Help me with a tech issue at the track.

I am the Hornet class tech inspector. A car has been protested due to an illegal performance device. The device is a MSD soft touch rev controller part number 8728. The driver claims it is there to prevent overrevving and has no performance benefit. The car is a mid eighties honda civic with a base model engine with a carburetor. I believe it is D15A2 engine. So the question is, can this device have a performance benefit for this engine? I should add that I believe this to be the engine, but it could also be some other 4 cylinder honda motor with a carb. It looks very stock to me.

The only argument that I could make against it would be as an unpermitted driving aid. Instead of needing to pay some attention to the RPM, you could just mash the gas and go. Did they not have a rev limiter on the car from the factory? I'd lean towards some other shenanigans going on if there was an OEM rev limiter and now all of a sudden there was a need to add another one.

I don't think there is any performance benefit. It works by dropping spark to one cylinder on a rotating order to keep revs at the set limit. For his purposes it's to save his engine in case of driver error or failure of trans components that would cause overrev.

If anything it makes it better for everyone because it can keep the guts inside the engine and off the track.

I would personally side with the driver. I would guess protester saw MSD and assumed he has a spark control box

IMO there would be no performance increase with a rev limiter. As the driver stated, it will prevent damage from over revving the motor and help reliability.

No performance increase. Competitors probably saw the MSD tags and thought it was part of a multi spark capacitive discharge system. It only works on stock points or inductive ignition systems like a GM HEI to limit revs.

Agree with above.

All US market D-series were injected (and have a built in rev limiter anyway). That engine is... oh heck, I can't even remember the nomenclature now. Old. The stuff with steel valve covers. They should allow him to put nitrous on the thing so that it's almost as fast as the competition. (They were fine running engines on the street, as I begin to get nostalgic for '84-87 Civics, but they certainly were not powerhouses)

I would validate the unit actually offers rev control (confirm rev limit with external tach on multimeter, scope, or timing light) and is not some other unit hidden in plain site with a potential performance benefit. Read the PDF manual on the soft touch rev control, confirm wiring colors and connections are typical, confirm function, and if it is all on the up and up, there should be no issues running it.

One could make a performance argument: Hondas typically use a hard-cut rev limiter. The soft cut could give him a small performance advantage by allowing him to run up to red line without fear of losing a few hundred rpm when he bangs off the rev limiter.

In reply to BA5:

Carbureted Hondas had a rev limiter? I thought they just ran up to the point where the teeny little carb couldn't flow any more air, or valve float at 6000rpm, whatever came first...

Whether it provides a performance advantage or not doesn't matter. Is it covered in the rules? Likely not or you wouldn't be asking. Let him go and fix the rules. It's an entry level class likely with an eye towards budget racing. MSD boxes aren't cheap so they shouldn't be allowed

Thank you for the input. The driver had to remove it. I was just trying to confirm whether it had actually given an advantage. I couldn't see from the google that there was an advantage, but I thought I would confirm with all you smart peeples. Ironic that his is the only carburated car in the class, and most of them are vtec Integras, including the protestor. But he is much faster and there is nothing worse than loosing to a clapped out E36 M3box. He has to be cheating right?

They only know he's cheating because they're cheating and he's still beating them.

In reply to Driven5:

Its also possible hes a rare driver AND knows how to tune his suspension.

WildScotsRacing wrote: In reply to Driven5: Its also possible hes a rare driver AND knows how to tune his suspension.

"In The Day" it was Pinto's in Mini Stock (NOT) around here But One Just Couldn't be beat, Or even Caught up to, Went around the track Like a saturday nite Drive and he was the only one out there. A Season and a Half before others caught up.

wae wrote: The only argument that I could make against it would be as an unpermitted driving aid. Instead of needing to pay some attention to the RPM, you could just mash the gas and go. Did they not have a rev limiter on the car from the factory? I'd lean towards some other shenanigans going on if there was an OEM rev limiter and now all of a sudden there was a need to add another one.

+1 for all of this.

All Honda electronic ignitions have ECUs with rev limiters. Check the passenger floor well. If it's a box the size of a little laptop computer in front of a steel kickplate it may be stock. This dates back to 1984.

An EW engine is internally OK short-term to at least 7500 RPM, and it has quit making power long before that. Have him remove the limiter.

I thought dirt track protests involved a man getting his ass whupped? ;) At least that's what a dirt guy that was running Chumpcar for the first time told me when I said I was thinking about trying dirt track.

Where was the rev limit set? If it was over 7200rpm, shenanigans. I'm not familiar with the Hornet rules. Even if it isn't a performance benefit, is it against the rules?

I have the same MSD box in my racecar. We lost the rev limiter when we switched from CIS/KJet injection to carbs. It's not very expensive (about $150 IIRC) and doesn't do anything except prevent an over-rev when you're on the throttle. I don't see how that's a performance advantage.

If it bothers you, just pop out the pill that sets the rev limit. Don't bother pulling the wiring.

He will be running this weekend without the Rev limiter. I suspect he will go just as fast.

In reply to Tyler H: That sort of protest at dirt tracks is not allowed anymore. A well known racer made some physical contact with another driver after a crash and was suspended for several races, losing his chance at a championship.

On the autocross track a soft limiter is a real advantage. I can hear cars bouncing of the limiter down the straights and slaloms all the time. Sometimes that's a big advantage over upshifting into a higher gear for a few seconds.
My car has a hard limiter, so when I hit the limiter the car falls on it's face. It's not only discerning when not expected, the power loss hurts driveability pretty bad.

I had one of those MSD soft touch things on my MG Midget vintage racer. I considered it a performance disadvantage because it would randomly start dropping cylinders at just about any RPM within 1000 of the limit I set. I tore it out and just ran without a rev limiter. The rpms would climb so slowly on that car that I could just watch the tach.

I paid about $100 for it, FWIW. I think I finally threw it away a couple weeks ago.

iceracer wrote: In reply to Tyler H: That sort of protest at dirt tracks is not allowed anymore. A well known racer made some physical contact with another driver after a crash and was suspended for several races, losing his chance at a championship.

Well, that's good to hear. Frankly, the fellow racer I was talking to about trying it talked me out of it.

GRM should do a Hornet project car.