What Rpm should i launch at with 4:11's? i am running 275/40/17 street tires all around. rest of the mods in sig. just wanna get some tips b4 i get to the track

 

What you probably don't want to hear is that with a stick, 4.11's, and street tires you will probably end up spinning all the way through first, halfway through second, and maybe chirp third... However, thats my guess unless some or all of the following occur:

Launch really low, almost at the bogging point, and slip the clutch out of the hole. You also need to pre load the drivetrain so as to minimize shock to the gears as 4.11's are weaker than 3.73's or 3.42's.

Also, do a few "test peels" on private property to see how low you can go in air pressure before the rear tires "cup". If they cup you lose surface area (and hence lose traction), however the 40 series sidewall is not going to provide any significant flex at the launch so you want to have as little pressure as possible without cupping.

Unhook the front sway bar at the track. Just wire up one side so the front end will find it easier to rise should you start to hook up. Put about 40 pounds of air in the front tires so they are nice and firm.

Feel free to have a full tank of gas. I am not a fan of adding weight but with 4.11's and street tires you will need all the help you can get, especially if it a "street night" when most tracks don't do much prep work except to wipe up the fluids and blow off some dust every once in awhile.

Try to follow cars that have slicks and try to line up in their tracks. Avoid shiny spots.

Bear in mind if you do hook up, especially if for some miracle yopu hook up at a high rpm, you stand a reasonable risk of breaking something in the rear.

The best things that you could do would be to go on a day when the track is having a points race because most tracks really do a good job of prep work on those days.

Get a decent set of drag radials and if you can afford it get 15 inch rims to put them on. These will make launching much easier. I have seen experienced drivers hook up with 40 series drag radials consistently when the track is well prepped. However since you are asking about tire pressure I am guessing you don't have many years of experience in launching technique.

The overall goal is that when you quickly release the clutch the weight of the car will transfer from the front to the rear to help the tires stick. That is why most drag cars have lighter front ends, loose front shocks with a lot of travel, and different springs. It is also why drag cars usually use a numerically higher gear like what you have but compensate for it by using taller tires and smaller rims to provide flex at the launch to minimize traction problems.

The best advice I have is to go to the track, try 24 pounds in the back, and if you don't hook try 22 pounds. If that doesn't work try 26 pounds. Trial and error will yield results sooner or later. In order to be certain of the proper tire pressure through trial and error, launch rpms, clutch release, and lane variance must be the same to adequately determine the effects of changing tire pressure, amongst other variables.

Go and try it. If you spinn too much at least have a good time and then figure out what your next move will be.

 

well i still have a system in my trunk (page 3 cardomain) so that added some weight. i plan on racing on a 1/2 tank of gas prolly. i under stand the 4:11's can break, but i dont plan on using drag radials or dumping it at 5k rpm, so shouldnt be a problem. i have the ta girlde w/ stud kit,and solid pinion spacer to give me a bit of "insurance"

i figure like 2200 or something and kinda slip the clutch and give it hell as soon as i hit 2nd.

 

Let me know when you plan on going. I need to make some shake down runs with my car and could help you out at the track. Also, if you are gonna race that Cobra there, you are more than welcome to borrow my drag radials

 

4.10s being weaker.. but what about 4.10 in strange 12 bolt... they should be fine (alot stronger eh?)

cory

 

When I had an M6 I would launch at 1500. I launch at 1200 in the auto. Every 400 passes I would break the stock rear. I too had a TA cover, and I had 3.73's, not 4s... I would pre-load for each launch and I always did a quick release with the clutch and not a dump. My goal was consistency and a good light because I bracket race. I rebuild the rear twice and then bought a 12 bolt. Haven't had any problems since.

That was my experience, yours may vary.

 

Ran into this problem last night...I got 4.10s and some street tires 275s+ lowered a little....plus mods on par with yours and... launching = teh suk ...

I was leaving at 1500-1800 and easing into it...to much and they light up...to little and everyone passes me...IMHO the street tire 4.10 game isn't worth trying to figure out it just sucks...the give it hell in second may work sometimes they still light up (I will admit I didn't drop tire PSI any this may help there)...buy some DRs and go from there IMO it works a whole lot better...I wore out the 245 nitto DRs on the salad shooters...and switched ZR1s with 275 Eagle F1 like the stock SS has...yeah the 245 DRs kill a 275 street tire...once again this game isn't worth it IMO...buy some good tires...you'll be glad you did...