Cummins power

[SteveSkinner]

Originally Posted by WILDEBILL308

WRONG sorry I just had to say that. What is needed is torque in an rpm range that is usable. The lower the rpm the better and the more responsive it will feel. You get speed with gears not high rpm if you want a drivable RV. Cases in point look at the Ford V10 it has pretty good torque for a gas engine but it is developed at a relatively high rpm. Go look at all the V10 owners complaining about how loud and how fast their engines are running when climbing hills. They have to do this because the torque band is much higher in the rpm band.
Bill

Interesting topic this. But as we are not producing engines our selves, well we really are wasting our time here.
The

[elainee]

Originally Posted by CJGJR

You saying that there is 300 RPM difference from 60 to 65 MPH? Or are you dropping a gear? My 500HP ISM won't climb a hill doing 60 but if I'm doing 70 it just flys over it. But i'm sitting at 49,000lbs.

my mh is a 2012 Tiffin 36' phaeton ..max loaded weight is 29,680lbs ..(no toad)final axel ratio 4.63:1
the 300 rpm you ask is close, the graduations are small on the engine tach so it could be any where from 25-50 rpm ..
60 mph in 6th gear going up a 6% it will down shift to 5th and if on a long climb it would drop to 4th gear.
65 mph up the same hill it will stay in 6th without a grunt. imho..the power to weight ratio is ideal

your ism500..500 hp @ 2100 rpm
1550 tq @ 1200 rpm
i checked the engine power curves (cummin power chart)
1700 rpm ...450hp
1700 rpm....1400 lbft looks like thats your sweet spot ..same as mine

peter d

[Genset]

Amazing to have the 4.63 rear on such a lite coach using the ISM500, with that setup under 30,000 lb, should fly over any mountain, my coach uses th 3.91 rear, towing a 5000 lb toad with the ISM AND GVWR 34,000, no issues, so why the 4.63 rear in light coach ? Seems nonsense to me as the ISM does so well in the lower rpm area.
Dave M

[elainee]

Originally Posted by Genset

Amazing to have the 4.63 rear on such a lite coach using the ISM500, with that setup under 30,000 lb, should fly over any mountain, my coach uses th 3.91 rear, towing a 5000 lb toad with the ISM AND GVWR 34,000, no issues, so why the 4.63 rear in light coach ? Seems nonsense to me as the ISM does so well in the lower rpm area.
Dave M

dave, letter i sent to CJGR i wrote that my 36' phaeton has the 380 hp 8.3 cummins..and it almost flys over the mountains
imho...the driveline engineers i believe came up with the best axle ratio 4.63 for performance and fuel economy..

peter d

[Genset]

Peter,

That makes sense, thanks
Dave M

[pocketchange]

To Awaken an older post.. and with reference to the OP.

My 01' HO ISB 1 Ton Cab & Chassis has an EDGE Comp 5 Step Chip in place set on #3. 350K plus miles grossing 36K w/40' Gooseneck Trailer. I love pulling away from all the new stuff going up hills and away from lights.
Keep an eye on the temp gauge and enjoy.