911 style fan shrouds

I am wondering if anyone here has knowledge of the functionality of a 911-style cooling fan shroud. Is it just for looks, worth the extra $$, cause maintenance problems later. I see JPS and other motor suppliers offer them. Tempting,but should I,or not, on a new build JPS,etc.?

Peter

Looks and big $!

http://www.aircooledtechnology.com/type1/dtm/index.htm

Personally, I don't like them. I've read quite a bit about them and the consensus is that they don't cool as well as stone stock VW tin. In addition, they aren't friendly when it comes to your distributor as its crowded next to the fiberglass shroud. Also, the oil inlet can be very tricky at times requiring you to ""very"" slowly pour oil into the crankcase. Aside from that, the alternator is very expensive as it's a Porsche item and if it quits, it will cost a bunch more than a VW Bosch or Motorola.

I do know that a lot of people have them on their engines and like the looks of the shroud so, it's all about money and how well it cools your engine.

I have one on my Raby type1, 2165cc. It seems to cool very well while driving, but the head temps go up rapidly when idling in traffic, especially when it is over 80 outside. Also, I don't know what the individual head temps are, but I've been told number 4 runs pretty warm in comparison to the other three(my sensor is on #4). The head temps come down when you keep the revs over 1500 for a few minutes. You would think a fan designed for a six would easily cool a four but it all has to do with the shroud design and fan speed.

As far as looks are concerned, the health of your motor should be more important than the look. I got mine for a good price, which is the real reason I got it. The only distributor you can use is a Bosch 009 or one of similar size. The Mallory or Pertronix won't fit. I solved the distributor problem by removing it and installing a distributorless system. The alternator, while more expensive initially, should be as reliable as any other Bosch product.

You WILL need a remote cooler, oil thermostat, filter, and relay for the electric fan. You WILL also need a full-flowed motor. These things are the only reasons mine works as well as it does. I would recommend a DTM or a factory doghouse with all the flaps and a thermostat. Or when Jake is done with his 547 shroud someday.......

Thanks for the input. I should probably stick with stock fan design.

Danny's engine was the last of my engines to get a 911 fan system.. Right after his engine was built I began my evaluations of cooling systems.

I was gonna say..... Danny, does Jake know you have that housing? :-)

When I was looking into my engine I didn't hear from anyone worth their salt that those were any good. Peter, you're wise to stick to stock.

Yeah, Jake knows and wasn't real happy about building my engine that way. In fact, I sent the whole thing to him plus my fan/alternator so he could dyno it with that and the exhaust system. This is really the only correct way to dyno an engine. It was at the beginning of the DTM days, and I got the 911 setup for nothing, so that is what I went with. I have redone the oil filler and sealed it to the case pretty well. It works fine, as long as you don't idle too long on a warm to hot day. Then the head temps come up, but go back down quickly when underway.

I really wanted one of those when I was looking at doing my engine. Pat said he wouldn't put one on for me (I'm sure he would have if I insisted, but he strongly advised against it).
I think they look awesome! I see them on the show bugs alot and always wondered how come they had them if they were so bad. I guess if you don't drive it much, or drive it in the right conditions, it can't hurt. I also think they look waaaaayyyyy cool on Spyder engines!!! Hopefully someday someone will come up with one for Type 1's that looks the same (similar) and cools as well as the original.

I have installed allot of 911 kits in our 550 Spyders also a dozen or so speedsters and never have had any cooling issues. I also know Fat performance builds 100% of there type IV engines with 911 kits and they have been around for more then 30+years so they cant be that bad. The kits I use have genuine Porsche fan and alternators I have not used the Bergman kit with a cast fan I am sure there is a difference.Just my .02 cents



Greg (Vintage Spyders)

Jake is working on his DTM V3. It is based on the original Carrera 4 cam motor. There is a thread on his forum that details this build. Here is a link:

http://forums.aircooledtechnology.com/showthread.php?t=1845

Join up and enjoy reading about it. After reading up and learning about Jake's formal back to back testing of these systems a few years ago, the 'look' is the only thing that is actually 'cool' about these systems. If you don't drive your car and just go to shows, then you might get by with one. A couple of guys have taken the 'Porsche' fan design and made internal vanes to help distribute the air flow, but that is a lot of work.

It's your engine and your money. Buy what you like, just know that those 911 fans don't cool evenly and that is the bottom line.

Jake reported that he has put a halt to the type 547 shroud. Too much money involved and too much time. Said he may resurect it later but not now

The DTM V3 is just on hold while the economy sucks.. This is a cooling system that will cost more than 2,000.00 US. It is also something that will take another 6 figure investment to complete and thats not something I am willing to do until I see that the jackasses in Washington can get us somewhere..

Lots of people have a huge interest in seeing the V3 DTM come to market and I hear from them weekly.. It will come with time and when it does it'll kick the pants off ANYTHING available and will be simple to install as well as have that "look" that everyone is looking for.

I put too much work into the design and my studies of the original system not to follow through with the V3 DTM unit.

I love the look of the 911 style fan setups, but I would never buy one unless the builder could prove that they cool like a 911 fan/shroud does. There are air diverters under the 911 shroud and behind the fan housing that serve a functional purpose, and I just wouldn't spend $2k on something like this for the look alone.

Jake, I saw some old posts of yours on a cal-look forum thread about an early 4-cam Carrera style fan setup that you were developing. Was that setup ever completed, or sold to the public? I'd pay $2k for that over a 911 style fan housing any day.

The system you are referring to is my V3 DTM, what I posted about earlier in this thread. It will cost 2K at minimum.

911 fans work great on 911 engines.. The 911 is 35% larger than the TI with much different component composition, and all but the 911T had ally cylinders.
Nothing at all wrong with the fan, the engine it is fitted to and the shroud that it is coupled to are the areas of concern that exist.

Those of us who have worked on 911 engines frequently know the differences.. The position of the first pair of cylinders of the 911 engine are enough of a difference to create inadequacies when the unit is applied to the VW engine.