tjZ06

Hey all, I'm looking at doing the Mojave Mile this year. I was wondering if you had opinions on what the appropriate tires for standing-mile events would be? Safety is my number one priority, performance second. I've never been much into drag racing (about two dozen passes in my ~12 years driving) but for some reason the standing-mile events sound like a lot of fun.

The car is a '02 Z06 with a ~600RWHP LS7-based 427. It has a whole host of road-course mods (big rad, oil cooler, ps cooler, trans/diff coolers, roll bar, harnesses, alignment shim/locks etc. etc.) and is getting Pfadt coil overs, upgraded hubs/bearings all around and spherical bearing bushing replacements (has VBP poly right now) before the event.

I'm planning to back off my alignment to very little neg camber, zero front toe (should I think about a hair of toe-in for high speed stability?), etc for the event.

I have a few tires available right now. I was thinking I'd run on my RA-1s (shaved and heat-cycled, but barely used beyond that). They actually provide very good forward traction, but not as good as a drag radial. I think they're better suited to nearly 200mph (I figure I'll probably go ~180ish if I can learn how to do this whole just go straight thing ) than a drag radial. Then again, there are some nearly 200mph drag radial cars in the 1/4. But I'd think a standing-mile would build up more heat in the tires than a 1/4?

I have 4 full sets of stock C5Z wheels (one w/ 710s, one w/ the RA-1s, and 2 empty) so I can certainly pick up some other tires for the event.

Thoughts? Any other things I should be looking at addressing on the car before attending?

-TJ

Sidney004

This one has the proper speed rating:
http://www.conti-online.com/generato...s/vmax_en.html
but 19" wheels(I presume to reduce RPM and heat.)
You would need a minimum of a (Y) speed rating.
"Tires with a speed rating higher than 186 mph (300 km/h) are indicated by a Y in parenthesis.[citation needed] The load rating is often included within the parenthesis, e.g. (86Y)."

John Shiels

proper rating for sure! Drag radials are for sustained speeds I assume if they are rated Y? Have all the required safety equipment to fun at that sppeed the group requires?

c4cruiser

A one mile drag race may not necessarily require a true drag radial. Given the distance, there may not be a requirement for extreme traction at launch or through the lower gears. You will be traveling at much higher speeds for a longer period of time compared to a 1/4 run.

I would think that something like 710's would be more suited to this type of event given the speeds to be encountered. Handling at high speeds will be a factor (even though it's still a straight line ) so a road-race type of tire might be better suited to this type of event over a drag radial. I would also start at the recommended air pressure you would use for a track event.

With the HP you have on tap, you may have to feather the car off the line and accelerate at a rate so the tires are at the edge of maintaining traction and not spinning. I would also avoid a water or bleach box before going to the line. With road race tires, you will want them dry. You cold heat the rears up a little with a mild burn-out.

63Corvette

I ran NT-05s at the Texas Mile. Many others also ran those or PS-2s or other appropriately speed rated street tires. Only a few VERY high hp (over1000rwhp) cars chose to run drag radials because they had no traction thru 3rd gear or so.
I don't personally agree that a 30 second run equates to "sustained high speeds".
IMO your RA-1s should be fine. There is virtually no heat buildup in the standing mile run. The only tire heating occurred during burnout for those doing so.
NOTE: Texas Mile had only .5 mile runoff. At my speed of 163 this was simply not an issue. However, for those running over 200mph (Top speed of the Meet was a Hayabusa at 261.5mph) the braking required from those speeds probably caused significant wheel/tire heating.....as well as other significant sphincter pulsations.

Sidney004

Tires designed for very high speed use take into account the centrifugal force(2000 G's at 200mph on a 30" diameter,) bead design and proper pressure recommendations for those speeds in addition to heat build up. Non rated tires may very well be capable of short duration high speeds as well.

tjZ06

I intend to run one of my sets of factory C5Z wheels, which are 17x9.5 & 18x10.5, no more 19s for me (I sold my CCW 505As a long time ago). My car has MN6 gearing, not the stock M12, so 5th gear is .74:1 but it has a stock-ratio 3.42:1 diff in it. My RA-1s are 305/35-18 in the back, for an approximate diameter of 26.4" and I spin the motor to 7k rpm.

So that breaks down as:

7000 RPM 217.24 MPH
6500 RPM 201.72 MPH
6000 RPM 186.20 MPH
5500 RPM 170.69 MPH
5000 RPM 155.17 MPH

I don't have the power to get to redline in 5th in one mile, so my gearing is probably good but not ideal. Of course, I didn't build the car optimizing around standing mile.

Just for giggles, if I were to switch to 3.90s it'd look like:

7000 RPM 190.50 MPH
6500 RPM 176.89 MPH
6000 RPM 163.28 MPH
5500 RPM 149.68 MPH
5000 RPM 136.07 MPH

If I could modulate the throttle in the first two gears, I think I'd probably pull a higher MPH w/ the 3.90s. Of course, if the tires just go up in smoke and I waste a lot of ground that might not be the case.

I have the safety equipment required by the group to run up to 190 MPH.

Another consideration of the standing-mile is that you are running for terminal MPH, not ET. A lot of drag racers note that they MPH a bit higher on runs with a slightly slower 60', and resulting lower ET.

Certainly the first 60' or even 100' are nowhere near as critical in a standing-mile as they are in a 1/4.

On the street the car hooks 2nd gear pretty well on the RA-1s, first is nearly useless. I have no idea if the runway has more or less traction than a typical street.

With respect to the water box, you never want to leave your tires wet. Proper etiquette is to pull around the water box and back into it. Thus the front tires don't end up wet and carrying water up to the starting line or onto the track. The burnout will take care of any water on the backs.

Did any of you happen to take tire temp readings? Or before/after tire pressure readings?

Thanks everybody,
TJ

AtomicZ

The RA-1s will be just fine unless you have a hard time putting the power down 1st - 3rd gear. Then you may need to look at drag radials. At you power level I would think you are fine. A soft launch and hit it.

tjZ06

Thanks for the input. On the street 1st is pretty useless. Given good conditions and some heat in the tires it'll hook 2nd though. For those that have done it, how do you find traction at these airports compared to the street? My only experience at airports is AutoXing, but that's not on a runway. The concrete pads I've AutoXed on at airports have great grip and I hook up better than any street I've tried.

-TJ

63Corvette

Yep! great traction for those with less than 1000hp, but very abrasive.

Joe_G

I ran 180+ last weekend 3 times with no problem on my Nitto Invos. In fact nobody had any tire related troubles all day including my buddy who borrowed my drag radials and went even faster.

Well this guy in a shifter cart had some trouble..those cart tires were not up to sustained 140!




He put a new tire on and went back out there!

tjZ06

Thanks for the input... and great runs! So you're doing 180+ on 450 RWHP? That's awesome. I'm looking at the Mojave Mile which is @ around 3k feet and 1% uphill but I have a bit more power.

-TJ

drivinfast

1st vid in my sig is MT 305 18s
2nd vid is nitto r888 18/30/335 there is no box, you gotta bring your own water if you want to do a water burn out
I spun first gear but got 2nd under control both times.

next time i have MH 18 345 which according to the web site are 28" tall,,I think i'll go faster with them

Pumba

TJ,

If you switch to 3.73:1 diff gears you would see the following speeds at these rpms:


7,000 rpm = 199.19 mph
6,500 rpm = 184.96 mph
6,000 rpm = 170.72 mph
5,500 rpm = 156.50 mph
5,000 rpm = 142.27 mph

For alignment, I would suggest you think about the following settings:

Front Total Toe: 1/32 inch In
Front Camber: Negative 0.5 degrees
Front Caster: As much as you can get

Rear Total Toe: 1/32 inch Out - Your wheels will align themselves to zero total toe under power.
Rear Camber: Negative 0.2 degrees

Thrust Angle: 0

Good Luck with the run.

Sidney004

TJ, Don't forget to take your video camera along! Do you think you can hit 200 with your gearing?

tjZ06

Great runs, thanks for the vids!

At this point I don't think I'm going to re-gear the car just for the standing-mile event. I'm primarily interested in track days, but the mile looks like a good time too!

I need to pickup a GoProHD like Dan Bratten has been using. I don't think I have the power right now for 200mph, and unless I get the car caged before Sept (very unlikely) I'm only legal to 190.

-TJ

tjZ06

I thought I'd post an update, and as another question. The Mojave Mile looks like it's out this year for me due to other scheduling conflicts. Instead, some friends and I have decided to focus our mile efforts on the Texas Mile in October.

I think I have my tire situation all squared away. I'll run my RA-1 fronts, but I did buy some of the new Hoosier DOT Drag Radials for the rear in 315/30-18. Those "should" be 25.44" which now makes my MPH by RPM in 5th gear look like:

7000 RPM 209.34 MPH
6500 RPM 194.38 MPH
6000 RPM 179.43 MPH
5500 RPM 164.48 MPH
5000 RPM 149.53 MPH

I still don't have the power to push much past 180 (I guess), but the slightly shorter tire should help a bit.

The car is going in this week for a full cage and fire suppression system (prompted by Road Course use, not really for the Mile but it doesn't hurt ) so I will not be limited to 190 MPH... not that I can surpass that anyway.

So, on to my new question: how well will stock C5Z Aero hold up at 180+ MPH!?!?! I've seen pictures of C5s doing ~150 on Road Courses with the hood severely deformed by air pressure. Thoughts?

Thanks,
TJ