TeamRX8

iTrader: (25)

you buy it for the potential, the actual number would vary by the course, the driver, the position of the stars, etc ....

TeamRX8

iTrader: (25)

Unfortunately 50/50 weight balence and good camber curves alone don't define a vehicle's handling balance. I suppose it's easy to make wisecrack's when you're following somone elses footsteps rather than blazing an unknown path ... or perhaps you exceeded OSHA's ppm breathing limit on Hoosier A6 fumes

Sparky

You make it enticingly easy.

altiain

iTrader: (3)

Because it offers an advantage, however small. In a sport where events are often won or lost by a few thousandths of a second, why wouldn't you buy that advantage if can afford to?

Somehow I have a very hard time believing that 28lbs of unsprung weight was worth up to .75 seconds on a 60-second course (just extending your own math to the typical course length used for comparison's sake.) A tenth or two? Maybe. Three quarters of a second?

ULLLOSE

iTrader: (1)

I am sure on the scales or on a dyno you could see a difference in wheel weight. With a very high end data system and only doing segment times you might see a difference on course. A run is to long and there are way to many chances to make a mistake to "see" a difference during a run. If you brake a course into segments, slalom, skidpad etc you might be able to find some time in one section but chances are the driver will make a mistake and give it up on some other part.

A prime example of this is the Packwood prosolo. Joe G ran STOCK wheels on sat with 50+ run old tires and was in 2nd place about .5 behind me. On Sun he put on his SSR light weight wheels and fresh tires he improved .3 total. So do you think Joe found his .3 because of new tires and light wheels or because he learned the course?

btw I made no changes and went .8 quicker on Sun.


Also at a local event I did one run in another guys RX8 that had an alignment he did by hand with a string and a set of V710s, was on stock shocks, swaybar and exhaust. One run in that car with him as a passenger was good enough for 2nd in BS only behind my own car by about a second. I have no doubt without him in the car and a few more runs to adjust to the stock suspension I would have been within tenths of my fully setup car.

The only significant improvement you can make to the RX8 is tires. Everything else, shocks, alignment, weight etc is tenths of a second at best,

Lets be serious everyone thinks their butt dyno is right on, but look around and you will see clowns on here telling you that the grounding kit they installed made the car faster.

rotor-te-rex

Do you run 3 runs Saturday and 3 runs Sunday at Pro Solos? If so:

Joe Goeke........Jason Isley
29.569..............29.543
30.911.............30.586
60.480..............59.898 delta .582 seconds

29.543..............29.092
30.528..............30.003
60.071..............59.095 delta .976 seconds

I really doubt it takes a driver like Joe Goeke or you a full 6 runs to find their best times. He was 4 tenths faster on Sunday and you were .8 tenths faster but all your fastest times were significantly faster on your last run which tells me you were sandbagging (.325-.6 faster per course on last run Sunday vs. runs 4/5).

Just out of curiousity, which times are left turns and which are right??

Pure speculation. A full second cannot be made up by kicking out a passenger. What minor adjustments? Sometimes having a passenger helps depending on car balance and predominence of turns. I recall being within .6 tenths of Ian Stewart with both of us in my Altima. Then I got out and his times stayed the same and I got slower never matching my first time.

ULLLOSE

iTrader: (1)

At a Pro you run four on each side Sat and two on each side on Sun. Looking at the Packwood results the top row is the left side course.

You are correct I typically do not find a lot of time from my first run till my last. The left side course at Packwood I sat on my very first run until my last run Sun when I finally nailed the finish. On the right side course I sat on my 2nd run until my last run on Sun, the big time pick up on the right side course was I downshifted for the turn around, which I had not done on Sat. I can assure you there was no sand bagging on my part as I do not care about the challenge competition, my goal every time is to win.

As far as how much time is a passenger worth, in my car it is almost exact, on asphalt on a 60 sec course I kick out an average passenger, 180 lbs, I pick up .5-.6 almost ever time. We just did a practice event on an 82 sec course and the three runs that I did not have a passenger were .7-.9 quicker than the 9 runs with. If your car is faster with a passenger you have something wrong with your setup. The RX8 is a somewhat low weight low powered car and every car is different. In my Corvette a passenger was only about .3 secs. In our Miata it could be as much as .8 on a 60 sec course.

TeamRX8

iTrader: (25)

not necessarily, it's course dependent. If a course is clockwise and has a lot of sweepers with minimal acceleration stretches having a passenger will help you run faster times. I've seen it firsthand, slower CCW and faster CW

as usual, it just depends ...

rotor-te-rex

From a January 2004 Dixie region event. We made our first two runs with both of us in the car, and our last runs separately.

STX Stewart, Ian Nissan Altima 56.15 55.421 59.444+2 55.492 DNF 55.421
STX Milstead, Cole Nissan Altima DNF 56.098 56.639 58.757+1 56.699 56.098

I weigh about 245 lbs compared to Ians 165lbs at the time (he looks like he has gained some weight since graduating). Unfortunately, it was a counterclockwise course so I can't use that as an excuse.

But I do speculate that with such a front-heavy car, my weight was aft of center of gravity giving the car more oversteer with both of us in it. You note that after 2 runs we were close. Then he stayed about the same separately while I got much slower.

StrokerAce

Another thread Coled to death by the dreaded Cole Context Switch. Is there no escape?

mwood

Back to the actual topic...hey, someone has to reign things in and pull us back from the netherlands of thread hijacking...

I received a response from John at CCW and he can make a set of Corsairs that would weigh between 17 and 17.5...for $2600/set.

I also sent emails to Kodiak and Bogart, just to see what their deal is...still waiting for repsonses.

The OZ wheel is starting to look really good...about 18.08lbs and you can get a set for about $1200.

Can anyone answer why the gold center Mazdaspeed wheel would be so much lighter (about .75lbs) than the gun metal grey center? It makes no sense to me, at all...

ULLLOSE

iTrader: (1)

Bogart can't help you, they don't do 18"s. Try Circle racing.

Even the guys at Mazda could not tell me why or cofirm the weight. I guess they could be from a different vendor, would not be the first time.

Call up Mazda Comp and order one of each color and send back the heavy one. Go for the Mags $$$$bags.

mwood

Another option is to do a group buy on the Kodiak wheels...maybe 16.5lbs for about $1900 set?

If there's enough interest, I can coordinate, I suppose...

Hi Flying 8

iTrader: (2)

Count me in if you can get the Kodiaks for that price. I just got off of the phone with them and got prices of $665.00/ wheel for one set and $566.00/wheel for two sets. That would be a great deal. Make sure you are talking about the 18x8 that has the offset as close to 43.65 as possible.

mwood

I spoke with Daryl right after you did

PM me for details...you'll be pleased with the numbers, including possible weight of the final product, once optimized...that is, if he can deliver on what he feels is possible!

Also, I plan on trying to include the Solstice autocrossers in this group. They are hurting for a good lightweight wheel option. Yes, they do have a different bolt pattern and may want slightly different offsets, but both those dimensions come in very late in the machining process and are easy to accomodate in a single build group.

mwood

Well, after putting out some feelers and considering the effort that would ultimately be required to put this deal together, I'm thinking that I'm going to bag the idea of putting together a group buy of Kodiak wheels.

I do believe there is a niche the Kodiaks could fill very well, the need for a reasonably priced true autocross/road race rim in the 18x8 size, that is not being served since SSR was bought by Tanabe. But, I just don't have enough upside to go through the hassle of organizing a group buy and deal with people's time frames and issues. It seems the guys serious enough to put up with any error in fitment or machining in the first delivery, which is quite possible with Kodiak, are few and far between. Most folks just want a decent rim with no pain, which is totally understandable!

TeamRX8

iTrader: (25)

it's not the first delivery, I worked through all that for you guys in 2005 ...

mwood

Right.

Still, if the wheels are quoted two month delivery and show up in three (or some other issue), I'll still have to deal with people who now feel that they're my "customers" ;-)

I may just try to get about 3-5 RXclub buyers to order at the same time, at least that way we can get a big price break...

TeamRX8

iTrader: (25)

I agree a GB would likely end up being a total PITA

Hyperborea

Given that you need a second set of wheels to put those tires on what would you use out of what is currently available for someone with no plans for national level competition? What do you use?

Thanks

mwood

Option 1: buy a set of used OEM 18" wheels for about $400/set
Option 2: buy a set of OZ Ultraleggera 18" wheels from tirerack for $1300/set

The OZ's will be about 5lbs lighter per corner. As far as the benefit of lighter weight, refer to the bit below, which I stole from the Solstice site (after a number of their less enlightened members questioned my pursuing 16lbs. wheels):

(regarding the value of lighter wheels)Just how much you ask? I defer to an equation from car guru Dave Coleman.

Effective weight of rotating mass = 1/2 weight(( wh radius x gear ratio x final drive ratio) / ( tire radius))

Effective weight means how much sprung weight you would have to remove to equal an unsprung weight reduction. Of course,with each gear change, the effect lessens.

So, for first gear with a 23lb, 18X8 wheel, in first gear (3.75:1), final drive of 3.91:1, and tire radius of 13.35 => 113.68lbs effective weight of the wheel.

With an 18.4lb 18x8 wheel, in the same gear, same final drive, and same tire => 90.94lbs effective weight of the wheel.

That is a 22.74lb per wheel difference in 1st gear. Your car will feel as though it is 90.96lbs lighter in first gear just by changing your wheels.

Reducing the OD of the tire on the lighter wheel will increase this effect making the car feel even lighter.

Physics can be stranger than fiction


Ooops, I see now you weren't asking my opinion, well I've given it anyhow...now it's Jason's (ullose) turn... :-)

ULLLOSE

iTrader: (1)

If you have no plans of Natl level racing there are two ways to go. #1 What I did back in the day before I spent all my time and money on autox was buy some cool street wheels and use my stock take-offs for racing. Option #2 if you are not into bling and don't care about cool street wheels just buy a second set of stock wheels to race on.

I use SSR comps, bought them two years when we bought the car and they were the only off the shelf BS legal light wheels I could find.

If I were going to do it now with the options out there I would go for the OZ, which is what I have for the street right now.

TeamRX8

iTrader: (25)

without knowing the true inertia difference it's an exercise in futility; it's not the weight that counts, it's the distribution of weight relative to the rotational axis and the biggest place to cut weight is in the hubcenter section, which is at the minimum radius i.e. minimal inertia change. It's entirely possible for a lighter wheel to have a higher inertia than a heavier wheel, physics can be stranger than fiction ...

mwood

I think the example above uses a constant for weight distribution...but, I didn't even stay at a Holiday Inn Express last night so wtf do I know?

StrokerAce

I'm dubious of the value of the lightness from a acceleration point of view. In a pure rotational view there should be virtually no observable difference to maintain a speed (rotational velocity). The difference in acceleration and deceleration would depend on the rate of change. For almost all cars that is very very small because they just don't accelerate the wheel a significant amount. If anything it matters more for braking because I doupt there is any car sold for the street that can accelerate faster than it can brake. And there it might actually help keep the wheels from locking under braking. No the primary benefit (IMO) is from the lower unsprung weight acting on the springs and shocks. The lower the unsprung weight the better the shocks can control the movement of the suspension in response to road conditions. With Forbes field being so rough there was extra emphasis on the shocks ability to control the tires and keep them in contact with the pavement. Moving to Heartland Park's smooth asphalt reduce the benefit of the lighter wheels (and uber shocks).

On my miata I did back to back runs with 11# and 15# wheels. Not doupt you could feel the difference. The lighter wheels did seem to be better through a section of rough pavement. However any easily measurable difference was easily within the run to run variation.

That being said I'd just as soon have the lighter wheels. (if only to make the changing easier) However I won't delude myself that they are what's keeping be from improving on my best nationals finish.

Ray