Oh no another rear radiator in beetle/suby question

[andk5591]

After perusing MANY posts on this, but also watching the Mighty Car Mods video, I am having a conceptual problem with why rear mount wont work. Still many months away from starting on mine (66 with a 95 or 96 2.2 non turbo).

Why rear? plumbing, no spare tire, bleeding and in general kind of mickey mouse approach IMHO.

What I am pondering - moving firewall forward quite a bit, so this would be a bottom breather. Not concerned about the storage area behind the rear seat anyway. - Top section would be removable for service and filling. May make the firewall itself removable as well. Would allow at least 4" of space between the radiator and firewall. Possibly a stock Suby or similar radiator with a proper fan side shroud to maximize fan efficiency drawing air into the engine bay, which would exhaust the heat like a stock Suby since there is plenty of open space around the engine. I can't see why this wont work and it seems too easy and why does nobody else do this?

I have built a VW woodie with a 1955 stroker that uses a box (think home hot air duct work rectangular elbow) to allow air to come up from above the transaxle (openings are about 20"x10") and using a couple small (I think 8 or 10") electric fans and have had no issues. Driven in traffic, cruised the highway for several hours in the summer at 80 MPH. ONly problem is I live on a mile long dirt/gravel lane and I end up with a bit of dust in the engine bay.

I know the general feeling is front mount is the only way to go. But why wont this work?

[Ol'fogasaurus]

After perusing MANY posts on this, but also watching the Mighty Car Mods video, I am having a conceptual problem with why rear mount wont work. Still many months away from starting on mine (66 with a 95 or 96 2.2 non turbo).

Why rear? plumbing, no spare tire, bleeding and in general kind of mickey mouse approach IMHO.

What I am pondering - moving firewall forward quite a bit, so this would be a bottom breather. Not concerned about the storage area behind the rear seat anyway. - Top section would be removable for service and filling. May make the firewall itself removable as well. Would allow at least 4" of space between the radiator and firewall. Possibly a stock Suby or similar radiator with a proper fan side shroud to maximize fan efficiency drawing air into the engine bay, which would exhaust the heat like a stock Suby since there is plenty of open space around the engine. I can't see why this wont work and it seems too easy and why does nobody else do this?

I have built a VW woodie with a 1955 stroker that uses a box (think home hot air duct work rectangular elbow) to allow air to come up from above the transaxle (openings are about 20"x10") and using a couple small (I think 8 or 10") electric fans and have had no issues. Driven in traffic, cruised the highway for several hours in the summer at 80 MPH. ONly problem is I live on a mile long dirt/gravel lane and I end up with a bit of dust in the engine bay.

I know the general feeling is front mount is the only way to go. But why wont this work?

Something similar came up in a conversation today. On my glass buggy, if I put a water pumper in the radiator would fit so far to the rear that it could be a problem coming down steep dune hills.

An option would be to mount the radiator in the firewall but in my case, the radiator would not need to be shrouded as there will be no rear seat. Getting fresh air to the radiator up front in the engine bay could be a problem.

Talking to guys with side mount radiators in tube buggies/rails, getting air to the radiator(s)... even using scoops did not work well. Some used a single radiator some tried dual radiators but getting fresh air directly to the radiator didn't work well. Someone just lately posted an airflow chart on VW bugs.

I have seen people here say they got the airflow to work so what i am posting is food for thought.

Lee

[Ol'fogasaurus]

https://www.youtube.com/watch?v=LtXOUrT ... e=youtu.be

This is the video I was talking about.

Lee

[bad62bug]

https://www.youtube.com/watch?v=D8_hQr-JKUM

I've done it

[andk5591]

Saw that - but no detail on how you did your conversion on the bug. Would be interested in details. Are there build pics?

Unless you are fighting an massive amount of conflicting air flow, the video kind of confirms what I have on the VW woodie. The low pressure at the rear of the car pulls more air into the engine compartment from any front opening and pulls it out the back. The only time I technically need to run the fans on that car is if I am cruising REALLY slow or sitting in traffic. So, my logic is, if I have adequate air flow to keep an air cooled engine cool, don't see how I cant keep a water cooled car cooled.

I can see how the top of engine mounted radiators would have a problem though...

[Jadewombat]

Front mount, rear, etc. is actually more dependent upon pressure drop across the radiator than location. An magnehelic gauge and real data on your car is worth a lot more than opinion. This is an excellent quick read:

http://www.autospeed.com/cms/article.html?&A=113176

OR, look at the boxster placement. Two small radiators in a highly turbulent area to carry the heat away out of the wheel wells.

[andk5591]

Good article. And by pressure drop across the radiator, you are talking about air flow through it. Since I am going to use one or more electric fans and fab or buy a decent shroud to make sure air is pulled through, I should be good. After looking at other rear mount installations I can see where the reason for the fail was.

[Jadewombat]

Correct, if the pressure is equal on both sides of the radiator there will be no flow and your fans will be running all of the time. A few measurements on your car of the high and low pressure areas, ducting and more measurements will save you a lot of guesswork. Don't assume air wants to swirl up and around in the rear of the car from below, etc. My starter on my bus gets hot as there's little airflow in that area even with the spinning CV joints/axles. The air passing under the bus wants to keep passing under out the back.

[bad62bug]

I cheated and ran this in front, between the apron and beam https://derale.com/product-footer/fluid ... 8an-detail running off the heater circuit.

when driving the front cooler does all the cooling,
i used a MR2 rad laying flat and sealed in the luggage area. this is a vid of the air flow out of the top of the rad.https://www.youtube.com/watch?v=CHELtUZnohk&t=52s

parcel shelf rad 2.jpg

[billz60vw]

I ran dual mini copper radiators in the back behind the rear wheels for awhile and ran ok.i ended up switching to a front radiator because I needed spots for an oil cooler and water/air intercooler,thats where they live now!

[Andy Somogyi]

I ran dual mini copper radiators in the back behind the rear wheels for awhile and ran ok.i ended up switching to a front radiator because I needed spots for an oil cooler and water/air intercooler,thats where they live now!

Nice setup man, is that an EJ205? So, even with boost, a pair of Mini Cooper radiators provided enough cooling, did you have any cooling issues? Did you run them in series or parallel? When you ran them up front, what size cooling pipes did you use?

I'm looking at running a pair of Cooper radiators up front in my 912 swap. That be awesome to hear that they provide enough cooling.

[billz60vw]

Yes ,they ran good no problems with my 2.5 sohc.even at 26 psi boost they were good.i ran 1.5 stainless tubing because it was free. I ran the radiators in series.You can check the pictures here.
https://www.thesamba.com/vw/forum/album ... prudenciop

[Ol'fogasaurus]

On the street I can see some advantages and also some limitations such as air volume and direction. Off-road... I doubt that they would work for long with all the "stuff" thrown by the rear tires which could also be a problem on the street where rocks are often found.

Very interesting question to say the least.

Lee

[Jadewombat]

Yes ,they ran good no problems with my 2.5 sohc.even at 26 psi boost they were good.i ran 1.5 stainless tubing because it was free. I ran the radiators in series.You can check the pictures here.
https://www.thesamba.com/vw/forum/album ... prudenciop

Do you have any actual numbers? Pressure drop at different points on the car? Specific water temperatures before and afterwards?

[billz60vw]

Nothing over 215f..thermostat opens at 205.