Isl, isx, ??

[EZDZIT]

The retarder provides quieter transmission braking than exhaust or engine braking. It is probably excellent for transit bus operation for this reason. I have observed that retarder use does quickly raise transmission fluid temperatures. The operator can see the temperature gauge rise quickly and even more quickly if more braking effort is operator hand lever selected.


That temperature apparently affects the life of the TES 295 fluid because Allison specifies more frequent transmission fluid changes for retarder equipped transmissions than for non-retarder applications. All retarder applications are termed "Severe Vocation" as compared to "General Vocation".


Ref: Allison Transmissions, 3000/4000 Operator's Manual, January, 2010.

[PineAcresRV]

I am going for a 2014 Dutchstar 4358 with a 450 ISL to a 2016 London Aire 4565 with 600 ISX (on order). Should I expect a huge power difference and what about fuel consumption , I have never test drove the ISX , the London weights approx 8000 lbs more then the my Dutchstar

[PDR John]

You're gaining 8000 lbs, but also gaining 150 HP and 700 ft lbs of torque. You could think of it like this: You're gaining a 3/4 ton Dodge pickup that does nothing but help push you down the road.

The hills you did slow down on before, you won't even notice now.

[Smitty77]

Originally Posted by PineAcresRV

I am going for a 2014 Dutchstar 4358 with a 450 ISL to a 2016 London Aire 4565 with 600 ISX (on order). Should I expect a huge power difference and what about fuel consumption , I have never test drove the ISX , the London weights approx 8000 lbs more then the my Dutchstar

As mentioned, the extra weight will not make this HP gain difference as dramatic as it would have been if both coaches weights were the same. That BIG BLOCK, Allison 4000, larger U Joints/Axles/Differentials, Cooling system, etc. really do add quite bit of weight. Toss in the coach itself will have more goodies and thus weight, and 8K shows up real quick!

I do feel you should notice an improvement in power, and hill climbing. And the coach should turnover at a lower RPM at speed, depending on gear ratios.

MPG I would expect to be less. Bet 1 1/2 if our lucky, but perhaps as low as 2 1/2 + less.

I'd ask on the owners group of those with similar coaches, what they're seeing in their usage.

Enjoy it as you run down the road!
Smitty

[PDR John]

I have a friend with a King Aire, same ISX engine, he weighs 8,000 lbs more then me. We get almost the exact same mileage, he just doesn't think about hills. No letting it run up before a big hill, he just sets the cruise and rolls with it.

My wife and I really like the London Aire, congrats with the purchase.

[Smitty77]

Originally Posted by PDR John

I have a friend with a King Aire, same ISX engine, he weighs 8,000 lbs more then me. We get almost the exact same mileage, he just doesn't think about hills. No letting it run up before a big hill, he just sets the cruise and rolls with it.

My wife and I really like the London Aire, congrats with the purchase.

Thanks for that info, it confirms what I read on the OP's other thread on the ISX. Glad to see these big engines can provide decent MPG when the foot is not down to the metal...

And yes to the effortlessness vs the finesse we medium to small block propelled rig owners must use, while climbing grades!

Smitty