JokerTypeR

I think this forum would turn out the best answers for this question and I hope it'll answer my question. I did some searching with no results, so I apologize if there's another one out there that I overlooked.

I hear all kinds of hype about the HP of an Si engine. I also hear that it "sucks" (exaggerated) because although it has horsepower, it has no torque. Many people say judge an engine on TQ and others say on HP.

What exactly IS the difference in the two? Why is everyone crazed over one or the other and which actually measures what, and how would it affect me as a driver?

Any help is greatly appreciated so I can understand the concept a little better.

Thanks in advance everyone.

DonF

There is an "old" saying HP sells motors, TQ wins races. That is mostly true. A 300 BHP 454 chevy VS a 300 BHP Honda, in the same car, will win every time.

Dan Ruddock

Horse power is a measure work done in x amount of time.
Torque is a measure of twisting force.

Horse power is a function of torque x rpm
Torque is a function displacement and manifold pressure

Dan

hu

Is it correct to assume the best way to gain torque is to stroke the motor? Is the best way to get horse power to rev the engine?

rjay8604

What has been said above is good. Also another point is usually performance oriented drivetrains will have gearing that compliments a car with less torque. Small engines with no forced induction make less torque, and so by using agressive gearing the torque output at the wheel will be similar to a car with more torque at the engine. Horsepower is ultimately what will decide how fast something can accelerate. Ferrari engines are like honda that they are very small for the respective usage, so they have little torque, but they still accelerate rapidly, because horsepower is what determines acceleration, it is physics fact.

Dan Ruddock

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hu &raquo;</TD></TR><TR><TD CLASS="quote">Is it correct to assume the best way to gain torque is to stroke the motor? Is the best way to get horse power to rev the engine?</TD></TR></TABLE>Your correct to a certain degree. If the displacement is kept the same a long arm motor will move the torque peak to a lower rpm and the reverse will move it up which will increase hp because torque x rpm = hp. F1 engines have twice the bore to stroke. Dan


Modified by Dan Ruddock at 7:13 PM 3/7/2006

HamiltonRex

goodinfo.

b20powereDA

dan, torque X rpm doesnt =hp. if that were the case then a decent b20 vtec with 160 lb/ft torque at 8500 rpms would mean that it has 1360000 hp. hp is measured in hp= tourqueXrpm/5252 than a 160 lb/ft torque b20 vtec at 8500 rpm would be a 259hp car.

Dan Ruddock

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b20powereDA &raquo;</TD></TR><TR><TD CLASS="quote">dan, torque X rpm doesnt =hp. if that were the case then a decent b20 vtec with 160 lb/ft torque at 8500 rpms would mean that it has 1360000 hp. hp is measured in hp= tourqueXrpm/5252 than a 160 lb/ft torque b20 vtec at 8500 rpm would be a 259hp car.</TD></TR></TABLE> Yea your right I forgot about the number it has been about 14 years since I did a dyno pull. Dan

NaIsGay

torque gets you off the line hp carries you down the track.. sometimes more tq can be bad.. why do you tthink the srt4s have had such trouble getting into the 10s then make just as much if not more tq then hp.. most dyno charts you see of quick hondas make example : 675hp and 400 tq

JokerTypeR

Good info, and I appreciate all the replies.

The ideal engine setup would be displayed below (by my understanding)

For the example, we'll pretend that both torque and HP are measured 1-3. 3 being high-torque or HP, and 1 being the opposite.

Drag (1/4mile): tq=2, hp=3 (because you're trying to jump the line, and get to the end)
Drag (1/8mile): tq=3, hp=2 (because you're trying to jump the line)
Auto X: tq=3, hp=1or2 (because there's quick, short jumps)
Top Speed (big oval track or salt-flatts): tq=1or2, hp=3 (because you're start isn't as important as getting down the track)

Reading that is kinda confusing to even me, I hope you all understand my description of what I'm attempting to learn.

Thanks again to help me learn why one would be more important than the other, and why people choose to measure how "bad-***" an engine is by using one number more than the other.

existanzcivicb20

very very good stuff!!!!!!!!!!

Black R

fwiw, I've seen two identical eg's race on the hwy - both cx's, one with b20vtec making 160whp and the other with an itr swap + toda cams making 180+whp, both having equal gearing. The b20vtec hatch would jump out immediately and pull ahead and hold it.

HP don't mean **** - it's all about the torque!!!11

GetawayInMoscow

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black R &raquo;</TD></TR><TR><TD CLASS="quote">fwiw, I've seen two identical eg's race on the hwy - both cx's, one with b20vtec making 160whp and the other with an itr swap + toda cams making 180+whp, both having equal gearing. The b20vtec hatch would jump out immediately and pull ahead and hold it.

HP don't mean **** - it's all about the torque!!!11</TD></TR></TABLE>

Yeah I seriously don't believe that a car with 20+ more whp would lose. It's not like a b20 is an LT1, there must have been another factor.

NaIsGay

in a 1/4 mile races 60ft is everything.. i bet that car with 20 less hp had a better 60ft then the other car but i bet the car with 20 more hp trapped faster

drdisco69

I see a lot of confusion in here. Horsepower is a unit of power, lb*ft is a unit of force. They are not the same, and they describe different things. In lieu of my own explanation, I refer the curious and unsure to the post by the "late" Dustin, aka HT Contributor:

https://honda-tech.com/zerothre...85478

JokerTypeR

Good stuff good stuff, still learning...

DonF

Hosepower is a mathmatical number derived for torque. ALL dyno's measure TQ and convert to HP. HP = TQx rpm divided by 5252..

EJtypeR

torque x RPM / 5252 = HP

rjay8604

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DonF &raquo;</TD></TR><TR><TD CLASS="quote"> ALL dyno's measure TQ and convert to HP. </TD></TR></TABLE>

Correct me if i am wrong, but aren't dynojets inertia based, therefore they measure horsepower, so torque is derived from the horsepower? Otherwise dynoing in 3rd would give greater torque than dynoing in 4th.

hu

Besides stroking an engine how do you build an engine to produce more torque?

rjay8604

You get more air into the engine so you can burn more total air/fuel mixture. That is the main way.

Combustion Contraption

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rjay8604 &raquo;</TD></TR><TR><TD CLASS="quote">Correct me if i am wrong, but aren't dynojets inertia based, therefore they measure horsepower, so torque is derived from the horsepower? Otherwise dynoing in 3rd would give greater torque than dynoing in 4th. </TD></TR></TABLE>

Dynojet's measure TQ directly, and convert it to HP. Thats why you have to enter in a gearing variable. Torque is something we can measure, HP is something we can calculate. Have you ever seen a horsepower wrench?

Here is a good read.
http://www.speedoptions.com/articles/3519/

Something to think about for those looking to gain torque via "stroking" a motor. When most people use the term stroke they refer to installing a longer stroke crankshaft, thinking thats the only way to gain TQ. Now to them i ask this:

We've all heard the phrase: "Theres no replacement for displacement." But displacement of what? Cubic inches in the motor, or cubic inches of air in the combustion chamber?

This thread could get good. I'd like to see it keep heading in the right direction.

rjay8604

Hmmm check this out. http://www.fjr1300.info/misc/torque-power.html
I'm not saying anyone's wrong, i'm still on the fence. But i am really leaning toward the Dynojets read horsepower not torque side. To each his own. Also you can't spin a torque wrench continuously, so you know

A dynojet measures the amount of time to accelerate a inertial drum. This results in a measure of power because you can measure power in any gear with any ratio, and the resulting power will be the same, but torque will vary with the gear ratio.

Also torque is the rotational version of work. If you spin a dynojet drum one rotation, you're doing the same work whether it takes you one minute or one hour. So that means if a dynojet measures torque, then a car that that takes 10 minutes to spin the roller 1 time would get the same resultant reading as a car that takes one 10 seconds to spin the rollers 1 time. Because they did same amount of rotations on the same rollers the work done would be the same. So the dynojet can't be reading the torque, because it also measures the time.



Modified by rjay8604 at 2:30 AM 3/9/2006

JokerTypeR

One thing I still don't understand about tq vs hp is why someone would brag about one and not the other as if it's more important than the other. From what I'm reading, one shouldn't be more important than the other, and it seems as though it's JUST a preference...

For example, everyone brags about the B16A1 pushing 160hp...but they say it's low in torque.

They also brag about the B18B1 having 127lbs of torque...but they don't say much for the hp rating.

If your theory is fact, shouldn't the engine be proportional to their other rating? (hp for tq, and vice versa) And if this is true, then why do people brag that the b18 is better cuz it has more torque over the b16, and brag that the b16 is better because it has a higher hp rating?