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RPM @ 70

GeorgiaKeith

GeorgiaKeith

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Just bought. 96 Chevy 3500 6.5 turbo diesel... Truck is clean, only 129k miles. Bought it from a friend. It's actually my first diesel. Cruise set at 70, how many rpm are y'all running? I'm about 2300. Running great just seems it turning pretty good.
 
There are many variables that need to be known that can affect RPM at a specific speed. Rear end gear ratio, tire size, and type of transmission (auto or manual, might make a difference for O.D. gearing, but not sure on this).

That being said, here's what I have. 94 K2500, 6.5 TD, 4L80E auto trans, almost worn out Toyo M55 265/75/16 tires, and 4.11 rear end ratio, and Tiny Tach for reading RPM's. At 60 MPH I have 2000 RPM's (definite RPM), and at 70 MPH about 2250 RPM (may be slightly more, not absolutely sure) as I haven't gone this fast very much until recently.

Don
 
Welcome, low miles-nice find.
Mines a hummer so closer to 3,000rpm.
Find out from your friend what he's done to it- at 100k harmonic balancer is due and is an engine killer. Many run well above 200,000 miles on original one, but IMO is not worth the risk.

Check out the stickies, there is a ton of info that will save you lots of time and cash for you new ride.
 
handcannon said:
There are many variables that need to be known that can affect RPM at a specific speed. Rear end gear ratio, tire size, and type of transmission (auto or manual, might make a difference for O.D. gearing, but not sure on this).

That being said, here's what I have. 94 K2500, 6.5 TD, 4L80E auto trans, almost worn out Toyo M55 265/75/16 tires, and 4.11 rear end ratio, and Tiny Tach for reading RPM's. At 60 MPH I have 2000 RPM's (definite RPM), and at 70 MPH about 2250 RPM (may be slightly more, not absolutely sure) as I haven't gone this fast very much until recently.

Don
Click to expand...
Cool. Thx. Mines stock, auto, factory size tires. That about what I'm running too. Thx
Will L. said:
Welcome, low miles-nice find.
Mines a hummer so closer to 3,000rpm.
Find out from your friend what he's done to it- at 100k harmonic balancer is due and is an engine killer. Many run well above 200,000 miles on original one, but IMO is not worth the risk.

Check out the stickies, there is a ton of info that will save you lots of time and cash for you new ride.
Click to expand...
thanks!
 
I think so. From what I've learned if your running stock turbo much past 70mph/ 22-2300rpm isn't really necessary any way. Just be careful owning a 6.5, I've become quit addicted and wont go back to gas of I can help it. :D
 
Oh and like Will said list any and all upgrades/ maintanence and then you can get suggestions from everyone on what's best to do from there.
 
Many trucks, and all Hummers, constantly run above 2300 rpm. That's just the bell curve peak, efficiency falls off and the factory turbos tend to start ramping up the iat. Centermounted gm6 tends to handle about 200 rpm more than side mounted gm6.

So don't be afraid to break the 2300 like its a red line- that's more around 3850-4000 depending on details. Keep in mind, lower rpm engines do have a tendency to live longer...
 
Thanks Will. :) that sounded less like it's gonna break at those rpms. I didn't mean it that way. Some times I'm not the greatest with words.
 
Oh, sorry I didn't answer -70 mph is 2,750 rpm closest I can tell. So I don't like going over 85 for some reason. Never pushed 100 yet- but one day it's coming...

AM General rated red line at 3,400 rpm in 95 n/a or turbo. Yeah... scare me...
 
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