Has anyone actually upgraded an ISL from 370/400 to 450HP?

[vito.a]

Has anyone actually upgraded a Cummins 8.9L ISL from 370/400 to 450HP?

Side thoughts:
Does it go over the Allison MH3000 transmission max torque rating?
Do the new motor homes with the ISL 450 come with the Allison 4000 series transmission?
What did the Cummins folks charge for this?
How did it affect fuel mileage?
Any overheating issues?

Thanks

[Cat320]

The 2012 ACs come with the ISL 8.9L, 450 hp, 1,250 ft/lbs torque Cummins and the 3,000 Allison.

[J Walker]

You should be in touch with Cummins, Allison, and the upgrade chip vendor to see if everything fits together. There are lots of controls built into the ECM software that controls and and even limits HP and torque in order not to over stress components. If you want to do this and can find a person or company that can do a fully integrated solution it would be ok. I really don't think that you will find such a source.

[bluepill]

MY OPINION is that both Cummins and Allison build quite a bit of reserve capacity into their products - That's what makes them so reliable.

That said, when you "upgrade" power you are cutting into that reserve. If you operate under extreme conditions such as many steep grades or heavy trailer towing in hot weather, you might exceed the limits.

Cooling is usually designed by the chassis builder, and may have a more limited reserve than the drive train. If you monitor the temperatures of the engine coolant and oil, the transmission fluid, and the exhaust gas you can probably operate safely.

Here is a question: If you upgrade from 400 to 450 HP, do you think that a 12% increase is really going to do that much for you?

[stik]

Quote:

Originally Posted by bluepill . . . Here is a question: If you upgrade from 400 to 450 HP, do you think that a 12% increase is really going to do that much for you?

400 to 450 HP? What increase in Torque does the mod give you?

[Cat320]

Quote:

Originally Posted by stik 400 to 450 HP? What increase in Torque does the mod give you?

My 8.9L ISL is 400hp/1,200 ft/lbs of torque. As noted earlier, the new 8.9L ISL is 450/1,250.

[vito.a]

bluepill, I agree the chassis builders not do not specify enough cooling system over capcity. My C8.3 is upgraded from 300 to 350+ and it runs great with lots of power, but you really have to watch it out west in the summer (over 100 degrees) climbing steep grades.

[Gary RVRoamer]

The newer Allison 3000 has been uprated to 1250 ft lbs of torque so it can legitimately be coupled to the 450 hp ISL engine. Whether Allison actually enhanced the tranny or just changed the rating, I do not know.

I suspect that if you hooked up a 45o hp, 1250 ft lb engine to an older Allison, Allison would say you were violating its specs.

[vito.a]

I was looking at the specs on a new motorhome with the ISL 450 and the Lazy Days web site said it had an Allison MH4000. Wondered if it was a typo.

[Coached]

I will not be surprised to see the 4000 transmission start being used with the new 450 Cummins. There is most likely a large "reserve" of power available in this latest ISL engine that can be accessed with aftermarket methods. However, the Allison 3000 will not take the increased HP. Cummins has long offered power "increases" through their facilities ... we had our ISC 330 increased to close to 400 hp and kept the Cummins warranty. This was done at an authorized Cummins Dealer and cost us about $2500, most of which is for continuation of the warrantly from Cummins. This program is still available according to our local Cummins facility. As the coaches get bigger and heavier and our thirst for more power continues I won't be at all surprised to see more of this being done? There is lots of cooling built into these new 450 setups too, especially with the side radiators.

[Cat320]

I just reviewed the publications for the new AC Revolution and AC Tradition. The Rev has a GCWR of 59,600 and the Trad has a GCWR of 61,600, both have the Allison 3000

[Mr_D]

With a Banks kit the ISC 350 goes to 435 and 1200 ft lbs. But the real gain is not shown in the maximum figures, it's in the MUCH wider power band. Maybe Cummins has done that with the new ISL's. Does anyone have the dyno curves from a 450 ISL?

I just found the Cummins factory dyno info: Nope they didn't gain much if any on the width of the power curve. I'll have to plot it on the other curves I have and post it.

[Mr_D]

Quote:

Originally Posted by vito.a bluepill, I agree the chassis builders not do not specify enough cooling system over capcity. My C8.3 is upgraded from 300 to 350+ and it runs great with lots of power, but you really have to watch it out west in the summer (over 100 degrees) climbing steep grades.

I put the Banks kit on our ISC and have no trouble with temps. Have a Spartan chassis with side radiator.

[Mr_D]

Quote:

Originally Posted by Gary RVRoamer The newer Allison 3000 has been uprated to 1250 ft lbs of torque so it can legitimately be coupled to the 450 hp ISL engine. Whether Allison actually enhanced the tranny or just changed the rating, I do not know. I suspect that if you hooked up a 45o hp, 1250 ft lb engine to an older Allison, Allison would say you were violating its specs.

I suspect it's from more experience running TranSynd over the years and more testing with the ISL.