the LT1 vettes are rated at 15-25 more horsepower than the lt1 fbodies because of a larger airbox/filter, bigger MAF, intake elbows, headers and mufflers. (maybe slightly bigger TB but im not sure) that is all, besides that nothing is different, same exact engine!!! i love pulling up to an extremley cocky lt1 vette driver and giving him a REAL run for his $$$ !


and a question about the dual cats on the 96-97's
- why in gods name would ADDING a cat increase horsepower? are they two higher flowing cats???

 

if all they had was that... than you could take a vette maf (bigger??) and plug it right into your fbody and it should work better than the stock one right?

 

Nope. That's the only diff. It's the same car except for the fact that its the 30th anny model lolol.

 

The difference in the hp rating was due to the less restrictive y-pipe produced for OBD2 requirements in '96. There may have been a different head casting number for some vehicles those years, but I don't believe the cars were rated by taking that difference into account.

 

All '96 and '97 cars DO have different head castings and they do flow slightly better than '93-'95 castings. However, I believe GM rated the cars 10 hp higher was due to the less restrictive design of the dual-cat y-pipe. '96 and '97 cars also have slightly different cam specs...but then again, so does every year of LT1 f-bodies.

 

so your saying all 96 and 97 lt1's got the 571 casting?

 

Where's the casting number on the heads? If it's fairly visible I'll look at my '96 and see what casting it is using. Of course, my luck says the casting number is under the valve cover, right?

 

TB was the same on LT1 vettes, as well as the MAF. The differences were:
larger airbox w/straight air intake path
MUCH better exhaust manifolds, almost as good as shorty headers
true dual exhaust

 

'96 and '97s have 561 castings.