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Discussion Starter #1
Hello all,


I have some questions in regards to the factory rev limiter on our Dmax engines


1. What is it set at?


2. Can it be raised?


3. How does it actually work? I.E. fuel cut off/pulse timing/width


4. Could bouncing off it to often cause injector failure or other engine damage?
 

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I know the stock limiter is round 3200 rpm's,


with the Quad 215 program I rolled almost 4400 rpms on my last dyno runs.


T
NY


As far as how it works.guessing it cuts fuel off same as the speed limiter.


I am sure anytime you are over revving an engine you could cause damage, however the duramax will rev higher than 3200 rpms when downshifting in T/H during a grade.


Any tech's know the answer ??????Edited by: GMC-2002-Dmax
 

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Discussion Starter #4
Wickedsprint said:
I hope not because whack the limiter at least once a day *shrugs*

I am grassping at straws here! Just trying to possibly identify other conditions and causes of injector failure and engine damage. Your testimony of bouncing off the rev limiter daily shoots holes in my theory. I just belive there are multiple injector failure reasons. Dirty fuel being the greatest but not the only.
 

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A diesel does not really slam intot he rev limter like a gasser, plus I only have 8k on my truck or so, plenty of time for them to give up the ghost.
 

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I hit the 3200 rev limiter quite often. When the motor is not fully warmed up, say about 170F and I'm wide open merging on the highway it will stay in 4th for a while and basiclly just sit at 3200. Seems to depend greatly on engine temp, I even got my EGT up 1200 without the juice because of this.



As far as engine damage, I believe the valvetrain can take it but the rod and main bearings may suffer over time when you ask a heavy piston and rod assembly to change direction at that rpm. Despite the fact that there is far less time for slow diesel combustion to take place also. But the way to make horsepower is rev the engine so rev on guys!!
I'll join you after my trans and quad 215 chip or maybe something new by then.



J
 

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Discussion Starter #7
I have never witnessed a high reving Dmax but have imagined one many times. A Dmax with 30" slicks shifting at 4400RPM sounds pretty evil to me! I understand all diesels have limitations on RPM do to the heavy rotaing mass but also the fact that there is just not enough time available for any type of complete combustion at the higher RPM. I am curious what the Dmax limits would be before you actually start loosing power? Edited by: Bronco
 

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Bronco said:
I have never witnessed a high reving Dmax but have imagined one many times. A Dmax with 30" slicks shifting at 4400RPM sounds pretty evil to me! I understand all diesels have limitations on RPM do to the heavy rotaing mass but also the fact that there is just not enough time available for any type of complete combustion at the higher RPM. I am curious what the Dmax limits would be before you actually start loosing power?

Sounds like mtomac's ride, less the slicks.


maybe ask him to post ...he drag races and run's low 12's maybe even high 11's......and truck pulls as well





T
NY
 

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The factory rev limiter and "top speed limiter" work the same....... they just limit the amount of fuel so the motor cannot turn any more RPM's. It's not an "on/off" situation...... it just "lays down" on you and wont got any faster.
 
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