Airflow problems, need opinions...
 

Most of you know about my bus with the Ecotec. I'm having problems moving enough air at speed to keep it cooled down. At idle it does fine, will cool right down, but cruising, it heats up. My bus is a panel with the divider right behind the seats that seperates the cargo area from the front, if I take the divider down and run with the safaris up/open, it runs cool as can be... but I don't want to run that way all the time. The cargo area is too noisy and sometimes the safaris are too much (interstate driving) so I need a new plan.

How I bring in air is from single NACAs on each side... I even added small "eyebrows" to them to try and help...
http://pic9.picturetrail.com/VOL267/...5/61168673.jpg

I'm thinking of going to double sized NACAs and a more extreme hood...

http://pic9.picturetrail.com/VOL267/...5/61168675.jpg
http://pic9.picturetrail.com/VOL267/...5/61168664.jpg

How do I know if I'm making a tall enough scoop?

I even tried a small roof scoop which did absolutely nothing !! It would have to be 2-3 times taller to get in the airflow... Why in the hell didn't one of you stop me from doing that???

http://pic9.picturetrail.com/VOL267/...5/61168668.jpg

Ideas? thoughts? comments?

How 'bout pulling air in from underneath the Bus. Along with the enlarged NACA ducts, you could use a large scoop and duct from the floor up to the radiator.

Or, with more dificulty, 2 remote radiators placed in areas that see more airflow. Somewhere up front, ahead of the axle if there's room.

I think the roof scoop would have to be much further forward on the cab to work. Does your bus have the fresh air vent over the windshield? Could pipe that through the cab if you had it.

I like the idea of the scoops under the bus. Don't want them too low though, would scoop up a lot of trash. Have you tried some extra fans on the radiators?

I think I would try something on the underside too. Might need some type of water trap/drain in the plumbing.

Thanks everybody. You all went the direction I was thinking too, underneath.
My bus isn't actually that low... no, really it isn't :p compared to some of the slammers I've seen, so I've got good clearance under there. Is the air any good? I can screen against debris and don't plan to do any wet weather driving so I think it is do-able.
I will work up some ducting ideas this week and see what fits... stay tuned :D .


EDIT:
Some things I forgot to add,
I'm running a pair of the largest fans I can fit, they do their job, it will idle at 180 degrees all day, there's just not enough fresh air coming in at speed.
The rad I'm using is four times the size that comes with an Ecotec, when you have enough air flowing, it runs 160-170 degrees even on a hot day.
They make duct fans for the NACAs but they're not worth it, they pull over 3 amps each and only put out 140 cfm...
I do have the windshield vent but it doesn't work/is blocked with the safaris open and that's how I ride 99% of the time...

Yeah, the air's fine under there, just as long as you get it from in front of the engine compartment. Screen out any debris.

I agree with drawing air from underneath and it wouldn't hurt to use some kind of a screen. Also, the larger NACA ducks might be a good step if this doesn't work.

No original ideas, but I just thought another 2 cents wouldn't hurt.

Finaly, the bus looks great :righton: I can't wait to see it in person.

Mike

I too an a fan of grabbing additional air from under the vehicle. I'm using ducts for extra air to my oil cooler. You should be able to fabricate a scoop that is W-I-D-E and connects to the torsion tube and feeds some furnace ducting that directs air to your rad.

Sandeep

I think the scoops would be fine if there was something that was drawning the air in either by a fan/blower or a natural flow. By having an opening of the air to go out the back of the van. have you tried opening the rear hatch a 1/2" or so to see if the air woud flow thru the bus any better. I would say a pop out window on the rear hatch would get the air flowing pretty good thru the back.
Just my opinion mind you.... it just seems the air either needs assistance getting in, or a natural source to get out. Kind of like the wind blowing into your bug thru the vent windows in the summer. then you pop open the rear pop outs and give that air someplace to go and whoosh its much cooler.
I'm no scientist, but I figured it is worth a try :D

Bullyboy,
I have added louvers to the rear hatch just below the window so it has a way to exhaust out the hot air. I also have a safari rear window and tried driving with it open, it didn't make any diff. Good ideas all around.
I've just got to get more fresh air coming in...

http://pic9.picturetrail.com/VOL267/...5/56323527.jpg

This is turning out to be more difficult than I thought. There is not a good place to come through the floor with my ducting... ideally, I would come up right in front of the torsion tube and it's a straight shot up the rear hump/firewall but there is too much frame and support in this area to start hacking. I would have to move forward at least a couple feet to clear everything. Imagine opening my side cargo door and seeing a pair of 6" tubes coming up out of the center of the floor and snaking back and up to the rear deck :eek: !
No, it's not a westy. No, I don't ever plan to camp in it or haul anything but butt, but that would just look like hell.
There is a fairly good place right in front of the rear wheels but then the duct catches everything the front tires can pick up... and if they hung down very much at all (which they need to do, right?) they would really stick out.
More head scratching to do... :confused:

EDIT: New twin NACAs ordered today to replace the singles.

Weld up a wide/low profile duct from sheet metal then transition to a round duct, kind-a like a woodstove hood.

I say go with the air from under the bus. Don't ruin the clean look of your bus with extra scoops. I would say what everybody else said, run a large wide scoop under your bus the entire width of your bus. Place a metal mesh over the front to keep trash bags and such from clogging your cooling system. Although also note that the airdam which you spent so much time making will cut down on the air that flows under your bus just like it is supposed to do. Have you considered any radiator additives like water wetter. Try to picture your bus in a wind tunnel and ask your self where would the air be flowing around the bus. You will have good dense air in the front but the rest of the way back the air would be turbulant. If you want to get good source of air for the radiator you might want to run the ducting all the way to the front of the bus and cut some intake holes into the front air dam. You could make some large rectangle shaped ducts to channel the air to the engine compartment. Paint them flat black so they are not as visable when looking at them. Also you might want to make the ends adjustable since they might need to project a little from the front to get into the good clean air. Just a few thought to consider.

Why not pick up the air at the air damn (small round ducts) and transition to to a 2"x10" sheet metal chase under the floor, then transition to a round duct and into the back at the rear tray.

That's definately the plan for the mouth of it but I think I have to keep the round duct a decent size too, at least 3" maybe 4" to get some volume in...


Lots of good ideas BG. I'm already using water wetter and a 50/50 mix on antifreeze. Don't worry, after the roof scoop fiasco I'm done adding scoops to the outside. That was a toooough lesson to learn :banghead: . The real reason I'm switching to the double NACAs is because when I taped it up there, I just liked the way it looks! If it happens to catch a little more air...bonus!
You brought up a very important point about trying to imagine where the air flow is... unfortunately, all I can do is guess and my guessing has been ultra sucky. (see roof scoop cluster) Running ductwork from front to rear is darn near impossible with the beam and steering stuff in the way so I've got to stick with catching it near the back. I'm gonna make some cardboard dummy boxes and fool with hangdown and clearances this coming weekend.
If anybody gets a brainstorm, lay it on me.

Dave, I just went and looked close at the front setup. It's really tight and jumbled up, no straight shot and the box would hang pretty low even at 2". I'll shoot some pics tomorrow in daylight and post'em later at night. That would be an excellent place to pick up the air though, but I'm still stuck on where to bring it into the cargo area ... kinda hard to explain, I'll take pics of that too. I really want to plumb it directly to the fans but I guess it would do ok if I just dumped it into the cargo area wherever it was clear and let it kinda pressurize the whole area.
Stay tuned, the saga continues...

Maybe build some hollow rocker boxes to carry the air to your engine compartment. Run some flexable tubing from the front air intakes in the air dam to the inlets in the rocker boxes. Use them to plumb the air all the way to the back and then use some more flex pipe to help guide the air to where it is needed.

There are a few watercooled buses in the UK that have their radiators fitted between the chassis rails with ducts attached straight to them. None seem to have any problems with this set-up (even a 400bhp NOS V8 bay window). I guess you could duct air up in the same way...
There are also a couple of cars with ducts built into the front bumper with rads mounted behind the front seats.

Rich
PS looks awesome anyway!

My buddy and I were reading through your dilema. There's a bunch of good suggestions from other people in the forum. I'm sure you don't want to deface your vehicle anymore than you have to. These were some of our observations.

1. At idle, no problem
2. At speed, problem-This may be due to the characteristics of the bus,
when you are pushing through the wind, you are displacing the wind in a
turbulent manner around the bus, not enabling your ducts to work
properly. Even if the air is flowing across the ducts it could be creating a
vacuum, starving the cooling air to the radiators by reversing the airflow
like a venturi. The closest thing we could describe it as is a sandblaster,
compressed air passes at high speed across an orifice picking up sand for
desired affect.

The wind tunnel idea is good. If you don't have access to a wind tunnel, place streamers (construction marking tape) around the ducts and radiator louvers and have someone follow you and video tape you at speed to note how the streamers react. If they push in towards the back you may have to reverse the route of the air to the radiator.

Crew hits on probably what I think is the biggest problem...
Any of you guys that have ever had a van or SUV knows what that back window looks like after a few weeks with no bath... absolutely filthy! The air just swirls back there, I'm probably getting a ton of turbulent air across the rear right where I'm trying to exhaust my cooling. If it was shooting down that back hatch, it would pull a serious suction on the louvers and my problem would be fixed... BUT, it would take a pro-mod wing to reach up into the airflow and make this happen so that puts me back to bringing in air from underneath. I think NO_H2O is spot on, but I would have to start the chase right behind the front beam, make it almost like a thick belly pan (that would be a plus!) and funnel it down to a couple of round ducts dumping up into the cargo floor. I seriously think that once the cargo area is charged with fresh air, the fans will take over and do it fine without having to run plumbing all the way up to the fans (oh that would look sooooo ugly).


Rich, I sure hope I don't have to start from scratch and move the rad, this is what I get for trying to outsmart you UK guys!

Hi

Love your bus. A while ago I saw a baywindow with a Subaru motor in it, he had a radiator mounted flat under the belly of the car. Loking at your setup, if the heated air just went down over your motor and out under the rear bumper you would get more flow I feel, like when you have an oil leak on a bus it ends up all over the back window.

Steve C

Got in late, I'm beat. No pics tonite.
This belly pan/air chase is gonna be the ticket. I did take a few minutes to look under there and this is really the ideal way to go. My duct would be 26 inches wide and 5ft long and 2 inches thick. There is a perfect place right behind the front suspension/tie rods to open the front of the chase up into a mouth that could be 5-6 inches thick without it even being noticable. I can funnel the rear into two 3 inch PVC ducts.
I'm excited again, this idea rocks! Thanks everybody for the support and guidance!
It will take a week or so for me to gather up everything and start working on it... I will report back as it develops.
:clap:

http://www.franklinsvwwerks.com/images/Eldad9.jpg

I yoinked this off Franklins site, Its a pic of that Ridiculous 23window with the A/C and Porsche 3.6 and....man i hate that bus, makes me mad...I need money

Airflow problems, need opinions...
 

I read all the ideas and agree with drawing air from underneath the car. I think the problem is getting the air out. If there is more air going out than coming in air would be sucked in through the vent. Just a thought. I am currently designing a was to fit a 350 crate engine into a bug for a friend and make it as least noticable as possible. My problem was getting air through the radiator without putting in the front of the car. I was at school one day and noticed the design that a Cassna 172 uses to cool there engines. I think I have the perfect idea. I can email you a rough drawing of it if you want. :idea:

Just found this post, dunno why I missed it before.

I am also thinking about using the underside of the bug (in my case) to pull the air. Somebody told me that there is a high pressure area right in front of the torsion beams. If that is the case, then I won't even need a big scoop, the air would be forded in there automatically.

If I were you I would start with that as well, just hack a hole in the floor (nicely) and see how much air is coming through when driving.
Use the string/tape method mentioned before to see if there is air coming in.

Are you sure those louvres are big enough to vent the bus ? Maybe try running without the backhatch for a bit to see if it makes a difference.
I was also wondering if there is a low pressure area somewhere near or at the back of the bus that you could use. If you would place a vent there, it would pull the air out of the back of the bus (and suck it in before the rad).

Just my 2 cts....

Rob.

When I was thinking about doing the subi swap I was planning on putting the radiator where the gas tank used to be. Lay the radiator down flat and over the fuel tank opening. I was going to cut inlet holes in the front apron and rout the air through the spare tire area with some fiberglass ducts that would merge into a shroud. I would then vent the hot air out through the top of the hood via some cool recessed ducts just like the race cars have. Just a thought. :)

This involves more cutting, but you could use small projectors as headlights, then use the remaining area of hte headlight bucket as a scoop and duct back from there. I think you'd have to do a false floor to make it look OK, but it involves more cutting, something I know you've had to do too much of already. I don't even know if it would work, but it would be right out front.

Jason

The "under bus duct" absolutely bombed! I had a sheet metal chase made that was 25" wide and 6" tall at the mouth, I had it flared down right behind the beam as low as I could without tearing it off on manhole lids... it did not produce very much air at all. The single NACAs on each side produced twice as much flow. I may have screwed the aero-namics with the front valance and made it push away most of the air underneath so it was doomed from the start.
NACAs are the way, especially with the hoods Carbon Joe is working on.

Hey Panel,
first of all you have a relly hard *** kicking bus. Its absolutely awesome.
I agree with everybody that said "go under". The reason is one and simple.
The bus doesnt have any aerodynamics (unfortunately), still great though, it is the same a solid brick (going plain to make my self clear.no offense). when air is blowing from one side, because of the graet frontal area the air pressure increases significantly (that why when pop you pop outs it should be realy breazy specialy when speed increases).But what happends from the edge of the brick's frontal area and backwards? Again a simple answer. Now think of a cut away of a tube. The more you bend it the more turbulent flow you get. This happens because the molecules of the medium running in the pipe (liquid or gas) that are towards the inside of the "turn" will try to continue moving straight thus creating a turbulence to the flow.

for the same reasons your roof scoop cant provide the "calculated air flow" or air supply. same with the nacas. In order to achieve their max performance you will need really big ugly and actually silly scoops to direct air into them.

A VERY IMPORTANT THING The longer the pipe the lowest the pressure you get at the end (for gases with ambient air flow)
Something on the above. A friend of mine has a beetle only for tarmac hiil-climbing or circuit racing. he runs a 2.0L type 1 with the normal style fanshroud and in order to provide enough air he uses a twin naca you were saying on each quarter window with 12x12 cm lexan "eyebrows" with a massive 8 cm opening. The car will ran at acceptable to high temps through the championship, but when its raced when really hot about 38-43 degrees C it suffers. The car is still able to wipe out any car in the competition.

Anyway
I hope that some of these will help. I know its long, but i believe it gets into things a bit more.

Chris.

A few adds to the previous.

1. Air flow under a bus is much less turbulent than the air flow above.
2. Along with the pipe you can imagine of an inlet manifold (port matching, flow bench stuff etc.

Also you can try this little experiment:
(trying to imitate a wind tunnel)
light a cigarrette and blow the smoke through a straw against some things a coke can or a...brick. lol. Try with different sizes and shaoes and you will see my point.

Chris

Panel, just out of curiousity, how did you determine if there was airflow ?
Or did the engine just run hot ?

Thanks,

Rob.

Got me thinking more about this. Check your cooling system VERY well for trapped bubbles. Any high point should have a stop**** to release air. As I recall, your cooling system wasn't too complicated on the water part, but if there is a vacuum lock, this whole thing could be just that the water isn't flowing around like it's supposed to. Not likely, but an option to your troubles.

Jason

Rob,
Had a buddy ride in the back and check airflow at speed. Nothing coming out of the floor, quite a bit from the side ducts.

Jason,
Did have a problem early on with air pocket but did a re-vamp and added a bleed in a trouble area.

The deal is, it is very stable temp wise, no spikes at all. At an idle, the temp is only 160-170. Every few minutes, the fans will cycle on then shut back down...just like they are supposed to. When you drive at sustained speed/load for say 10-15 miles, the temp will start to creep up and continue climbing until you stop. I have seen temps as high as 230 before I pulled over and let it idle for a few minutes. It is just airflow. Getting the right balance.

Airflow problems, need opinions...
 

Try this. Remove the front air dam and see how much air flow you get from the bottom of the car.

mike,

Can't Mike, it's all steel and welded on.