I have a 1972 GMC Sprint with a 350 ci, it has an edlebrock carb(I think its about 600 or 650cfm) it has an edlebrock intake and hooker headers, so mostly a stocker. But I was wondering what your guess would be for what its pullin for horsepower. I am also looking at putting a mild cam in it, what do u think it will have afterwards?

Chadly

There is no good way to estimate hp unless you have a Desktop Dyno program, and you have to know all the particulars about the engine (cam profile, head flow, etc). Even then, it is only a ballpark figure. If it is mostly stock with only an aftermarket intake, carburetor, and headers, you are probably looking at 10-12 per cent over the stock numbers.
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Lynn
'32 3W

Therapy helps, but screaming obscenities is cheaper.

Actually, I have done paper calculations on engines that have come pretty close on the dyno (usually most are within 5%).

The formula is this;

HP = ATMOSPHERIC PRESSURE X CUBES X VOLUMETRIC EFFECIENCY X STATIC COMPRESSION RATIO X PEAK POWER RPM/ 792,000 (A CONSTANT FOR GASOLINE MOTORS). For example, my wife's 69 Camaro figured to be;

HP= 14.7(NOMINAL) X 357CI X 1.0VE X 10.5CR X 6200RPM/792,000= 431.36

The dyno revealed 418 average but the atmospheric figure would have been 14.5 instead of 14.7. This is due to the altitude of Atlanta and the barometer reading that day. So the paper figure would have been 425hp instead. This was a very good 3% error tabulation.

For your engine and I am guessing at all these figures (you will have to get your compression ratios etc) might look like this AS STOCK;

HP = 14.7 X 350 X .90 X 8.5 X 4600/792,000 = 228HP

By upgrading your cam you are doing two things by this equation. You are SLIGHTLY improving VE/affecting DCR (dynamic compression ratio)and making peak power at higher rpms. Now it may look like this;

HP = 14.7 X 350 X .93 X 8.5 X 5100/792000 = 261HP

I am sure that we have some more hp figuring gurus here that will chime in with their take.

I can't take credit for this formula and can be found at http://www.edelbrock.com/automotive/math.html


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Steve "Jack'Stands" Jack

Yeah but would the engine color twist the equasion? Chrome? ..No chrome?
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WPoC

We all know that chrome goes faster, followed closely by polished stainless and polished aluminum. LOL.
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Lynn
'32 3W

Therapy helps, but screaming obscenities is cheaper.

Lets not forget the stickers.
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WPoC

Thanx guys, that helps a bit, what is the rating on a stock 350ci?

Some of the earley smoger's were rated down around 150. You had to use a calander instead of a stopwatch when at the track.
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If you want it yesterday, then call me tommorow and I will have it ready today.

It sounds like Steve also snowed you guys too. Good answer Steve but you lost me way back some where. Lol Ray
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Grumpy

If it's been done don't do it!!