ShopTalk Forums | Aircooled VW Tech & Restoration Help

I have a 914 with a stock 2.0 with Euro pistons that I race in some pretty hot weather. Is there a way to use a 911 fan or some other higher capacity fan to keep the head temps down a bit. I currently see 375-400F and the weather is only getting hotter. Thanks!

-Greg

Yes,
There are a few conversions available to cool your motor.
FAT Prefromance sells one
Call Vince for his Down The Middle system
>>>We are currently taking a limited number of orders for the DTM Type IV Conversion Kits. With all the positive support from this board and my father's customers/friends I believe moving forward with this is the proper thing to do. I have contacted all of his suppliers and the ball is now rolling. Thank you for your support.
Vince Locicero
503-341-9513

>>>

Has anyone done any kind of dyno testing to determine how much HP is lost using these 911 type conversions? Also, is the fan required for any type of balancing on the motor...what I mean is can you remove the fan? I know of several race motors that have all the blades removed from the fan, mine has every other blade removed, and cool air is ducted from the front at the air dam through the car and through the rear firewall to the front of the fan housing. Do I need to even keep the fan for balancing? Just a thought.

Thanks Vince! I'll give FAT a call. Good luck keeping the DTM alive. I know what a pain coordinating all that work can be. My deepest sympathies for you and your family's loss.

Unfortunately I can't cut big holes in my car to duct air in from up front based on the class rules I run in. I'm just looking for a bolt on fan that will pump more air over my heads to keep them cooler. Any ideas?

I run a 1.8 F Prod in the heat of Florida and the only way I can keep the oil temps in line is with the 911 fan package. I also have a small front cooler that I run the morning sessions at Sebring taped up and untaped in the afternoon. Oil temps never go over 210

Do you mean an upright 911 fan package or can you bolt a 911 fan into the stock 914 location? If it bolts in the stock location, where did you get such a package? Is this the FAT product that Vince is referring to? I can't run an upright system because I need to keep the Djet injection in the class I run.

Thanks Mark!!

-Greg

All the 911 fan setups that I know of are uprights. You're hosed on that...

Your best bet now is to try to get as much cool air into the engine bay as possible. Air goes forward along the top surface of the rear trunk lid, so you don't want to mess that up.

I know one guy who fabbed a fiberglass duct that goes on the side and back of the "sail panel" and pushes air into the mesh side panel next to the engine lid. http://members.rennlist.com/chuxter/#TempTests

I know another guy who has a deflector just off the upper rear edge of the roof. This curved deflector pushes air downward into the engine bay. It's only an inch or to long, but it goes most of the width of the roof.

With or without that mod, a GT-style engine lid (two mesh panels instead of one) should help a little bit. Remove the rain tray also.

Finally, make sure your engine tin is all in good shape and there are no leaks in it. All holes should have gromets, and there should be a rubber seal all the way around the edge of the engine bay to keep air from the underside from getting sucked in. The cooling air goes out the bottom of the engine after it is done cooling things, and you don't want this warmer air re-ingested.

You do have the thermostat and flaps hooked up correctly, don't you?

--DD

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1974 VW-Porsche 914 2.0 (Type IV powered!)

Pelican Parts' 914 Tech Geek http://www.pelicanparts.com

Uhmmm... Actually, I don't remember. I use the 27 BTDC timing mark (red blade of the fan) and twist the distributor until it lines up.

I can't really picture exactly what you did--I think you described it adequately, but it just isn't clicking in my head. But you should remember that advancing or retarding the timing too far can result in higher head temps.

--DD

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1974 VW-Porsche 914 2.0 (Type IV powered!)

Pelican Parts' 914 Tech Geek http://www.pelicanparts.com

Ah, interesting. Well, at this point I'm probably timed for about 19-20 degrees BTDC. Should I shoot a little higher?

I can get my CHT to 375-400 degrees with relatively easy driving on the street. My sheetmetal is all in place and I have most of the rubber plugs as well. I just dropped a valve seat and I don't want to drop another one at Thunderhill this weekend.

The car already runs a little rich. I guess some experimenting with my timing is in order.

Thanks again Dave.

-Greg

[This message has been edited by 914Racer (edited 07-14-2002).]

As usual, thanks Dave! I fabricated a duct that takes air from right above the roof and feeds it directly in front of the fan via 4" tubing. We'll see if that helps.

Now I have a question regarding timing. If I want to dial back my timing to help keep things cooler which way do I twist the dizzy? I used Pelican's excellent template to mark my fan. I took the ol' timing light and set the timing to 27 BTDC. Then I twisted the dizzy so the timing mark on the fan housing was about half way between the 27 degree mark and the TDC mark. That should've effectively retarded my timing which should help keep head temps cooler. Right?

Thanks again!

-Greg

[This message has been edited by 914Racer (edited 07-14-2002).]

Most of the racers i've seen use the 6" pipe ducted from the front. It works well enough that many have blades removed from the fan to reduce load.

I have a bad memory, but I think Racer Chris uses a Corvair fan system on his racecar. It would fit, if you can't use the ductwork in your class. It would have to have a fanbelt, most use a total loss systems with the stock fan housing.

Greg, If you're gonna race a 2.0, get used to dropped valve seats. I have no idea why, and neither do my engine or machine shop guys, but the 2.0 heads tend to drop the valve seats fairly regularly. I know a couple 914 racers that won't run the 2.0 heads just because of that. In 8 years of racing, I've never dropped a seat in a 1.7 or 1.8 head.

Thanks for the info. I've heard of people using water injection to help keep things cooler. I'm trying to find some info on one installation I heard about that put a nozzle in front of the fan which squirted water when the car went to full throttle. The water would then blow over the heads and cool things down. Sounds like a band aid to me though.....

Thanks again.

Hi Greg,

My Corvair fan setup won't work with D-Jet. The fan sits right where the intake plenum goes. You can see a picture of it on my website. There's nothing you can do to change the fan with the stock FI. If you can duct fresh air to the fan inlet that will help.

I would think that the dropped seat problem could be alleviated by installing seats with a higher interference fit, like 8-10 thousandths, instead of the usual 4-5. I don't know, maybe that would just increase the likelyhood of cracking the head, which I know is an issue with the 2 liter heads.

As far as head temp goes, I wouldn't think that retarding the timing will help. In fact, advancing it may be a better idea, like to 32 deg BTDC. 100 octane unleaded race fuel should work ok with that timing in a stock engine.

How do you know you are running a little rich? Do you have an O2 sensor, or EGT? This weekend I noticed that my heads hardly got above 350, in about 90 degree weather. The EGTs were between 1250 and 1300. The oil temp got to about 210 on Sunday. I could probably make a little more power by leaning out a little to get the EGTs up to 1350, which would make the head temp go up too. My 1.7 liter is making similar power to a stock 2 liter, maybe a few more hp.

BTW, what exhaust system are you using? It can have an effect on tuning as well as head temps. The header I build will help your engine make more midrange torque and the D-Jet will maintain a more constant a/f ratio.

I think mixture and timing are probably more important for you to control head temp than the cooling fan, unless there's something wrong with the tin, or flappers.



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Chris F.

www.tangerineracing.com

I agree with Chris about the timing and the impact on head temps. I run about 32 degrees btdc too, but use CAM II Purple 114 octane. I've never hooked up my Cyl head temp guages, I do follow the EGT closely though.