7cz or 6nz more than 2300rpm??

PDI in st. george utah can. They can get way higher I hear.

 

you can loosen the valves will help a little ..............my 6nz550 will turn 2300 i ran the overhead instead of setting them 15/30 i set them # 16/32 just playing around it would turn 2400 sitting still never got to drive truck myself but driver said it ran good ...............

 

You wont see any more RPM under load no matter how you set the valves or anthing else for that matter. The engine is electronically limited to 2300rpm, once the engine gets to 2300rpm the engine cuts the fuel under all circumstances. The only way to increase rpm is to modify the ECM. I dont know anyone capable of this but I am sure there is people out there who can.
There are some C15 marine files that allow 2400rpm but I dont know how they'd go in a truck engine as a marine file cant control a cooling fan, jake brake, crusie control, etc.
Why do you need more RPM anyways?

 

well i duknow i saw the tach hit 2400 with my own eyes sitting still, like i said i never got to drive the truck but why didn't the computer cut off fuel then ............the engine would only pull to 2225-or so before maybe it would have pulled 2300 never got to see had injector tip crack about a month or so later they had to remove them all to find it then dealership set all the valves when they put it back together

 

Often when you free rev an engine with that much rotating mass the engine does cut the fuel at max rpm (eg 2300 ) but the momentum of the accelerting rotating mass (crank, rods, pistons, flywheel, etc) allows the engine to rev past the max rpm limit. it is possible for an engine with a 2300rpm limit to flash to 2400, I have seen engines that are limited to 2120 rev to 2200 unloaded however you cant achieve this under load because the engine is reving so much slower and as soon as the engine cut the fuel at 2300 the weight of the truck its pulling stops the acceleration of the engine.
Also you tach could be out a bit, I have seen KW tachs out a fair way due to picking up from the alternator insted of the ECM.

The only other way to over rev one is coasting down hill at speed, pick a low gear and dump the clutch....may seem impossible but I have seen it done, the engine ECM had recorded a max rpm of 3014, the engine accelerated so violently it sheared the air compressor crank clean off and pulled most of the valve collets clean through the valve rotators. Never seen anything like it before or since.

 

My 1LW 3406E logged 2860rpm and lived to tell about it, my timing sensor went bad, motor was cutting out bad, split the shift and motor decided to rev on its own. ECM logged 2860rpm and nothing broke.

 

Man that thing must have been singing at 2800!!! you were lucky, I have never seen one rev to 2800 and survive, I have seen C-12s go 2600 and live though. Most of the over revs I see are down hill on the jakes and they dont survive much over 2100 rpm with the jakes on.