My 5C I bought earlier this summer came with rad air scoops that were installed years ago when the PO had overheating problems with the original 8V71. It has had a 6V92/HT740 for several years now, and it only gets warm on big hills in hot weather. And less so lately as I am learning to drive it: watching the exhaust and shifting the Allison properly.
I never liked the old church or hockey team bus look of those scoops, and after reading here how they're probably not very effective, I removed them to see if it made any difference. Also the squirrel cage fans are very strong and pull a lot of air into the rads, so I thought the scoops would not help much, if at all...
It did not make any difference!
We went to Calgary this weekend and back last night. The trip is over the Rockies with serious long uphill pulls. The temp was the same as before with the scoops. Mind you the weather was cool. But I know the bus well enough now to see that there was no difference. 180 on the flat, 190 up the hill. If the scoops were any good, it would've gone higher without them.
JC
We still have the scoops on our MC-8 (they were on it when we bought it). I have thought about adding a 3/4" or 1" wickerbill to the front edge of the radiator openings? Any comments? Leave or remove scoops? Add or don't add Wickerbills? Jack
A wickerbill adds pressure in front of it and lowers pressure behind it by diverting air away from the flat surface, and adds chaos (chaotic, tumbling air flow) behind it. Probably you want higher pressure at the radiators so the opposite of a wickerbill is what you would want, but there isn't really one of those. I add wickerbills to things when I want to encourage air to flow out of an opening, sometimes. You want air to flow into the radiators. But it's hard to really say. Air does strange things sometimes.
Brian
Jack at one of the first rallies at the horse show arena I spoke with a gentleman and I think his last name was Rosschester from Carolina, and years ago I believe he was involved with NASCAR and he said the scoops were useless as the coach would create a vacuum just like the NASCAR cars did when they did all of the drafting.
I am surprised that the scoops wouldn't be effective. Seems like the same principle as the vent windows on a car. Unless maybe it is because with the engine at speed the blowers are already pulling so much air in that there isn't any left in that area for the scoops to grab?
Scoops are a joke if a Eagle comes here running hot and has scoops and a cross mud flap I remove both 99% of the time it will run cooler another trick if you have a factory oil cooler for the Allison mounted on the engine remove the T stat on the left bank in the summer it will amaze you how cooler the tyranny and engine will run with no restriction to the cooler and 1 T stat will keep the warm enough in the summer time. won't work in the winter.
And if you don't have double filters on the Allison add 1 it helps with cooling the MCI needs all the help you can get just measure the circumcise times the length of the filter and see how many more square inches of cooling you will gain by adding another filter works for me.
good luck
Quote from: luvrbus on September 12, 2010, 09:28:43 AM
Scoops are a joke if a Eagle comes here running hot and has scoops and a cross mud flap I remove both 99% of the time it will run cooler
I guess that goes to show the differences in engine compartment cooling designs. On an RTS if the cross mud flap is missing or damaged it significantly reduces engine cooling capacity. An RTS needs that vacuum under the engine compartment.
I will relate a story that Fred Hobe may have told me and few others one year at Bussin ?? about some work he did with a casually interested aeronautical engineer.
If the details are wrong, blame the demon spririts...
Anyway:
Yes, the mickey mouse ear scoops made money for those who sold them, and little else, they may even get the air to somewhat spin OUT of the rad entrance. The advice is to dump them.
So, some rough calculations and a few mock-ups run up and down the I75 near Fred's place did produce interesting results, to the point that it appeared they were forcing more air into the rads than the fan could push out!
A steel nerved run with the fan compartment doors OPEN on an MC8 seemed to prove it, when the temps started dropping at speed. When you are running an 8V71T, that's trust in the engineer!
It went no further, as there was no probable return on the investment required to do the proper engineering/testing to ensure the reasons for their results, and ensure they wouldn't fail under other conditions. The world had already gone 102" wide and 45' long, and pretty much solved the cooling issues on the new stuff with big side mount radiators. So, no commercial fleet opportunities.
And Fred had a perfectly good cooling system to begin with.
So, a bit of fun for two guys trying out the stuff they knew, applied in a different way.
As for busnuts... we do have a penchant for stealing ideas, rather than buying manufactured items... once the first set were seen on a coach, it would be too easy to copy them for free.
The leading edge of the scoops, as I recall, which were similar to the ones Fred already was running on his coach, came a lot further forward, covering a lot more of the rad screen than a layman would think was appropriate.
Fred's summary for the MCI?
Run the smaller pulley to speed up the fans, and ruthless fan maintenance, the cones leading into the squirrel cages intact or replaced, each and every fan blade clean and remove all evidence of the dampers and shutters. And the fan compartment must be SEALED, around the door, and around the rads, and any corrosion inspected closely for air intrusion.
I would humbly add that a northern busnut concerned about cool temps may successfully keep the shutters. The dampers are the ones more likely to get lazy and don't open fully, and block the already small outlet from the fans, even when in the open position.
happy coaching!
buswarrior