What makes torque?

[Makaio]

I've noticed in a lot of posted dyno numbers how HP and TQ values differ greatly. Some of the guys making "X" amount of horsepower make more torque than guys with the same or 'close to' horsepower output. What mods increase torque?

Aloha,
Matt

[KTA]

The lower the rpm you make your horespower at the greater the torque. The turbocharger, injectors, timing, and camshaft all can greatly effect your torque.

[Makaio]

KTA,

PM sent. What I was getting at was how come two trucks with pretty much the same mods, just different brands of parts, and one will make 350/750 and another will make 320/860? Or are the dyno numbers inaccurate? I know every pump reacts differently but, shouldn't dyno numbers be pretty close with the same mods?

Aloha,
Matt

[swank]

i'm guessing in that situation, timing is a major factor. advance the timing and the #'s get closer together, retard for the opposite effect. (i think)

is this correct, brian?

[KTA]

That is what I PM'd him when he asked. The other factor is almost the same mods is not the same as the same mods. I have seen big diffrences between diffrent vendors products as to how they actually perform. For example 370's are NOT the same as DDP's similar but not the same, therfore you can expect a slightly diffrent curve.

[Makaio]

Thanks Brian and Dave. Yeah, makes sense with timing. When I had mine just a tad more, the truck pulled like a son-of-a-b****. I backed it down a hair cause the other half said it was too loud.

Aloha,
Matt

[dpuckett]

KTA, What I was getting at was how come two trucks with pretty much the same mods, just different brands of parts, and one will make 350/750 and another will make 320/860?

The other guys pretty much answered this, but I will add a differnet angle. One must consider at what RPM you are getting x HP and y torque. If they both make a max of 350hp, at 2500rpm, but one is making 110ft-lbs more torque, then he is making the more HP lower in the power band. It goes back to the equation (and correct me if I have my variables in the wrong spot)

HP= Tq(RPM)/ 5252.

Plug in numbers for a lower RPM, with all else equal, and your torque will go up.

Daniel[/b]

[CAJUN 93]

i've seen that formula before and the weird thing is if you use it hp and torque are equal at 5252 rpm. it has to be mathmatically. i've seen dyno sheets that dont support that.

what i wonder is do chassis dynos measure hp and tq or do they measure one and then calculate the other based on rpm? if thats the case do they take into account acceleration rates? enquiring minds want to know...

daryl

[KTA]

A dynojet or other inertia dyno measures hp and calculates torque. A mustang or a load dyno measure torque and calculates hp. Some dynos like a dynocom are capable of doing it both ways. The numbers SHOULD be the same either way if the dyno is calibrated correctly. Many dynos are not calibrated, the owners just plugged them in and went. If a dyno sheet shows hp and torque not crossing at 5252 it is wrong, assuming of course the scales are the same. Alot of sheets they don't cross at 5252 because the hp scale is diffrent from the torque scale.

[CAJUN 93]

yeah, i got into a heated discussion on a gas site a few years back cause i said hp an tq have to be = at 5250 because hp is a function of tq. he said they were independent of each other. it got into a physics discussion and i conceded defeat due to possibly looking like as much of a fool as he did if it kept going .

seems to me that comparing dyno results from different machines is about the same as comparing cylinder head flow numbers from different flow benches. kinda futile.

daryl