3rd Gen Engine and Drivetrain -> 2003-2007 5.9 liter Engine and drivetrain discussion only. PLEASE, NO HIGH PERFORMANCE DISCUSSION!

What RPM is safe?

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Old 03-03-2010, 07:45 AM
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What RPM is safe?

I was pulling out from a side street onto the main road the other day and got on it pretty good because traffic was coming and the back end broke loose. I shifted as quickly as I could but I saw the tach at almost 3500rpm. The truck still runs and drives fine but any time I see a tach in the red zone I get scared. I've got a smarty jr and exhaust but other than that the truck is stock, did I hurt anything?
Old 03-03-2010, 07:55 AM
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Don't exceed 3500 or you will risk slapping a piston. I have hit 3500 on several occasions and have been fine, but that is its limit. You will be fine bud.
Old 03-03-2010, 07:58 AM
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doesn't the computer limit the motor to 3400 or so?
Old 03-03-2010, 08:02 AM
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I can hit 3500, but I also am running beta programs.

But yea there should still be a limiter for safety.
Old 03-03-2010, 08:52 AM
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I dont really know alot about our truck programming but I can tell you my mustang will limit the RPMS to 6250 no matter what the crappy factory tach says. So I would think if our truck has a factory rev limiter it wouldnt go past that set rpm no matter what. sorry i could give you more info
Old 03-03-2010, 10:07 AM
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A guy stopped me yesterday and asked about my 5500 truck. Said he just bought a used 2500 and wanted to know the difference. I admitted I just put some extra 5's on it.

He told me about his new muffler and I said I ordered a shift kit. Then he said maybe he needed a shift kit because his truck will rev to 5500 rpms before it will shift. I said that would be really bad because redline is 3200.

He mentioned hitting 5500 to 6000 a couple more times. I don't believe it could ever happen, but I do know some trucks that will run 4200.

A quick burst above 3200 with a stock engine shouldn't hurt.
Old 03-03-2010, 11:29 AM
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2500 Hemi perhaps?
Old 03-03-2010, 11:33 AM
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Originally Posted by steelblitzkrieg
2500 Hemi perhaps?
Nope, diesel. He kept calling it the small 5.9 engine.... New to Cummins I'm sure!
Old 03-03-2010, 11:45 AM
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What year? Maybe it's the old 5.9 Magnum? Chances are they had no idea what they were talking about. I don't think our RPM gauge even shows above 4K does it?
Old 03-03-2010, 11:49 AM
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Originally Posted by steelblitzkrieg
What year? Maybe it's the old 5.9 Magnum? Chances are they had no idea what they were talking about. I don't think our RPM gauge even shows above 4K does it?
It's an 06 and a diesel. I think our tach goes to 4500 but I may be wrong.
Old 03-03-2010, 11:52 AM
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Ya, I just checked it goes to 5k. Maybe they're just used to seeing a 7-8k Tach and needle placement at a 2 o'clock position which would be around 5-6K if I remember my Mustang and Jeep well enough.
Old 03-03-2010, 11:55 AM
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He's taking it back to the dealer, I advised him NOT to tell them it's revving to 6 grand....

I think I convinced him Smarty jr is a great addition....
Old 03-03-2010, 11:58 AM
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I have had mine to 4k two or three times due to mechanical over rev. Always scares me bad.
Old 03-03-2010, 12:04 PM
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I've had mine over 3500RPM's. Tow/Haul Mode when coasting down a decent grade with light braking it'll downshift and hold 3500RPM's or so. I can't imagine it's too dangerous if the computer is allowed to do it.
Old 03-03-2010, 07:32 PM
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Thanks for the replies guys, that puts my mind at ease. Still not something I plan on doing ever again but at least now I know that if it happens I don't have to worry too much.


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