Tune Cummins ISB 300 HP Engine for More HP

[fagnaml]

I'm still "new" to the motorhome world having owned a 2007 Damon Astoria 38' motorhome for six months (the motorhome is much more enjoyable and easier to use versus my previous bumper pull Tracer Executive 32' travel trailer). The Astoria has a Cummins ISB 300 HP engine with an Allison MH 2500 five speed transmission which is fine for towing a for door Jeep Wrangler Unlimited in the hill country of south Texas. However for a vacation this summer to Estes Park in Colorado, I'm a bit concerned about the engine's capability on the steeper roads into Estes Park. RV Masters maintenance shop here in Houston (which did very good pre-purchase inspection and initial routine maintenance service) said they could tune/optimize the engine to easily get another 50 - 75 HP of output which they stated would give me the power and confidence needed for driving in the Colorado Rockies.

Has anyone ever had their Cummins or other diesel engine "tuned" for additional horse power output? If "yes" were you pleased with the results? Were there / are there any concerns associated with this "tuning"?

Thanks for any and all advice!

[wolfe10]

Start by verifying with Allison that the 2500 is OK with added HP/torque.

Then verify that the your cooling system is over-sized enough that it can handle the added heat load (the time you will use the extra power is on those long grades where coolant temperatures are already likely rising.

[garyreed]

We are all newbies at one time or another. I have owned mine for 5 years and still feel like a newbie.

I know there are lot's of opinions on this subject and am excited to read them so for now I will give you mine.

Drivetrain manufactures design all of the needed systems for set HP ratings. That being said, there maybe some room to accommodate more power. There are some upgrades that just involve tweaking the parimeters in the ECM, others involve changing hard parts, turbo,air pipes, CAC, air box and filter. ect.

It has been my experience that to push the HP to the limit may have unintended consequences that may include overheating, premature engine failure, transmission and driveline trouble. All of these issues may be worst case scenario but still expensive and unnecessary nontheless.

You did not mention what they want to do or change and what it will cost.

I am from the school that if you are happy with the preformance 95% of the time. then just take it easy when you are in the mountians. and enjoy the view. If you are worried about those two cars behind you, guess what, regardless of the HP they will still be there.

Going back to the subject of confidence, that is one thing you cannot buy. That will only come from getting to know your coach and what it will do. The only one gaining any confidence is the salesman selling you the HP, and selling you repairs afterward.

Dependability is King in my book. I do not like setting on the side of the road.

Gary

[GARYGIBSON]

DITTO! TO WHAT GARY AND BRETT SAID! Relax and enjoy the ride.

[manholt]

Feel the same here! There are lots of places in Texas that I would like more power, however I know that it comes with a price, so I just downshift and enjoy the wonderful scenery! There are plenty of hills on I-10 West of Bourne that slow me down. Unless the road to Estes Park in Colorado has changed in the last 5 years, even if I had a 600hp, I could not take the corners any faster than I would do now in 4th gear. Loss of rpm is the biggest culprit on any mountain road for a DP!

Save your $$$, be happy, no worry! A Motorhome DP or Gas is not meant to be a sports car! My 2 cents.

Carl

[wildebill308]

If you do anything I recommend you have good boost and EGT (exhaust gas temperature) gages installed. I recommend them even if you don't do any mods.

The key to claiming the steepest longest hill is your left hand. When you hit a hill that slows you down just down shift till you can accelerate. Now just hold it at 2000-2200 rpm and enjoy the ride. This will keep your coach from overheating. The biggest problem is other traffic you will want to stay right but if you end up behind slower traffic you will have to slow to stay in line unless there are more than 2 lanes on your side. Even if you had 650 hp you don't want to try to pull around a slow truck when you are doing 40 and closing traffic behind you is doing 75-80.

Do you have the 5.9 or the 6.7 engine?

Bill

[rlbarkleyii]

The Cummins ISB and Allison 2500MH tranny combination is near maxed out in its stock condition. The 275-300 ISB puts out around 600 FT pounds torque and that is the max rating for the 2500MH tranny. I spent almost $550 USD for Allison to tell me that. While the engine could by fueled/ boost up too 375HP or more, can not boost the ISB without damaging the 2500. The 2500 is a older tranny that had limited capacity, that is why they went to the 3000, 4000 series ect. for the big dogs.

REPEAT THE 2500MH and all the 2500 variants can not safely handle more than 600 Foot pounds torque.

[manholt]

That's cut and dry and so is, stay away from "RV Masters" in Houston, TX!

Carl

[chuckftboy]

My ISB / 2500 combination is factory rated at 340 HP / 700 ft lbs torque.

[jimmiemward]

Here is the link to Allison's data for the 2500 transmission.

http://www.allisontransmission.com/docs/default-source/specification-sheets/int2500_sa5340(201306)blk.pdf?sfvrsn=2