Dynoed today

[12secondv6]

Interesting.

Well.... my soon to be 4:10's... are forged and lightened by 6 lbs ;)

[HAZ-Matt]

Originally posted by OneQuickV6:
Correct. It's only power as seen by the dyno though, like stated earlier, the motor's still making the same power.

I'm not sure what exactly you mean. Whether on the street or on the dyno, with lower gears you are still accelerating everything from pistons and rods to the torque converter impeller, gears, driveshaft, axles, etc. at a higher rate. The motor does lose power because you are accelerating it's reciprocating mass more quickly and that takes more force (granted most of this does not equate to much horsepower).

[Just Another V6]

Originally posted by 12secondv6:
</font><blockquote>quote:</font><hr />Originally posted by OneQuickV6:
</font><blockquote>quote:</font><hr />Originally posted by Just Another V6:
tire psi on dyno means nothing...

Pardon?? I've seen 30rwhp swings because of tire/wheel combos, on multiple occasions! Please don't fill this forum with false statements..it's one of the last on the board that is still untainted. </font>[/QUOTE]100% true!

A GOOD dyno shop will ask if you have dynoed before and what tire psi.

I have been to....countless dyno shops and put my bird on countless dyno's.

Tire PSI WILL affect dyno #'s/ graph.

To put it in lamens terms.

I take a car (DOES NOT MATTER WHAT KIND) and I have 15 psi in the tires and make a run on the dyno

I then raise the tire psi to 40 and redyno.

Comparing a rotating tire/ wheel combo of 15 PSI vs 40 PSI, which has MORE and which has LESS rolling resistance?

My example is one of somewhat extreme's... but... seems like an easy way to provide one basic example of how tire PSI would affect dyno #'s

Just Another... quit the crap talking! </font>[/QUOTE]WTF? Thats exactly what the hell Ive been saying. Tire PSI doesnt increase your engines HP! It makes the rollers think that there is less resistance. WTF! Are you guys not able to comprehend?

[arthansen]

I have been using a formula to calculate rolling friction and the HP to overcome the friction. I plugged some numbers in the equation and came up with the following information.

At 139 mph (which is where my car topped out on the dyno), it takes 59 hp to overcome the rolling friction of 2 tires (only ones that mater on a dyno)with the tires at 15 psi. With the tires at 40 psi, it only takes 18 hp to overcome the friction. This would result in a messured HP difference (on a dyno) of 41 hp at 139 mph.

Hope that makes sence.

[ January 24, 2005, 02:45 PM: Message edited by: arthansen ]