread in which someone mentioned they had problems with detonation on a similar setup. Basically, they claimed that the Vette L98 bottom end with thirdgen L98 cast iron heads had such a high quench that it would detonate BAD no matter what. This was due to the vette pistons lowering the compression ratio with the larger chamber cast iron heads, as they were designed for the smaller chamber aluminum heads. Any thoughts?

SpitotRs305

pick the right head gasket will solve the quench... but that doesnt mean it wont detonate... but i dont under stand what you mean the vette L98 rotating assy. and the Fbody should be the same... they used smaller cc heads to change compression in the vette...

MikeDwhoROCZImports

iTrader: (1)

Someone mentioned that the Vette pistons are different enough that they would lower the compression by about one point (in comparison to a third-gen L98) when used with cast iron L98 heads .

I'm worried that, even using a FelPro shim metal head gasket (.015" compressed thickness...approximately the same as the factory head gasket at an estimated .016"), I'll still have too much quench AND a low CR.

SpitotRs305

okay well CC the piston head and find out measure the compression distance and rod length then determine how many cc's they add to combustion chamber if you need to replace them hypers can be had for $11 a piece...

89RsPower!

Not all L98 vette's came with aluminum heads, my 86 came with cast iron heads, KB2- CAST IRON CYLINDER HEADS and L98- 85-91 STANDARD ENGINE, 350 250HP TUNED PORT INJECTED as per my rpo list.. I think sometime in 86 they switched over to aluminum heads.. not positive.. if anyone knows for sure I'd love to know!

rel3rd

iTrader: (1)

You are correct. Not sure of the time frame, but early production 1986 Corvettes had iron heads, later year production models had aluminum ones. Supposedly, the first aluminum ones weren't all that great fwiw...

MikeDwhoROCZImports

iTrader: (1)

Yeah, but I'm not planning on ripping apart the bottom end, and I can't use anything but stock pistons for the auto-x class I'm running in. I'm just wondering if Vette "stock" is the same as Camaro "stock". I guess I could go to a chevy dealership and try to cross-reference part numbers...