How about highest sustained RPM?

[Crunch]

The fuel mileage discussion got me to wondering about high RPM's, considering our redline is just over 3000. I don't like to keep it in the red all the time, but I ain't afraid of the redline either. But who has had the highest sustained RPM's? By sustained I mean at least 30 seconds (admittedly an out of my hat number) in any gear and any driving conditions, i. e. towing, steep grade, etc.



I've had mine up to about 3500RPM for 30 seconds or so, just to put a bit of healthy stress on the engine. Who's done higher for longer?

 

[CATCRACKER]

i have gone that long at 3500 for over 3-4 minutes doing 110+ although i would not say anyone esle should do that. these engines are not effected when running high rpms.

 

[XcumminsX]

catcracker. . LOL WHAT ARE YOU THINKING!!!!!!!! your rig is for sale and your saying that!!!!!!



Nick

 

[timjones]

Piston speed on these engines does not become a problem until about 4500 rpm. So 3500 is just not that big o deal.

 

[XcumminsX]

why is the redline so low then??



Nick

 

[David Muench]

It's not a 3rd gen but I've heard that Schied's pulling dually runs 6,000-8,000 rpms.



Or it could just be a rumor, I have no idea.



XcX: Just because the engine won't fly apart at 4500 doesn't mean the fuel delivery system can keep up, especially now that the fuel system is electronically controlled. The engines already have to go back to a single injection event instead of multiple at high rpms.

 

[Crunch]

Originally posted by David Muench

It's not a 3rd gen but I've heard that Schied's pulling dually runs 6,000-8,000 rpms.



Or it could just be a rumor, I have no idea.

Good grief! Those are high RPMs for some gassers. If I saw that on my tach I'd be worried about an impending Code Brown! What are they doing to get that kind of engine speed?

XcX: Just because the engine won't fly apart at 4500 doesn't mean the fuel delivery system can keep up, especially now that the fuel system is electronically controlled. The engines already have to go back to a single injection event instead of multiple at high rpms.

Excellent knowledge to pass on. Sometimes the unexpected tidbits of knowledge are some of the most valuable. How about running the HPCR pressures all the way back to the tank? As long as you didn't have to pop the cap off the tank to fill it that 35 gallon reservoir should keep the engine supplied. Of course, that plastic tank might need some reinforcement...

 

[David Muench]

Originally posted by Crunch

Good grief! Those are high RPMs for some gassers. If I saw that on my tach I'd be worried about an impending Code Brown! What are they doing to get that kind of engine speed?

That is the secret question, isn't it? I would think a lot of balancing and blueprinting, and an interesting injection system. .

Excellent knowledge to pass on. Sometimes the unexpected tidbits of knowledge are some of the most valuable. How about running the HPCR pressures all the way back to the tank? As long as you didn't have to pop the cap off the tank to fill it that 35 gallon reservoir should keep the engine supplied. Of course, that plastic tank might need some reinforcement...

I don't think it's necessarily a pressure issue. The injectors are now fired electronically by a computer. At 3500 rpms the computer is firing the injectors (assuming a single injection event) 350 times a second. Assuming it's not just injecting blindly, it's also taking measurements and calculating the injection duration and amount of fuel to inject. And unlike a PC, this has to be a real time system with no lag.



Those are my thoughts at least. . I'm not a Cummins engineer, but there are a couple lurking in this forum. Maybe they can shed some official light on your question.

 

[supersonic]

I'll tell this much were not turnin' 6-8,000 RPM. More like 5.

 

[Crunch]

Like, WOW!

Originally posted by supersonic

2003 FORD F-350 4x4 super-cab LB SRW w/12v. Twin Turbo Water Injected CUMMINS Diesel (WELL in excess of 1,000HP!!!)

Gotta love this TDR jazz! I'm learning something every day. I thought water injection required a carburetor. Your truck sounds like it will not only leave the ricers in the dust, but have enough power to double-back from the finish line and crush them like bugs.



How did you get so much torque on the `98 Dodge?

 

[J.R. Adkins]

Hey Sonic... ... ... . Better watch it!!! The good Dr. might ask for a dyno sheet.



Its not real if he has not seen it!!



5500 rpm here. 6000 breaks stuff:{