Well I asume it was the rev limiter or it floated the valves? Whatever it was it happend at 5400 RPM's just for a split second I was just getting ready to let off, but I can tell you a V-10 at 5400 sounds like 12,000, I wish I had a camera with audio outside the truck but if I had that it might have chucked a rod out the side Oh I was moving in second gear not in neutral.

 

The PCM will shut off the fuel before you can float the valves. You felt it shutting off the fuel.

 

Thats what I figured I was going to let out at 5500 I guess the computer is a 100 rpm's smarter than I am. I won't let it happen again I just had to try it once, glad everything held together.

 

My 04' limiter was set at 5300rpm in drive from the factory. It is worthless to rev a stock 2V V10 (5400-5500 rpm) that high especially an NPI. It is out of its useable power range at that rpm. Do it enough and the powdered rods may throw a fit.

 

Between looking at the dyno charts and actual driving experience with both 3.73 and 4.56 gears I'd have to agree with the fact that there's very little reason to run the 6.8L V-10 over about 4500 to 4700 rpm. Anything more is a waste and 9 times out of 10 you'd be better off to shift up to the next gear at that point as in most cases you'll still be over 3000 rpms and above the peak torque of the engine and well into the power band. There are very very few times towing anykind of trailer that I have ran into where if I was over 4500 rpms shifting up to the next gear wouldn't hold or increase speed. Actually, I can only think of a single time that's happened and I was towing 11k lbs up a 14% grade and I just kept dropping speed and gears untill I was all the way down to 1st! I made it to the top but I reminded myself to take a different route next time!

 

Come to think of it, now that I've got the 4.56s I bet I could pull that hill in 2nd!

 

Put mine in tow/haul and from a rolling start it will hit the limiter every time because the trans can't shift fast enough on wot to keep it from happening.