Dyno Results And Wheel Sizes

[PASHEN]

The dyno measures tractive effort at the rollers. It doesn't matter what sort of car it is, what size wheels or what diff ratio or gear ratio. It doesn't even care who the driver is.

The dyno doesn't measure driveline losses, wind resistance, tyre resistance or weight.

Any figure taken from the dyno has to be manipulated by the software/operator in order to make figures the customer can relate to and is happy with.

People who use dynos to extrapolate absolute power figures are kidding themselves. It is a tuning tool ONLY.

I don't know how many times this has to be explained before it will be accepted as THE TRUTH.

I suppose however, that without dyno figures to talk/argue about, this forum would be a pretty boring place so ... ALL POWER TO THE DYNO!!!

<{POST_SNAPBACK}>

I hear what you're saying mate, and believe you. My point is that people who are modding their T'S are chasing RWKW and are paying big $$ in the pursuit of more power. We aren't dyno experts, and could be getting ripped off, or at least less than what we are paying for, if we don't know the difference.

In the last 4 months, APS, C & J Motorsports, and HPF have ALL said that the power figures would be different depending on what size wheels I had on at the time. It's just friggin frustrating, you know?

[Turbo6man]

PASHEN> Dyno operators will try to please their customers by providing figures/results/answers that they think the customer will be happy with. I don't trust any software or dyno operator to be able to provide reliable, repeatable outcomes.

If it is true that wheel sizes can alter the figures then that indicates to me a very poor software program or inept operator. Like I said the dyno measures ONLY one thing, tractive effort at the rollers. EVERYTHING else after that is calculated and therefore open to misinterpretation or errors.

[JB]

Good question Dave, so bigger means less rwkw reading????

Smaller means more??

Any tuners with their experiences?

[Cobra]

for sale : 50rwkw in the form of 3" rims

[PASHEN]

Good question Dave, so bigger means less rwkw reading????

Smaller means more??

Any tuners with their experiences?

<{POST_SNAPBACK}>

That's what I'm trying to find out JB. I hear what turbo6man is saying, but why the discrepency in figures?

Your 305rwkw what on 17's. Now that's you're riding on 19's, take it down to HPF and get them to dyno it - see if there's a difference?

[eatV8]

I am not sure about dyno, but down the strip it definatly has an effect. Bigger the wheel the more weight and rotating mass the power must try spin...

On a side note which may help work something out here. On a TV program here they were prepping a Acura/Honda Integra type R for race duties. After they fitted their big brake kit the power level @ the wheels dropped by about 10hp. The expert on the show operating the dyno said this would be because of the extra rotating mass of the brake assembly even though the race brakes weighed less then the factory set up.

[Cro]

I'm like you Cobra...my brakes wont allow for standard 17's to be fitted.

<{POST_SNAPBACK}>

From memory you just got the PBR upgrade which is just like the Ford Premium Brake option. 17's will fit around these.

[ktford]

Do wheel sizes affect the dyno result?  I mentioned that they do to Scotty last year and he pissed himself laughing.  Would like to hear from people who:

sorry Dave, it was a piece of Norman Hotel steak blocking my wind pipe ........ honest. Like Cobra, I'm seeking a set of minilites for BP, that'll screw 'em :lol:

Scotty

[PASHEN]

haha...twas a fine steak mate.

I'm now trying to find answers to the very reason you choked yourself laughing for.

[TBO240]

The dyno measures tractive effort at the rollers. It doesn't matter what sort of car it is, what size wheels or what diff ratio or gear ratio. It doesn't even care who the driver is.

The dyno doesn't measure driveline losses, wind resistance, tyre resistance or weight.

Any figure taken from the dyno has to be manipulated by the software/operator in order to make figures the customer can relate to and is happy with.

People who use dynos to extrapolate absolute power figures are kidding themselves. It is a tuning tool ONLY.

I don't know how many times this has to be explained before it will be accepted as THE TRUTH.

I suppose however, that without dyno figures to talk/argue about, this forum would be a pretty boring place so ... ALL POWER TO THE DYNO!!!

<{POST_SNAPBACK}>

so why do they use 1to1 gear ratio......traction effort is the torque reading in newtons on dyno chart which is not nm of torque and gear ratio will effect rwkws ...changing wheel size or inflation will change finale gear ratio.