This question is intended to help me understand;

First, my question is specifically about an ignition RPM limiter that turns off the ignition to limit RPM.

My desire, help me understand why such a limiter can or does cause engine damage.

Only thing I can contribute. Back when I still ran the machine shop, I had one customer with a 3step in his nova. Always did a fairly hard burnout on the three step at 6200rpm iirc. Every year near the end of the year he broke the oil pump or the pick up tube.

To add to my previous post. In my own car I use a two step for starting line and over rev only. Years ago I got into the habit of going wide open on the line when both are staged, all four lights on. Two step is usually around 3400 / 4000 rpm. I have never seen any I'll effects from that when ever I have to into the engine.

I am guilty of being on the two for extended times and only thing I have ever had happen was years ago lost a couple oil pump pickups. Lucky me no damage and have beefed them up since and not lost one for a long time.

I have zero proof of anything but man, I cringe every time I see someone do a huge burnout ****in and bangin off the 2-step or sittin on the line on the transbrake for a few seconds

My understanding of this is about harmonics and controlling vibrations. All your parts that move have a natural frequency, and when it hits that, it resonates and dramatically increases the amplitude of the vibration.

This is the same forces at play that allows a singer to break a glass with their voice.

The frequencies change as the engine goes though the revs, but if a parts resonate frequency is where your rev limitor is set, and its held there for a period of time, bad things will happen.

I think the rev limiters ability to hold the engine at a very specific rpm is where the issue is, granted, I am sure introducing misfires into the equation doesn't help.

Inner and outer valve springs are designed with different natural frequencies to help cancel them out.

why does anyone need a 2 step for a burnout? They cant watch the tach and throttle the gas? Been racing for 17 years and use the eye, tach, and foot technique and never had a problem or issue with consistency.

quote:

Originally posted by ski_dwn_it:
why does anyone need a 2 step for a burnout? They cant watch the tach and throttle the gas? Been racing for 17 years and use the eye, tach, and foot technique and never had a problem or issue with consistency.

The original topic before this one was about dragsters. How far they put you in the water and how much water there is...stickyness of the burnout area. It's easy to not have enough throttle and rattle the heck out of the car. Or too much and wing it. Why chance it? My three step burnouts are smooth and consistent. I will say there is a big difference with the digital ignition units on how smooth they are on the two step. If I ever heard anything not smooth in the burnout, I would kill the ignition. Broken valve spring almost for sure. Caught it twice. Easy to hear with the smooth two step.

Going way back to when 2 steps first started being used, yes stuff showed evidence of using the 2 steps, and bolts loosened up. That’s what I found. Seemed like more cracked cranks and rods and various other engine parts showed issues.

I hated 2 steps and avoided using them.

I footbraked and resisted going to a trans brake and 2 step for bracket racing.

When I Super class raced I used no chip with a trans brake.

I eventually gave in and used a 2 step and trans brake like most everyone else.

Modern boxes and 2 steps are not like the old stuff. Popping and banging as I used to describe them.

I’ve made endless runs using a rev limiter at various rpm and have no evidence of anything breaking or any other issue. Multiple cars, engines for years.

The parts used in the past just plain s-u-c-k-e-d compared to today. The early rev limiters were harsh.

Stock GM cranks, rods.....crack prone.

Would I prefer not to use a rev limiter, yes but it’s just not practical in many categories.

Keep it to a minimum time is the best you can do.

Bracket racing I used a starting line control and it hits the 2 step for less than a second before launch.

Super racing, on a 2 step for about 2 seconds....go to mat with 4 lites on and tree takes about 1.5 seconds to go....

Add short burnout rev limiter time.

I’ve seen various people able to break an anvil and others who rarely hurt stuff..


Watched guys do burnouts at rediculous rpm and blow up engines and stand there scratching their heads asking why??

Had a guy blow up a LS 7 so bad the cam busted in 2-3 pieces and pushed up out of the block.

He was hitting an 8000+ rev limiter well before the end in 1/4 mile racing with a flat tapper cam and thought that was ok....

quote:

My understanding of this is about harmonics and controlling vibrations.

^^^ This
Here is an opinion you can trust.

https://rehermorrison.com/tech...abusing-your-engine/

Only proof I have is my stuff. 2 step and burn out chip used ever pass on my 582. MSD Digital 7 ignition. At 500 runs I took it apart for the first time, but only because I wanted upgrade the Rods to Crower billet. Rod bearings looked like when I installed them and went back in. Coated mains coating was mostly gone so replaced them.
I suspect older analog rpm limiters did not work the same as digital ones and that could be how this bad reputation was made legendary

It has always amused me that folks will complain about 1/4 mile racing because it is "hard on parts" but they'll sit in the burnout box with the engine up on the chip for longer than it would take to cover the distance from the 1/8th cone to the 1/4 mile stripe.

Am i the only person that remembers the 80's when super gas ran the entire track on the chip (stutter box)?
If stuff was going to brake, it was then. LOL

Joe

The down track stutter box as they called it was banned because of some S/G racers using it out there.

I can name one in particular but won’t. He used it on the top end and you could hear it from the starting line. Others used it mid track with black smoke trailing the car.

NHRA banned it. Hard to tell today if someone is hitting the chip but once in a while I’ve heard it out there. Not very often and not in the recent past...