Airflow problems, need opinions...

[Panelfantastic]

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...

[boygenius]

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.

[ricola]

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!

[crewcab1964]

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.

[Panelfantastic]

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!

[Steve C]

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

[Panelfantastic]

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.

[kra710]

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

[coffinator]

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:

[Rob]

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.

[boygenius]

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.

[volkdent]

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

[Panelfantastic]

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.

[beetle1303]

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.

[beetle1303]

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