2002 Thomas 5.9 cummins power increase

[Rusty]

Originally Posted by Stu & Filo. T

On a RE bus , what if a person where to make a scoop say around 2 in out into the airstream & as large as the intake screen for the radiator??

I think it would be huge for cooling. Problem is in traffic, needs boost of electric fan or 2. Monitor gauges, idiot lights/alarms.

Heat .Kills. Diesels. They have much higher compression/tolerances. Good clean flow of quality oil paramount.

[cadillackid]

another way to remove heat from a diesel is removing heat from the OIL...

a large oil cooler could help pull heat away from the engine... cooler oil is going to act as coolant of sorts on cylinder walls and pistons..
-Christopher

[cowlitzcoach]

The biggest issue in regards to cooling is you are trying to move air from a low pressure area to a high pressure area. In other words you are working against the laws of physics.

Scoops might add some extra air flow at certain speeds. But once you reach a certain speed the scoop won't be adding all that much to the cooling effect. I have driven Gillig buses with and without the high capacity air scoop that was on the roof. Those buses overheated just about as soon and as often as the Gillig buses with the same power package with the standard radiator air intake in the side of the bus.

About the only thing I can think of to aid in cooling would be to have fans that could move a greater amount of air through the radiator core. But much like the high capacity air scoop you do reach the point of diminishing returns between how much HP the fans are sucking up and thereby making more heat and how much cooling air the fans are moving.

If there was an efficient way in which to mount a radiator with a greater area (wider and/or taller) it would probably be one of the better ideas.

Believe me when I say over the years we have done a lot of different things to try and get better cooling in an RE bus. About the only thing that works is to slow down when the temp gauge starts going up.

[Stu & Filo. T]

Originally Posted by cowlitzcoach

The biggest issue in regards to cooling is you are trying to move air from a low pressure area to a high pressure area. In other words you are working against the laws of physics.

Scoops might add some extra air flow at certain speeds. But once you reach a certain speed the scoop won't be adding all that much to the cooling effect. I have driven Gillig buses with and without the high capacity air scoop that was on the roof. Those buses overheated just about as soon and as often as the Gillig buses with the same power package with the standard radiator air intake in the side of the bus.

About the only thing I can think of to aid in cooling would be to have fans that could move a greater amount of air through the radiator core. But much like the high capacity air scoop you do reach the point of diminishing returns between how much HP the fans are sucking up and thereby making more heat and how much cooling air the fans are moving.

If there was an efficient way in which to mount a radiator with a greater area (wider and/or taller) it would probably be one of the better ideas.

Believe me when I say over the years we have done a lot of different things to try and get better cooling in an RE bus. About the only thing that works is to slow down when the temp gauge starts going up.

Ok left side of my bus has the radiator with hyd driven fan, Rt side has a screen I assume is to help move air thru engine compartment so I'm thinking ,make a sheet metal scoop on left side forcing air into radiator then electric fan on Rt pulling air from eng compartment out the Rt side.

[cowlitzcoach]

I actually think pusher fans work better than puller fans.

We experimented with changing the rear engine compartment door with a lot of expanded metal screen. That actually made things worse.

We had seven Gillig Schoolcoaches with the Cummins C-190. They all had the high capacity air scoop sticking up over the roof. What we found worked the best was to close off the screen on the curbside compartment door. It forced all of the air to go through the radiator and then down past the sides of the engine where it went into the rear low pressure zone. The vacuum at the back of the bus really scavenged the hot air down and out of the engine compartment.

I think what would have solved our overheating issues is if we had gotten a radiator that was taller and wider and mounted it at an angle in the back of the bus. With ductwork the stock belt driven fan would have still worked just fine. I think the main problem wasn't air flow. I think the main problem was a lack of cooling capacity.

Just remember, however you mount your radiator you need to make certain that any air is actually going through the radiator core and not leaking through somewhere else. The air flow is going to seek out the path of least resistance. You would not believe how much air can squeak through a 1/4" gap around a radiator!

[Tango]

In aviation (and some older, 2-stroke MC racing engines) they use what is known as a "still air box". The old radial engines out in the open would overheat like crazy once they started developing big power and going faster...what they learned was, it was not so much the volume of air going over the cylinders as it was the time that the air had to extract heat. The solution, which seems counter intuitive, was to enclose the cylinders to keep the air in longer. In other words, getting a lot of air is a good thing, but if it passes over the cooling elements (whether fins on cylinders or a radiator) too fast...there is no cooling taking place. The ideal is to have a large area coming in with a smaller area for it to exit.

[cadillackid]

air-boxes dont serve as much with time of cair as they do in directing of air and not creating turbulence...

if you just blow a fan at a set of fins.. yes some air goes through the fins.. but what you get is the rotational motion of the air from the blades pushed perpendicular to the fins. you can get air swirls in between the fins that actrually help to impede the airflow rather than increase it..

an air box helps to keep air going the same direction esp when driven by a fan or a prop.. puller fans in theory should fix this by creating a vacuum and sucking air through then creating turbulence.. but the turbulent air behind the find can also act to slow it down... plus puller fans tend to be sucking air in from cracks and unsealed areas of the chamber...

pusher fans tend to be able to build higher positive pressures on the air intake side than is possible with a vacuum on the back side.

air boxes also can help to avoid hot air recirculation that happens with just fans blowing at things...

-Christopher

[Krazyistkarl]

Being in Canada, it doesn't get too incredibly warm for the most part. And I've got a FE bus

[eliyahu]

The 188-220 Cummins cam is said to reduce EGTs in excess of 300 deg F. with the additional upgrade of the S400 Turbo. Plus all the performance you get, however stronger valve springs and head studs are recommended with this upgrade.

Also a larger intercooler will do the job.

Lower inlet temp with an increase of volume will always result in lower EGTs.