jond

I was watching one of the car shows sunday, and they installed a big brake kit on a car. The brakes were bigger, but lighter. They lost 7whp.....
Their theory is even though the rotors were lighter, the mass was further out, and this caused quite a bit of whp loss.

This made me think of tire weights. The RE010's weigh around 19lbs and 205/50 Azenis weight around 22lbs I think. About 3lbs more. This being very far away from the center line, I would think, would eat up quite a bit of power.

Has anyone dynoed before and after installing Azenis, or any 205 wide tire?

OR does anyone know the math to figure it out? I would assume its around a 6ft-lbs of torque loss(2tires * 3lbs * ruffly 1 foot from the centerline)

If this is right, these cheap tires could be eating up $1000 of horsepower.

Art Vandeleigh

haha, i was watching the same show. sports car revolution on speed channel. they were testing it on the mugen sponsored rsx-s. i did find it very interesting that they attributed the hp loss to the rotors and not the larger diameter wheels. i would assume it would cause the same effect as the brakes...probably more so i would think......

RTW DC2R

just run on the r1m y0

hmmmm...as far as those big brakes and the loss of WHP is concerned...that seems like an AWFUL LOT of whp to lose from very slightly bigger diameter brake rotors. Id be willing to bet that more of the loss was attributed to ambient changes like temp, humidity, etc. Did they change wheels too?

Nick248

I dynoed my car back in 2000 with a set of badly bald Re010's (195/55) on a set of Rota Formels. These rims weight roughly the same as stock. It resulted in a figure of 179.xx

1 week later, I dynoed my car with stock rims and newer AVSi (205/50) and reulted in a figure 170.xx. Although not the same day, the temp, bar. pressure and humidity were almost the same. Nothing was changed, AT ALL, other than the tires and rims.

The AVSi's were heavier than the bald RE010's. I believe it was the weight difference that contributed to the delta.

..... just my past experience

-Nick

Tommy_Gunns

IMHO, the extra grip of the azenis is worth the weight difference.

RE010 = blah, I'm not impressed.

jond

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nick248 &raquo;</TD></TR><TR><TD CLASS="quote">...It resulted in a figure of 179.xx

1 week later, I dynoed my car with stock rims and newer AVSi (205/50) and reulted in a figure 170.xx. </TD></TR></TABLE>

9whp. Thats almost as much whp as a nice header.

^jefs0ng

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Art Vandeleigh &raquo;</TD></TR><TR><TD CLASS="quote">i did find it very interesting that they attributed the hp loss to the rotors and not the larger diameter wheels. </TD></TR></TABLE>

They lost a total of 12 whp or something because of the wheels AND rotors. After they put the catback on, they had a total loss of 7whp.

nsxtasy

The RE010's rock! Not only do they stick nicely (even when it's wet), but they give a great handling "feel". I love 'em.

ZygSpeed

I wonder how much the type of dyno being used (Mustang/loading vs. Dynojet/inertial) makes a difference in the detected/measured power generated by a car?

This would seem to be one of those cases where a loading dyno might give more realistic results in light of the changes made to the car. After all, the "car" (its motor) obviously didn't make less power because of a change to the brakes and tires.

Does make you think about having to accelerate a larger wheel/tire combo.

jond

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by zygspeed &raquo;</TD></TR><TR><TD CLASS="quote">I wonder how much the type of dyno being used (Mustang/loading vs. Dynojet/inertial) makes a difference in the detected/measured power generated by a car?
This would seem to be one of those cases where a loading dyno might give more realistic results in light of the changes made to the car. After all, the "car" (its motor) obviously didn't make less power because of a change to the brakes and tires. </TD></TR></TABLE>

I dont think it would matter. As long as both dynos are measuring Net HP(hp at the wheel), the weight of tires should show up. The percent loss should be the exact same on both dynos.

The gross hp wont change, but that can only be measured by taking the motor out of the car, and is kind of irrelevant number anyway. Irrelevant in the since that scoobys make 30 gross hp more than ITR's, but put down the same hp to the ground.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">The RE010's rock! Not only do they stick nicely (even when it's wet), but they give a great handling "feel". I love 'em.</TD></TR></TABLE>
Me too. I always thought people went to Azenis to save money, not for a better tire.