are the factory hp ratings for new cars based on crankshaft hp, rwhp.....what? how does a 320 hp factory ls1 rating of today compare to the factory ratings of the old school musclecars back in the day. i know they used gross hp ratings back then ( is that crank???). just wondering. if theres a thread already on here, just point it out ( i looked, couldn't find one). just trying to clear up something i've been fuzzy about. thx.

 

The LS1 F-body's are pretty much rated at the rear wheels....... Or UNderrated at the the Crank if you want to say that.....

 

they pretty much add the two together and divide by 2, 305(rw)+345(fly)=650/2=325 haha

 

To put things in perspective, a 69 Camaro with a 375 horsepower 396 puts down about 260 rwhp. The 396 was rated at "gross" horsepower instead of the "net" horspower they list today, meaning the net rating would have been more like 335.

 

I disagree, my fathers "stock at the time" 396/375 put down a little over 400rwhp and 430ish tq through a muncie 4spd

And as far as the 60+ muscle car era, they had the timing on those vehicals set at 2 degrees advanced..... thats quite a bit of power when you consider that the optimum timing is 36 degrees...

 

I find that hard to believe there'd be that big of a difference between your Dad's "stock" 396 and mine. 400 rwhp is a lot of power and most of those cars ran around 100 mph in the quarter dead stock, further reinforcing the 260 rwhp. Either your father's 396 was some kind of factory freak, or it was far from stock.

I dynoed my old 340 Dodge Demon. Car weighed 3400 race weight and the highly modified motor turned 7700 rpms (solid lifter cam and max ported X heads). Turned 118 mph in the quarter. The result on the chassis dyno? 350 rwhp. I find 400 rwhp for a "stock" 396 extremely hard to swallow, sorry.

 

Stock motor is what i meant to say :-D

 

wow, u should all know by now that factory ratings mean nothing. they are supposed to mean flywheel or pure engine output. however , for marketing, insurance, etc etc, they are not always as they say.
there are cars from the 60's that put **** power down, then others that put down way over hp ratings . this is for a couple of reasons:
1. old ****** engines
2. there is more then just a "396", they sold many configurations over the years


as for the fbodies endowed with the ls1...they didnt want to compete with the corvette so they lowered the numers. ls1

 

btw what is ls1 Z28's stock weight?

 

To answer the question;
In 72 the industry changed the rating system from SAE Gross to SAE Net Power, essentially dropping the advertised rating on any engine about 20% overnight.
SAE Gross did not include any accessories/ air cleaner or factory exhaust, headers were even used at times. To get RWHP in this case you would take into account accessory loss (20%) plus drivetrain loss (15-20%)
SAE Net basically is as the engine is installed in the car, all accessories, air cleaner and factory exhaust. This allows us to use drivetrain loss (15-20%) only when we estimate RWHP.

Hope this clears it up

 

2002=3439 lbs.