Cooling issues on D-13

[SwanTechEnt]

Hey everyone,

After running Thunderhill raceway this weekend and with a couple previous races, I am having some issues trying to keep the engine running cool. The air ducts I have on the car are definitely somewhat hacked up and do not fit very well, and I have been having to tape up the gaps between the air ducts and the body work, This method somewhat works, but when everybody was just getting to 240 degrees Fahrenheit in the 100 degree weather during this weekend I am worrying my head off in the car and having to slightly back off to keep the oil temp from passing 270 degrees.

Is there any hope in trying to fix the air ducts I have to try and get them to work better? Is there any out there that are the same as mine that i can buy new? Has there been anybody else with this same problem and has found a solution?

The pictures of my car can be found on this thread
http://www.apexspeed.com/forums/showthread.php?t=39934

I found a couple of pictures of some other air duct styles of some other D-13's and this is one that seemed to stick out the most
http://images.thesamba.com/vw/gallery/pix/302667.jpg

I can post more detailed pictures within a couple of days in case anyone would like some

So...any suggestions?

[provamo]

let me suggest that you copy whatever works for other owners of that particular manufacturers model

i would guess that moving those "intakes" away from the roll over structure would be a good start

[Dietmar]

Somehow my reply got posted under MYSTERY Calwell. The reply is the same, the location is different.
Dietmar
www.quixoteracing.com

[S Lathrop]

The air scoops shown on the second car in your post are similar to the scoops I made for the Zink Z12. Chuck Brewer may still make those. 513-677-0132.

Half the cooling problem is on the exit side. The D13 is bad because of the large frame rails blocking the air flow off the bottom of the engine. You can accomplish a lot by ducting the exit air to the rear and the side of the engine.

Rerouting your exhaust pipes to the side or above the cylinder head will help a lot. Then you can get a good exit duct for the bottom of the cylinders.

[problemchild]

With that nice big oil cooler, your problem is the head cooling. You are missing the part that connects the scoops to the tin. The car I worked on with those scoops (in 82) had a one-piece fibreglass assembly that sat in there like a fanshroud and hooked everything together.

[Daryl DeArman]

The air ducts I have on the car are definitely somewhat hacked up and do not fit very well, and I have been having to tape up the gaps between the air ducts and the body work

With that nice big oil cooler, your problem is the head cooling. You are missing the part that connects the scoops to the tin.

Based on his description of what he is doing, I'm guessing he has those scoops, they just aren't shown in the photos.

In any event, make sure those scoops are sealed at the junction of the cylinder tin. Make certain the litlle diverter piece of tin is there at the base of the cylinders and the head....otherwise the air is going to go right between the barrels and straight out the bottom without going out and around.

How are you ensuring that the air entering between the roll hoop is going through the oil cooler? If there is an easier path for it to take, it will. Basically turning that big ol' oil cooler into a heat sink.

I'd want to know O/T going into the cooler and O/T coming out. Find out if the cooler is doing much of anything.

Make sure you are using a good oil at those temps.

Send Dietmar some more photos. He has run a D13 for ages . He also has helped many a D13 owner here in SoCal accustomed to running in those air temps.

[S Lathrop]

The scoops that I referenced in the photo do not use the stock VW tin. They consist of the scoop and the cylinder heard/barrel enclosure. I based the design on what we were doing for FSV at the time.

I don't think you can push enough air through the stock tin to cool the heads and barrels properly. The Tin work was designed for a engine powered fan.

[Hardingfv32]

Is this what you mean by proper exhaust of cooling air flow? 180 deg oil on a 95 deg day.

That is a 3 X 4" oil cooler mounted below the exhaust header. The flap on the cooler is to control flow. That setup was good for 120 deg oil on a 70 deg day. Just learning how to adjust the system.

Brian

[S Lathrop]

I would call that using a diffuser to extract cooling air from the engine. That would be a perfectly legal and valid approach.

What we had looked like a rear facing, reverse cooling air scoops. Infact we did try the reversing the extractor ducts and do a reverse cooling system that used the exhaust system to help extract air from above the cylinders. One of the variations of the Zink Z12. It did not work that well.

I think the frame rails of the D13 prevent the diffuser approach.

[Hardingfv32]

Not shown well in the previous photos is that the cooling is from below, fed by side ducts (original D13 concept?) with openings in front of the drivers butt. A true raised nose.

Brian

[provamo]

i admire your enginuity

[S Lathrop]

As I said, I never got the reverse flow to work well enough. But I did not do all the modifications that I should have done to the engine baffles. There are 4 deflectors that have to be reversed; 2 on the barrels and 2 on the head.

My latest work was inspired by Mark Edwards' car. I built the car so that you can see the entire head and cylinder barrel by looking over the front beam just inside the upright. The inlet ducts are entirely within the engine sihlouette, like a J3 Cub.

Hopefully the car will get to the track this year.

[Hardingfv32]

While I realize the importance of frontal area with the types of bodies we are designing for, I am very skeptical that you can get proper cooling without breaching the engine silhouette. By the time the air flow reaches back as far as the rear roll hoop, it is a complete mess 1-2" near the surface with no surface pressure. No way you can get good airflow over the engine without a duct or deflector that violates the engine silhouette. In my case, I wanted some form of cooling exhaust duct which further complicates things.

Of coarse it can be argued about just how much and of what quality cooling system is required for best performance. My attempt is a swing for the fence. About as optimized as you can get with as small a frontal area as possible. The car could not get much more complex. The car is new and needs the engine optimized for the new cooling conditions. In these early stages of development, the performance benefit is NOT jumping out at me.

Brian

[papak]

I had a Beach back in 1979 that had "bottom-up" ducts. As I recall, they worked well enough but I was always having to remove the ducts during the weekend to pull out rubber "marbles" from the fins. I was also getting rattling sounds by the end of the race from the minor pebbles and such that would accumulate in them (they were aluminum). My guess is that with all the debris I sucked up, they drew a fair amount of air. Of course, I was running toward the rear of the pack as well. They used the upper shrouds on top and bottom (the barrel deflectors were on the top of the cylinders) with a simple curved deflector that aimed toward the rear out of the upper duct.

[S Lathrop]

Mark Edwards' and one of Bill Noble's cars cooled well enough to be very competitive without scoops wider than the engine silouette. For short tracks such as Blackhawk Farms, I have added exit ducts and had very good cooling when the standard scoops did not work well enough. Neither of those cars have as good air flow under the engine as I have in in my new car.

Also what I am doing on the new car is only a slight evolution of my previous cars. By doing the roll bars similar to my FF/FC cars I can form the frame much closer to the driver and pinch the body in starting at the drivers elbow. The scoops go under the drivers arms.

[SwanTechEnt]

Here are some pictures of my setup.

The air ducts definitely do not fit well within the tin over the cylinders & heads, so im sure I am losing some air through those gaps. The engine does have all of the proper flaps underneath. The third tubing that is black and is running next to the air filter I put in as an attempt to get more air to the cooler.

On another note, does anybody know if the molds for the D-13S bodywork are still out there and/or is anybody making any? Just curious because mine is fairly beat up (considering I got hit on the left side by a SRF on the last day of driver's school and the tail flew off during the first race this past weekend )

[Hardingfv32]

Are you up for moving the oil cooler to the nose? This 3/8" slot is feeding a 4 X 6" oil cooler. This setup provided 180 deg oil on a 75 deg day.

Brian

[provamo]

Harding, what is the size of your duct inlet (in square inches) for that 4x6 cooler?

[Bill Bonow]

Terran,

In looking at the photos, I'd be suspect about how much air is getting into (and out of) your oil cooler. It certainly is large enough, but if air doesn't exchange through it, large size will have no effect. The Evolution FST uses similar head ducting and a stock VW cooler. Typically, we have a hard time seeing more than 215 F oil temp and 300F head temp in a drafting/close racing situation on a 90 degree day and 1600 makes a lot more heat than the 1200.

My suggestion would be to get a increased volume of cleaner air into and out of the cooler you have and I'll bet the temp goes way down. If you do start working on head ducting, a head temp gauge is pretty much manditory during development.

[provamo]

dude...you dont have ANY DUCTING to your cooler, you have three hoses blocking flow to it...sorry, i haven't had my morning coffee

its no mystery that you are having cooling issues

basically you need a positive head of pressure for your SEALED inlet that will guide the airflow THROUGH the cooler then exit to a region of lower pressure

rant on: plug those holes in the dam LOL (might need a second cup of java)

[Bill Bonow]

Just like Ralph, I looked a little closer at the photos and, yes to all his comments. In addition, I noticed you are without any heat sheild between the exhaust and cooler. In effect, what you have there is an oil heating unit. Make a heat sheild to block out radiant exhaust heat, but don't block off air from exiting the cooler.

[Daryl DeArman]

How are you ensuring that the air entering between the roll hoop is going through the oil cooler? If there is an easier path for it to take, it will. Basically turning that big ol' oil cooler into a heat sink.

In effect, what you have there is an oil heating unit. Make a heat sheild to block out radiant exhaust heat, but don't block off air from exiting the cooler.

I think we are on to something....

[problemchild]

I personally like radiant exhaust heat to warm the oil in the paddock while not affecting oil temp at speed ..... but otherwise agree. Get some air through the cooler!

[Hardingfv32]

Using the current cooler location, you need a well shaped box/plenum in front of the cooler that the hoses route into. Possibly you could use a stockcar brake duct if you can't fab a box. Also consider adding flaps to the scoops on hot days to collect more air into the ducts. The quality of the air flow is not that great that close to the roll hoop.

Nose cooler location... The original opening was about 3 X 7", but that was way too big. That is why the aluminum cover. The air quality is wonderful at the front of the car.

Brian