nagiamar

Hi Folks,
i had discussion with one of my colleague, he was saying that by having the bigger or smaller size engine there won't be any change/additional in horse power.
So can anyone explain who the car horse power is impacted by engine size.

Thanks for your help

lugrug

Are you asking about engine size vs. HP in general or specifically about available Mustang engines?

Kurt_OH

GENERALLY, with all else being equal (relative capacity of intake/exhaust/fuel system, bigger = more power.

Why? Because ideally you'll feed a fixed ratio of fuel and air into each cylinder. Since engine output is directly (well, proportionally but now we're spitting hares - or is it hairs?) related to the amount of fuel you burn, the more of this air/fuel mix you can get into your cylinders, the more power the engine produces.

That's why turbos/superchargers produce more power: they jam more of this air/fuel mix into your cylinders. Note that just adding more FUEL won't work: you must maintain an appropriate ratio of air to fuel. Compressing the air/fuel mix vapor DOES maintain the ratio while increasing the amount of fuel added to the cylinders.

Why is it that "all else being equal" matters? Because larger displacement doesn't necessarily promise that more of the correct ratio air/fuel mix will arrive and be burned properly in the cylinders. Cam timing, valve, intake, port, and exhaust size/shape/contour and a thousand other factors all affect it.

socalwrench

To put it simply- larger bores equal more area to push on (larger surface area) that also use more air and fuel (again, in the larger space); longer strokes equal more rotational force, or torque, on the crankshaft from the increase leverage (longer rods have a similar effect but that doesn't change cubic inch displacement). On side note, the relationship between bore and stroke directly affects the horsepower and torque curves.

So, a larger engine usually means more power. Rotational weight and cylinder efficiency become more demanding with larger engines. Remember, torque is the amount of work an engine can perform, and horsepower is how quickly the engine can perform that work.

lugrug

Also, Higher compression ratios equal more power in engines with all other things being equal. This is limited to how high you can compress w/o detonating the fuel/air mixture. This in turn is controlled by the octane rating of the gasoline you are using. It's all good to try to run 13 to 1 compression until you figure out you need something like 100 octane which you can't buy.