Inliners International Forums General Discussion Engines Chevy 292 Power Numbers

Just got the call from my engine builder in Oceanside CA. Monte from Machine Tech Racing Engines. I can't say enough good about this guy. He went way above and beyond in building my engine. I wanted a completely streetable, reliable engine with some flair and of course as much power as possible within these constraints. This is in response to another post from another site....

Hey Bama fan. I have a 292 being built by an engine builder right now. I am running dual 38 webers, shorty headers. The head has had extensive work done and is being pulled for more work. It has a mild cam, can't remember specs, but will post when I get build sheet. Initial compression was a tick below 9. Has roller rockers and HEI ignition. Numbers so far...270 hp and 280 tq . Builder wasn't happy with numbers, so is milling head for near 10 compression and reworking head. Extra work being done at no cost! Headers would not seal and were checked on 2 different heads. They had to be welded and machined to fit properly. I will post more info as it becomes available.
Brian

Final Numbers
Compression 10 to 1
Horsepower 285
Torque 315


1968 Camaro 292-muncie m-22
1974 Chevy Nova 350 th350
1972 Chevy C10 confused 305 needs help!! (In Progress)

I,D rather have the compression at the 9 aprox level personally

(Static) compression is just a number, means nothing without knowing the cam specs. Sounds like the cam needed more, just to come alive. It may not be as "mild" as he thinks it is, and it was bleeding off compression. Good call by the builder. If it had too high compression for the cam, it wouldn't have made that much more power.

If it had too high of compression for the cam, it probably would have detonation problems & made less power.
If he was running pump gas, that is.

MBHD

IIRC, Kirby's mild 250 w/12 port made 320 HP. Can't remember the torque though, anyone?

10-1 should be fine on good pump gas 90-93 octane

Still impossible to make that claim I can build you an engine that runs cool and fine with 14:1 compression on pump gas. And I have. And I can build you another that will detonate and die quickly with just 10:1.
Without the rest of the engine specs, those numbers mean nothing, and are not an indication of how high octane fuel you need etc... it's just incomplete data.
I have held in my hand cams that require 20:1 to 24:1 compression ratio for the engine to run right. That's gasoline not diesel in case you were wondering

Still. Sounds like he should be fine, just ask what octane the builder designed the engine to be run with. if it's optimized for 93, you can't run 87.

Personally I see no point in building a performance engine to use 87 octane fuel.

ALSO WHEN YOU BACK THE TIMMING WAY DOWN FOR HI-COMP WHAT HAVE YOU GAINNED ?

Sounds like a good build. I would also like to know the cam specs. And what other work was done to the head.

Answer: The possibility of dangerously hot exhaust valves.

One more reason I don't advocate too high of a CR on a street engine.

IMHO much of the "dynamic compression" commentary is over-rated.
Every engine has its full stroke volume compressed at its torque peak, and frequently well before (obviously reduced proportionate to VE).
Exactly when that happens is a function of IVC point vs. RPM: a mild engine will capture more of its stroke length at low speed, and flatten out. A hot engine will have lower trapped volume at low speed, and (if the cam choice is correct) turn fast enough to capture its nominal volume at higher RPM.

If you still have dynamic compression in your power range, one of these things is true:
1. bad observation and/or bad analysis of data
2. wayyy too much cam for the RPM range
3. more static CR will generally help, but not always

Harley-Davidson's very efficient flathead race engine (KR) used 270° @ .050" cams for 7,000 RPM peak power... with 5.5:1 static compression.