How much RWHP do those "heavy" wheels rob? Answers inside fresh from the dyno!
03-07-2006, 10:01 AM
#21
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St. Jude Donor '12
Originally Posted by topless99
could the higher gearing resulting from the taller tires have anything to do with this? There is over an inch difference in the height of these tires.
03-07-2006, 10:25 AM
#22
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Care to elaborate? It sounds like you are saying a dyno can't take gearing into account, which is false.
Do you mean something more subtle?
Do you mean something more subtle?
Originally Posted by Dan_the_C5_Man
No, that is incorrect (a common misconception); the measured "power loss" on an inertial dyno with lower gears (3.90's, 4.10's) is NOT due to "increased frictional losses", it is due to the rate the drum is accelerated over time (which is precisely how these particular dynos measure torque and ultimately horse power).
This whole thread shows the true value and accuracy of a steady-state dyno (Factory brand dyno, etc.).
This whole thread shows the true value and accuracy of a steady-state dyno (Factory brand dyno, etc.).
03-07-2006, 11:17 AM
#23
Melting Slicks
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St. Jude Donor '05-'06
Originally Posted by pianoprodigy
My test was as accurate as it could be. Would I have preferred to use the OEM 18" Z06 wheel in the rear? Sure, but it wasn't available. Regardless, my test is still completely fair and accurate with regard to its results.
Dave
PS I will be trying this same thing soon and will post results as well.
03-07-2006, 11:21 AM
#24
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St. Jude Donor '05-'08
Originally Posted by LV Vette
I think this post just increased the value of the old wagon wheels for using as drag wheels only. Correct me if I’m wrong, but aren’t they about the lightest and strongest wheels in 17 and 18 inch sizes?
Thanks,
Clayton from Las Vegas
Thanks,
Clayton from Las Vegas
Wheels
19.2 lbs, front; 21.4 lbs, rear - 97-99 OEM wagon - Src
22 lbs, front; 29 lbs, rear - 97-99 OEM wagon - Src
17 lbs, front; 19.5 lbs rear - 97-00 OEM magnesium - Src
17.5 lbs, front; 19.5 lbs, rear - 97-00 OEM magnesium - Src
18.08 lbs, front; 20.06 rear - 00 OEM standard, thin spoke, high polish - Src
17 lbs, front; 20 lbs, rear - 00 OEM standard, thin spoke, painted, no sensors or centercaps - Src
16 lbs, front; 20 lbs, rear - 01 OEM standard high polish - Src
19.6 lbs, front; 21.4 lbs, rear - 01 Z06 forged - Src
19.2 lbs, front; 21 lbs, rear - 02-04 Z06 cast/spun - Src, Src
24 lbs, 18x10.5 - 00+ repro high polish - Src
28 lbs, front; 32 lbs, rear - Z06 chrome repro - Src
23 lbs, front; 26 lbs, rear - Z06 chrome repro - Src
23.5 lbs, front; 24.5 lbs, rear - Z06 Motorsports, polished - Src
20 lbs, 17x8.5, 58mm offset, front; 23 lbs, 18x9.5, 65mm offset, rear - PWO - Src
22 lbs, 18x10.5, 58mm offset, front - HRE 545 w/clear center - Src
27 lbs, 18x12, 74mm offset, rear - HRE 545 w/clear center - Src
24/25 lbs - Z07 wheel weight, front - Src
28 lbs - Z07 wheel weight, rear - Src
03-07-2006, 11:27 AM
#25
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St. Jude Donor '05-'08
thanks for the write-up.
I have been trying to tell people that this additional mass although doesn't sound like much really has an affect on the car.
01 Polished Thin spokes weigh up to 12lbs per wheel less than Z06 Repros. That is 48 lbs and basd on your numbers 16 rwhp
I have been trying to tell people that this additional mass although doesn't sound like much really has an affect on the car.
01 Polished Thin spokes weigh up to 12lbs per wheel less than Z06 Repros. That is 48 lbs and basd on your numbers 16 rwhp
03-07-2006, 11:36 AM
#26
Safety Car
Originally Posted by Dan_the_C5_Man
Wait a minute, hold on, can't believe someone hasn't caught on to this yet..
There is a 4.2% difference in the rolling diameter between the two wheel / tire combos.
Is it a coincidence that there is a 3% difference in the power output between the two?
Everyone knows (or that understands how a Dynojet dyno operates) that the effective gear ratio (like running 4.10's) has an effect on the numbers as compared to the "standard", i.e. stock C5 w/ stock wheels and tires.
So I'm not saying that the extra weight of the combo had zero effect on your results, I am saying that the total rolling diameter delta probably had as much or more of an effect than the extra weight.
Gotta compare apples with apples, which did not appear to happen in this case.
There is a 4.2% difference in the rolling diameter between the two wheel / tire combos.
Is it a coincidence that there is a 3% difference in the power output between the two?
Everyone knows (or that understands how a Dynojet dyno operates) that the effective gear ratio (like running 4.10's) has an effect on the numbers as compared to the "standard", i.e. stock C5 w/ stock wheels and tires.
So I'm not saying that the extra weight of the combo had zero effect on your results, I am saying that the total rolling diameter delta probably had as much or more of an effect than the extra weight.
Gotta compare apples with apples, which did not appear to happen in this case.
03-07-2006, 11:48 AM
#28
Melting Slicks
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St. Jude Donor '08
Originally Posted by Wicked Weasel
Here are the weights
Wheels
19.2 lbs, front; 21.4 lbs, rear - 97-99 OEM wagon - Src
22 lbs, front; 29 lbs, rear - 97-99 OEM wagon - Src
Wheels
19.2 lbs, front; 21.4 lbs, rear - 97-99 OEM wagon - Src
22 lbs, front; 29 lbs, rear - 97-99 OEM wagon - Src
I have seen this info many times, why the difference in weights for the same wheels?
Can anyone explain?Thanks,
Clayton from Las Vegas
03-07-2006, 12:13 PM
#30
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St. Jude Donor '05-'08
Originally Posted by LV Vette
I have seen this info many times, why the difference in weights for the same wheels? Can anyone explain?
Thanks,
Clayton from Las Vegas
Can anyone explain?Thanks,
Clayton from Las Vegas
my guess is different suppliers. I will see what I can find
03-07-2006, 01:13 PM
#31
Burning Brakes
What’s the repeatability and accuracy of the dyno?
Can a dyno produce repeatability within 4%?
How accurate is it? How was it calibrated?
My guess is no. But I really don’t know.
Can a dyno produce repeatability within 4%?
How accurate is it? How was it calibrated?
My guess is no. But I really don’t know.
03-07-2006, 01:13 PM
#32
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Originally Posted by LV Vette
I have seen this info many times, why the difference in weights for the same wheels? Can anyone explain?
Thanks,
Clayton from Las Vegas
Can anyone explain?Thanks,
Clayton from Las Vegas
Sorny
03-07-2006, 01:32 PM
#33
Burning Brakes
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This thread has made me feel a lot better about buying 04 polished Alum. Z06 factory wheels instead of the heavier repos. Thanks..... 
Last edited by Chuck01; 03-09-2006 at 10:35 AM.
03-07-2006, 02:00 PM
#34
Unsprong weight
Piano thanks for the post I think it was very informative. I think we can all see what you suspected and proved. I think the road racers would support you for more than the loss of HP. Braking and handling are also great effected by increased unsprung weight, rotating or not!
Thanks again!
Thanks again!
03-07-2006, 02:52 PM
#35
Le Mans Master
Originally Posted by jmautox
Care to elaborate? It sounds like you are saying a dyno can't take gearing into account, which is false.
Do you mean something more subtle?
Do you mean something more subtle?
If not, we'll simply agree to disagree.
A quick search on the net yielded these documents, http://www.enginelogics.com/dynod.html, http://www.sdsefi.com/techdyno.htm and there are many, many others on this subject.
03-07-2006, 03:06 PM
#37
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St. Jude Donor '08-'09
Originally Posted by Wicked Weasel
my guess is different suppliers. I will see what I can find
The Weights and measurements thread where those numbers came from are a compilations of different posts forum members have made over the years. I suspect that 22/29 lb stat is a set of repros since every stat I've come across over the years rates the OEM 97-99 wheels as 19.2 lbs, front; 21.4 lbs, and the Y2k wheels as being 19/20 lbs.
03-07-2006, 05:03 PM
#40
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Very informative. When I switched to after-market wheels my #1 priority was they had to be lighter than stock (2003 Z06) which are already light. Every other characteristic was secondary. It did not take long to discover that light weight (like power) cost big money. The wheels I finally settled on were lighter than stock by 1.5 lbs even though they are wider but; they cost 1200.00 dollars each. Alternatively; you could buy heavy wheels and spend the X-tra $ on horsepower. Thanks for the information!