Speedmonster185

iTrader: (1)

Ok, I have a quick question I've been curious about for a while. I know the F-body's were underrated with the ls1 and actually made the same power as the 'vette, so was it the same way with the LT1s? Were they actually 300bhp like the 'vettes and just advertised lower by GM, or were they really restricted somehow?

Thanks for easing my curiosity

infinitebird

iTrader: (11)

yes, the LT1 was underrated similar, about 300 fwhp is correct.

96lt1m6

iTrader: (31)

the difference as i see it is the air intake and the dual exhaust!

sweet-94z28

iTrader: (30)

I would say the exhaust is the huge difference. My car runs better than my dad's vette ever since I got the chambered straight pipes.

gatorhead

iTrader: (4)

They were detuned and restricted due to intake and exhaust.

Speedmonster185

iTrader: (1)

So really f-bodies would stand to gain a lot more with bolt-ons than the corvettes it sounds like.

bigbadblack93z

iTrader: (8)

They are just restricted. a 52 mm TB, hypertech and k&n cai I put down 251 with 120k miles on an otherwise bonestock car.

1994Z28Lt1

iTrader: (1)

my car is an M6 and i had it dynoed when it was bonestock before i did any mods to it and the dyno sheet is in my sig it put down almost 271 hp and 314 ft lbs tq on a dynojet and those numbers are SAE corrected as well

with an m6 numbers for driveline loss are usually in the 13-15 percent range so that would have put my stock engine at just a bit over 310 hp, underrated? very much so

CaribooLou

iTrader: (1)

Lt1 For Life^^^^

tspence45

iTrader: (30)

Not too shabby considering our cars are rated at 275hp and 325lbft at the crank. I want to get my car dynoed sometime after I get some LT's, true duals, and a mail-order tune, to see what I can put down. The community college I'll start going to next fall for automotive classes has a dyno, so hopefully I'll be able to do it sometime.

99.9percenter

iTrader: (2)

Nope!!! 275 flywheel with the f-body single cat y-pipe. It was the same engine as the Vette but with the f-body single cat y-pipe and s-10 air box 275 hp (I had the factory dyno sheet in my hands).

Speedmonster185

iTrader: (1)

Sounds like nobody agrees

infinitebird

iTrader: (11)

You are sorely mistaken. Please do basic research before making these kinds of uninformed statements.

275 flywheel is what GM rated the LT1 in the f-body. That is NOT accurate, considering that most stock autos dyno 250-260 rear wheel and most manuals 260-270. Doing basic math with a reasonable drivetrain loss percentage you can easily conclude that 275 flywheel is a substantial underrating.

This has been gone over so many times on this forum. Please do a search.

slippinsideways

when i had my car baslined it was 298 hp to the wheels and 325ish ftlbs to the wheels
only thing it had was an intake and exhaust...

so underated i would say!

gatorhead

iTrader: (4)

If I may add something here that might make a difference...........
The two of us could build identical motors using identical parts and they would not dyno the same, so with that in mind 200k plus assembly line based cars would fall into the same category. Ther are the ones referred to as factory freaks, but that too is just one or two out of thousands in that particular lot.
The difference between the years could aslo be attributed to the fact that one had a single cat and the other dual, and the dual outflowed the single. Depending on the year you would see a relavant factory rating in most cars, but not all, same as an advertised 400hp crate motor some are well over some just under.
I am not arguing just stating this. I also am partners in a speed shop and we have a mustang dyno and the average, rather what I would use to baseline auto LT1's in 240 rwhp, and manual 260rwhp.
Changing any component and reflashing the pcm will give you a standard 300fwhp same as a vette which came with the optimum tuning package and free flowing exhaust and intake. You wouldn't want a 20k car selling next to a 50k car with the same advertised numbers and thats why they do it.
Back in the heydays they did it to conform to insurance regulations, and a recent episode on American Muscle cars dynoed the engines as they were. I believe the engines were the chevy 409, hemi(BIG ONE), Ford 427 and a few others. The hemi dymoed 800hp.......and was advertised at 450 now THAT IS UNDERATED!
Again folks it is bench racing, not a life or death thing and there are many published articles that support both claims as mentioned above, just thought I would give my take on it.

1994Z28Lt1

iTrader: (1)

This has already been disputed and its been deduced that the hemi that supposedly dynoed 820 hp was heavily modified, according to the testing it put down 820 hp at 6400 rpm, this is completely bogus because it would take more than 100% volumetric efficiency to produce those numbers at such a low rpm

and when you think back and consider how close vehicles like the 1970 ls-6 chevelle 454 rated at 450hp (considered closer to 550) and the Buick stage I rated at 360 hp (probably closer to 550 since it ran right with the LS-6. both of these cars ran right with the hemi's at the time which definitely makes you question the validity of a supposed stock 426 hemi putting down 820 hp

1994Z28Lt1

iTrader: (1)

check out this website and take a look at what the 1970 hemi cuda trapped in the quarter mile and how close it is with the ls-6 and buick stage I and these 820 horse hemi's idea can be put to rest

http://www.musclecarclub.com/musclec...s-50fast.shtml

StealthFormula

iTrader: (35)

^^I heard something about that 820hp 426 Hemi from a friend, talk about BS being stock. I heard they were more like 500-550hp motors from a Hemi guru.

zigroid

iTrader: (22)

I heard of a hemi cuda dynoing 330-340 rwhp stock through a 4 speed manual.

gatorhead

iTrader: (4)

I watched the episode and spit my drink up when the numbers came in.....I thought the Ford 427 was high too at 600 + hp........
Both moot points as I was just stating that those were truly underated as compared to a 20 to 30 hp underating found today. Back then it was for insurance, today it is emissions.