Would Be A Cummin

geok · May 6, 2013

Has anyone put a 12 valve cummins in a motorhome so you can go to tractor shows a little more cheaply? Was it worth the trouble? What kind of milage different did you get?

VicS · May 6, 2013

Have a neighbor that has one in a class A motorhome. It came in there. He says it is geared to slow. It is on the governors at 75. He was pulling a enclosed trailer with a modified stock car. Don't think mileage was great, because he drives flat-out. Vic

ben there · May 6, 2013

there was a good size motor home on Victoria,Tx Craigslist few weeks back with a 5.9 Cummins 12V

IaGary · May 6, 2013

The price of the swap or even buying a new diesel considering the cost of diesel verses gas at the pump, I don"t see how a diesel will ever pay in any vehicle. Unless you put on 30,000 plus miles a year and pull a load all the time.

Just my opinion.

Gary

Sprint 6 · May 6, 2013

This is what I ask every person that asks me about diesel swaps. Do you want to do it to try or for mileage? If you want to do it to prove you can, great. If you are doing it for mileage you are wasting time, money, and probably turning your truck and the parts donor into two parts donors.

Brad Buchanan · May 6, 2013

Hey geok.

Perhaps I am a bit naïve but I was wondering why a person who drives a vehicle that has the aerodynamic profile of a plywood outhouse go to the trouble of replacing the engine to pick up a mpg or so.

Brad

fixerupper · May 6, 2013

Brad, your response made me chuckle. It sounds like an interesting project.

One thing to consider when switching to diesel is the gearing. The 5.9 hits the governor at about 2400 RPM's The gasser will go maybe 1000 RPM's above that, depending on the engine. My 24v 5.9 seems to run happy in the 1900-2100 RPM range when pulling hard for long distances. How fast does your motor home go at 2000 RPM's in top gear? That's about the top cruising speed you will be running with a 5.9 in there. During a hard pull in a lower gear at 2000 RPM's how fast will you be going? Do you drive mountains where you'll be out of RPM's and creeping along when it kicks down, or are you on the flatlands? Maybe you aren't interested in going faster than 55-60 MPH so speed isn't a factor then. One thing going for the Cummins is it will run hundreds of thousands of miles under load without wearing out. I haven't seen any gasser go anywhere near that far under the same conditions. Jim

T in NE · May 6, 2013

A P-pumped or VE-pumped 12-valve? The P7100 has a higher HP potential but the timing advance and tunability of the VE44 makes it a better MPG prospect. Turning the governed speed from 2700 to 3200 is pretty simple as well, there is one spring to change in the VE44, and two to change in the P7100.

Then you can get a cam from Colt or Hamilton, get peak torque at a lower RPM, that will help with fuel mileage. A timing spacer from M&H, which allows more timing advance at top end, while not sacrificing low-end torque- makes a bit of difference.

Unless you are planning to really pull some weight behind the camper, chances are you'd end up re-gearing as well, or getting a Gear Vendors unit.

You can make some changes and make the swap work for fuel economy, but you are going to spend a lot of money doing it, especially if you need to buy the motor.

geok · May 7, 2013

There is a pile of playwood on wheels with a bad engine, cheap. There are 97 model dodge 2500 selling cheap also. Was thinking of combining the two. Doesn't hurt to think and ask questions.

Would Be A Cummin

geok

Member

VicS

Well-known Member

ben there

Member

IaGary

Well-known Member

Sprint 6

Well-known Member

Brad Buchanan

Member

fixerupper

Well-known Member

T in NE

Well-known Member

geok

Member

Similar threads