Does freed horsepower = added horsepower

[uvbnhad]

This is something I've been wondering about lately. Does freed horsepower equal added horsepower? I think you can break down horsepower into those two categories. When you add under drive pullies and bigger exhaust it isn't necessarily adding horsepower to the car as much as it is freeing up the engine to perform better. Take that and compare it to something like a supercharger and its adding power or at least that's the way I look at it. I guess you could say that anything you do is technically adding horsepower but I think I'm asking it the correct way.

[1sicklx]

I see your way of thinking, but you also have to think if a free-flowing exhaust is freed hp, then wouldn't better flowing heads and intake fall under the same category since they are simply allowing for more air while the catback is allowing the exhaust to exit less restricted? I guess it's all in how you want to look at it.

[QWKSNKE]

i would consider it added hp. Cause an engine is rated at 'x' hp as it sits including the accessories. So if you change the pulley's out and receive a hp gain, then it is added hp

[Italian LX]

You can't "add" power to a motor without some sort of forced induction. You're merely giving back power that was already there.

Horsepower is horsepower whether it is being added or taken away. A motor puts out a certain power rating and then a percentage of that is taken away by accesory drag, drivetrain loss, ignition timing, etc. The wheels don't know the difference of how the power was made and they don't care where the power came from; the car will accelerate the same if the same net result is given.

If you really want to get technical, even though you're saying that a blower adds power, you also have to remember that it take a lot of horsepower away to acheive that increase.

[TheJeanyus]

Horsepower is just as rough on the rods/pistons/crank no matter how you get it, IMO. The energy released by combustion is just as powerful - it doesn't know whether it's getting it from a supercharger, turbocharger, nitrous, etc. Sure, a supercharger puts drag on the engine and nitrous "hits" harder so there are some differences, but I think the power level the shortblock can support is about the same.

[Wicked]

Originally Posted by QWKSNKE

i would consider it added hp. Cause an engine is rated at 'x' hp as it sits including the accessories. So if you change the pulley's out and receive a hp gain, then it is added hp

I agree 100%.

But things like pulleys and exhaust are two different things. Pulleys allow gross power that was used to turn the accessories to go out the back end of the crank instead, i.e. NET hp. Exhaust however, actually allows the engine to create more GROSS hp.

In terms of s/c versus turbo, the gross hp may be the same but the net(output into the transmission) will be different due to the power absorbed by the blower.

Italian is not really making sense if he means that running free flowing exhaust and heads doesn't make more hp, but instead frees it up.

[Italian LX]

Originally Posted by Wicked

Italian is not really making sense if he means that running free flowing exhaust and heads doesn't make more hp, but instead frees it up.

Damn, I thought you were like an engineer or something.

The only thing in an internal combustion motor that makes power is the cylinder combustion and its force down on the piston. Everything else is merely there directing the air where to go and channeling it in the right direction.

You can calculate how much horsepower a gasoline motor should make given things such as compression ratio, stroke, bore, etc. However, we all know that the net output is obviously dependant on a lot more things that restrict the flow of air in and out of the cylinders. This means that technically everything that is not part of the short block or combustion chamber is restricting the output of that motor -- this includes things such as head ports, valves, headers, intakes, etc.

If you agree with the above, than you can see where I come from when saying you can't add horsepower... you're merely finding better flowing components that don't rob as much power.

[Wicked]

Originally Posted by Italian LX

Damn, I thought you were like an engineer or something.

The only thing in an internal combustion motor that makes power is the cylinder combustion and its force down on the piston. Everything else is merely there directing the air where to go and channeling it in the right direction.

You can calculate how much horsepower a gasoline motor should make given things such as compression ratio, stroke, bore, etc. However, we all know that the net output is obviously dependant on a lot more things that restrict the flow of air in and out of the cylinders. This means that technically everything that is not part of the short block or combustion chamber is restricting the output of that motor -- this includes things such as head ports, valves, headers, intakes, etc.

If you agree with the above, than you can see where I come from when saying you can't add horsepower... you're merely finding better flowing components that don't rob as much power.

I am an engineer, you don't have to explain the combustion process to me.

We could argue all day about this.

My point is, a perfect engine without restriction does not exist.

You yourself said "A motor puts out a certain power rating and then a percentage of that is taken away by accesory drag, drivetrain loss, ignition timing, etc." You were correct here. But that same motor is rated using a exhaust system, intake tract, etc. So by removing the intake tract and using a free flowing exhaust, more air gets in a creates more combustion pressure and therefore more power.

[coupe]

The combustion process takes place...but that's not power. It's simply heat energy. The energy expands exerting a force on the piston, shoving it down the cylinder...This becomes work.
The power produced is a measure of how quickly this work can occur (and is multiplied by the number of cylinders working).

There are a number of resistances to this power--> accessories, poor heads, poor intake, and especially compression (ever hear a starter struggle to turn a 15:1 motor over?).


You could say power was increased or freed up. Doesn't really differ. It depends on your reference. But if you add fuel, air, spark...then you're obviously adding the potential for the engine to make more power...

[TheJeanyus]

The way I see it, adding fuel, air, or spark is adding to the engines capacity to make power (I think we all agree there).

Freeing up the exhaust and intake only allow the engine to make that power with less resistance (i.e., the exhaust stroke doesn't eat up as much power since it isn't as hard to push the exhaust gasses out, the intake stroke doesn't require as much power to pull air into the cylinder against vaccuum pressure (assuming it's not a boosted application)).

Underdrive pullies and removing accessories (power steering, A/C, etc.) allow the power these devices were using (and therefore the engine was obviously already generating) to be transmitted through the drivetrain and power the wheels instead of the accessories.

Does that make sense? I've been at work for 13 hours now, so things are a bit foggy.