7500 launch

[evileclipse909]

So I know this is a bad idea but has anyone launched their awd from the factor 7500 rev limiter and lived to tell about. I had a friend try to program an eprom chip for me to set up a 5500 2 step but al that did was set the rev limiter to 5500. But when you hit the rev limiter it sounds and acts just like 2 step. So I'm wandering just how bad I'm gunna screw up the drivetrain by hitting the 7500 rev limiter until I build boost then launch it. Who has done this. I wanna hear horror stories.

 

[dylnwit]

I see some busted CV shafts in your future if you try it, that or some major transmission problems, all depends on how you let out the clutch. If you slip it a little on take off, you might get away with it a few times, but if your just dumping it from the line, expect an expensive repair bill. I'd think the first thing to go would be one of the rear CV shafts. Other possibility would be that you would total your transmission's input splines, so the clutch wouldn't want to disengage when you went to grab 2nd.

I'd go with ruined input shaft splines, or rear CV shaft failure.

While we're on this kind of topic, has anyone tried launching in second? I hate how quick that shift comes up.

 

[evileclipse909]

Me too. 1st gear feels worthless. I keep getting beat by grandmas off the line because of my turbo. I dont even build boost in 1st.

 

[Jeff99GS]

HUH? You don't build boost in 1st??


If you Launched at 7500 you would be bouncing off the rev limiter until you shifted into second.

It wouldn't work....You'll just end up glazing your clutch and ruining a bunch of shit.

 

[JEFFREYCASTGSX]

Your profile says your fwd? You should be launching at way below 5500(ie 4000), maybe its obvious whoever set up your chip doesnt know what he is doing.

 

[Jeff99GS]

Your profile says your fwd? You should be launching at way below 5500(ie 4000), maybe its obvious whoever set up your chip doesnt know what he is doing.

I think he swapped to AWD.

It just won't work. That is the reason its called a 2 step. There is essentially 2 different rev limiters.
If you hit the stock 7500 limiter then release the clutch, you will CONTINUE to hit that 7500 rpm limiter until you shift into 2nd gear. It would make NO sense and would never work...so don't even try it.

 

[JEFFREYCASTGSX]

I think he swapped to AWD.

oh well then in that case the first thing to go is your "stock" clutch.

 

[matthewdesigns]

I have my launch rpm's set to 5K for my AWD, I get a little wheelspin, and then first gear is gone in a hurry. Anything more and I just overspin. I can't see any good from launching at the rev limiter.

 

[evileclipse909]

I see. I just wasnt sure because when I launch a 5k with no 2 step it just drops down to 3k and I have no boost. then when I finally hit 2 lbs its time to go to 2nd. And yes the car is now an awd gst. The mods are in my profile. I just wanna hit boost in 1st without going back to my smaller 63ar hotside.

 

[diambo4life]

Shift faster. Launching at the rev limiter is a dumb idea and a sure way of breaking parts.

 

[donniekak]

If your launching a turbo car without a 2 step the best method isn't to hold at a specific rpm, but to "bounce" up to it. Here is a vid to explain better. YouTube - World's Fastest Dodge Stealth 9 Second Pass

 

[andy4g63]

SOME people do it all the time... hehe.

YouTube - John Shepherd's 7sec DSM NO NOS! 8/15/2006 (Inner View)

 

[donniekak]

But that actually was a 2 step. Matt monet in the vid i posted doesn't use one. He just bounces the pedal. The car is actually just tuned with a piggy back, and ran 8's.

 

[Jeff99GS]

SOME people do it all the time... hehe.[l]

That is NOT the stock rev limiter that John Shepherd is using. He has a SET rpm that he launches at and probably NO rev limiter above that. Im sure he is shifting around 10 or 11,000 rpm!!

 

[Rob10_99]

Yeah looks like the tach is in the upper 10k when shep shifts.

If your 2 step isn't working correctly, is it programmed to your clutch switch you most likely and should have removed/unpluged?

Oh, and, dont launch past 5 or 6k you are just burning your clutch.

 

[twicks69]

That turbo is tiny -- you should have absolutely no issues reaching 30+psi on a properly tuned and setup vehicle. I had no issues seeing full boost (35-36psi) by 5500rpm in 1st gear with my old 6152's, and had that boost level by 4700-4800 by 3rd gear.

As well, I was using a 2-step around 5500rpm and a redline of 8400rpm. I would usually build around 15-20psi right after disengaging the 2-step when I launched the car, and would quickly hit full boost well before leaving 1st gear, and then full boost quickly back into 2nd gear.

Get a clutch that can handle the abuse -- Quarter Master Twin Disk, and preload the drivetrain by using the e-brake to stage the car, and gently slip the clutch on the line to build boost, and then launch. Your transmission, axles, and transfer case will most certainly like you a hell of alot more than doing clutch dumps at 7500rpm.

My old setup with the GT4088R would utilize the 2-step around 7400rpm and had the redline set at 8500rpm. I had no issues building 20-30psi based ONLY on 2-step not utilizing anti-lag whatsoever.

Granted, I use AEM EMS, and not a chip....

 

[JackM]

I have to launch my car at around the 7k RPM range due to the engine I have (no weights on the crank, 2.0L, 288 cams, GT37R, etc). It WILL NOT go if lower than that. I have never broken anything doing this. You can launch at any RPM as long as you don't shock load the system. Shocking the system is what breaks stuff. Preloading and smooth is the way to go.

Jack

 

[Jeff99GS]

YES you can launch at ANY rpm....BUT this guy is talking about launching off the STOCK rev limiter and NOTHING else.

It won't work because he will NEED a HIGHER limiter after the initial Limiter. Otherwise he will hit the 7500 limit and continue to hit the 7500 limit until he shifts.

Now if he launched at 7500 and had a redline of 9000 then it would work....BUT launching off the stock rev limiter will NEVER EVER EVER work. Its NOT a two step (in the voice of kindergarten cop) Its NOT a TWO STEP.

 

[1stGenTSi]

YES you can launch at ANY rpm....BUT this guy is talking about launching off the STOCK rev limiter and NOTHING else.

It won't work because he will NEED a HIGHER limiter after the initial Limiter. Otherwise he will hit the 7500 limit and continue to hit the 7500 limit until he shifts.

Now if he launched at 7500 and had a redline of 9000 then it would work....BUT launching off the stock rev limiter will NEVER EVER EVER work. Its NOT a two step (in the voice of kindergarten cop) Its NOT a TWO STEP.

This is incorrect. You will not "continue to bounce of the 7500 rev limiter" unless the tires are spinning or the clutch is slipping (one of which is likely to happen.) If you have a heavy clutch, sticky tires, and don't break something then the rpms will drop down after the clutch is released.

On a side note I've done dozens of 7k+ RPM launches. This was on my old awd talon I didn't care for too much, but I never broke anything. This car was mostly stock and anything less than a 6k launch and it would just bog down. I am by no means recommending trying this though. Now I have a 2-step and love it.

 

[Jeff99GS]

This is incorrect. You will not "continue to bounce of the 7500 rev limiter" unless the tires are spinning or the clutch is slipping (one of which is likely to happen.) If you have a heavy clutch, sticky tires, and don't break something then the rpms will drop down after the clutch is released.

On a side note I've done dozens of 7k+ RPM launches. This was on my old awd talon I didn't care for too much, but I never broke anything. This car was mostly stock and anything less than a 6k launch and it would just bog down. I am by no means recommending trying this though. Now I have a 2-step and love it.

OK you might get about 10 feet before you start bouncing off the rev limiter again
You would need a Higher Redline IMO.

 

[1gentalonfan]

I hold my rpm at about 6k and let the clutch out really fast (not dropping just fast), and i get a split second of tire spin and then its at redline anyway and rocketing into second. My car launches flawlessly like this and all i have done is the boost up(with supporting mods) and an amazing 6 puck clutch. Oh and an 8 lb flywheel. I have yet to break anything.... except the speed limit in about 2 seconds

 

[DSMTyson]

Solution. Buy ECMLink OR get someone that knows what they are doing to program your EPROM for a 5500rpm 2 step.