Mudflap/Air Dam

[Lin]

I have been putting this off until summer was approaching since I do need all the cooling I can get.  I thought that I would post pictures because I thought that the way we did it was a bit interesting.  I had a couple of seat rails left over from when we bought a couple of van seats to use.  The idea was to use the rails to mount the mudflap.  It seems to me that the idea worked fine.  See what you think of the picks.  For anyone that notices that the mudflap is a long way from the ground, I believe that pulling off the ramps will solve the problem.

[jackhartjr]

Lin, that is exactly what we will do..Thanks!
Jack

[buswarrior]

Materials used successfully include the rubber ribbed flooring and old conveyor belts.

happy coaching!
buswarior

[Lin]

I think this is old conveyor.  When I got the bus, it was mounted below the rear bumper which is a no-no.  I have been saving it for its new home.

[Lin]

Do you think that it would be good to undercoat the brackets here, or that create future problems if I had to remove it for some reason?

[luvrbus]

I would protect the bolts makes easier for to remove the flaps they are not going to work on a MCI like they do on a GM because of the high radiators ,the MCI brings cool air in over the engine then the vacuum created by driving helps remove the hot air from the engine compartment with the flap you defeat that but I hope it works for you then you can do away with vise grips


good luck

[Lin]

Thanks for the input Clifford,

I am not sure what you mean by vise grips.  Could it be my c-clamp bracket for keeping the back doors open?  I really like that one.

As I understood it, the mudflap across the back created a positive pressure under the engine and therefore limited airflow and cooling.  But that moving the flap behind the rear wheels would create a negative pressure and help out.  Are you saying that that will only work on a GM due to the different radiator location?

[Ed Hackenbruch]

The PO put 26" wide mudflaps behind each wheel that extend 10" below the wheel well. He also put on a full length "Hula Skirt" or "Whiskers" mounted under the bumper. My 5A with 8v71 and auto tranny  runs right at 175-180 degrees. The whiskers seem to protect the headlights on the toad but still allows air to pass thru.  I am thinking that since there is a large gap between my mudflaps that some of the air that hits the flaps is forced thru that gap which may help with drawing hot air out of the engine compartment. Nothing to base this on,.....

[jok]

Great, and timely, topic.

I recently returned to Michigan from Florida and I noticed the temperature was a little high going through Tennessee with 80+ degree days. I have a 1990 Prevost 8V92 (towing a Suburban) and have the original air dam, which is forward of the engine. It appeared to me that the front of my bus is lower than the rear. While I was driving along at 65 mph I raised the front of the bus about an inch. The water and oil temps started dropping and then ran about 15 degrees cooler.

Should I adjust the auto ride level in the front or should I modify my air dam?

Thanks,
John

[JohnEd]

Thanks for the input Clifford,

I am not sure what you mean by vise grips.  Could it be my c-clamp bracket for keeping the back doors open?  I really like that one.

As I understood it, the mudflap across the back created a positive pressure under the engine and therefore limited airflow and cooling.  But that moving the flap behind the rear wheels would create a negative pressure and help out.  Are you saying that that will only work on a GM due to the different radiator location?

You got it right.  Put the flap directly behind the rearmost axle and the low pressure that the flap creates will "suck" on the engine compartment and increase air flow through the rads, be they MCI or side mounted or even the rear mount you see on S&S.

If you put a flap at the extreme rear, you will "vacuum" up fine sand and road stuff and shoot it up at your toad.

If you put a flap on the front it should be as close to the front of the bumper/bus as possible.  That one will drop the air resistance a lot.  Cut theses things to just drag the ground.  They will soon wear to the exact max length practicable.

I notice that the new trailers have a "wedge shaped" air dam that extends from just behind the 5th wheel to just in front of the rear wheel truck.  That will reduce the air resistance back there.  Don't know how that could be utilized in a bus.  I did that to my 240 Z car and I could "pop" across 3 lanes at 130 like it was doing only 75.  My problem was "lift" and i pretty much solved it for a car that weighed in at 2,300 lbs.  The whale tail was a tremendous boost but I only see some S&S with that appendage and its worth is dubious.  Extending the roof lip at the rear will reduce the vacuum at the rear and aid MPG and keep the rear clean but it would be counter productive for cooling.  Less suck...less load to maintain speed, better mpg and less need for cooling.  Maybe a trade off? My old 73 Winnie has the roof extended by dint of the sides in the rear being cut short in the middle so it acts like the roof had a lip.  it stays clean.  Nothing new under the sun.

John

[JohnEd]

As far as that truck is concerned:  Put the air damn directly in line with the radiator.  There is cooling air that goes up and into the front of the rad.  If you hang the flap from the rear of the front bumper you will cheat the rad of that ram charged air coming up from beneath.  Every car and truck I have seen of late is configured to "use" that air that is piled up under the front BUT in front of the rad.  In the stock config the air that passes that rad will become high pressure behind the rad and impede air flow.  The config with the damn right under the rad will create a high pressure in front of the rad and air air flow and the are4a behind the rad will get low pressure that will air air flow thru the rad and also reduce the total air flow beneath the vehicle.

There are so very many designs out there that you should think your actions thru.  Pics would be good for the discussion here. Hint, hint.

John

[luvrbus]

JohnEd, I bet you a dinner at Bates the first 100+ day out here Lin will remove it lol,I know for sure it will not work on a Eagle with the side radiator it adds 10 degrees to the transmission and engine temperature have a couple out back that I removed

good luck

[Lin]

I have seen several recommendations to put the flap there, but I guess that only a test on a grade on a hot day will tell if this one will work.  I sure hope it does since I have already done the work, and I need extra cooling.   Anyway, with the way it is installed it will take 10 minutes to remove or replace it.

[luvrbus]

A good hot day on a climb will tell Lin,your new auto is going to add to the heat inside the compartment,I do hope it works for you Lin watch the transmission temp because you are cutting off it's air supply

good luck