New Engin HP?
Thread Starter
Heel & Toe
Joined: Apr 2008
Posts: 19
Likes: 0
New Engin HP?
Hello everyone I have a 1976 engine that I recently swapped into a 1975 I know that the 76 engine originally has 180 hp @ 4000 and torque 270 @ 2,400 but I have added a somewhat heaver cam with new rocker rollers a Edelbrock high-rise manifold and Carb, Hooker headers and 2 1/2" exhaust and a few other small things such as a clutch fan. I am going to put it on the DYNO in a month or so but I was wondering if anyone had any kind of estimate to what I can expect number wise.
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
Only if it's a red vette! 
I'd be guessing less than that...... on a chassis dyno I figure the '76 model's 180 hp would be putting ~125 neddies at the rear wheels
on a good day.
Given that the heads on this buildup don't appear to be modded, the gains from cam and manifold and carb alone won't be that dramatic.
Some cam specs would make it clearer to see what may occur.
I figure if he gains 50 real horses from the engine mods, he should be happy. So I'd say 175 rear wheel horses on the chassis dyno.
But if it's a red vette, it would of course, be much higher
I'd be guessing less than that...... on a chassis dyno I figure the '76 model's 180 hp would be putting ~125 neddies at the rear wheels
on a good day.Given that the heads on this buildup don't appear to be modded, the gains from cam and manifold and carb alone won't be that dramatic.
Some cam specs would make it clearer to see what may occur.
I figure if he gains 50 real horses from the engine mods, he should be happy. So I'd say 175 rear wheel horses on the chassis dyno.
But if it's a red vette, it would of course, be much higher
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Burning Brakes
Joined: Aug 2006
Posts: 1,155
Likes: 0
From: San Diego California
GM has never advertized rear wheel HP- its not good for marketing cause the numbers look too low. The 180 HP was SAE net- measured at the crank with accessories. This method applies to all cars, 1972 and later.
Burning Brakes
Joined: Aug 2006
Posts: 1,155
Likes: 0
From: San Diego California
My guess is just 200- 210 net HP, especially since you didn't swap out the 76cc smog heads. Do you have a true dual 2 1/2" exhaust from the new headers? What are the new cam specs?
Thread Starter
Heel & Toe
Joined: Apr 2008
Posts: 19
Likes: 0
Yes i have 2 1/2" true duel from the headers. I am not to sure on what the Cam stats are. I will be puting the car on the DYNO in a couple days I will post the numbers with a more deitaled discription of everything that I did to her
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
My rear wheel hp in my '80 L48 was 165 and that was after a rebuild that included flat-top pistons with valve reliefs and Crane Energizer cam (216/216 @ .050") but before I added headers, Lars-rebuilt carb, DART heads, true duals, h-pipe, 700R4, new diff/gears, etc. Tuner woke the engine up with a good recurve (including an adjustable vacuum advance unit) and found close to 40 rear wheel horsepower that was hidden with the wimpy OEM ignition curve. Be sure to make this tuning adjustment. After all of my mods, I have 225rwhp and 289rwtq. My ignition curve is pretty spirited, I'm 'all in' by about 2500rpm with about 36degrees total. Makes for a fun ride. 
P.S. I could probably find a little more hp with good roller rockers and roller cam/lifters... those are down the road with the next rebuild. Last rebuild was in 1999.
P.S. I could probably find a little more hp with good roller rockers and roller cam/lifters... those are down the road with the next rebuild. Last rebuild was in 1999.