HP guestimate from the past, whats your guess? - Pontiac GTO Forum
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post #1 of 4 (permalink) Old 04-17-2018, 08:35 PM Thread Starter
 
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HP guestimate from the past, whats your guess?

Thirty five years ago I had 1970 GTO with a 455. It had a crane cam, long tube headers, Edelbrock manifold, holly carb and an MSD ignition. Stock heads and bottom end. M22 and 3.55 posi. At the time it felt pretty fast. I was trying to gustimate how much power it really made. I figure starting off with the gross ratings of 360hp and 500lb-ft, taking a guess that net power at the crank in the car would be around maybe 310hp to 440lb-ft, add maybe 30hp for the cam and bolt on’s to bump that to around 340hp and maybe 450lb –ft…..maybe….. and then the actual rear wheel numbers would be something approaching 300hp and 400 lb at the rear wheels……..maybe…..?

What do you think It could have measured at the rear wheels on a dyno for that combination?


Trying to come up with an estimate to relive old Pontiac glory. I recently acquired a 1972 GTO that’s a completely numbers matching 400. There is no hiding the fact that 250 rated net hp from the low compression 400 makes this car as quick as my Subaru SUV… So I think that numbers matching mill and drivetrain would be happy to go into storage. Planning a build to produce more power then my 70 did 35 years ago……..
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post #2 of 4 (permalink) Old 04-18-2018, 12:10 AM
 
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Very nice 72 , good luck with the build.
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post #3 of 4 (permalink) Old 04-18-2018, 05:00 AM
 
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I would say that a properly tuned original '70 455HO, which had the #64 heads & the 068 cam would have made real close to the advertised hp & torque. It was way under-cammed. So, a good cam, similar to an 041, could have easily put it up near 400hp, at the flywheel. IMO

http://www.wallaceracing.com/enginesearch4.htm
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post #4 of 4 (permalink) Old 04-18-2018, 09:46 AM Thread Starter
 
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The advertised hp was the older "Gross" rating of the engine out of the car....would be nice....
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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

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