Hey guys, I'm currently upgrading my C5 to run some standing mile events in 2011. The combo includes a 408" iron block, F1R Procharger, dual in-tank fuel pumps, and methanol to keep IATs in check on the long pulls. I'm planning to run the stock 6-speed with 3.42 gearing. The car has a 6-point cage and harnesses.

Any words of wisdom? Are drag radials appropriate for those speeds/duration? Any aero considerations? Should I expect any blower belt issues? Any tuning lessons-learned?

Thanks!

 

Trailer the car unless you got ***** bigger than King Kong or a brain smaller than a parakeet.

I recommend a recirculation pump, spraying the return on the counter shaft. because the acceleration will push your fluid to the back of the trans case and starve your counter shaft. 5th gear will be the hardest on the transmission. Don't shift hard. Just firm. Don't put your hand on top of the steering wheel. Place it on the side for more control at high speeds. It will decrease the possibility you will even slightly jerk the steering wheel at 190, which could ruin your day. Make one pass and take it easy and see where you're at. If you don't have HPtuners, buy it, learn at least some tuning basics and log the car. There's an absolute ton of difference between tuning a car doing 4th gear pulls on a dyno and running through the top of 5th from a dead stop.

That should be enough to get you started thinking.

Have fun and good luck!!

 

One of biggest factors in a "top speed" run like a mile is gearing. The stock C-5 mn-6 does not have proper gearing to make it to 200 mph if that is what you are shooting for. 5th and 6th gear is not ideally spaced. A mn-12 has better gearing because the 5th and 6th is closer together. You still would need to lower the overall gearing a bit. On an mn-6, the 5th is good for about 185, but it would take a long time to get there and 6th is wayyyy to high. 6th is good for around 280 mph, but your motor ould never pull it. I would think an mn-12 with 373's or 390's would be ok for mile runs if you want to get max top speed.

 

I did some quick calculations...

With an MM6, 3.42 gears, 25.5" tire and a 6,800rpm shift point, I would be shifting from 4th to 5th at 149mph. This would put me at 5,000rpm in 5th, right in the meaty part of the torque curve. 6,800rpm in 5th gear is 203mph so I could potentially run it out the back door in 5th and still make 200mph. I do agree the .84 gear ratio of the M12 might be better. Am I thinking about this properly?

 

These threads seem to be more and more lately about the mile events, they're fun.

First and foremost, trailer your car.

Second, understand the event, the rules and come prepared. DRINK LOTS OF WATER, treat it like any other racing event.

Check, double check and tripple check your equipment, safety first!

Never assume you're going to go out and break landspeed records the first time out, try to relax and have fun: Look at event one as a building step to come to grips with what you need to go faster.

Tires: I ran NT05R drag radials, fine at mys peed, not fine at 200+. Most guys are running R888's or A6/R6's. (nitto / hoosier) basically road course tires.

are you a coupe or a Z06? Coupe's have an aero advantage over the Z06's.

It sounds like you're building a BIG Power car, so you should really enjoy letting it stretch it's legs. Brett's words of caution on the trans cooler is a good one. Ensure you're confident in your ability to brake from 190+ to zero fairly hard.

As for the gearing, it's the secret to those who go fast. Sure, you might be running out in 5th in your calculations, breaking 200 just barely, but do you know how much power you need to do that in the span of 1 mile?? Are you going to have (more) than that much?

If you put a taller rear end and the M12 in, you'd have a better shot at going faster, but that's just my opinion, go do it once then fiddle.

I'll say this about the 1 mile events: it's way more difficult to go 200+ in a mile than run a 9.xx 1/4 mile, mostly because we haven't been trying to do it for nearly as long as drag racing.

 

All very good points. My only initial goals will be to have fun and safely bring the car home.

 

That's the best way to approach it- you'll have a blast and be instantly hooked on the speed rush.

 

You will have fun!
Sounds like you have the right attitude - first run or two are all about getting comfortable in the car, on the track, with the shutdown area, braking from high speed, etc.
Working your way up to all out run is the way to do it.

Something to keep in mind about launching the car, the surface for most venues are unprepared in any way. You can warm the tires to help, but you will not be able to launch the car anything like at the strip. Street launching the car is more applicable to how it will be at most events

Be smooth. As fun as it is, bang shifting the car and getting sideways will generally not benefit your mph as you have to pedal it with abrupt steering corrections. Fast smooth shifting and throttle application generally yields the best results.

My personal preference for tires is a R compound treaded road race type tire as opposed to a soft sidewall drag tire. The road race tire will not offer quite as much traction at launch(hard sidewall), but will be much more stable at high speed 150+ and will respond far better(stability) to high speed steering corrections should they be needed.

 

Hey Bret - do you know of any vendors for such a recirculation pump? Is the typical road race trans cooler setup doing the same thing?

Thanks
2B

 

I've always wanted to attend this event and run my Vette. I guess it is pointless trying to hit 200 in an auto with 3.42s though. I'm currently hitting 144mph at 5750 rpm in 4th.

Good luck with your quest to the 200 mph club

 

Not sure why you'd need to drink lots of water, unless its extremely hot ? It'll just make ya wanna pee lol

You'll only be in the car for a few minutes at a time ?

But tyre safety is probably the most important. Check all tyres and valves etc are in good condition, and suitable for high speed.

Ive used various tyres at speed, and my car is ****e in terms of aerodynamics.

555R and MT DR's actually felt fine. Have also used 888's, which again are totally stable. The 555's and DR's were actually only around 25psi too. That was just to about 190mph.
At the most recent event, I did use Hoosier DR's at around 30psi.
The track was very poor, with algae or moss growing on a lot of it through lack of use. I was still breaking traction in 5th around 180/190mph. 888's did this too, but the Hoosiers felt so unstable.

Generally, It would be best to use a proper tyre with a stiff sidewall though.

As for gearing. IMO to have the best chance of hitting 200mph, you want 200mph to be pretty damn close to peak power in whatever gear.

 

I don't see any reason you couldn't use a scavenging pump. It'll be much easier on the pump than oil draining from a turbocharger. Turbowerx exa pump is the one of choice.

 

Forgot about it till stevietubo mentioned it

Valve stems- short solid (not rubber) valve stems (bolt in style) are required by land speed organizations(SCTA,USFRA,etc) though i am not certain if standing mile requires.

DEFINITELY a good idea if you intend 150mph +

they are reasonably priced so cost is not a biggie

 

My take on the Texas Mile and my mere 190 mph runs with 771 rwhp DS1C. I ran stock C6Z Hooisers 325/30/19--stock C5 height and shifted at about 150ish to 5th gear well before the 1/2 mile. I was at 5k at the shift and this is not in the power band in 5th gear as I went through the traps at 6200ish at 190 mph. It seemed to me that until I hit 5500 or so that I was not in the sweet spot (drag is why here) and at that point I was now at the 7/8 mile. I did 4 runs, lowest 189 highest was 190.6 mph. I had zero issues watching my boost guage hit 20lbs on my last two runs on my shift to 5th gear.

How much power you going to make and TQ, I was at 640ish in TQ, and about 600 at 6800. I had zero belt slip, and the F1R will make more power and more chance of belt slip in that long of a run. If you have lots more power you can go for sure faster than I did as 5k will be more in the power band, or you can change your tranny to the same specs as the C6Z and there 5th gear would have gotten me to the mid 190s and maybe further. Blower cars need more HP than juice cars in the mile as our efficency goes down in boost that long. If I still had my C5 I would of turned off the meth and added a 50 shot of spray to keep my efficency up and more hp, I had the fuel and tires for more speed, even the brakes and suspension, I had the entire package except for gearing and hp.

Good luck and hope to see you at the Texas Mile in March 2011

 

The motor is currently apart for freshening, it made 670/610 on 8.25:1 compression, 231/239 115 cam and approx. 14 psi boost with no meth. The new combo will have more compression, more cam, and meth. Hoping for 800-850 with the new combo without going to crazy boost levels. We'll see what the dyno says. I probably won't make the Texas Mile in March, I'm hoping for a date early next year at the Miami Mile, which is much closer, to shake it down.

 

I wish you good luck and run with your current gearing see what you do and then go for the tranny change or add some juice if you do not hit the magic 200 mph

 

Thanks! I'll get my feet wet the first time out and that will help with what changes are needed to run a big number. From those who have done it, it definitely sounds like the 1.00 4th to .74 5th gear spacing doesn't work for 200mph.