Rev Limiter ???

[dylchris]

thanks

I am going to call MSD and ask the question; I do not see how interrupting the ignition circuit will stop the revolutions in motion other than what egoracing said, I have used sevearl of his offerings and they were always spot on. I understand the physics of weight and friction and it makes perfect sense.

Thanks and I will learn from your input.

[Egoracing]

i shot the pinion out the front of a set of gears in the middle of the straight one night, got my foot out of it as soon as i heard the bang. motor never hit the chip (had an incar cam running and could hear everything happening) and reved 2-300 rpm past the chip. ran at a different track two weeks later, was down on power and found two bent push rods and every exhaust valve was bent after the race. talked to my engine builder and he told me its common when the motor has heavy load on it and something like that breaks, the rpms come up so fast that the rev limiter can't catch it in time and the motor can over rev. so it does happen.

to answer the guys original question, if you're driving around the track, full throttle, on the chip the whole way around it might cause some problems. if you're only hitting the chip for a second or so at the end of the straight away, you should be fine.

I would havbe the chip checked. A truck sereis that used them would find differences in chips when they were tested and 2-300 would fit into the 400 rmp window they found. Some were less than labled and some were more.

[mbaker76]

Don’t take for granted that your recall on the tach is correct either. Our tach recall reads about 3-400 rpm faster than the actual peak rpm. I thought we were blowing way past the chip but when I put in a low chip or just simply rev and hold at a given rpm, then hit the recall it always showed faster. I have also heard it the other way, the tach is slow and recall will be lower than the chip. Might be something to check.....

[cheaterleaddog]

I can do this [cheat rev limiter]

A friend bought a car once that DOMINATED and when the new owner got it he only was a 5-8th place at BEST! After about a month the original owner came to the track and came buy and told him once the race starts to flip a switch on the dash marked "cooler" and push the radio button during the race. He did and the car went about 700 RPM over the chip that was sealed into the box. He had it wired to bypass the box with the switch and button. You had to have them both set or it would not go past the limiter.

I have the capabilities to do things like this for as little as $100.00 for more money can make it remote control from pits.

[ep33510]

Rev Limiter ???

Xtremeracing

The HEI module rev limiter should cut things out if its loaded or unloaded. I have seen the MSD boxes with the Chips have their sockets loosen up and add resistance to the soft touch circuit. That added resistance will cause the limit to be moved Up or allow the box to free wheel if one side the chip does not make contact.

Yes, the MSD boxes can be Blueprinted to eliminate the common 150 rpm low issue with the chips. We have three versions ( 1% rule, 400rpm, Racer choice) depending what direction you would like to go. If you questions please feel free to contact me.

[4bangerhotrod]

these engines rev really quick with no load on them. so if your at a lower rpm when something breaks the engine gains rpm amazingly quick just because the chip cuts fire to it doesnt mean the chip is going to grab the crank and stop it from turning faster than the # thats printed on it, its called momentum, its really hard to slow something down thats spinning that fast. think about it its commonsense which is what seperates alot of racers cause besides from driving abilitys most of the things on these cars use commonsense to figure out how a setup or anything on the car will work or react. these engines will free rev past the chip, but if your going past your chip by thousands of rpm you may have something wrong.

[Clark8669]

no problem

An MSD rev limiter with the engine at whatever chip you put in box give or take 100 rpm. The motor being loaded or unloaded has nothing to do with how it works. It will cut the spark to random cylinders to keep the engine at that specific rpm. And it doesnt hurt the engine to put it up on the chip for a few a few seconds. Thats the whole point of the system. For example when drag cars do burnouts and stage they put the motor up against the chip till the light turns green. And that can be for up to ten seconds at times

[LowTechRacing]

these engines rev really quick with no load on them. so if your at a lower rpm when something breaks the engine gains rpm amazingly quick just because the chip cuts fire to it doesnt mean the chip is going to grab the crank and stop it from turning faster than the # thats printed on it, its called momentum, its really hard to slow something down thats spinning that fast. think about it its commonsense which is what seperates alot of racers cause besides from driving abilitys most of the things on these cars use commonsense to figure out how a setup or anything on the car will work or react. these engines will free rev past the chip, but if your going past your chip by thousands of rpm you may have something wrong.

The rotating assembly could just spin free if it didn't have heads. But the engines your talking about are light weight, high compression, and tight tolerances. The light weight means it has less momentum. The high compression forces push down while the piston is coming up slowing it. If no spark from the ignition to light the af mix you just slowed the engine down. Momentum is not enough to over come a rev chip by thousands of rpm's. To many things working together to slow it down.

[4bangerhotrod]

compression is the reason it wont rev thousands past the chip but theres so much momentum thats the reason they will rev a few hundred past the chip if something breaks. ive seen it happen way to many times and it's usually between 200-400 rpm past the chip if the engine is down in the rpm range when the part lets go, but if its close to the chip when it lets go it usually wont go past the chip.