280Z1977

Here is somthing I posted a long time ago on another board....

"The Only Thing You Really Need to Know
Repeat after me. "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*." :-) "

Now, how many cars' torque curves continue to rise all the way up until redline? Not many(if any). That is where horsepower comes in.

Actually forget that, when do most cars make their most torque? Usually right in the middle of their powerband. Now imagine if you had to shift right at that point, that car would be pretty slow. Horsepower allows you to use your entire powerband.

To continue at what RPMS do most people launch their cars? Lets just say a constant average is 3000RPMS. And lets just say a constant redline is 8000RPMS. Now most cars/engines reach their peak torque in the middle of the their powerband, in this case 4000RPMS (RSX's peak torque I believe??), after that it gradually falls. So torque is only important for those 1000RPMS or so, the rest is almost all horsepower. Even after you shift (since most people don't know that shifting earlier is sometimes better) your RPMS usually drop down to a point after your peak torque number. So all that is there is horsepower.

Torque would be useless without gearing. Think about working on your car and you have a bolt that just won't come off, so you add a breaker bar thats adding gearing. It is the same amount of torque(you pulling) just better gearing with the the breaker bar. The horsepower is you being able to keep pulling the same, without that, no torque at all.
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When I first wrote this I was really tired so don't hold it against me.

Tomtwtwtw

Again, torque is what an engine produces, and based on how fast an engine is moving, and how much torqe is behind it, you can determine how much power that engine is generating. Horsepower is determined by torque, not the other way around.

The point of horsepower on a dyno is not to determine where your engine is strongest, but rather to determine where your engine is *losing* power. Your engine is strongest at peak tq, but as long as it doesn't drop much afterwards, it's worth it to rev longer. Your tq is already going down at your peak hp, it merely indicates where it's going down too fast to be worthwhile. In most cars, with ideal gearing, you shift at your peak hp to bring you back to your peak tq, the strongest point in your powerband.

Look at the 06 Si again, for an example. Peak tq is 6100, peak hp is 7800. The close ratio transmission would ideally shift from redline back to the 6k rpm range. I don't know what it really does, I haven't seen it, but that's ideal. The Cobalt makes peak tq around 4400 I think, and peak hp is at redline. It has wider gearing, but as you can see, it has a wider powerband because of the abundance of tq available earlier on.

You should know I'm not saying hp isn't important, but you make it out to be the only thing worth knowing. Quoting your last statement, you do indeed calculate hp from a dyno, but you *measure* tq.

Edit: 5252 rpm is merely where tq = hp, but has nothing to do with where any car has it's tq peak. If you look at any dyno, this is where the lines cross.

OniMirage

you need both torque and horsepower. torque basically will translate in your cars ability to get up and go until your car is moving enough to create sufficient horsepower to keep it going even faster. A cars peak torque and horspower will never be the same and peak torque normally always happens before peak horsepower and neither can happen at the same time

280Z1977

We are saying the same exact thing, just different sides. I have never said that horsepower is all that is worth knowing, just more important when looking at acceleration.

TXRLU

haha, ok I won't comment since I guess the Cobalt and the Civic SI apparently don't way ANYTHING.

I saw this on the Redline Forums and it seems rather appropriate

http://videos.streetfire.net/search/...D5C9BB11A9.htm

Hey Tom, I pulled that TQ number from www.lamborghini.com but I also remember an article where they compared the torque of the Duramax to that of the lambo. I mainly just needed some numbers to prove my point. What's funny is that we aren't arguing (at least I'm not) that HP is a totally useless number. Did you know that the HP and TQ of an engine is exactly the same at 5252 RPM? So we know at least that they are related, so all things being equal, the SI has a similar HP rating (mfg rating anyways) but it falls 40lb/ft of torque lower than the SS/SC.

OniMirage

in mechanical terms, if your engine cannot produce torque you CANNOT move no matter how much horsepower you have. At that point you would need to push the car down a hill in order for it to get up and go try dragging that down a road. Comparing to a truck is actually a perfect example. What about a torque wrench? are you producing more horse power with your arm to make that wrench move? or are you producing rotational mass (or torque) with your arm to make it move? What happens when it starts getting harder to turn that wrench to the point where it doesn't move? will horse power help or more torque?

TXRLU

a big ass hammer would probably help more...........

OniMirage

Tomtwtwtw

Peak hp and tq technically can be the same as long as it happens at 5252 rpm and that also happens to be the engine's redline...but yeah, that will never happen. Also peak tq will never occur at a higher rpm than peak hp because of the relationship between the two. (I know you said normally always, but it's definitely 100% of the time. No need to give yourself any wiggle room on that statement )

Tomtwtwtw

It's very likely that it was in nM then. It's an n/a engine that's simply not big enough to generate that kind of tq. If you want big tq numbers, though, look at AMG...they got an engine putting out something like 740lb.

Edit: I checked the UK version of their website (the main one won't load at work for some reason) and it states 650 nM of tq at 5400 rpm.

phxSS

All of you, SHUT UP!!

Tomtwtwtw

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280Z1977

I fixed that peak torque at 5252 thing. I was really tired a long time ago when I wrote that.


Lets see if this makes sense, torque is the amount of work an engine can do, horsepower is the rate at which it can keep doing it.

"Torque would be useless without gearing. Think about working on your car and you have a bolt that just won't come off, so you add a breaker bar thats adding gearing. It is the same amount of torque(you pulling) just better gearing with the the breaker bar. The horsepower in this instance is you being able to keep pulling the same and as the bolt gets looser pull faster (more RPMS=more horsepower with the same torque applied)." - ME

Another way to look at it.... a power drill has horsepower and torque. The more horsepower it has the faster you can spin a screw into a wall, now the more torque it has the thicker/tougher a wall you can screw into.

Tomtwtwtw

You can also think of hp as the momentum of the engine, as it were. It all boils down to physics...torque is a measurement of force, horsepower is a measurement of work. Work is the result of a force being applied to something. So torque is the force being applied from the engine, and the horsepower is the result of said force. My arguement the whole time has been that neither is more important, but that if you want a really fast car, you need both low-end and high end.

Wow...I remembered something from high school.

SS4ME

Finally, some true insight!!!

280Z1977

**** high school physics. Actually that was one of the funnest classes in high school.

ssritz

Actualy it was at an autoX and the local drag strip. Mind you my car isn't stock. My mods ar gmp headers and exhaust weapon r torque dampner and injen intake. I still have the stock tires and suspention. Oh and just to put it in the clear I beat him by a bumper length.