Auto Mathmatics

Does anyone know how to comvert displacment values into horsepower? :smoka:

you cannot convert displacement into horsepower as there are WAY too many variables.

if you could, then that means a motor double the size of an H22 prelude would put out 400hp... but we all know very few 4.4 litre + motors that do that.

the only formula for horsepower is converting the torque numbers into horsepower:

Tq x RPM / 5252 = horsepower

How can displacment effect horsepower? I am wondering what type of horsepower a bored out h22 would produse with a 2.7 dislpacment? :smoka:

Originally posted by crj_lll
How can displacment effect horsepower? I am wondering what type of horsepower a bored out h22 would produse with a 2.7 dislpacment? :smoka:


that's impossible to figure. displacement increases torque, but so does compression, valve depth, timing... etc.

increasing displacement increases torque. increased torque creates increased horsepower.


BUT increased horsepower does NOT mean increased torque, as peak torque can remain unchanged, but making the torque come on at a higher rpm can increase horsepower without increasing torque.

increasing your effective maximum rpm also increases your horsepower without increasing torque as long as your torque ratings dont drop off too quickly at a higher rpm redline.

there's a lot of variables, mainly the technology...

which is why you can get 800 hp out of an F1 motor that's under 4 liters.

or 500hp out of a viper 8.1 liter v10.

or you could get into hp/l, the honda crutch, and go with the 120hp/l of the s2k, while the viper makes only 50 or so hp/l.

it's all about how you use it, not how much you've got.

consider that 2 different 2 liter motors, 1 turbo, 1 na, make completely different power at the same displacement.

there are power numbers available for stroker kits, as they come with everything for the kit, so on a stock motor with a stroker kit, you can give a very educated guess as to what power is.
which is what most manufacturers note on their sites.

Originally posted by drift



that's impossible to figure. displacement increases torque, but so does compression, valve depth, timing... etc.

increasing displacement increases torque. increased torque creates increased horsepower.


BUT increased horsepower does NOT mean increased torque, as peak torque can remain unchanged, but making the torque come on at a higher rpm can increase horsepower without increasing torque.

increasing your effective maximum rpm also increases your horsepower without increasing torque as long as your torque ratings dont drop off too quickly at a higher rpm redline.


Ok, this is definatly helping. Do you know the equation to figure out torque as a factor of displacment? I know you mentioned that timing, compression valve depth would need to be known. How would those factors be added into an equation and are there any others needed? :smoka:

there's quite a few variables, including how you tune your motor.

two identical (for the sake or argument, lets use b16 motors with cam gears, and standalone computers for tuning) civics can get completely different numbers depending on tuning, even though they both have the same displacement.

increasing displacement will increase hp and tq, but there's no set formula to do it.

it's all about increasing the efficiency of your motor...

Originally posted by crj_lll



Ok, this is definatly helping. Do you know the equation to figure out torque as a factor of displacment? I know you mentioned that timing, compression valve depth would need to be known. How would those factors be added into an equation and are there any others needed? :smoka:


are you blind? there is no equation! ok, let's say i give you the valve depth, cam timing, overlap, engine rpm, engine dsiplacement, stroke length, rod length, compression ratio... blah blah blah.

well, you still have ignition timing, rate of swirl, fuel type, ignition voltage and source... blah blah blah.

in other words, you're looking for a mathematical solution for an abstract problem.

UNPOSSIBLE.