Pray

iTrader: (7)

I have heard that heavier wheels will effect dyno numbers/track numbers. But does any one know by how much? I swapped rims on my 02 Z06 to the Z06 Mtrspts. They are 16lbs heavier in the rear and 12lbs in the front. That seems like alot of extra reciprocating weight at the rears to effect dyno numbers. And alot of extra weight total to effect track numbers. After I swapped the rims I went back to the track and noticed that I was on average 2mph slower than a previous trip. However there was a +1,000 difference in the DA between the two days that should account for a mph or so.

The reason I am asking is. I am trying to break the magic 500rw mark out of my garage built, factory headed 383. I put down 487/442 SAE Corrected on a DJ yesterday. I did one last tweek that should have put me at 490/445 but ran out of time to verify. The only two bolt ons I have left are YT UL RR's (which are on order) and an EWP. I think together they will give me the extra 10rw I am looking for.

Alvin

iTrader: (2)

The heavier wheels hurt you most during fast acceleration. I built a mathcad sheet to figure the losses on a 400rwhp car by looking at a recorded run. An additional 15 pounds per wheel accounted for around a 2.5-3 rwhp loss.


They will hurt you most at the track where the wheel has much greater acceleration like in first gear.

Pray

iTrader: (7)

Thanks. So I am not loosing much of anything on the dyno, but I am being hurt on the track. That makes sense. The accelleration on the dyno is much slower so the effects are not as great.

Redlinez

iTrader: (5)

It does affect you just like a lightweight flywheel can boost your numbers on the dyno. Good to hear your Vette is flying! You could always bring an extra set with you and swap them to see.

PewterScreaminMach

iTrader: (7)

Think about how much more difficult it is to spin a wheel that weighs 40 pounds plus the weight of the tire versus one that weighs 55 pounds, then double that. PLUS just figure in the extra 56 lbs you added to your car of "unsprung" weight. They say a ROUGH estimate is a tenth for every hundred pounds or 10 hp. The wheels are going to lose you a few hp possibly PLUS add the extra weight for the car to pull. You may see a couple tenths difference. Then again, you may see nothing depending on how much other variables like the weather and track prep change.

Pray

iTrader: (7)

I should rephrase what I said about the wheels. The wheels as a total are 28lbs heavier. They are 8lbs each in the rear and 6 each in the front. On the dyno I am only turning another 16lbs.

Swapping wheels is a good idea but to me it isn't realistic to what you are going to be running on the street. It is great to get some awsome times with a drag pack and removed sway bar and what not. (Which I am going to do to see what my combo can really do). But when that guy pulls up next to you on your way home, you want to know what you can run. It's great if you can run low 10's on the track but if you only run 11's on the street then what good is it? So when I go to the track I run what ever gas I have, leave the tool box and other crap in my car and see what happens. That is just me. That is why I was wondering about the wheels. They are going to be on the car when it counts.

Thanks Redline. I just found another 10/10rw peak and 14-20rw down low. So we will see what it will run the next time the track is open.

rocksws6

iTrader: (4)

Something else to think about is the diameter of the wheel. For example if you were going from a 17 to a 19 and they are both the same weight the 19 is going to be harder to turn because of inertia. The weight is further from the center of the wheels in other words. So if you were going from a 16 to a 15 and they weigh 8 pounds more then its likely that its not going to make much difference at all.

DONAIMIAN

iTrader: (18)

Unsprung weight is bad weather you look at it as acceleration, deceleration (braking), and handling.

Redlinez

iTrader: (5)

You think like me. I left the child seat in, spare/jack and everything. I do try to get there with 1/4 tank or less though. A toolbox would have to come out though.

s346k

iTrader: (4)

my buddy went from a set of zr1 wheels to stock snowflakes and picked up 3 mph. made many runs on the zr1s @ 111 mph, switched the next week and went 114. wheels definately make a difference on the track - don't know bout the dyno.

Pray

iTrader: (7)

Redline. I love the looks I get when I take my daughter to the track. People come over to the car and see the childs seat, then I go out and run a high ten bottom 11. Priceless.

s346k. That is a huge gain. I don't think the zr1's are that heavy to begin with. Weather could have played into that some what. But any way. I am going to try to find some 16" Weld Draglights and make a poor mans drag pack. I want to know what the car can really do.

dug

iTrader: (10)

the zr1 wheels could have been aftermarket, which are known for being heavier than oem.

the flakes are light

s346k

iTrader: (4)

the weather had no effect. i raced my car both weeks (back to back) and my car was dead consistent. the wheels made a huge difference, if it wasn't the wheels we must've had a tailwind that apparently had no effect on my car haha.