dwhiteZ28

iTrader: (5)

Are LS1 F-body and corvette HP ratings net or gross (flywheel)? If net, I would expect the rear hp dyno values to be close to the advertised HP. That seems to be the case since if i recall correctly, most 4th Gen LS1 F-Bodies dyno stock close to 300 RHP. If net, then what would the pre-1971 equivalent flywheel HP be? Thanks.

jrp

iTrader: (16)

net but underated in the fbody.

z98

The way they used "hand-built" engines with no air cleaner, no accessories, and "tubular manifolds" for those tests, LS1's would probably have been rated 400+ back in the day

dwhiteZ28

iTrader: (5)

Then how is "net" defined, i.e. is it equivalent to dyno HP or does it carry another definition? Thanks..

Black Z/28

Net is engine dyno with all the crap hooked up, i.e., belts, accessories, etc. Gross is engine bare naked. Then there's chassis dyno...

66deuce

iTrader: (1)

i read somewhere that if you used the old gross rating the ls1 would be around 400 hp.i would say this is pretty accurate seeing how most bone stock ls1 f-bodys run around mid 13 sec. at the strip.

Black Z/28

You're right. Check out this web site where they dynoed a bunch of different Mustangs from the late 60s. It's Interesting (and funny) to see what the 'real' rwhp is on some of these 'muscle' cars.
http://www.ncinternet.net/~durham/dynoshop.html

66deuce

iTrader: (1)

yeah,the only muscle cars that i can think of that had as much or more power than the ls1 cars were big block cars.hell,even some V6 motors of today make almost as much power as some old small blocks of the 60s.

dwhiteZ28

iTrader: (5)

Thanks..but then I ran across this entry in the Camaro White Book, page 43 which reads, "Horsepower ratings changed in 1971 from gross to net (output at the rear wheels, allowing for accessory and driveline losses." Now this sounds more like dyno RWHP. What gives?

cyphur

iTrader: (10)

When most cars get their horsepower ratings from the factory, its at the flywheel. Pure and simple.

Black Z/28

No, I don't think that's right. They changed from engine without accessories (Zero load) to engine with FULL accessories and exhaust. This means all accessories (Alternator, AC, PS, etc. & full exhaust w/cats and muffler(s), etc.

John_D.

iTrader: (2)

There was a time when they rated the engines at the rear wheels... That didn't last long though, maybe 10 years.

For example, my 1978 Trans Am, with the 403 cid California engine, was rated at only 180 hp. But that thing would fly.