350 Chevy HP?

[footballolson]

I have a 350 Chevy in my 71 GMC and i wanna know bout how much HP it has. Only thing done to it is it had a 4 barrel edelbrock carb on it. Any ideas of hows much HP?

 

[Anonymous-0]

Not enough information to make any kind of a guess. Maybe if actual compression ratio, camshaft specs, heads used, which intake and carb, how it is tuned, and what exhaust was used was all known. But even then, it would only be a guess.

There are several formulas that can predict horsepower if you know the vehicle's speed at the end of a quarter mile dragstrip, but I think you also need to know the weight of the vehicle as raced.

If you are really interested in getting a fairly accurate reading, most cities have businesses that have chassis dynos. You drive onto the drums, they strap the vehicle down, and then have you run it through different RPM levels, turning the drums with your tires. It usually isn't too expensive.

But that reading will only be accurate to some degree: the readings will compare to other vehicles on the same dyno, but it will not necessarily give totally accurate standard horsepower readings. And while there is a definition for what a horsepower is supposed to be, manufacturers have not always used that definition exactly when advertising horsepower.

In the late 60's lots of engines were advertised as delivering more than 350 horsepower. They had high compression and fairly hot cams. Yet by the mid 70's, almost no car engines advertised as much as 250 horsepower from the largest engines. But those lower horsepower rated cars were not THAT MUCH slower than the earlier cars, if you compared similar models and weights. The manufacturers were just under government pressure to make their advertising more "real" and also the insurance industry had really jumped on high advertised horsepower cars with outrageous rates. So they computed the advertised horsepower of their vehicles differently than they had earlier.

Advertised horsepower stayed very low through the 80's and early 90's, but there still were some fairly fast vehicles. Then in the late 90's I saw that many vehicles had higher horsepower advertisements. Like 250 horsepower minivans. And recently, most big pickups offer medium sized V8's that are supposed to have more than 300 horsepower. It would be interesting to see an accurate comparison of those new engines to the engines that had been rated so very low.

The Chevy 350 is a good power producer. I would doubt that a decently tuned mild 350 would show less than 200 horsepower on a dyno, but it might show a lot more, depending on the dyno and how the engine has been built. The car magazines regularly have buildups that have 350's putting out over 500 horsepower. But I would guess that such an engine would be pretty useless in anything but a pure race car, since it would probably not idle worth beans and have very little low end flexibility.

If it really matters to you, run your pickup on a dyno or find out more about the formula that will give you a horsepower number from a quarter mile dragstrip time slip. Good luck!