Now that the trans has learned this Predator tuner is mighty nice,the 85 hp tune makes it go like hell. I removed the speed limit and set it at 120 ,got to 117 when it dawned on me that the rpms were in the red .how fast can I safely spin this thing without causeing damage ? :eek:

I am sure it has a rev limiter on it, for accelerating, but on downhill braking I have had mine to over 4000 rpm.

The red is not "bad". As it states in the manual, the dashed-red does not mean you should start sending flower's to your Dmax's mother. It is ok to go into the dashed red when you are using the Allison's grade braking...just by all means dont go into the SOLID RED. Im not sure why they even bothered putting the dashed red line on the tachometer...its pointless because in stock form, a Duramax wont even fuel over ~3400 rpm IIRC. Guys have had their Duramax's rev limiters removed before and I dont think anyone has run into serious problems. As a rule, I think the Duramax's are safe until about ~4600 RPM. Maybe faster, but you'd be playing with fire. The reason a stock 'Max cuts off fuel at ~3400 is because they didnt want people running for long periods of time over that speed. For short bursts, its fine.

---Ben

You should only get a little way into the red anyway, mine hits 120 right at 3600. No big deal.

You should only get a little way into the red anyway, mine hits 120 right at 3600. No big deal.

You gotta account for your larger tires, if you're speedo isn't recalibrated.:)

I read that the Duramax was balanced up to 5,600rpms