how does torque work.

[frusciante fan]

so as all of you know i'm not exactly a genius and i'm a little confused about torque. obviously more is better but...

 

for example a 3.4 DOHC has 215 fpt@4000 rpm, while the Gen I 3800 has 225 fpt@3200 rpm. so what does the amount of rpm mean. do you want the ft lbs to be higher and the rpm lower, or the opposite?

[jdcutty]

The torque reading is the highest amount of torque that the particular engine gives and the rpm reading with it is the point where it gives the highest torque. The lower the rpm, the more low-end torque (and prolly more low end power) that motor will have, and vise versa.

 

Torque is a measurement of rotational force that is applied to something. So in a car, torque refers to the rotational force applies to the trans-axle by the motor.

[chadz34]

Basically, the DOHC makes maximum torque at 4000 rpm. Therefore at 4000 rpm on the tach you are making 215 feet pound of torque.

[frusciante fan]

so if a motor has a high rpm it has more top-end power? and if somebody with a 3.4 were to brake-torque they'd rev to 4000rpm?

[chadz34]

Yes, high rpm's mean high end torque/ I don't know about the brake torque, I have never tried it in my Z34 maybe some one can help you with that. I think mine would wanna move before it'd get to 4000 rpm.

[frusciante fan]

thanks. makes sense now. kind of hard to evaluate the true power of a car without knowing what torque really means.

[JakeMetz63]

You want the highest torque at a lower RPM and the Highest HP at a higher RPM... usually.

[Darkness]

Torque is the only force your engine produces which can actually be measured. Horsepower is a calculated number, which reflects torque at certain RPMs. That's how some of these newer cars have high horsepower ratings and dreadful torque ratings. Basically because they make their power at 6k+ rpms. Old Pontiac engines, on the other hand, were not known for high horsepower ratings, but had torque that could pull tree stumps out of the ground, and made it below 3k rpms.

 

Look here for a more in-depth explanation:

http://vettenet.org/torquehp.html

[gp90se]

Im going to take a different view on this

 

3.4 vs a 455

 

for shits and giggles, they both have 200 horse and 300 foot lbs torque.

 

The 3.4 having making the torque at higher RPMs will pull better when it reaches its max toque (around 4k) but wont get off the line well (little tire spin)

 

a 455 will pull a house off the foundation because its max torque is going ot be around 2200 rpms, but have no power high end.

[MoTox8410]

Horsepower is the force that determines how fast you hit the wall.

Torque is the force that determines how far you take the wall with you after you hit it

[gp90se]

thats why I said for shits and giggles, keeping it simple.

 

had an 80s regal with a 455, 3 outta the 4 wheels were sitting on the ground from the torque twisting the car so bad

[88Regal Limited]

Hp is how fast you can keep the car moving and accelerating. Toyque is how hard you can rotate the tires (helps get off the starting line) You want TQ at low RPMS and HP at Higher RPMS. 8)

[GutlessSupreme]

Torque is the only force your engine produces which can actually be measured. Horsepower is a calculated number, which reflects torque at certain RPMs.

 

x2 :withstupid:

 

Torque is how much work is being done.

Horsepower is (essentially) how fast that work is being done.

 

I believe the formula is horsepower = (torque x rpm)/5280, or something to that effect.

[Prospeeder]

the TGP is perfect, 225tq at 2100rpms and 205hp at 5200,

the 3.4 dohc seems a bit high for my tastes, 210/15 hp at 5200 rpms and 215 at 4000 rpms

[gp90se]

I owned a TGP, and just took my 3.4 car for a spin, the high end torque feels better launching....but thats an entire other debate I plan on starting when the GP is a daily driver.

 

High end torque is better for highway racing and merging.

[sdwhite]

One horsepower is the ability to lift 550lbs one foot in one second. It's a measurement of work over time.

 

One ft/lb of torque is one pound of effort on a weightless one-foot long rod connected to a shaft. It is a measurement of force.

 

Horsepower and torque are intimately related but very different measurements.

 

Generally, you'd like to have a high flat torque curve over the RPM band and an increasing horsepower curve.

 

My '70 350 creates 290ft/lbs around 2000rpms and peaks at 390ft/lbs around 3600. 330hp peaks at around 4500rpms...nice, cuz that's about where it shifts.

[z34Phoenix]

http://auto.howstuffworks.com/horsepower1.htm

 

personally i like the Tq on the DOHC it is great! since the 225's i have have limited traction there is no reason for me to have all 215+ ft/lbs off the line... well now that i think of it i would like to have it at like 3800 rpm. that would be just perfict for me... i guess after doing the 13* mod i'll be all good

[Canada]

My '70 350 creates 290ft/lbs around 2000rpms and peaks at 390ft/lbs around 3600. 330hp peaks at around 4500rpms...nice, cuz that's about where it shifts.

 

Actually, you would want to shift AFTER peak power. You don't weant to shift, until you are making the same level of power in your current gear as you would be in your next gear. Here is a good example.....its a chart of a dyno pull of a stock 3.4L DOHC and the Getrag 284 gearset, the idea is to shift when the lines cross.....this way you are making the most avalible horsepower all of the time.

 

 

 

 

 

 

 

 

Everyone has their own view of what horsepower and torque are.......yet know one understands it.....come up with whatever analogy you want (Power sells cars, torque wins races or Torque gets you off the line, Power gets you down the track...you name it), there all pretty far off. Dave Coleman has written many articles in SCC about this subject.

 

My verison?

 

Well....its....

 

HP = (TQ*RPM)/5252

 

I think that describes it best of all.

 

Just remember.....torque can be multipled by gear ratios for the cost of rpm.....horsepower stays the same, no matter what. (Assuming no drivetrain loss of course.)

[88Regal Limited]

Canada, you are too damn smart!

 

BTW lovein the avatar!