Cooling the Beast, question?

[jcussen]

Good article on coach performance and what effects it.
https://www.rvtechlibrary.com/engine...erformance.pdf

[Old Scout]

….you have to love an optimist but building a better "mouse trap" is hard work and doesn't seem to happen all that often....with so many combinations of RV shapes and sizes, weights and engine sizes....it is amazing how consistent the MPG is for mid-size DPs --maybe 7.5 to 9.5????? You have to go a lot bigger or much smaller to get outside this range [or down wind/down hill] on a consistent basis.... Doubt if you can make a "scoop" large enough to replace a hydraulic fan.....and if you did--the DW would probably have a fit with the way it looks--IMHO/personal experience!!!!

[jcussen]

A lot of DIY bus converters with the old two strokes, used a sprayer type system, that sprayed water through nozzles onto the radiator when temps went too high. The water evaporated on the hot radiator and cooled it down. Have seen some buses with scoops around the trailing radiator opening, but bear in mind that when you really need the fan, foot to the floor, in 4th gear doing 45 mph, going up a 6% grade, that scoop will not do much.

[Skip426]

Originally Posted by K7JV

That fan doesn't demand nearly the load you are fearing. If it required 75 HP your hydraulic fluid temperature would be going thru the roof in pretty short order. A 75 HP ELECTRIC motor is about the size of a grease barrel, or larger. There is no way to get that kind of sustained power from a motor as small as the hydraulic motor on your engine fan, or from your hydraulic pump either, for that matter. If you saw that number in print, I would expect a missing decimal point, as 7 ½ HP would be an overkill. One to three might be more what I would expect to see.

I believe the 70 HP load on the engine is covered in this PDF. Graph #6

I do know that when my side rad hydraulic fan ramps up to high ... I'd better not be passing a semi on a hill .

[jcussen]

Originally Posted by Skip426

I believe the 70 HP load on the engine is covered in this PDF. Graph #6

I do know that when my side rad hydraulic fan ramps up to high ... I'd better not be passing a semi on a hill .

If you look at graph 5, same PDF, you will see about 50 hp on high fan, at 1800 rpm. This is foot to the floor, max hp, on a 525 hp Cat C-13. Big engine for a heavy coach. Thinking a smaller 450 hp ISM would not pull near that amount.

[Kurt Averill]

A couple of questions - Joe, is your 450 an M11 or a N14? IIRC in 96 to get 450, it would be an N14?
And for Windecker - I recently had the CAC rebuilt (R&R by me) and rebuilt the turbo on my M11 - which is actually a 98 by serial number - no sign of any sensor in the piping or CAC. Do you know exactly what the sensor input resulted in? I am wondering if it operated the elect solenoid valve in the fan circuit - my "Hillam Controls" wiring diagram shows the solenoid valve operated by the "fan clutch supply #2" circuit in the ECM - and I believe that output is switched based on a temperature input - maybe from the sensor in the CAC piping - or lacking that, perhaps just on coolant temp. My 38 Exec is no doubt lighter than a 40' Sig, and I have never gotten over 8. I have also never seen the temp over 200, and I have never heard the fan really dial up either. Of course there are no trips from here that don't involve a lot of hills - but it sounds to me like Joe's Sig is doing very well!!

[jcussen]

Have had two ISM coaches one 450 hp and one 500hp, on both default fan speed was low, because the intercooler would always need air flow, even if cooling water temp was low. Engine water temp switch via ecm, would change valve position on hyd line to high when water temp was over 190 f. CAC has a sensor that allows to read temps on a silverleaf, but don't believe it can control fan speed.

[Windecker]

Kurt,
I also had the joy of rebuilding my CAC and radiator, also done by myself. It was a task!
I can't answer you question exactly. The wiring diagram for my 99 showed a temp sensor in the intake system and in parenthesis said something like (Cummins ISM-11) or something similar. It was not in the CAC itself nor the immediate ducting to it. It could have been in the intake from Cummins and it may have just been tied into the JB Radiator Specialist system installed in my coach, not sure.


It would make sense to turn the solenoid valve on with either coolant or air temp needs. I do not recall how it was wired, sorry.

I will say, I never saw a fall off of power with my ISM-11 on even the longest hills. A light coach with a lot of torque, was a great thing.
My DD seems like it is really strong at the bottom of a hill and looses some umph as I go up. But, DD coach is much heavier so it might just be a weight thing.
Windecker

Originally Posted by Kurt Averill

A couple of questions - Joe, is your 450 an M11 or a N14? IIRC in 96 to get 450, it would be an N14?
And for Windecker - I recently had the CAC rebuilt (R&R by me) and rebuilt the turbo on my M11 - which is actually a 98 by serial number - no sign of any sensor in the piping or CAC. Do you know exactly what the sensor input resulted in? I am wondering if it operated the elect solenoid valve in the fan circuit - my "Hillam Controls" wiring diagram shows the solenoid valve operated by the "fan clutch supply #2" circuit in the ECM - and I believe that output is switched based on a temperature input - maybe from the sensor in the CAC piping - or lacking that, perhaps just on coolant temp. My 38 Exec is no doubt lighter than a 40' Sig, and I have never gotten over 8. I have also never seen the temp over 200, and I have never heard the fan really dial up either. Of course there are no trips from here that don't involve a lot of hills - but it sounds to me like Joe's Sig is doing very well!!

[joeplazek]

Originally Posted by Windecker

Joe,
Not sure what the coiled sensor is you are talking about but what I had mentioned is that the Cummins ISM-11 normally has a temperature sensor in the CAC (Charge Air Cooler) ducting to help with proper cooling of everything.
Essentially, when you compress air (which is what the turbo is doing) it gets hot. They pipe that air through a cooler between the turbo output and intake of the engine, called a CAC. It is an air to air cooler to help cool air going into the engine which helps produce more power (cooler air is more dense) and help cool the engine (hot air going in is bad). But, denser air takes more fuel...

I found with my ISM-11 the hotter it was out the better it ran, the better MPG I got and the better power I seemed to have. I assume because all the tire pressures would be elevated, oil and grease that is lubing various parts on the drive line are thinner when hot and that the CAC was cooling the air enough to help with minimize the added outside air temp.
Or so I want to believe

On mine it was just a little sensor in the duct but I don't recall exactly where or what it looked like, sorry.
Windecker

The sensor that I seen is a coil sticking out of a electrical box in open air on the engine side of the rads. I will get a picture of it. Looks like it would sense engine compartment heat.


joe

[jcussen]

Had a Series 60 that had a two speed fan with an adjustable orifice for adjusting low speed fan rpm. Thought I could save fuel, if i just eliminated low altogether, so adjusted to 0 rpm, high speed still worked at 190 f water temp, so thought I was fine. I had a silverleaf display on the dash that read intake manifold or CAC exit temps. I quickly found that intake manifold temps would climb rapidly any time engine was producing boost. Believe most manufacturers recommend intake manifold temps to be no more than 30 degrees above ambient air temps, but I was running 50 degrees plus, over ambient.
I quickly readjusted low speed fan back to original setting. As mentioned, anytime turbo is compressing air, heat is produced which must be removed by the charge air cooler and fan.
A DD repair shop did tell me the CAC temp sensor is used by the ECM but he thought it was only used to determine fuel injection settings.

[Old Scout]

….according to my SilverLeaf, intake manifold temps are "elevated" at about 160 degrees so Cummins would probably de-rate some where above that.....found that in cold weather, if I didn't get up to engine ops temp before pulling a grade, the mechanical wax valve would not open and intake temps climbed. As soon as engine reach ops temps and wax valve opened, fan would kick on and intake temps dropped dramatically.....Example--climbing the hill outside Van Horn TX in the morning--started driving thru town to warm up before starting the climb--no more check engine light!!!!

[jcussen]

Originally Posted by Old Scout

….according to my SilverLeaf, intake manifold temps are "elevated" at about 160 degrees so Cummins would probably de-rate some where above that.....found that in cold weather, if I didn't get up to engine ops temp before pulling a grade, the mechanical wax valve would not open and intake temps climbed. As soon as engine reach ops temps and wax valve opened, fan would kick on and intake temps dropped dramatically.....Example--climbing the hill outside Van Horn TX in the morning--started driving thru town to warm up before starting the climb--no more check engine light!!!!

So your wax valve only has high speed when water temps are up, and no low speed at all? What is causing the check engine light? Interesting thread from a few years ago.
https://www.irv2.com/forums/f123/int...re-152710.html

[joeplazek]

Originally Posted by jcussen

A lot of DIY bus converters with the old two strokes, used a sprayer type system, that sprayed water through nozzles onto the radiator when temps went too high. The water evaporated on the hot radiator and cooled it down. Have seen some buses with scoops around the trailing radiator opening, but bear in mind that when you really need the fan, foot to the floor, in 4th gear doing 45 mph, going up a 6% grade, that scoop will not do much.

Water Spray would be an elaborate set up. Imagine the engineers that came up with that configuration. I hear you on the air flow when you need it most. This has been an interesting subject and its making me think.

[joeplazek]

Originally Posted by Kurt Averill

A couple of questions - Joe, is your 450 an M11 or a N14? IIRC in 96 to get 450, it would be an N14?
And for Windecker - I recently had the CAC rebuilt (R&R by me) and rebuilt the turbo on my M11 - which is actually a 98 by serial number - no sign of any sensor in the piping or CAC. Do you know exactly what the sensor input resulted in? I am wondering if it operated the elect solenoid valve in the fan circuit - my "Hillam Controls" wiring diagram shows the solenoid valve operated by the "fan clutch supply #2" circuit in the ECM - and I believe that output is switched based on a temperature input - maybe from the sensor in the CAC piping - or lacking that, perhaps just on coolant temp. My 38 Exec is no doubt lighter than a 40' Sig, and I have never gotten over 8. I have also never seen the temp over 200, and I have never heard the fan really dial up either. Of course there are no trips from here that don't involve a lot of hills - but it sounds to me like Joe's Sig is doing very well!!

This is a M11. Cummins changed the engine a few years after dad bought the coach because of fuel economy not what it should have been. It was the fans being plumbed wrong from the factory all this time but no one could figure it out. The engine specs from the tag on it reads, serial 34888478 family VCE661EJDARC manufacture date 11/97 model M11-450EPLUS 661cu in . 10.8 litres . 450HP rpm idle 650-800 1450 PEAK TORQUE So I would say this is a 1998 engine