Installing a ISM Cummins in a H-40

luvrbus · January 13, 2011, 09:24:20 PM

Ok guys here is the question has anybody installed a ISM in a Prevost a friend bought a new 500 hp 1550 torque ISM and 4060 Allison a while back at BlueBird.
The ISM 500 hp we are told needs gears to run at 1800 to 2000 rpm at top highway speed (70 to 75 mph) he was heart broken when Gregg at Southern Plains told him except around 5 1/2 or 6 mpg on the engine and Allison combo that sucks so now he thinking about a 60 series they are only 1 inch longer than the ISM the 60 series is taller but that is not a problem the 8v92 with top mount turbo the 60 are the same height.
His question is should he scrap the idea and stay with 92 which gets around 7 to 8 with the B500 he has or sale the ISM and look for a 12.7 Detroit looks to me like any 4 stroke is going to be a nightmare installing in his H 40 because of the tag axle, got any answers guys he is reading lol btw his 92 dropped a valve in Ft Stockton Tx

good luck

Ace · January 14, 2011, 03:55:17 AM

Clifford, the 60 series will fit the h-40 with no problems and since prevost has everything he will need, not much to fabricate.

Busted Knuckle · January 14, 2011, 04:09:20 AM

Quote from: Ace on January 14, 2011, 03:55:17 AM
Clifford, the 60 series will fit the h-40 with no problems and since prevost has everything he will need, not much to fabricate.

I agree and plenty of cheap donor buses that have engine, trans, mounts cradles and all.

BK

luvrbus · January 14, 2011, 06:27:50 AM

He has a very early H-40 somewhere around 1989 or 1990 trust me there is no room that is why he wanted the ISM,we are trying to reach Dan (Utah claimjumper) that installed a Cummins in his XL our understanding is the engine compartments are the same on that year model so if you read this Dan give me a call I lost your number.
Still trying to figure out why this 500 hp ISM has a different operating rpm speed than the 450 hp all the literature we can find supports what Gregg has said even the mileage factor and it being a new engine Cummins will not change any setting.
Sonnie may have him another job lol, fwiw this H-40 came with a 6v92 we stuffed a 8v92 DDEC IV in it several years ago with the B500

good luck

RickB · January 14, 2011, 06:38:02 AM

Is it because his isn't tuned to such a high HP output the reason that Brian Diehl get's such great mileage with his?

Last time he went on a trip it was like 10 or 12 mpg (I'm guessing here) which made alot of us 5-6 mpg drool.

Rick

Hard Headed Ken · January 14, 2011, 07:14:30 AM

"He has a very early H-40 somewhere around 1989 or 1990 trust me there is no room that is why he wanted the ISM,we are trying to reach Dan (Utah claimjumper) that installed a Cummins in his XL our understanding is the engine compartments are the same on that year model"

I'm installing a 60 series in my 1988 XL and there will be about 2 inches of clearance over the valve cover. I made locating jigs to make sure the crankshaft and transmission output shaft were in the same location (Z and Y axis) as the 8V92 that came out of it. I've never took any measurements from a H40 engine compartment so I don't know if the engine compartments are similar. I will have to make an extended box for my inspection/service door inside the bus. It's under the bed so that's not a problem. I would think the overall length would be a concern, at least it's really tight for me and I'm using a short transmission. The Eaton Ultrashift. I think the B500 maybe a little shorter but the diameter is much larger near the tail shaft. It would have not worked for me because the tag axle goes under the transmission in the older XL's.

Ken

TomC · January 14, 2011, 08:14:42 AM

If you're running 70-75mph, then 5-6mpg is an accurate figure. Lower that cruise to 65 mph, and you'll be in the 6.5-7.5mpg range. Lower to a proven fuel stingy 55mph and you'll be in the 8.5-10mpg. Personally-as much as I like the Series 60, it is a big block truck Diesel (along with the Caterpillar 3406, C15; Cummins NTC, N14 and ISX) that is really to big. The Cummins ISM (along with the Mercedes-Benz 4000; Caterpillar 3176, C10,11,12,13) is a medium size block that will get the job done well and be far easier to install AND do maintenance on. I would go with the Cummins ISM. Good Luck, TomC

Ace · January 14, 2011, 08:16:45 AM

Clifford, I don't see where the difference is from the what you call early model h's. If they put a series 60 in a 92-93 model, it should fit with no problem. My friend has one in his. Its exactly like mine. That's the only reason I even considered doing the swap. I know it will work.

kwidd · January 14, 2011, 09:05:20 AM

I put a cumins m11 in my 81 prevost. If I run 65 mph I get 11 on the best day but average between 9 and 9.5. I have it set at 400 hp. It has plenty of power and there is lots of room in the engine compartment. I'm running an allison 654 with a 2.64 axle ratio. Kent

Tom Y · January 14, 2011, 12:54:17 PM

Kent, Are you concerned about the 654 holding up to the torque? Seems lie for the engine? Tom Y

kwidd · January 14, 2011, 02:26:27 PM

I've been running it like this for 3 years and all is still good. With the light weight I'm not to worried. I my old Crown with a 8/71 turbo I had a 643 in it. That was 15 years ago and is still going although we did re power it with a L10 pumped up to about 330 hp. I'm not sure how many miles it's gone but it's still going strong. Kent

Brian Diehl · January 14, 2011, 02:55:31 PM

Quote from: RickB on January 14, 2011, 06:38:02 AM
Is it because his isn't tuned to such a high HP output the reason that Brian Diehl get's such great mileage with his?

Last time he went on a trip it was like 10 or 12 mpg (I'm guessing here) which made alot of us 5-6 mpg drool.

Rick

no, just 9.0 mpg across 4500 miles ...

robertglines1 · January 14, 2011, 03:08:11 PM

Like Ken said it depends on year and tag axle configuration. It changed in early 90's on XL for sure I would ck H-40 and make sure. Bob