That sounds logical to me.

 

If the larger rims weigh considerably less than the smaller ones maybe. Another factor is the size itself. Since torque = Fd, (F being force, d being distance) increasing the radius of the wheel effectively lowers the force that the tire applies along the ground for a given amount of torque. So for the same weight wheel and a set amount of torque applied to the axle, a larger wheel will produce less power on the dyno than a smaller one.

 

right, but on low profile tires, you could conceivably increase the rim diameter, and decrease the tire height, leaving you with a larger rim size, but the same overall tire height, correct?

 

correct, so if you have larger rims with lower profiles that keep the diameter the same, and they weigh less, then you could be applying more power to the ground. But you would be running some mighty low profiles on 19s to do that.. talk about buuumpy! Not saying they didnt though, it is entirely possible.

 

yeah...you'd be riding on a pretty thin strip of rubber, huh

 

I like this post even though it's an old question...brought out some logical thinkers. ^ ^ Now this is how the rest of the forum should be have. ^ ^

 

Put it this way... you would have one hurtin bladder

 

lol!

 

This is from a stock Scion tC, dynoed in 3rd gear:

http://www.draxas.com/dynos/StockScion-tC.jpg

 

Thanks for posting

 

That should be 143.49 HP... the 153.41 is the TQ. This car was indeed stock. Dynoed at R&D Dyno in Gardena, CA... owned by Phillip, the current President of the SoCal tC Club.

We are set to do another dyno very soon with K&N Intake, AlphaWerks Header, Draxas S-PIpe and Draxas Exhaust...

 

Most Ive seen are about 140+- a few each way. It really depends on too many things to give something exact.

 

hmmmmm, i have a question...if torque = force x distance...wouldnt the further away the force is from the radius mean more torque...so larger wheels would mean more torque? for instance...lets say a force of 1000# at a distance of 2 inches would be a torque of 2000...and then a force of 1000# at a distance of 4 inches would be a torque of 4000...isint 4000 greater that 2000? engifineer...tell me where the mistake is in my logic...cuz something doesnt make sense...

 

The Force is the force applied from the wheel to the ground, the torque is applied at the center of the wheel, or the axle, so the formula T = Fd, reworked to solve for the actual force transmitted to the ground is F = T/d. So if d (the radius of the wheel in our example) grows, then the actual force applied to the ground or dyno (or F) reduces. I am almost 99% sure that the dyno results spoken of here are not calculated to account for wheel diameter. So as far as the force actually applied to the ground (the force that is moving the car) is concerned, the larger wheel = less effective force for a given engine torque and wheel weight.

Ok... if I messed up any of that.. bear with me.. I have had a couple of beers this evening

 

hahaha oops........ like i really give a ____ though......

 

boo..i hav an auto..oh well..any idea on how to get rid of some throttle lag besides grounding kit and torque damper?

 

Neither one of those will remove throttle lag. Throttle lag is a result of the drive by wire setup; there is a delay between input of pedal actuator, and output from ecu to TB. Neither a grounding kit (supplying more ground wires to the chasis/frame), nor a torque damper (prevents engine from "torque twisting") can help electronic programming delays.

 

Can you elaborate a little more on that please? What is a drive by wire setup? TB? Ground Wires? "torque twisting"?

Thanks in advance.

Greg

 

Older cars used to have an actual cable connected the gas pedal to the throttle valve of the engine. A throttle valve opens or closes, to allow either more or less air to be mixed with fuel. So techincally, all these years, we've been misnaming the right most pedal...it's really the "air pedal". Some newer cars have removed this in favor of "Drive by wire" which is basically an electronic setup. The throttle response is computer controlled, not physically controlled like the older cars. The idea here is supposed to be a more econimical setup, as far as gas mileage goes.

The throttle body (sometimes referred to as TB) houses the thottle valve. All it does is controll the amount of air the flows from the intake manifold, into the engine, where the air is mixed with the fuel.

Ground wires. That should be self explanatory....they are wires that ground the electrical system on your car. There's a lot of debate on them, in regards to adding horsepower (by means of creating a stronger spark at the spark plugs, I suppose) as well increasing current for electrical systems. You'll have to form your own opinions in regards to what ways ground wires can help.

"Torque Twisting"....I'm not sure that's really an actual term, it's really something I made up. The idea here is this: if your car is in neutral (or neutral/park for an auto), and you open the hood with the engine running, and you gun the engine, you'll see the engine "flex", or "twist". What's happening is the engine is producing centrifugal force (circular motion), and the amount of force (torque) is enough to cause the motor mounts to give a little. While this isn't a huge deal, if you are racing, tenths of a second is not only an eternity, often it is enough to determine the winner, and the first person to lose. So the engine damper acts as an extra brace to keep an engine from flexing (torque twisting) as much, which keeps *both* drive wheels firmly planted, which equals better traction. Without the damper, if you stomp the "air pedal", you can more easily feel one of the wheels struggling for traction as one side of the engine is flexing.

Hope this helps.

 

i always try to explain by telling people to go look at their lawn mower's throttle LOL