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I am looking through the Helm manual on a seperate topic right now - I'm not sure if its been addressed or not, but I believe there may be a way to "bypass" the ECU rev limiter feature.

According to the helm manual, the ECU will cut fuel to the injectors when it senses the tach voltage signal reaching a certain point (at 6900 RPM). There is two things which could be done.

1. Since the emanage can control the injector duty cycle, AND at what RPM the injectors fire - just map an injection signal past 6900 RPM. This is all theory mind you - and I personally wouldn't try it unless you have a built engine due to the fact that the rev limit exists on a stock engine for a reason! I'm not too sure if there are other factors that the ECU would do as well (such as pull engine timing or whatnot) about 6900 RPM - BUT the E-manage can control that too!

2. Clamp the voltage signal going into the ECU from the tach so that the ECU never sees the voltage from 6900 RPM. A crude method, but it would work....

Anyhow, just my 2 cents on this for those of you who care....

 
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Sounds great in theory but I wonder what rev our engine can handle at its maximum since it may be higher than 7k but maybe not by much. I wouldnt do it since some serious problems could happen if you over rev.

 
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Need for speed underground.... REDLINE = BLOWN ENGINE.

 
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well, by passing the rev limiter is worthless anyway since we don't have a wide powerband at top end. And i'm not too sure what exactly the e-mange can do, but i know your timing will have to be adjusted. And of course new valves, springs and retainers.

 
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You guys aren't listening - I posted this because with headwork it SHOULD be possible to go pat 6900 RPM!

 
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Just because it can go past 6900 RPM doesnt mean its going to be making any power there.
It depends on how much you alter the torque curve.

 
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Just getting rid of the rev limiter won't do jack ****, you have to radically modify your engine to actually make use of the higher rev limit. I know "high" revving engines are cool and all... but it's not going to do jack ****, as you get into the higher RPMS, you need to upgrade your valvetrain, otherwise you'll bend the **** out of your valves and probably trash your pistons, cause they'll hit each other. NOW, if you wanna go D17 all motor, go for it, but it aint gonna be cheap, there are much easier ways to get more NA power. Keep in mind the higher the engine is revving, the more gasses it has to expell per second, so you're going to need to do lots of work for it to actually 1 make power, and 2, not destory itself. Lastly, with a higher revving engine, your con-rods will stretch more, so you have to take that into account as well.

 
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Hopefully we will see some aftermarket turbo cams and valvetrain in the near future from Exospeed. Even with that done I would think about getting crower or eagle rods for the extra stress that bottom end is going to endure.

Guys, you WILL make power up there with a cam with more duration and lift. I can't wait to see what becomes available to us in this area.

But more on topic with your post, that sounds like it might work. Actually I don't see why it wouldn't if that is what the ECU relies on to cut fuel.

 
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not only do you have to think of head work, you're putting alot of stress on the block internals

 
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Thanks Dober - I don't understand why everyone else is cutting down this idea. I posted this as information, ala FYI for those who care. I don't plan on doing this as I don't have a built head / block / etc - however FOR THOSE WHO DO CARE, there may be a method around it (as described above), which is why I posted this in the TECH section, as in "this is a technical discussion."

 
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I just agreed with you, you did all of the research! Nice work BTW.

 
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I agree, your workaround is a good idea, the only probelm is, your ECU probably uses the RPM in some way to actually calculate how much fuel the car gets, therefor.. above whatever RPM you set it at, it's gonna get the same amount of fuel... this could be a very bad thing...

 
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i'd be more interested in removing the speed governor more than the rev limiter...

 
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The Greddy Profec-E01 can eliminate the speed limiter. It has a function that limits the max voltage output of an input wire. If you could somehow measure the voltage at or near the max speed before it cuts off, then cut that wire, run it through the e-01 & set the max voltage. This would then only send a maximum of that voltage, telling the ECU the car is only going max speed, so you shoul be able to accelerate beyond that. You can also measure your true speed if you have another velocity display (like the Apexi Rev/Speed meter) tapped into the speed wire before the e-manage.

 
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opto so fuel is cut off at 6900rpm in an ex?
so running the car to 7100rpms is a waste of time?
are you saying that 6900 is the ideal shift point without power loss?

 
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I dunno about y'all, but my rev limiter dosen't kick in untill somewhere around 7200 RPM. I can do over 60 in second.

It would be frickin' awosome if you could figure a way to turn 9k with the engine. Strong enough valve springs and maybe some reworking of pullies and whatnot as well as strengthening of the internals would be a really cool and fun way to go with it. The only problem I see would be getting a cam.

Anyone know if/where you can get custom cams made and how much they cost?

 
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you can send them out to have them reground but there is no direct replacment yet. exospeed was considering it down the line but the chances don;t look good. the cost of R&D comparded to the profit made? andf then every other major manufaturer just uses their R&D and makes their own quicker and cheaper.

 
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I have titanium springs & retainers in my ported head that is not installed yet, and I would like to rev to 8500, but I can't do that yet. I also have a cam that was reground by DH-Racing for a turbo setup, but my turbo is taking so damn long, I am selling it before I even used it, $350 takes it.

 
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[QUOTE=opto_isolator]2. Clamp the voltage signal going into the ECU from the tach so that the ECU never sees the voltage from 6900 RPM. A crude method, but it would work....

QUOTE]

Can you tell me which wire this is and where i can find it?

 
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[QUOTE=Ghost33]Well - first off, in your PM I would not recommend doing this if you are running an LX ECU on an EX motor.....If you had the car wired properly, and the ECU is the correct on, you should not have any issue revving past 3800 rpm......

 
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i have the right ecu for the motor, i just wanna try and see if this works, so can you tell me which wire it is?

 
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Everybody needs to stop cutting on people with this idea, 1st of all if people want to blow their stock motors by getting rid of the rev limiter then let them do it, but for those people building up bottom ends and heads...this info can be very helpful. That's what I hate about trying to get information off of here and HT, any idea is bashed by the morons who "know everything" if you don't like an idea great, but don't knock it...I am not saying to not give constructive criticism but it seems like in every thread someone is saying the persons idea is dumb...grow up.

 
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I have an 03 LX, and what I've gathered from reading threads on this subject matter is that it would be an absolute bitch to actually disable the rev limiter, and driving with it disabled could be even worse? Would the Greddy E-01 realistically work has anyone done it? I must go faster than 113 mph, if the EX's are going atleast 125 mph, than why can't the lx's, is it because of the V-TEC in the ex's, what gives????