Definition of horsepower

[fritz_269]

Old PH post (written by fritz_269):

HP = (Torque * RPM) / 5252
Torque is measured in Foot*Pounds (ft*lbs) or Newton*Meters (N*M) - (the above formula works for ft*lbs)

Picking up one pound from the ground to one foot off the floor is one ft*lb of WORK. Torque is a measure of WORK, expressed for a twisting motion (like an axle or a tire).

Horsepower is a measure of POWER.
POWER = WORK/TIME.

If it takes you a day to pick up that 1lb weight, you don't have much POWER. If you do it in a millisecond, you've got a lot of POWER. To move a car fast, you have to have a lot of POWER.

RPM (Revolutions per Minute) is what gives us the time relation in the formula, and we see that HP is always a linear multiple of Torque. If anyone tells you different, they don't know what they are talking about. HP and Torque are always strictly related through RPM.

Big V8 engines have a lot of torque at low RPMs, but have a lower RPM redline. They have to get their HP from a big Torque number. Honda NA 4cyl engines have a low Torque, but a very high redline - they can get their HP from a high RPM number. You see, there are two ways to get HP -> Torquer vs. Twister.

[VTEC_boi]

That is awesome Fritz, and the coolest thing is that I actually understood one of your posts! lol

Weird thing, the B16A2 actually (if rounded) makes 161hp.

Because it makes 160.624524 hp at 7600rpm :smoker2:

Just wanted to point that out...

[fritz_269]

Are you sure that it doesn't make exactly 160 hp from 110.568412 ft*lbs of torque at 7600 RPM?

[VTEC_boi]

DAMN YOU! hahaha I used the 111 lb./ft. one....

[Moppie]

Try 7,800rpm for the 160hp peak.
Its the same for the 167hp B16a2.
(unless your talking about the USDM engines, then bah! )

[Kohhal]

Hey Fritz(and others), check out this link, explained it all to me very well : bhp and torque explained

[Someguy]

Diggin' up all the old goodies to break in the new site I see (I like it).

Next let's try: "Is it more effective to calculate ideal shit points based on total area under the torque * gearing curve or hp curve?" Some interesting dyno-graphs cropped up the last time.

[fritz_269]

Originally posted by Someguy
Next let's try: "Is it more effective to calculate ideal shit points...

Usually just one in the morning is pretty good for me.

[VTEC_boi]

Originally posted by fritz_269

Usually just one in the morning is pretty good for me.

Bwahahahahahahahaha!!!!!!!!



7800rpm for JDM B16As eh? Cool, Moppie - and you're right "(unless your talking about the USDM engines, then bah!)"

[82civicwagon]

thats the best ive ever seen it put by anyone im glad that theres people like you out there helping educate others.:flash:

[Someguy]

Originally posted by fritz_269

Usually just one in the morning is pretty good for me.

Do you granny shit, or do you power shit?

[bbpro]

Originally posted by TheMasterG
Hey Fritz(and others), check out this link, explained it all to me very well : bhp and torque explained

Can't believe I actually understood that. Now if only someone can calculate the ideal shift points for a 2000 Civic Ferio SiR. The version we have over here is 160hp@7600, 110lbft@7100. The gear ratios aren't in the manual, and i suck at math. Thanks. Peace.

[whttrshpunk]

I really can't help with the shift points, but I have a question.
Lets say a 12 pack of 12 oz cans is $1.99,a 2 liter bottle is .99 and a 3 liter bottle is 1.50...which one of those would be the best "value"?

[fritz_269]

Originally posted by whttrshpunk
Lets say a 12 pack of 12 oz cans is $1.99,a 2 liter bottle is .99 and a 3 liter bottle is 1.50...which one of those would be the best "value"?

I'm not going to do your homework for you! But I will give you this hint: there are 33.81 US fluid ounces in one Liter.


Optimal shit (errr... shift) points for maximum acceleration are fairly straightforward to calculate. But you must have an accurate chassis dyno graph, peak numbers are not nearly enough. Usually it's done by hand with some graph paper and lots of iterations, but there are some good computer programs to do it too (like the Mr. Gasket Dragstrip2000). I find it hard to describe in words, but it's basically just maximizing the area under the dyno curve throughout each gear's RPM range. Fortunately, for most Honda engines the power peak is right near the redline, meaning that a redline shift is the best you can do in any gear.

Someguy - I think that iterative integrating under the hp curve or looking at the intersection points of the torque*gearing curves should give you exactly the same result. Wheel torque = engine torque * gearing, and wheel hp is just a linear function of wheel torque and RPM.
:smoker2:
PS> Power shit. LMAO.

[J SPEC SilEighty]

Originally posted by TheMasterG
Hey Fritz(and others), check out this link, explained it all to me very well : bhp and torque explained

That's a really good explanation. I would post and thank that guy but I'm not a member of the site. Very nice.

Thanks TheMasterG for posting it.