Everything You Wanted To Know About Car Measurements(HP, TQ, Gear Ratios etc.)

[FlatlineSi28]

still hard to understand the tourque and hp thing haha.. am i retarted?

[ryker]

Think of torque in this format -

Leg Muscles and a pedal bike. The power you can press down on the pedal for one stroke is torque. The more torque the more power you can press with.

HP is torque times cranks on the pedal.

100lbs of muscle strength at 4 pedals per second

or

25lbs of muscle strength at 16 pedals per second

In each of the above the same HP is created.

[08_si_civic]

what gear is the gear ratio at 1:1

[pjeterm]

what's the drivetrain % loss on 07 civic si sedan

[KingMarineM16a4]

Originally Posted by pjeterm

what's the drivetrain % loss on 07 civic si sedan

Well 197hp from the engine, most people dyno 175 or so. So about 12% drivetrain loss.

[08WhiteCivic]

this is DEFF a great write up/thread.

[KingMarineM16a4]

Originally Posted by 08WhiteCivic

this is DEFF a great write up/thread.

Thank you!

[ryker]

Originally Posted by bossman

Figured I'd add some more info to this..

Your TQ peak will come when your engine is operating at maximum VE (Volumetric Efficency).VE is how much air and fuel is burned in the combustion chamber Vs. Combustion chamber size i.e 2 liters in our case.Hondas,with their excellant head design and cam events actually have a VE above 100% at TQ peak proving that high redlines are NOT a bad thing.Horsepower being a mathematical formula of Tq @ X RPM is just another way of equating how well your engine is breathing at higher RPM's.If you had an enginethat made the same TQ at every RPM from 0-10,000 then your HP would climb in a diagonal incline proportional to RPM.As to what is more important peak TQ @ high RPM Vs. peak TQ @ median RPM that is another thread all by itself.

[bossman]

I just wanted to point out that it appears noone mentioned that @ 5252 Rpms Hp will always be higher than Tq and below it Tq will always be higher.I've personally seen some fishy dyno sheets on here before(not this thread but on 8thcivic).If the meeting point of Tq and Hp is above or below 5252 by a large amount 500 rpms or more then that dyno sheet(be it chassis or engine dyno)is suspect.

[bossman]

btw..great write-ups everyone,it's good to see actual research and data instead of speculation and opinions.

[e60.deluxe]

Originally Posted by bossman

I just wanted to point out that it appears noone mentioned that @ 5252 Rpms Hp will always be higher than Tq and below it Tq will always be higher.I've personally seen some fishy dyno sheets on here before(not this thread but on 8thcivic).If the meeting point of Tq and Hp is above or below 5252 by a large amount 500 rpms or more then that dyno sheet(be it chassis or engine dyno)is suspect.

im pretty sure ive mentioned that, but anyway, my guess is that those dyno sheets use different scales for HP and torque. look carefully, sometimes theres a scale on the left side for one, and another on the rightside for the other.

[ryker]

Originally Posted by e60.deluxe

im pretty sure ive mentioned that, but anyway, my guess is that those dyno sheets use different scales for HP and torque. look carefully, sometimes theres a scale on the left side for one, and another on the rightside for the other.

I hate those charts like that.

[Willie Mack]

A car geeks dream. Time to fire up the dyno.

[072civic]

subcribed

[BMWTech2008]

Originally Posted by 08_si_civic

what gear is the gear ratio at 1:1

Referring to the Civic si?

5th gear is pretty damn close, somewhere like .92:1 (but its a overdrive gear)
4th gear isn't as close but it's what everyone uses, 1.2:1

[DevilDoc87]

omg my head hurts.. i hate math, but this is good stuff. :/