IROC_385Z

Anybody remember if the 230hp/330tq rating is at the motor or the wheels? If it is at the wheels, does anybody know the actual motor HP/TQ?

DJP87Z28

No factory HP/TQ numbers are at the rearwheels, only the Flywheel numbers are stated. What year engine is in question??

IROC_385Z

I have an 88 that used to have TPI...i since have build a 385 carbed motor and was just wondering because desktop dyno predicted 474 lb/ft at the flywheel and that got me wondering about my factory motor.

Thanks for the response!!!

BTW....I could have sworn that i had read that all HP numbers since mid-70s were at the wheels...huh.

Morley

Close, but no. Since the mid 70's all HP numbers are "Net HP" vs the old "Gross HP" that was used before.

IROC_385Z

So then what is net vs gross?

Morley

Gross HP is what the factory was able to coax out of the engines using open exhausts, headers, non factory timing...
Net HP is what the engine puts out as it will sit in the car.

IROC_385Z

Got it...gross is like the engines potential where net is the more honest version.

Morley

Yep, you got it. But, in the late 60's early 70's they were known to lie in the other direction too, Pontiac's R/A IV was a good example.

Verviticas

Untrue, 4th gen ls1's are rated rwhp, which makes them even faster then the number would let on.

possible reasons for this, include, to make the corvette seem faster (Sometimes even rated at 350hp), less hp yet faster car is more impressive (more efficient drivetrain), or because gm wanted to appear to be a more "honest" company.

DJP87Z28

Where in the world did you come up with that dumb statement??

Morley

Untrue, no U.S. car mfg uses RWHP, all flywheel.

Verviticas

its been discussed even on this very forum, do a search, ls1 rwhp. plus i have my buddies 2k2 ls1 camaro ss dyno sheets to prove it. completely stock, 2nd day he had it, it put down 312 hp with potenza so2's (he changed the tires the day he bought the car).

i dont care if you guys believe me beacuse ive seen it with my own eyes. ill post a link to some site or posts that mention this, wont take me more then 5 mins.

Verviticas

Here

and here

and here


i got a few ls1 swapping sites, (for swapping ls1's into 3rd gens), usually they'll tell you the benifits, or have some sort of page telling you what its an advantage to have an ls1, almost ALL mention they are rated rwhp most of the time, and are actually producing over 340 flywheel.

seach for yourselves. if u still dont believe me ill mail you a copy of the dyno chart. just email me ur addy in a self addressed stamped evalope. i'de be happy to prove you wrong. :lala:

DJP87Z28

Now where in the original question is the mention of LS1???
The relpy was "all US Mfgs rate Horsepower at the flywheel", which is correct. Now you thrown in the numbers for the LS1 claiming RWHP with your friends & buddies 4th gen cars which may or may not be BS. Again GM and I say again GM RATE the HP at the flywheel and not by the results your so called friends get in their testing. LS1 are another subject of conjecture.

IROC_385Z

Lol, yea...it was hard to tell if anybody answered my question or not

Thanks guys!

Abubaca

iTrader: (3)

Well, I don't know any hard policy info one way or another. I'm not saying who does what for what motor.

What I do know is that I've seen two LS1 cars put down 300 (approx) RWHP.

Could the factory rating be a VERY low flywheel HP #? Sure, but I've seen the results with my own two eyes. That very dyno day has made me wonder as to how the factory rated HP as well.

XSVortex

iTrader: (1)

I know GM has historically shown lower horsepower numbers to make insurance costs cheaper to the consumer, thus being more desirable. the '67 l88 vette is a good example. This may have been behind the LS1 4th gen's, explaining the higher rear-wheel horsepower than the "factory" flywheel numbers would lead you to believe. I dont know if this is the case, but it could be.

Black 91 Z28

GM and every other car company rates thier cars at the flywheel. Period. That's how it's done. The LS1 are rated at the flywheel too but the rating is BS. They underrate them for some reason...probably for insurance or so the vette owners feel more secure. If there is any doubt about where it is rated go to a dealer and ask.


For further proof I'll offer up my car. Its faster than when I bought it and I've dynoed it. The results and mods are in my sig. Now if the factory ratings were at the wheels then my mods would have only taken power from me. If the factory rates the power at the flywheel my car would have had 196 hp and 276 tq at the rear wheels. Thus my mods would have made me more power as is illustrated.

-David

ericmac450

I'm with David on this one LS1's are just under rated from the factory.

Hell my 99 Z28 with a lid and cutout put down 318hp/ 331 tq.



But yes, they ARE RATED AT THE FLYWHEEL. In my 1999 Camaro Broucher (sp?) it gives the Z28 a rating of 305hp and 320ft*lbs.

wanarace

This is why I buy GM. I'll take a company that under rates their cars anyday, over a blue oval company that has to issue a recall for lack of power.

The LS1 is not the only under rated motor. GM was pretty conservative with the LT1 rating as well. Anybody here ever drive a Impala SS and the Mercury Maurader? The Merc has 40+ hp on the the Impala. But the Impala is quite a bit faster.

Funny thing is the Camaro probably has the 2 most underated motors in history. GM rated the 302 in the Z's at 290hp, when it's probably closer to 380hp. The ZL1's were rated somewhere around 425~hp and make closer to 600hp.

Guest

This comes up so many times, and then you have those that insist the ratings are RWHP. SAE net. Go look up SAE, and then look up where HP and net gets involved and there you will find out how they actually do the testing, rather than making guesses based on a number you read on a sheet of paper.