damage from 2 step launch rev limiter? V.s pneumatic SLC

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?

2 steps have been in use for 30 years or more. Even cars with trans brakes use them. No issues.

All the ads for the starting line controllers say "Throw away that engine destroying 2-step!"

Do you believe all ads?

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?

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

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.

Another thought, does the RPM's you are attempting to hold make a difference?

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.

I have heard a 2 step beats the thrust bearing up. I have never seen any evidence of it on any of my junk.

I wouldn't mat a stick shift car against the two step no matter the RPM on the starting line
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
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 That was way before two steps, circa 1973
IHTHs

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.

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

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.

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 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.

watching larry`s car makes you want to take a step back

Never seen that video my man Jeff actually spoke in camera, Im still in shock

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.

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.

On my MSD 2 step I cracked the same cylinder on TWO blocks in damn near the same spot on both engines.. I had
measured the walls on the block to try to eliminate different issues and as far as I know I couldnt find
anything wrong except the crack.. I was told later by a so called big time engine builder the the MSD 2 step
is hard on the block.. since that time I never used the 2 step.. now days I just put my foot to the floor
on the trans brake(stalled the engine at 6200 rpm) and never had a problem since

I am just a casual tinkerer/hobbyist and the old school analog MSD 2-step makes me cringe. The new rev limiters are much smoother. I have an add on digital Pertronix rev limiter that is smooth as silk. It took me a second to figure out what was happening the first time I hit it. The cool thing about that little box is that it also provides a nice clean tach signal for the NOS mini progressive. : D

You have to think it beats the heck out of the timing chain but what do I know. I imagine folks running a belt drive will have less ill effect of the (bang bang bang) MSD 2-step. You put an analog MSD (6AL, 7AL) powered car on the 2-step in the city and watch people duck or hit the deck lol.

I have an SLC in the Road Runner. This was in the car when I bought it.

I like taking advantage of the accelerator pump action on the launch.

Engine speed is 1500 to 1700 RPM when the throttle pedal is matted. Not as high ans most 2-steps.

I think i get a little more of a hit from the torque converter coming off of a lower RPM.

John

Great info, guys. It gives me a lot to consider. Thanks everyone!

Years back, I used an adjustable idle step up solenoid acting on the throttle linkage, hooked up to a switch on the dash. I would flip the switch to bump it up to my pre-adjusted launch RPM, then shut it off once I was done shifting. If I was on a pro tree, I tried to stage last so I could turn it on after 3 bulbs were lit, then feather the clutch to stage. If I was on a sportsman tree, I had more time so it didn't matter who staged last. It actually worked OK.