Drag radials 5500+ launch RPM?? who done it?
 

so I went to the track today. did about 4 runs or so. for some reason the car always bogged. I went as high as 5600RPM!!

I am running 18" c5 z06 wheels and hoosiers drag radials. 17-18psi hot.

is this normal??? for it to bog at that high of an RPM?? or am I doing something wrong? I try to slip the clutch as much as possible but with this carbon clutch I dont really know how to. it used to be easier when I had the stock clutch and the ZR1 clutch.

I am running the RPS BC3. it grabs nicely I think but every time it acts a little different.

should I go higher??? I was worried I was going to break an axle or hurt the Diff....?? I just dont understand. I have C5 axles btw.

so my question is should I go higher? or get the tire pressure higher so that it doesnt get as sticky? I am really new to drag racing. any feedback would be appreciated....

Thanks:thumbs:

The biggest problem you are having is the much lower rotating mass of your flywheel and clutch. The moment of inertia of the BC3 is probably about a third of the stock clutch. Lou Gigliotti has a video where he launches his Z06 with a Tilton triple clutch at 7000 and it bogged almost to stall before the car started to move. Super light clutches work really well in road race cars, but not for drag racing. If you go with less traction at the hit, the car will probably break loose when you hit peak torque in first gear. Sorry, tough problem. Don't worry too much about breaking stuff if it is bogging. You probably aren't shocking the drive train nearly as much as you would at a lower rpm with a heavy flywheel.
Gary

I had a similar issue, I'd launch at 5500-6000 and would bog real bad. The Hoosiers are super sticky and I found with only doing a light burnout in first gear to clean them off before a run seemed to help. They don't need much heat to grip. Don't get them too gummy before the launch and they should be a little more forgiving off the line.

1)clutch release needs to change and throttle input
2) air the tires up and do consistent burn out methods until you are just barely rotating the tires faster than the car is moving.
3)BOGGING is way way way worse than spinning! You will break parts dead hooking and bogging eventually. As long as its not hopping go for the light spin of that's what the car likes.

What ET MPh did you turn?

Bog is 10 times worse than a spin launch for ET and MPH.

Bogging from a low MOI clutch grabbing too hard is likely what you are experiencing.
Don't launch higher for now---air the tires up like FP said. You must figure out a minimum rpm that you car cannot go below after the launch in order to produce a successful launch. I guarantee you that your car is bogging below 2000 rpms if your 60' aren't good. Ask Carlos if that cam likes to be @ 1500 rpms. We all know the answer is no. A data logger with help explain this and correct this along with the info below.

Tips to prevent bog:
-Keep heat out of the clutch.(Quick burnout, pump pedal, cool clutch, frequent fluid changes, etc.)
-Try and ride the clutch and not let it hit hard on initial grab. Have clutch pedal right below engagement @ launch can help with the latter.
-Agressive throttle delivery with a lower rpm launch (with elevated tire pressure) and maintaining rules above
-Launch @ a progressively higher rpm, if the setup allows, and only after all the above

It's easier to learn and to accomplish on a bias ply tire.
Your goal is to get that clutch to grab as soft as possible and when it does the tires are either slightly spinning or the car is moving quick enough the prevent the motor from pulling down.

light clutches are a bitch.. last clutch was around 20 lbs heavier and with more power, i had to go from 5500 to 6300.. i've sense switched to a shorter tire and now i'm having to figure out what they want.. i also try to allow 1 to 1 1/2 hrs between passes to let the clutch cool off..

The Tilton is much lighter than the BC3. We have been successful launching our various cars on both the BC2 and BC3 with aluminum FWs. Stonabones69 went 9.25 in his BC3 equipped C5. Axles do break on a deadhook. :(

Thanks for your post Gary. it is a tough problem. I really cant seem to figure it out. I was thinking with a little more air in teh rear tires it will help. it will probably wont hook as good but better than going over 6000RPM?


hmmm I will give that a try and see. I have been doing really hard burnouts with those just to get them really sticky but now I dont want them to be lol.... its weird. this is really a good idea though. I will give it a try:thumbs:

1) I try to follow Ranger's instruction where he says to not floor it when you release the clutch, but I am having a hard time doing that. my instinct wont let me haha...

2) thats what i was planning on doing the next time I am out. I was at 17psi hot. I will try 19s and see how they react.

3) I have been told the same too.

I ran 11.2@126.9 with a 1.81 60ft. this is on a higher DA than my 11.1@127. car is still not tuned. 2deg knock. will get it tuned for sure before the next test n tune.

the clutch does grab hard. but I manage to slip it a little but it will still bog. I try to slip it as much as possible to perform a good launch, but with this clutch, its really hard. I will air up the tires. probably do 18s or 19 and see what happens. I would like to stay around 5000RPM just because I dont really want to break things with a higher RPM launch.

I think my torque is not that bad at lower RPMs but I dont know why it bogs really hard and wont catch up quick. I do have logs of my runs if anyone wants to look at them. you can see in the logs how the rpms drops hard from bogging.

- I thought the BC3 loves heat? or I might have understood this wrong. but I was told carbon clutchs loves and work better with heat. and I changed the fluids just before going to the track. and after those runs it was a little dirty but not bad at all.

- I will try to have the clutch right before engagement. it does sound better. will give it a try and yes I try to ride the clutch out but with this clutch I cant seem to be consistent. because as I mentioned it acts differently every time. and i am guessing thats due the carbon discs.

- I am good at that lol. I floor it as soon as my clutch is all the way out. I was told not to do so though...!

I will try those tips and see what happens! Thanks :cheers:

I had to wait about an hour between my first and 2nd run. the last two I only had about 15mins between runs. but that didnt really change anything. this stuff is not easy as I thought it will be :(

thats what I am afraid off. especially if it bogs at a very high RPM (as in 6000++!) what do you suggest Gary? Also I dont know if you experienced this with your BC2 or some of the BC3 that you mgt have tried. but did you notice that the clutch acts differently every other run? even on the streets mine would acts differently 40% of the time. some times it feels like it grabs REALLY hard even though the clutch didnt get hot yet. other times it will act normal and drive easy (cold and hot). sometimes it feels like its slips and grabs hard like right away.

I am getting my new transmission installed next week. I will double check the clearances and make sure everything is ok. I will probably take the clutch out and inspect the discs too and also measure the thickness.

PM sent.

RPM transmissions mentioned to check the tranny input shaft really close for burrs that the clutch plates can hang up on.

we got it cleaned up. thats what Rob@RPS said too. we will give it a try now and see what happens. because the disc thickness were fine and the clearance was good. hopefully this will sold the problem.

Thanks

z06 traction spinning problems at strip
 

my friends 09 Z06 750 rwhp wont hook at drag strip, from a dead stop if he launch's at 2000 rpm and then punch's the throttle leaving the tree, it is like being on ice, he spins the tire;s all the way down the track through all gears he has pfdat coil shocks on it also, and mickey thompson ET drag radials, my other friends 07 hooks and even bogs from the start, same tires, stock suspision he has 550 rwhp. the 750 rwhp car hooks better on the street it seems. what can he do to get rid of this spin on the track. his 750 rwhp car is the only one doing this it seems on the strip, can get hp to the ground. thank you

That sounds like a ****** prepped track?? Or worn out tires? What pressure? It might be a combination of things. But he needs to figure out the right pressure. 18psi seems like the right starting point and figure out from there. Good burnout. And good prep.

he had tires down to 16 pounds, and still spins them, he is pushing 750 rear wheel hp it is a lot, but his friends 07 550 rwhp seems to launch and hook good, could it be the pfdat coil shocks they have dampning adjustments on them, but i wouldnt think it would cause this bad of a spin at start, like on ice when he launches,

How old are the radials? could be dry rotted. What size radial is he running? Maybe to thin of a sidewall or too short of a tire. How is he launching???

tires are only 4 months old 345 Et II mickey thompson drag radials.