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Discussion Starter · #1 ·
Got an 06 GT with a Hellion turbo. Been to the track a couple times, not a well prepared track, a lot on the slick slide. So as a result I've gotten the car against the rev limiter a couple times (set at 6250 rpm if I remember correctly). Ya, some was poor technique, some was the lousy street tires I was running, etc.

As I did some research on the rev limiter in different forums found out it cuts the fuel, not the spark! Bad thing, leans out the motor.

Question is is there a way to change the rev limiter to cut out ignition rather than fuel? Whether its in the stock rev limiter or some aftermarket device.

Any help would be appreciated.
 

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Honestly, I'm not sure if there is.

What you may want to do is add 104 octane unleaded race gas to the tank when you make some passes. The added octane will help protect you against detonation to some degree.

Otherwise, I'd get me some track tires to help keep of the rev limiter!
 

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+1 Eric.

The last thing you want to do is pull fuel on the top end with forced induction. That is a bad combo. You must have already had your car on the dyno, so just raise your rev limiter in your tuner. I have my rev limiter set on 7k on the '02 although my shift light is set on 6.5k......

I would much rather replace valve springs than pistons.......
 

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Discussion Starter · #4 ·
Thanks for the replies. Thought behind cutting spark and not fuel was to keep the engine from leaning out. Better fat than lean.....
 

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Thanks for the replies. Thought behind cutting spark and not fuel was to keep the engine from leaning out. Better fat than lean.....
Yeah the TCS in the Shelby's actually do that to my understanding because the car comes with an S/C.

However, the Gt computers don't have a function for this. They also don't have a function to release the reverse gate on the TR6060 trans. However, those are the only major differences I know of.

I think short of a FAST or Big Stuff 3 aftermarket computer system you really don't have an option for cutting the spark as apposed to the fuel. Maybe a Versafuel would give you some option there but I'm not positive.

I'd just raise the rev limiter. Put in a good shift light set 500 rpm below the rev limiter (say set rev limiter at 6800rpm and shift light at 6300rpm). that will allow you time to process the shift light coming on and make the shift prior to banging the rev limiter. You can datalog your runs and if you get faster on the shifts you can adjust accordingly. Of course you need to set this up around your power band. if you have a Dyno sheet see where the power band flattens out and use that to determine shift point. Your optimum shift point may be closer to 5800 rpm.

That and add a little 104 race gas for protection.

Oh and new tires!:gringreen
 

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Discussion Starter · #7 ·
PLstang, got the shift light and the tires, haven’t been to the track yet with them, hoping this weekend.
Question on the 104 octane race gas. How about an octane booster with the 91 octane we’ve got here at 6000’.
Shinerstang, had considered the MSD 2 step to help stage the car and for the "cut the spark option," but read on other forums that it trashes cats very quickly due to a lot of raw fuel going directly to the cats while staged, so passed on the idea. Hadn't considered the option pointed out below posted on another forum. Thoughts on this……:scratchchin
You could get an MSD 2-step and wire it so it's always on (still master switched though), then set the rpm limit on that to 6200 and set the redline in the computer to 6700, this way when you hit 6200rpm's with the 2step on it will cut spark and not fuel.
 

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You should not be cutting spark for a rev limiter on a car with catalytic converters. The reason that the factory cuts the fuel and not spark is that if they cut the spark, there would be LOTS of raw fuel from the cut-out cylinders pouring into the converter, which would burn it up in a matter of just a few minutes.

What you may want to look for is something like the top-fuel cars use. Their rev-limiter setup doesn't cut out anything to any cylinders, but rather retards the timing when they hit the rev limiter. This is the best way to avoid damaging any components from lean mixture (cutting fuel) or burning the cats (cutting out spark).
 

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Discussion Starter · #9 ·
What you may want to look for is something like the top-fuel cars use. Their rev-limiter setup doesn't cut out anything to any cylinders, but rather retards the timing when they hit the rev limiter. This is the best way to avoid damaging any components from lean mixture (cutting fuel) or burning the cats (cutting out spark).

Excellent idea.....any thoughts on what that a top fuel like rev limiter might be for the 06 stang?
 

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I think you might be over thinking the problem. Remember the more electronics you have on your car the more crap to screw up!

I have banged the rev limiter on my GT several times, under boost and spray. It doesn't mean the motor is going to go Boom instantly. You just don't want to stay on it long, either shift or lift one or the other.

Heck a lot of the old timers believe that if you were shifting a stick car properly it would bang the rev limiter once between each power shift.

Anyways, I think if you correct the rev limiter by setting it up, set your shift light accordingly, and get good tires you'll be fine.

A two step is good in the burnout and at the launch but you really don't "have" to have one. i don't run one at all (Although I launch on a transbrake so the T/C determines my rev).

i think with the three things you are already doing the problem will go away!

Just remember, if you hear that sound shift or lift!
 

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You never sit on a 2-step any longer than a few seconds.....
Unless your Don "Burn you down" Burton then you sit on the stupid 2 step all night long in the pits and keep the competition awake all night!!:laugh:
 

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I'm not sure what that would look like for an 06, but if i didn't like my factory rev limiter, i'd be on the phone with Mallory finding out!
 

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Eric I am a little retarded on the art of racing so could you tell me what exactly happens when you hit the rev limiter. Would this ever happen in an automatic? Does the engine just start cutting out? How do you know when you hit it and when to let off? Thanks
 
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Eric I am a little retarded on the art of racing so could you tell me what exactly happens when you hit the rev limiter. Would this ever happen in an automatic? Does the engine just start cutting out? How do you know when you hit it and when to let off? Thanks
I'm not eric but this will answer your question.....:gringreen

A rev limiter does just what its name implies:

it limits the revolution speed of the engine. A rev limiter is placed in the electronic circuitry that prevents the engine from over-revving. At a pre-set rpm - say 7,000 rpm - the rev limiter engages. Once the engine reaches 7,000 rpm, it interrupts the signal to the coil, alternating on/off, slowing the firing sequence, and preventing the engine from revving past 7000 RPM.

To answer how will you know it is best described as a real bad miss to the equivalent to a spark plug wire falling off

if you hit the chip you will know it.....:)
 

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Reggie nailed it on the head!

The rev limiter in the 05+ GT's is a function set in the tune. If you want to change it simply make the change in the tuner. However, if your really not savy to that type of thing it's best to leave it alone.

The chances are very slim you would hit the rev limiter on an automatic. The only way I know to do it is to lock it in a gear. Not to say there are not other ways....that's just the only one I can think of!:gringreen
 

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OK thanks for the replies:bigthumbsup. So is that what they adjust on a valet tune, just set the rpms really low?
 

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OK thanks for the replies:bigthumbsup. So is that what they adjust on a valet tune, just set the rpms really low?

Yep they basicly can put a speed limiter in the car.

The Kenne Bells actually have a vallet mode. By setting it the blower bypasses the boost at all times.
 
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