Increasing Engine Performace for 2006 Monaco Dynasty ISL400

[monacoman06]

Has anyone had any experience with increasing performance with either an engine tuner or muffler on a Cummins ISL 400? It is in a 2006 Monaco Dynasty Platinum IV coach. I am looking at a TS PERFORMANCE POWER PLAY MP-8 Tuner and AERO EXHAUST muffler. Any comment would be greatly appreciated.

Jim

[wolfe10]

Jim,

Welcome to the FMCA Forum.

I would sure not start with a "tuner" or other engine modification.

VERIFY that you have little air restriction on the intake-- what is your AIR FILTER MINDER reading?

Many have reported good results with Magnaflow mufflers and quieter than the Aero mufflers. If you have the two stage engine compression brake (vs just exhaust brake) exhaust noise can be an issue.

As with the intake side, how much you gain by going to a free-flow exhaust depends on how restrictive your current set up is. Said another way, if the intake and exhaust are properly sized for your ISL, you will not gain that much. If they are restrictive, you will gain more.

[monacoman06]

Thanks Brett.

The top of the yellow in the air minder is at approximately 17. Does not look like there is any restriction in the air filter. I was reading the article on engine tuners in the new Escapee magazine and it sounded good, but have reservations about using one. I had a 1990 Monaco Signature with a L- 10 Cummins and I had spoken with someone at Cummins and they also recommended not to use a tuner with it. Based on this latest article I was curious to see if technology had changed. I average around 7 mpg while towing and cruising at around 65 mph. Tach reads about 1725 RPM and I was looking for a little improvement

JIM

[wildebill308]

I would definitely add gages for EGT and Boost before doing any tuner mods. I would add them any way so you know what is going on and to detect possible problems.

Bill

[Fijidad]

Thanks Brett.

The top of the yellow in the air minder is at approximately 17. Does not look like there is any restriction in the air filter. I was reading the article on engine tuners in the new Escapee magazine and it sounded good, but have reservations about using one. I had a 1990 Monaco Signature with a L- 10 Cummins and I had spoken with someone at Cummins and they also recommended not to use a tuner with it. Based on this latest article I was curious to see if technology had changed. I average around 7 mpg while towing and cruising at around 65 mph. Tach reads about 1725 RPM and I was looking for a little improvement

JIM

I would say if your ISL400 is operating at 1725 RPM at 65 mph, something is not quite right with your running gear. Take a look at the attached link about this engine producing its maximum torque of 1,200 ft. lbs. at 1,300 RPM. At 65 mph, I'd expect you to be closer to that 1,300 number. If you're regularly operating at 1,725 then you're off it's maximum torque and that may be why you're wondering why there isn't more power. Dan

http://cumminsengines.com/uploads/docs/4971107.pdf

[wolfe10]

Actually, his RPM/speed is in the correct range. Peak torque RPM is the LOWEST RPM at which you can safely operate the engine under load.

Except on dead level ground you would not want to be cruising at peak torque RPM, as the slightest grade would cause either a downshift or cause the engine to be operated at below peak torque RPM.

Also, were you to be geared such that 1300 RPM was 65 MPH in 6th gear, you would need to be going that speed before it would shift to 6th gear! Bad idea.

We also have the ISL 400 and our RPM at speed is within 50 of what Jim reported.

[manholt]

7mpg at 65? I'll take that any day! I run at 63mph on economy mode. That's 1600 to 1650rpm. Avg. mpg 6.5/7.2. On a 425 Cummins.

Carl

[obedb]

IMHO. The factory installed an engine that Is probably more than capable of moving your DP with a toad down the road and over grades at an acceptable speed . Why would you want to soup up something that already works well? Have all systems that could affect the performance been serviced? The stuff that you could add at this stage is probably overvalued. You are driving a large vehicle, not a sports car. I know. I am a grouch. If you are passing 18 wheelers on a hard pull, you are good. What more could you do other than dumping money into a really big ride?

[hermanmullins]

Monacoman,

I to have a 400 ISL in our 2002 Dynasty. Towing a Chevrolet 1500 crew cab 4x4. I have enough power to make it up Wolf Creek Pass, 10,850 ft., in Colorado with out any problems. Yes I went slow but everyone else was just as slow, cars included.

Factory setup was done to accommodate the coach. I believe at that time the engineers knew what they were doing, now I'm not sure.

Herman

[five]

7mpg at 65? I'll take that any day! I run at 63mph on economy mode. That's 1600 to 1650rpm. Avg. mpg 6.5/7.2. On a 425 Cummins.

Carl

That's your weight, Carl. My ISL routinely got around 8.3 cruising at 60, pulling a toad...GVWR was 34,600.