1974 Westy EJ22 belly mount radiator question

[Spoon776]

So I have had my 1974 Westy with an EJ22 subaru swap for a couple years now and have had problems with cooling on hot days here in California. I have recently abandoned the engine bay radiator set up for a belly mount system. The problem I am having now is that my fans constantly have to cycle on even when driving down the road. I will attach pictures of the set up i went with. Today I fabricated a scoop for it to see if it would make a difference, but it still cycles while driving and now its also harder for my fan to cool it down. I have a 2013 Grand caravan radiator with stock fan and shroud installed. The radiator should be large enough to handle the job, but my question is is it better to run a fan shroud or is it possible that it is restricting my airflow too much. Any advice would be helpful to make my setup work. Thank you.

Current set up

Testing

[SGKent]

Skills is the guy to ask. Generally speaking, air does not like to make 90 degree turns. It tends to fight back by building high pressure. That may be what you are fighting.

here is how they solved it on the P51. It worked so well that the hot air actually gave them a boost in speed as well.

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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[panel]

Fans on top I'm assuming ? Are they blowing or sucking ?
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My '65-Subaru EJ20 Turbo conversion

[panel]

[Spoon776]

It is a single 16” fan with shroud mounted on top and is pulling configuration. The radiator isn’t perfectly horizontal as it is angled down in the back roughly 1”. I know thats not much, but thats all the clearance i have. If i removed the shroud and bought a slim aftermarket fan, it would be able to angle a little more.

[SGKent]

P51 is vertical because the air has less change of direction. That allows more air and better cooling. I used it not as a how to do yours but to try to get your head around that air has mass, like lots of beach balls, and it jams up when forced to turn 90 degrees. Think of water in a river, it likes to bend around things. Air is a flow like a stream is.

Below is a bus example on how someone moved air into their under bus horizontal radiator. Each louver is a curve that guides the air thru the angle change. I grabbed it off a youtube. You'd also want diverters on the top that nudged the airflow back into the air stream.

The whole idea is to bend the air into the direction you want it to go, and not just try to force it to turn 90 degrees. Ideally, the system below would have a little slope to it so the back hangs a little bit lower than the front. This is probably parallel with the ground to minimized road debris strikes.

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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[Spoon776]

That makes sense. I will try to find a way to make the air more streamlined on the top side so that it doesn’t just slam into the floor of the bus.

[my59]

Typically in a building exhaust system, better to suck air thru ductwork than to blow it.
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my59: Well son, my grandfather died before I got to drive it, so does that answer your question?
our79: sunroof bus w/camper interior and 2.0 FI
Other:'12 Jetta, '77 Benz 300D, and a 74 MG Midget.

[Shonandb]

I just used my donor's rad and fans in a similar setup to yours but installed a temp switch to cycle the fans on when the coolant temps reach 190F. I pull a trailer and have driven the Bus in outside temps up to 100F and the coolent temps remain below 210F.

I wonder if you have air still in your system or are you using an aftermarket thermostat?
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76 Westy with a 2.5L Subaru SOHC + Vanagon (010) Automatic Transaxle
Build & Trip Thread: https://www.thesamba.com/vw/forum/viewtopic.php?t=758760
Previous 1973 Panel Bus:
Click to view image

[Spoon776]

How big of a gap does your radiator fan have from the floor to the bus? Mine is roughly two inches and im wondering if that could cause a high pressure issue.
The computer is controlling the fans based on the engine temperature.
Does your fan cycle on and off while driving down the road?

[Shonandb]

The leading edge of my rad fan touches the floor and the back angles down a few inches away from the floor. My fans only cycle on and off when driving in traffic or on days when outside temps are 90F and above. Today it's about 80F and my before rad temp peaked at 95C/203F and after rad temps stayed around 83C/184F. I heard the fans cycle on a couple times driving in traffic but not when we were on the hwy.

I'm using the Subaru stock cooling fans so they are not as slim as the Spals. If you are using a larger rad maybe you need to make sure that air is getting forced through the rad and not past it. I found that using proper temp foam insulation between the rad and the scoop tin helped more air go through the rad and the fans cycle less often. Do you have noticeable gaps between your rad and scoop/duct tin where air can pass through?

Maybe read member W1K1 's build thread as he outlines how he did his.

Here are a couple pics of my setup.

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76 Westy with a 2.5L Subaru SOHC + Vanagon (010) Automatic Transaxle
Build & Trip Thread: https://www.thesamba.com/vw/forum/viewtopic.php?t=758760
Previous 1973 Panel Bus:
Click to view image

[skills@eurocarsplus]

fans cycling even in underbelly setups is just a fact of life, especially when it's boiling hot.

your setup could use some improvements but I stopped giving out advice on the subject when people stopped listening, and everyone runs something jusssssst different enough that it's impossible to accurately advise anymore.

that said, for a long while I literally handed out the recipe I use only to have 1-2 out of 10 people actually use it, the rest said it was too expensive and the parts I listed were just out of their budget.... so I can't help if we're not all running the same thing.

As long as your temps are stable, fans running while going down the road is kind of normal depending on the ambient temps
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[jmstu76]

The fan on my engine runs as soon as I fire it up and keeps running until I shut it down. Even when it's cold out.



Oh yeah, still air cooled
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James

'76 Deluxe Sage Green Westy
2258 cc GD case 78mm CW crank, 2.0 H-beam rods 5,325” 22mm pin, JE forged pistons with 15cc dish, JE rings, type 11 clearanced oil pump, CB Eagle 2205 Type-2 “Torque Special” hydraulic cam with matched lifters fed by CB Dual Weber 40 IDF MX with 6” foam air filters, currently 55 idle, 130 main, 200 air correction, 32 mm venturis. 27in General Grabber AT2 All Terrains, Berg Shifter, stock '76 exhaust HPC Ceramic Coated. 11/18/2020

[Spoon776]

I do have roughly a quarter inch gap from the side of the radiator to the scoop. I will buy some foam to seal the sides better and see how that does. I also see that yours has a bigger opening than mine, so I will make mine bigger too to see if it will make a difference. I’m in central CA where it is pretty common for temps to hit 110-115 in the summer. Thanks for the help….. Skills, thanks for your input. Your build threads have been a tremendous help in getting my bus on the road.

[Spoon776]

[Ceckert64]

This is what I did for my EJ22, it worked well and stayed cool after making the scoop bigger. I made the open space around the radiator closed off to force the air from the scoop into it

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1964 sunroof Beetle Restoration "Herbie"
“Joann” 1970 Elm Green Squareback
1972 Yellow Tin Top Westfalia -Sold
“Fitz” 1971 Westfalia Poptop EJ22 swap
“Rome” 91 Syncro

[W1K1]

mines a pusher, 2 -13" spal fans, i followed Veedubnut's build, the fans only come on in slow moving traffic after driving for a while, it usually stays in the mid 180's for temps

a panel on the belly to smooth out the air coming in

hangs pretty flat, almost even with the frame rails

all closed up around the edges, so air has to go through

made a scoop for it last year

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http://www.thesamba.com/vw/archives/manuals/jim_martin_engine_build.php

1973 super
1965 squareback 1500E
1971 bay window westy- subi swap

[Spoon776]

Just wanted to give an update. I got the scoop put back on today. I made the opening roughly 3” wide compared to the 2” as before, and I also used foam strips to Seal the gaps between radiator and scoop. I took it for a test drive and the fans never kicked on while driving. Actually I saw the temp gauge drop while going down the highway. It was only 85 degrees today so I will have to test it when it gets hotter to see how it does. Thanks for all the help!

[panel]

That's goods news

And W1K1 .....what did you use for scoop material underneath ? Looks like flexible black plastic of some sort ?
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My '65-Subaru EJ20 Turbo conversion

[W1K1]