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ReidGreh · 09-20-2022, 10:24 AM

I have recently purchased a 2011 6.7L ISB powered Avanti 3106 with a 1000MH Allison transmission. The engine was produced in 2009 and is at 2007 EPA regulations.

The previous owner said it was a bit of a dog in the mountains. I haven't been to the mountains yet, but not impressed with the power.

I researched the specific engine serial with Cummins and was surprised to see that the HP was governed back to 195HP with 520 lbs. torque. The Allison is rated up to 300HP and 575 lbs. With a simple cal change I can move that up to 260HP and 300lbs.

Looking for thoughts on making this move. Recognizing that the torque will be over, I would need to not be putting the pedal to the medal, especially in the mountains, but would hope that the extra margin would be helpful at times w/o destroying the trans.

Looking for thoughts on fuel economy as well. Also are there any other limiting components in the drivetrain I should consider?

BTW - This unit was advertised at 220hp, yet, per Cummins governed back to 195.

Thanks

Skip426 · 09-20-2022, 10:51 AM

I've always thought that the Allison 2500 series wasn't enough trans to use behind a 6.7 ISB .

Somewhere in the construction of the chassis a decision was made to save a few dollars , when the chassis manufacturer decided to offer the 1000 series they must have contacted Cummins to see what would work for power, why Allison and Cummins allowed the combination is anybody's guess.

Your aware of the transmission's limitations , and if you have the engine programing done by Cummins you'll probably have to sign wavers , saying they are not responsible for drivetrain failures .

Skip426 · 09-20-2022, 10:55 AM

Quote:

Originally Posted by ReidGreh

. With a simple cal change I can move that up to 260HP and 300lbs.

Is the torque # here a typo ? Should it read 260 HP & 600 lbs ?

Alpine36 · 09-20-2022, 10:58 AM

Pump it up!
And install a trans temp gauge.....

vito.a · 09-20-2022, 11:50 AM

I think you're playing with fire. The MH1000 transmission spec for RV use is 746NM, or 520 Lb Ft.

153stars · 09-20-2022, 12:49 PM

Your probably best to keep loaded weight low. Pull hills out of eco setting on trans pad, down shift if lugging long climbs.

Crasher · 09-20-2022, 04:01 PM

What good would the extra HP be if you couldn't use it due to the torque limit of the 1000 transmission? If you did the upgrade, you would probably have two expenses. One doing the upgrade and another rebuilding the transmission. Not sure it's worth it.

ReidGreh · 09-20-2022, 05:46 PM

Quote:

Originally Posted by Skip426

Is the torque # here a typo ? Should it read 260 HP & 600 lbs ?

Should have actually read 620lbs for the recal'ed torque

ReidGreh · 09-20-2022, 07:14 PM

Quote:

Originally Posted by vito.a

I think you're playing with fire. The MH1000 transmission spec for RV use is 746NM, or 520 Lb Ft.

Thanks Vito - The printout I got from Allison says 575 lbs for a non-SEM/LRTP trans and 660 lbs for a trans with the SEM/LRTP engine management system. This unit does not have the SEM/LRTP.

ReidGreh · 09-20-2022, 07:20 PM

Quote:

Originally Posted by Alpine36

Pump it up!
And install a trans temp gauge.....

Anyone want to chime in on Alpine36's idea of monitoring trans temp? Will trans temp tell the whole story?

I'm really wrestling with 195hp in an 18000lb motorhome - but may have to abide by that.

Alpine36 · 09-20-2022, 11:02 PM

Fwiw, I know plenty of Duramax truck owners who are pushing 400hp with the Allison 1000 series transmissions. Can it destroy one? Sure, if your careless. Will you subject your coach to the same torture of mud bogging or rolling coal burnouts? Not likely. Every tuned Duramax owner I know runs a heavy duty trans cooler and monitors the temp gauge regularly when working it hard. The Allison 1000 is basically a redesigned 542 series and easily rebuildable and performance parts/mods/re-flashes are plentiful. If, and that's a big if, it fails turning up the hp/torque it's not the end of the world. Reworking that trans isn't difficult or overly expensive.
I'd rather take the chance and have a well performing coach than suffering driving a slug. But that's just me....