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Question Mountain Aire Cummins ISX?

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Neal

Staff member
RVF Administrator
Joined
Jul 27, 2019
Messages
11,477
Location
Midlothian, VA
RV Year
2017
RV Make
Newmar
RV Model
Ventana 4037
RV Length
40' 10"
Chassis
Freightliner XCR
Engine
Cummins 400 HP
TOW/TOAD
2017 Chevy Colorado
Fulltimer
No
Is the ISX in the MADP the same engine as in the higher line coaches just tuned down to 500 HP?
 
Different engines. The MADP is an X12 or 12 liter rated for up to 500hp
The higher line engine is the X15 or 15 liters rated up to 605 hp
Sure would like to have the X15 in my DSDP! lol


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Robert & Sandy Spence
Acworth,Ga
2016 Newmar Dutch Star 4369
2019 F250 Super Duty
2015 Jeep Wrangler JKU
 
Is the ISX in the MADP the same engine as in the higher line coaches just tuned down to 500 HP?
Yep; just smaller displacement. ISX-15 (KA/Essex/LA) is a 15-liter engine rated to 600-605 HP while the ISX-12 in the MADP is a 12-liter (actually 11.9-13 liters, depending on configuration) rated at 500 HP. They were replaced in 2019 with the X-15 and X-12versions. Pretty much the same engines as the earlier versions, but a bit lighter.

TJ
 
When I was attending Spartan Academy, the question was asked about the possibility of seeing an X-15 in a 40 or 43 foot coach. The answer was “no, it wouldn’t fit”.


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While at Cummins for my recent head gasket repair I inquired about the ISX (assuming the 605 of course). They didn't speak highly of it as they said it's too much for a RV, it runs too hot. Also had the piston issues in the past which they said Cummins corrected. Of course this is one service tech's opinion just like the various opinions on tire pressure. I was just curious how the service history of the ISX (15) compared to the ISL.
 
The same block that is now the X-15 605 was previously the 650. I think Cummins “fix” for the piston issue was to down-rate the engine.


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