Horse Power Question?
Drifting
Joined: Jun 2000
Posts: 1,476
Likes: 1
From: Mt Juliet TN
Re: Horse Power Question? (1bad69)
I'd be willing to bet its more then 15 to 20%. From what I've been told they had no accessories hooked up when they did the tests back then. A modern car has a 15 to 20% loss but they have the accessories hooked up when they measure them at the crank.
Melting Slicks
Joined: Feb 2002
Posts: 2,298
Likes: 1
From: Sodertalje/Sweden
Re: Horse Power Question? (TTop Tony)
I'd be willing to bet its more then 15 to 20%. From what I've been told they had no accessories hooked up when they did the tests back then. A modern car has a 15 to 20% loss but they have the accessories hooked up when they measure them at the crank.
Drifting
Joined: Jun 2000
Posts: 1,476
Likes: 1
From: Mt Juliet TN
Re: Horse Power Question? (BB wowbagger)
It seems like someone told my they started in 71 or 72. From what I remember the LT1 went from 370 hp to 320 (or was it 320 to 270) from one year to another without a change in the engine. Just a change in the way they measure it.
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Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Re: Horse Power Question? (Steve Adkins)
No way sto*k.
Gross to net ratings in 72.
71 LT-1 330 Gross 72 255 NET
Another ex. you may not be able to find! Have posted before.
425 Gross 325 Net
:cool:
Gross to net ratings in 72.
71 LT-1 330 Gross 72 255 NET
Another ex. you may not be able to find! Have posted before.
425 Gross 325 Net
:cool:
Burning Brakes
Joined: Oct 1999
Posts: 1,041
Likes: 1
Re: Horse Power Question? (Steve Adkins)
Yes, in 1972, there was a change Gross vs. Net. In addition, in 1972 GM lowered the compression ratio of all of its vehicles to run on lower octane fuel.
For instance, a 1969 427/435hp car was only 435 horsepower running on an engine dyno pulling absolutely nothing except the crank, cam, rods, rockers and pistons. In 1972, they lowered the compression then rated the engines while pulling the alternator, pumps etc. In addition, the horsepower ratings were slightly lowered on some cars to lower the cost of insurance. While I can't say I've ever seen a stock '72 on a dyno, there's a chance that some of the higher horsepower option cars were slightly underrated.
On modern C5s, where stock horsepower rating has been 350 for many years, the average stock dyno pull usually falls between 295-310 rear-wheel horsepower. 6 speed cars tend to pull higher numbers than the power-sapping automatic.
Sam
For instance, a 1969 427/435hp car was only 435 horsepower running on an engine dyno pulling absolutely nothing except the crank, cam, rods, rockers and pistons. In 1972, they lowered the compression then rated the engines while pulling the alternator, pumps etc. In addition, the horsepower ratings were slightly lowered on some cars to lower the cost of insurance. While I can't say I've ever seen a stock '72 on a dyno, there's a chance that some of the higher horsepower option cars were slightly underrated.
On modern C5s, where stock horsepower rating has been 350 for many years, the average stock dyno pull usually falls between 295-310 rear-wheel horsepower. 6 speed cars tend to pull higher numbers than the power-sapping automatic.
Sam
