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Topic: Sedona RPM- WISDOM (Read 661 times) previous topic - next topic

Sedona RPM- WISDOM

Wisdom needed
General
8.3 with Pacbrake

Uphill no issues 5th mostly, some 4th

7% 5MI DOWN 2300RPM in 4th.. still needed to brake...too fast

Back to Tucson, longer 6% 7miles
Can I take it in 3rd, what RPM IS OK..?

Re: Sedona RPM- WISDOM

Reply #1 –
In 3rd gear you might not have to brake much at all. From what has been posted the Allison will upshift at redline.

Re: Sedona RPM- WISDOM

Reply #2 –
John,

I believe we both have the same engine.  At Cummins QuickServe Online there is a listing of the important RPM numbers for my C8.3L.  They are reproduced below.  You can see that the Governed HP is rated at 2400 RPM.  The engine can obviously run at that RPM without damage.  I have personally always used 2400 RPM as my maximum engine speed when using my exhaust brake.  I find 4th gear at that RPM and around 40-50 mph will usually work very well on most hills, but 3rd gear at 2400 (and a lower speed) might work better for a 6-7% grade.

ADVERTISED HP:  300 @ 2200 RPM

GOVERNED HP:  285 @ 2400 RPM

TORQUE PEAK (lb-ft):  820 @ 1300 RPM

HIGH IDLE:  2760 RPM

GOVERNOR BREAK RPM:  2450

Re: Sedona RPM- WISDOM

Reply #3 –
Chuck, as usual your KIND information remembers my poor eyesight...

Thanks !

Re: Sedona RPM- WISDOM

Reply #4 –
Quote from: craneman –
In 3rd gear you might not have to brake much at all. From what has been posted the Allison will upshift at redline.
Good suggestion!

The Allison is supposed to upshift but ours keeps on going well past the normal shift point. Ours shifts at 2130 (fuel cutoff) at full throttle but I manually upshifted on a downgrade at 2300 rpm as it was still going up. Tried it without the Jake turned on just to see how high it would go.

Pierce

Re: Sedona RPM- WISDOM

Reply #5 –
Going from memory on my previous 1994  coach with a Cummins 8.3 300 hp and pac brake 

RPM limits:

2500 rpm under load.

2800 rpm under no load (down hill).  Best if valves have been adjusted on schedule to run that max downhill.
 

Re: Sedona RPM- WISDOM

Reply #6 –
Thank you ALL...

Made it DOWN 3rd, still needed a bit of brake when it got to 250 RPM

MANY THANKS ,