More air into the engine compartment

LEJ · Post by **LEJ** » Thu Jun 08, 2006 4:19 pm

I'm going to have to find another way because I have an exterior spare tire carrier...

All I have to do is to give it time and I'll figure it out, one way or another???

LEJ · Post by **LEJ** » Fri Jun 09, 2006 1:13 pm

As I explained, I have a spare tire carrier and while at my local Motorhome/trailer supply store, I ran across a set of louvers approximately 4' x 12" (used in various places on a motorhome to vent heat, exhaust, fumes etc)

As stated before, I have a 2110cc engine and since yesterday, it now has an external oil cooler along with the factory dog house.

I cut a rectangular hole where my license plate would normally be affixed and installed the louvers. On a short drive, I "seemed" to notice a difference but the real test comes Sunday when I drive to Irvine to the VW Classic.

I'll report back later if this works. If it does and your license plate is in the normal spot, you could easily build some "stand offs" to mount the license plate further from the body of the car and that should allow air to circulate through the louvers.

Kubelmann · Post by **Kubelmann** » Fri Jun 09, 2006 8:33 pm

I would be interested in how your idea works. I have an extra rear engine cover that somebody drilled 1 1/4" holes behind the license plate area. I bought it thinking perhaps I would put a thermostat controlled electric fan in that area with a filter to keep dirt out.

Captain Spalding · Post by **Captain Spalding** » Fri Jun 09, 2006 11:20 pm

Kubelmann wrote:I would be interested in how your idea works. I have an extra rear engine cover that somebody drilled 1 1/4" holes behind the license plate area. I bought it thinking perhaps I would put a thermostat controlled electric fan in that area with a filter to keep dirt out.

Before you go to the trouble and expense of the fan, it might be worthwhile to find out if air is being sucked into the engine compartment or pushed out. Maybe LEJ could test that on his way to Irvine on Sunday.

IanEpperson · Post by **IanEpperson** » Sat Jun 10, 2006 2:54 am

I've got a stock 1600 in my Thing, and put a Gene Berg temp stick on it a few years ago. When I take long trips, I try an cruise down the freeway at 65 (this is California), and it used to be that after about 10 minutes of that, the temp stick would trip and I'd pull over for a few minutes of cooling. After much frustration, I rigged a small block to hold the deck lid open about 2 inches, and then I'd be able to go for 30 minutes or longer before the temp stick would trip.

When I had all the body work done, I had them cut the deck lid, offset the license plate and install a set of louvers behind the plate. Now when I drive on the freeway with the lid closed, I can run for about 30 minutes - just like I used to with the lid cracked open.

So, not very scientific, but my anecdotal experience says that the louvers help quite a bit.

This summer, I'll put my new 2270 in her and I'll watch the temps closely.

LEJ · Post by **LEJ** » Sat Jun 10, 2006 11:56 am

Captain,

If the Bernoulli Effect is in play here, rushing air past the side louvers should expel air from the engine compartment while the rear louvers should be drawing air????

We'll see tomorrow !!!!!

Captain Spalding · Post by **Captain Spalding** » Sat Jun 10, 2006 4:34 pm

For those who don't know, Bernoulli's Law states that there is an inverse relationship between air speed and air pressure. Low speed = high pressure, high speed = low pressure.

On most cars, the air intakes are located at the area of highest pressure. The air intakes for the Thing, sadly, are not.

The illustration below is an educated guess as to how Bernoulli's Law relates to airflow across the Thing. Dark blue equals higher pressure, light blue equals higher speed. The area behind the car gets a lot of garbage turbulence. So an intake behind the license plate is likely to see a mix of pressure and vacuum.

Continuing with the educated guess, at low speeds, the suction inside the engine compartment created by the fan sucking air into the shroud and blowing it out over the cylinders is higher than the aerodynamic effects on the car. At higher speeds, the aerodynamic pressure drop around the vents becomes too great, and the fan can no longer do its job. Hence Mondshine's max cruising speed.

LEJ · Post by **LEJ** » Sun Jun 11, 2006 12:27 pm

I was a very cool day when I drove to the VW Classic (65 degree's or so).

I took the 241 toll road to the 133 toll road and my corrected speed was anywhere between 62 and 65 MPH. Engine oil stayed at 190 on level surfaces until I hit some hills and it rose to about 200, cooling off to 180 on the back side of the hills.

When I drove home, it was still cool (under 70 degree's) and the same oil temps were recorded so, initially, it seems that the louvers at the rear license plate helped as did a non-fan assisted 6 pass oil cooler above the transmission.

mondshine · Post by **mondshine** » Mon Jun 12, 2006 10:22 am

I believe there are two seperate elements at work which have made my solution so successful.
First, The new air intake faces forward and cool air intake increases with vehicle speed.
Second, the cool air is directed into the fan inlet, not the rear of the engine compartment.
There has been some discussion of oil temp. on this topic. While sane oil temps are important, it is CHT which is the killer. Oil temp will rise with sustianed rpm. CHT will rise with sustained load. It is the high load of 65 mph which heats up the heads in stock Things. This is because in the stock configuration, the fan cannot draw enough cold outside air to cool the heads. If you don't believe it, bungee cord your license plate to the bumper and remove the engine cover completely. Drive at 75 mph for half an hour and watch your CHT. I predict a marked drop.

Best regards, Mondshine

LEJ · Post by **LEJ** » Mon Jun 12, 2006 2:57 pm

After seeing the photo's of his setup, it looks like it would really supply the engine cooling intake with a bunch of cold air.

Mattt · Post by **Mattt** » Thu Jun 15, 2006 11:08 am

Are the pictures of his Gary's setup posted somewhere? Id like to see them. Thanks.

Woreign · Post by **Woreign** » Wed Jun 21, 2006 5:47 am

I just pulled out two pieces of foam (looked like seat cushion foam) from behind the side vents on my '73 Thing. They were full of dust and dirt, and made me thing that there was no way any fresh air was getting through them. Is there a reason for the foam? Was this a factory installment or something a previous owner did? I've owned my Thing for less than a month, and I'm still getting acquainted with it...

Thanks,

Warren

markie61 · Post by **markie61** » Thu Jun 22, 2006 4:14 am

Woreign wrote:Was this a factory installment or something a previous owner did?

Most DEFINITELY from the previous owner. Maybe he thought he was keeping his engine compartment cleaner or something...

Mark

tooter · Post by **tooter** » Thu Jun 22, 2006 9:23 am

Ok, I've read about folks that put extra holes in, remove or hold open the lid, added extra fans, scoops, oil coolers, scientific air-flow calculations, etc... But....(prepare for something dumb or an AH-HA moment here) has anyone considered just taking out the rubber engine compartment seal to increase flow?

LEJ · Post by **LEJ** » Thu Jun 22, 2006 9:54 am

Yes, you can remove the rubber seal but the problem is that it's right where the exhaust heat is its greatest. Others have removed the engine tin that is between the fan shroud and the firewall but I don't know if that helps.

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More air into the engine compartment

More air into engine compartment