Limiting RPM in MG-E? Keep idiots from screwing me!

[Carl Johansson]

Ok guys, 87 NA 5 speed manual . We have gutted the thing caged it and use it to run the 24 hours of lemons series. so far 14 races, not a single lap lost to mechanical, and same engine never touched for 12 races, which = just about 200 hours of racing.

So now , I am about to put a new driver in the car, (because they are paying me to do it!). My biggest fear is that he's a bubling idiot, or worse, thinks he's rthe next Jr!
Our whole secret to making this thing last is that we NEVER rev over 6000 RPM. we shift. That works great with the 3 drivers we have, completely disciplined, completely buy off on the no overrev!

But this guy, may blow a shift, may get caught up in the competition, may not RPM match on the downshift, he could screw it up in alot of ways!

On my other cars (non toyota) we have an MSD ignition that we just put in a chip to set our own rev limit, but i am not familiar enough wirth this engine, and it's electronics to know what to do!

Anyone know a simple cheap way to limit RPM to 6K in this thing (hopefully reversable after we get rid of the idiot!)
Carl Johansson
Auberry Ca

 

[kotu100]

If you think he's an idiot why let him drive in the 1st place?

 

[radiod]

How much are they paying you to let him drive vs. how much will it cost to redo the engine....brakes....clutch.....transmision........you get the idea :icon_razz

 

[te72]

I'm with these other guys, why even let this guy drive? Maybe if he has a spare engine built on the side to fix what he might breatk...

That said, sounds like it's all stock anyway, why bother revving past 6k? NA's won't make any real appreciable power up there anyway, they peak around 5500 IIRC...

 

[ForcedTorque]

why bother revving past 6k? NA's won't make any real appreciable power up there anyway, they peak around 5500 IIRC...

Determined racers don't pay any attention to facts! Shit, shifting takes away valuable time

 

[Carl Johansson]

First of all, for whatever reason, that car pulls strong through 6200. but what often happens at the end of a straight is that the guy is reving it out, if he shifts, he loses time, both on the shift, then an extra downshift, and an unsettled car in the corner. but If he doesn't shift, he will have to back off earlier, alot of guys with testosterone issues think that there is a third option - keep it floored until you have to cram on the brakes. That is the slowest option, and by far the hardest on equipment, but who knows what goes on in peoples heads!

To answer another question, 5K guys, plus 2500 if it wrecks. It costs me about 2K to buy and build the car, and if the engine is fubar I budget another 600 for a replacement! But i also have 1000 bucks of tires for this race, , and 400 bucks worth of brakes, and I have to transport 3500 miles round trip, so it's not a big money maker, but I kind of like the novelty of it, and why not give these Euros an asian woody by driving a supra in a N am. race!

we have 2 supras, identical pretty much, and a spare engine, and an extra spare head, but we will only bring 1 car there.
it's a street car mascarading as a race car, it has 175K miles on it, sooner or later it goes boom! But i want it to go boom because it wears out and dies valiantly, instead of a missed shift kaboom! or a slow agonizing BHG death on the track!
and actually the car will be manned by 5 guys for the 24 hour race, I know 3 of em are spectacular, but have no idea about the other guys!, Team leader drove with Johnny OConnell at nurburing 24 last year, and is doing it again this year, but he drives race cars, not junk! I'm just looking for cheap insurance to cover mistakes made by one unfamiliar with the car, sorry i shorthanded the description earlier, just looking for RPM limit ideas.

 

[te72]

Don't mean to come off dissuading, certainly not. I admire your courage, and a car that's made it that long under such conditions! I would think you could wire something into the ignition system that cuts power at your desired RPM, but I wouldn't have any idea what exactly. Hopefully someone on here has an easy fix for you.

 

[IJ.]

Umm buy a limiter?

 

[Greek]

Install a machine that every time he revs it past 6,000, a metal fist pops out beneath the steering wheel and punches him in the testicles. That will surely keep is testosterone in check.

 

[radiod]

If you're just looking to cut at 6k rpm, I'm sure that can be set up with something like a Bee-R, but there's got to be a cheaper alternative than that particular unit. You just need one limiter, the Bee-R essentially does two.

 

[casgallo]

rev that ainimal to redline if need be its only 300 more rpm? Have faith in the 20 yr old 7m!

 

[Poodles]

Factory rev limit is safe, and no rev limiter can stop an over-rev from downshifting to the wrong gear...

 

[Backlash2032]

Factory rev limit is safe, and no rev limiter can stop an over-rev from downshifting to the wrong gear...

Was about to say the same thing.

 

[te72]

Factory rev limit is safe, and no rev limiter can stop an over-rev from downshifting to the wrong gear...

Either one of my old Miatas can tell you that much. Turns out, electronics have little to do with mechanical rev limits.

 

[Poodles]

Yep. The ignition and fuel could be completely off and it would still damage it if it's reved too high. It also means you lose your man card because you suck at driving :rofl:

 

[supraguy@aol]

Aside from a Bee-R, I can only think of the MSD units, with a tach adapter.
One can usually be had on craigslist or a Chevy/ Ford forum for a reasonable amount.

 

[shipkiller]

you could make a small board with a common pic that input the rpm signal and could cut the power to the igniter via a relay. Unfortunatly it would be quite complicated and the ecu will probably trow some code at that moment

 

[te72]

Yep. The ignition and fuel could be completely off and it would still damage it if it's reved too high. It also means you lose your man card because you suck at driving :rofl:

Ahh crap... don't tell me you've never missed a shift in the Miatas before. Like using an exacto-knife for a shifter. Let's just say top of 3rd intending to go into 4th, but being 2mm off on your throw, ending up in 2nd, that's not a good thing. HELLLLLLOOOOOOO 10.5k rpms...

 

[DonS1mpson]

Could someone explain to me exactly what these 200RPMs between 6k and the limiter do to a 7MGE to suddenly make it implode?

It certainly is a new concept to me, and give me getting a 'drift spec' NA that I intend on taking road racing monthly it is something I'd like to know.

 

[te72]

Earlier 7m's with the 6m crank will rev to 67xx before cutting off the fun Don. Unfortunately, they don't really make much usable power beyond 5500-6000, depending on setup. Being a long stroke, small bore (in relation to stroke) engine, they're designed for lower rpm torque, not screaming along at higher rpms... Revving a stock NA beyond 6k is essentially pointless.