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View Full Version : 396 realistic HP, sizing fueling

Hubert
06-20-2018, 04:07 PM
Deleting account
FlintTony
06-20-2018, 06:45 PM
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!
carpoor
06-21-2018, 02:43 PM
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.
carpoor
06-21-2018, 10:50 PM
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.
RBeckman
06-22-2018, 03:08 PM
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.
FlintTony
06-22-2018, 07:22 PM
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.
carpoor
06-22-2018, 10:26 PM
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.