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damage from 2 step launch rev limiter? V.s pneumatic SLC #2918484
05/04/21 03:20 PM
05/04/21 03:20 PM
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Hemi_Joel Offline OP
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Does a 2 step launch control hurt the motor? Like matting the gas with no load (stick car) against the rev limiter? If so, what damage does it do?

How about these pneumatic starting line controllers? Anyone use one? Pros and cans of each? I can see that one preserves the accelerator pump shot, one wastes it. What else is there to consider?


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
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Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Hemi_Joel] #2918490
05/04/21 03:29 PM
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2 steps have been in use for 30 years or more. Even cars with trans brakes use them. No issues.


69 GTX 68 Road Runner
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: JERICOGTX] #2918495
05/04/21 03:33 PM
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Hemi_Joel Offline OP
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All the ads for the starting line controllers say "Throw away that engine destroying 2-step!"


[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
RP23J71
RO23J71
WM21J8A
I don't regret the things I've done. I only regret the things I didn't do.
"Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Hemi_Joel] #2918500
05/04/21 03:51 PM
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Originally Posted by Hemi_Joel
All the ads for the starting line controllers say "Throw away that engine destroying 2-step!"


Do you believe all ads?


69 GTX 68 Road Runner
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: JERICOGTX] #2918508
05/04/21 04:04 PM
05/04/21 04:04 PM
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Hemi_Joel Offline OP
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Well, you get about 50 passes per motor. How do you know it's not from the 2 step? My motor had weird damage on the valve tips. How do I know it's not from the 2 step?

Last edited by Hemi_Joel; 05/04/21 04:05 PM.

[img]http://i.imgur.com/boeexFms.jpg[/img]
31 Plymouth Coupe, 392 Hemi, T56 magnum
RS23J71
RS27J77
RP23J71
RO23J71
WM21J8A
I don't regret the things I've done. I only regret the things I didn't do.
"Wise men talk because they have something to say; fools because they have to say something. ~ Plato"
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Hemi_Joel] #2918511
05/04/21 04:12 PM
05/04/21 04:12 PM
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Marion, South Carolina [><]
an8sec70cuda Offline
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Originally Posted by Hemi_Joel
All the ads for the starting line controllers say "Throw away that engine destroying 2-step!"

I've heard that before too, but never seen any evidence of it. twocents


CHIP
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Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Hemi_Joel] #2918519
05/04/21 04:23 PM
05/04/21 04:23 PM
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The first time I heard a two step was about 30 years ago. The only thought I had was all the banging cannot be good. I have used two steps on all of my race engines. They do not bang like the ones from many years past. They are extremely smooth. Maybe MSD changed the recipe from the originals.

Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Hemi_Joel] #2918520
05/04/21 04:25 PM
05/04/21 04:25 PM
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Another thought, does the RPM's you are attempting to hold make a difference?

Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: R3 Racing] #2918522
05/04/21 04:27 PM
05/04/21 04:27 PM
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I recently changed my car from an MSD 6AL w/ a two step limiter to a digital 6AL-2. The rev limiter on the digital box definitely sounds smoother. Very different sound.


CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: an8sec70cuda] #2918525
05/04/21 04:32 PM
05/04/21 04:32 PM
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Park Forest, IL
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I have heard a 2 step beats the thrust bearing up. I have never seen any evidence of it on any of my junk.


"Everybody funny, now you funny too."
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Hemi_Joel] #2918552
05/04/21 05:12 PM
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I wouldn't mat a stick shift car against the two step no matter the RPM on the starting line tsk twocents
Push the clutch in all the way and then use the throttle pedal to bring the RPM up against the two step is my choice work
I use to start dumping the clutch pedal at 5000 RPM and floor the gas pedal at the same time in my old NHRA stocker 1970 Hemi Cuda 4 speed car, shift at 7000 RPM years ago before the better clutches came out like available to day up That was way before two steps, circa 1973 shruggy
IHTHs


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Cab_Burge] #2918673
05/04/21 09:59 PM
05/04/21 09:59 PM
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The thing I liked about a SLC when I used one in Super Pro was the ability to mat the throttle at a dead idle and have the car hit the two step at the exact same time before the car launched every pass. Especially important with mechanical fuel injection.


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Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Hemi_Joel] #2918731
05/05/21 06:14 AM
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Originally Posted by Hemi_Joel
Well, you get about 50 passes per motor. How do you know it's not from the 2 step? My motor had weird damage on the valve tips. How do I know it's not from the 2 step?


Your issues, have more to do with the number of revolutions on the crankshaft, than it has to do with the 2 step.


69 GTX 68 Road Runner
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Cab_Burge] #2918732
05/05/21 06:19 AM
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Originally Posted by Cab_Burge
I wouldn't mat a stick shift car against the two step no matter the RPM on the starting line tsk twocents
Push the clutch in all the way and then use the throttle pedal to bring the RPM up against the two step is my choice work
I use to start dumping the clutch pedal at 5000 RPM and floor the gas pedal at the same time in my old NHRA stocker 1970 Hemi Cuda 4 speed car, shift at 7000 RPM years ago before the better clutches came out like available to day up That was way before two steps, circa 1973 shruggy
IHTHs


I'd be willing to bet every single Stock, and Super Stock car running a stick in the last 20 years, has parked the throttle right to the floor, on the 2 step, and it's never been a issue.

Now, if you are the type to go up on the 2 step the instant you stage, and the person in the other lane hasn't even lit the top bulb, then yeah, I could see an issue.


69 GTX 68 Road Runner
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: JERICOGTX] #2918764
05/05/21 09:14 AM
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Originally Posted by JERICOGTX
Originally Posted by Cab_Burge
I wouldn't mat a stick shift car against the two step no matter the RPM on the starting line tsk twocents
Push the clutch in all the way and then use the throttle pedal to bring the RPM up against the two step is my choice work
I use to start dumping the clutch pedal at 5000 RPM and floor the gas pedal at the same time in my old NHRA stocker 1970 Hemi Cuda 4 speed car, shift at 7000 RPM years ago before the better clutches came out like available to day up That was way before two steps, circa 1973 shruggy
IHTHs


I'd be willing to bet every single Stock, and Super Stock car running a stick in the last 20 years, has parked the throttle right to the floor, on the 2 step, and it's never been a issue.

Now, if you are the type to go up on the 2 step the instant you stage, and the person in the other lane hasn't even lit the top bulb, then yeah, I could see an issue.


^^^^^^^THIS^^^^^^^

The older 2 steps from say the mid 1980’s were hard on parts. Also depends on the brand. I’ve used older Mallory analog stuff and it did it sound like the MSD boxes.

The biggest issue I found was using mechanical injection and a 2 step. If you are at say...5000 RPM on the 2 step and your foot is on the floor the barrel valve is wide open. You are just hosing fuel into the chambers. I’ve seen bearing damage doing that.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: madscientist] #2918852
05/05/21 12:20 PM
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I have seen no evidence that 2 steps hurt engines although I agree it sounds like it should...The functional difference between the 2 step and pneumatic limiters is mostly carb tuning. With the two step the carb is wide open so there are not any accl. pump concerns (ramp, size squitter vol. ). With pneumatic those are a concern. With a 2 step (or similar) I think you can mitigate your potential damage generation by how you use in I see quite often racers go in and get on the 2 step , some time even before the opponent has staged shruggy In my earlier days of racing and racing on a Full tree I preferred to Top bulb leave so I would release the TB on the top Bulb and and floor it on the second bulb. For those of you not using Delay boxes it becomes little tougher but manageable, Most recently I have tried and like leaving off the converter, no two step involved. better reaction time and very consistent.


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Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: W.I.N. Racing] #2918884
05/05/21 02:03 PM
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watching larry`s car makes you want to take a step back no

Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: theraif] #2918901
05/05/21 02:47 PM
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Never seen that video my man Jeff actually spoke in camera, Im still in shock


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Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Al_Alguire] #2918923
05/05/21 03:44 PM
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The turbo guys dump fuel and retard timing to ignite the fuel in the pipes and help spool the turbo. Seems to work but you better have your exhaust well built lol.


68 Barracuda Formula S 340
87 "Chrysler" Conquest
Re: damage from 2 step launch rev limiter? V.s pneumatic SLC [Re: Bad340fish] #2919004
05/05/21 07:04 PM
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Years ago I used both and I liked the throttle thingy better, it didn’t induce misfire. Both where only used at 3-3500 with a box but never pushed until the 2nd bulb.

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