HP/Torque ? - Chevelle Tech
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post #1 of 9 (permalink) Old May 28th, 19, 11:49 AM Thread Starter
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Dan
 
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Location: Central NJ
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HP/Torque ?

Hi guys, I recently installed this motor in a 69 Chevelle and was wondering what kind of HP/Torgue it puts out. I didn't build it for racing but the throttle response and power are exactly what I wanted . So it got me thinking about the numbers ! You guys have tons of experience so I am sure you'll be pretty close.
Looking for flywheel numbers !

454 30 over . 461
PP 236 Heads
XE 268 H Comp Cams
Comp Cams Roller Rockers
TRW Forged Flat Top Pistons
1 3/4 Summit Headers
Edelbrock Performer 2-0 Intake
Holley 3310
HEI Dist.

I know this build is NOT a crazy high HP build , but it sure feels good cruising 1!
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post #2 of 9 (permalink) Old May 28th, 19, 12:29 PM
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Gene
 
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Re: HP/Torque ?

Hey, it has that early flat TQ curve that makes it fun! Whats in a number anyway!?
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post #3 of 9 (permalink) Old May 28th, 19, 12:54 PM Thread Starter
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Dan
 
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Re: HP/Torque ?

Quote:
Originally Posted by 427L88 View Post
Hey, it has that early flat TQ curve that makes it fun! Whats in a number anyway!?
So true...but go ahead let it fly, I won't be offended !
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post #4 of 9 (permalink) Old May 28th, 19, 2:25 PM
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Mike
 
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Re: HP/Torque ?

This link will provide an estimate, if you know the compression.
Rough Engine Horsepower Determination Program
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post #5 of 9 (permalink) Old May 29th, 19, 9:42 AM
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Gene
 
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Re: HP/Torque ?

Flat tops and 236PP heads = what compression?
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post #6 of 9 (permalink) Old May 29th, 19, 10:25 AM Thread Starter
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Dan
 
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Re: HP/Torque ?

Quote:
Originally Posted by 427L88 View Post
Flat tops and 236PP heads = what compression?
We were thinking 9 to 1 or so , the original were ditched and somewhere in the neighborhood of 7.8 .
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post #7 of 9 (permalink) Old May 29th, 19, 10:31 AM Thread Starter
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Dan
 
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Re: HP/Torque ?

These are the new pistons.
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post #8 of 9 (permalink) Old May 29th, 19, 12:14 PM
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Re: HP/Torque ?

Flattop and open chamber heads get you 7.8:1 - the original with a dish would get you 7.3:1 even though it was advertised at 7.8:1 - bad habit GM has used over the years, either rate the compression with a smaller dish (or flattop) piston than what is actually used, or rate with a smaller chamber than what is used.

The standard 350 used in the 1970's and early 1980's was rated at 8.5:1 when the actual compression was 7.8:1. My 1982 Corvette was rated at 9:1 (actual 8.5:1), 1969 Grand Prix 400 rated at 10.5:1 (actual 10:1), 10.25:1 Olds 455 is actual 9.5:1..... you get the idea.

Your open chamber heads depending on where you get your information are listed as either 113cc chambers or 118cc chambers - most actually measure around 121cc chambers. If you use a .025" stock deck clearance using a flattop piston and about a .025" shim gasket you come up with a whopping 7.8:1 compression (real world). If you want 9:1 you need to go with about 100cc chamber head.
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post #9 of 9 (permalink) Old Jun 17th, 19, 3:59 PM
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