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Old 06-20-2018, 03:07 PM
Hubert Hubert is offline
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Default 396 realistic HP, sizing fueling

Deleting account

Last edited by Hubert; 02-04-2021 at 02:05 PM.
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Old 06-20-2018, 05:45 PM
FlintTony FlintTony is offline
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Before anyone can give even a ballpark number, some things must be factored in. Compression ratio, valve size, flow numbers for the aluminum heads, camshaft profile, which exhaust system will be installed. Will it be a stock stroke crankshaft?

Wow, 17K original miles? What's the backstory on your car? Sounds interesting. Good luck with the build!
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Old 06-21-2018, 01:43 PM
carpoor carpoor is offline
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This is the one I bought for my folk's car...

https://www.summitracing.com/parts/sne-550-516

The engine is a .040" over ATK 454, .100" dome pistons, hyd roller, fully CNC'd AFR 265s.

The system I bought says good to 650 HP, will be more than adequate for their 454. I estimate their engine around 550-575 @ the flywheel.
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1972 SS 454 Chevelle LS5/M21/12 bolt 3.73 posi
1969 Malibu COPO L72/M20/12 bolt 3.31 posi
1968 Malibu LQ9/4L80E/12 bolt 3.73 posi
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Old 06-21-2018, 09:50 PM
carpoor carpoor is offline
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Prior to 72, GM over rated their engines. There was a story about it in Super Chevy about a decade ago. A 70 LS6 454 450 HP only made about 280 to the wheels. (18-20% drivetrain loss means that it really only made about 340-360 real world HP) They used gross HP rating vs the current SAE net ratings.

A healthy, modded 396 should made 450 HP no problem, maybe more. You'll be more than safe with the 650 HP unit.
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1972 SS 454 Chevelle LS5/M21/12 bolt 3.73 posi
1969 Malibu COPO L72/M20/12 bolt 3.31 posi
1968 Malibu LQ9/4L80E/12 bolt 3.73 posi
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Old 06-22-2018, 02:08 PM
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RBeckman RBeckman is offline
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I can tell you that when I rebuild my 396/325 I just changed the cam to a RV cam, had the original heads cleaned up and had the original quaderjet gone through and a Corvette aluminum intake and added headers and it made 410 hp and 454 torque @ 3200 rpm for torque on the engine Dyno. Also a stock HEI GM ignition.

The intake was a 427/390 out of 69 so I had to put a riser on for the linkage to work.
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Old 06-22-2018, 06:22 PM
FlintTony FlintTony is offline
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Neat story Hubert. Sounds like it should be rust free. A big bonus for you.

I had an L78, 69 Chevelle with an all original driveline. The factory rated it at 375 HP. It actually "felt" like it had more HP than that. I compare that feel to the cars that I have now. Both Chevies have 427s in them One dynoed at 450 and the other one is a hair over 500. A pretty decent build for you to consider would be something along those lines. You would have to drop the compression ratio a little to run on the shit gas that we have now.
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Old 06-22-2018, 09:26 PM
carpoor carpoor is offline
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Someday, I would really like to pull the LS5 out of my 72 and stick it on a dyno. Most likely will have to settle for a chassis dyno instead. I had a spare LS5 that I was going to put together to stock specs. None of the trick stuff mine has... oiling, valvetrain, etc. Just wanted to see the difference.
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1972 SS 454 Chevelle LS5/M21/12 bolt 3.73 posi
1969 Malibu COPO L72/M20/12 bolt 3.31 posi
1968 Malibu LQ9/4L80E/12 bolt 3.73 posi
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