Porsche Fan

I have used the so called 911 alternator, fan and shroud on a Beck Spyder running a 2387 type 1 engine. I did not drive it all that much before I sold it but have read all manner of opinions on them pro and con. I all can say for sure is they do look good. I also agree with the school of thought that says the 911 style fan setup on a type 1 will either over cool or under cool depending on the rpm the engine is running and the original Type 1 fan shrouds have air ducting vanes and thermostatically controlled  flaps to allow the engine to come up to temp. in a timely fashion.  Do a search on samba you will come up with a lot of info. about this. If you want the best cooling fan setup for a big displacement Type 1 engine look into getting a Raby DTM fan shroud. I have run one of them in a Speedster and they do work better than the stock VW fan setup.

There are numerous CMF air capacity Porsche fans and different capacity alternator,  There are 5/7/10 blade 911 fans - each put out a different amount of air flow --- and accompanying drag on the engine. There are T1 fan alternatives too - the early skinny fan and later wide fan as well as welded balanced fans - none are $1k. More like $100.

I think most who opt for the 911 type fan setup do it for the look more than the cooling performance. Another issue to consider is the forced deletion of the stock oil cooler. You are then doing all the oil cooling with one remote cooler instead of the two that is usually needed in our cars. I have seen those who run the 911 setups and I have too, but today I would stay away from it. Search what Jake Raby has to say about them. Unless the look is a must have I would stay away from  going this route.

They do look stupid cool 

WNGD posted:

They do look stupid cool 

Yes they do.

I like the look of them better in a Speedster, where you're staring down the barrel of that big axial fan, than in a Spyder.

I believe Raby said he never could quite beat the cooling of a 30hp-style stock VW housing with a later doghouse for the oil cooler on the back of the shroud.

What he did do with the DTM, however, is get the larger Type 4 oil cooler integrated into a Type 1 cooling system, and blow enough free air onto it with the fan to make that worthwhile, all without over- or under-cooling any of the cylinders. 

That's what that silly-looking curled bit of ducting does. 

I like that my Spyder engine is a Raby with a DTM and have decided not to mess with the fan shroud.

But if I were building a Speedster engine, for the best combo of looks, utility and price I'd go with a stock VW shroud and try to make the engine look Porschey with the oil filter and stuff. 

An interesting read                                              https://www.thesamba.com/vw/fo...p;highlight=bergmann

Wow- it’s a long thread but I’m getting the gist of it. Thanks for the reference. 

Ed,

Jake was able to do better than the late stock OG tin (designed by The Sainted German Engineers) with the Type 1 DTM, but not by a lot.

Another thing to keep in mind with the 911 shrouds is the parasitic HP losses with the fan. They’re likely overstated by theSamba crowd, but it’s still something to seriously consider.

Thanks for the correction. 

Blake posted:

Wow- it’s a long thread but I’m getting the gist of it. Thanks for the reference. 

Yeah, it was a lot of trial and error for him to get the thing anywhere close to balanced- not only front to back but also side to side. There was a guy on the German Look Forum (Sandeep? from Toronto?) who also undertook the same quest with another Porsche style shroud (don't remember the make), but didn't document it nearly as well. It might be mentioned in the Samba thread?  I don't see only having 1 cooler as really being a problem, but the hp loss and lack of some kind of thermostat for quicker warm ups are deal beakers for me. I have to agree, though, they do look great in a Speedster engine compartment! Al

@edsnova wrote- "But if I were building a Speedster engine, for the best combo of looks, utility and price I'd go with a stock VW shroud and try to make the engine look Porschey with the oil filter and stuff."

Why the need to dress it up into something it's not? A high-performance VW aircooled engine on it's own is already a thing of beauty!

@Stan Galat- Does the DTM incorporate a thermostat/flaps assembly?

Just my aesthetic. 

Stan, My DTM didn't have any thermostat/flap system.

Thanks, @Jimmy V. 

Anybody else?

Jimmy V. posted:

Stan, My DTM didn't have any thermostat/flap system.

None of them do. The observation was regarding total cooling, and thermostats and flaps don’t help with that (the thermostat and flaps are for warmup). Guys will argue this point, but I’m just relaying data from 15 years ago. Jake Raby is a lot of things, but his data is generally rock solid  

Please don’t misunderstand – I’m not saying a DTM is better overall, I’m saying it has the capability to cool slightly better than the stock set-up, for applications when absolute total cooling capacity really matters (like when you’re running 10.6:1 compression).

I was asking, Stan, because I think quick warm ups are an important part of the equation and should be considered when looking at alternative cooling systems.

I agree with ALB.  Type 1 engines without the flap system wear out long before stock built engines with the proper thermostatically controlled flaps for proper warm up. It was designed in the original engines for a reason and they ran 100k miles if maintained correctly. None of us will probably drive our cars this amount but this is one of the reasons I decided to get away from the VW Type1 engine.  I wanted a setup I could take off on long distance drives and not worry about the car breaking down or over heating or getting a clogged jet. Each owner has their own goals for what they build their car to do. This is what makes this hobby so much fun.

Gene Berg claimed, Jimmy, that VW aircooled engines in southern California (where it's reasonably warm all the time) suffered 12-15% more wear when not equipped with the thermostat and shroud flaps. Up here in southwestern B.C. (I live in the metro Vancouver area), engines in everyday drivers without the thermostat/flaps would not reach operating temps for 4 1/2-5 months during the late fall/winter/early spring and never used to last more than about 50,000 miles. You know the engine isn't reaching operating temps when a dirty white mayonnaisy substance forms under the oil filler cap. 

One way to help with quicker warm ups and higher operating temps at this time of year- remove the rear engine sheetmetal (the apron separating the exhaust from the engine compartment) to allow pre-heated air into the fan and carburetor(s). The 1 friend of mine that still drives a Beetle year-round does exactly this when it starts to get cold (2-3 weeks ago this year), throws it behind the rear seat and re-installs it  when it gets warm again (usually the beginning- middle of April).

And part of VW's answer for cars in arctic climates was heavily chromed valve covers (who says they don't radiate heat?). Besides a block heater (I believe incorporated into the oil drain plate, but don't quote me on that) I don't know what else they did. Al

ALB posted:

I think quick warm ups are an important part of the equation and should be considered when looking at alternative cooling systems.

Jimmy V. posted:

I agree with ALB.  Type 1 engines without the flap system wear out long before stock built engines with the proper thermostatically controlled flaps for proper warm up. It was designed in the original engines for a reason and they ran 100k miles if maintained correctly. 

ALB posted:

Gene Berg claimed, Jimmy, that VW aircooled engines in southern California (where it's reasonably warm all the time) suffered 12-15% more wear when not equipped with the thermostat and shroud flaps.

Yep. That is the conventional wisdom.

However (and just for the sake of discussion), I wonder why when Porsche was designing the 911 engine, they did not feel the need to do any of it (the Rube Goldberg flaps-n-bellows). I'm sure they were every bit as smart as The Sainted German VW Engineers, and I'll bet they were just as concerned about longevity. They certainly didn't leave it off to save money.

Conversely, I've wondered why The Sainted German VW Engineers felt it was worth the time and money to design, manufacture, and install a ridiculously complex and breakage-prone thermostat and flap arrangement on an engine with the horsepower of a garden tractor.

I'm just guessing, but perhaps the reason has to do with the amount of heat the two engines produce.

The stock VW fan and shroud are apparently quite overbuilt for cute little OG 4-bangers, since a stock set-up will easily cool a 150 hp engine (which is 6x as much as the original 1948 Type 1 engine). Without the warm-up stuff, I can easily imagine a 25 hp engine never coming up to temperature. I can see Hans and Fritz, firing their 6:1 prototype for the first time, and figuring out pretty quickly that they were going to need something to choke off the air pouring over the heads and cylinders. That would certainly explain why the entire affair looks like an afterthought.

Porsche's 911 engine, on the other hand, was a high-performance machine right out of the gate, and produced an enormous amount of heat as a result. I doubt that getting up to temperature quickly without wires and bellows was as much of a challenge.

It's not unlike my engine in that regard. I'm running 10.6:1 compression in an engine compartment with notoriously poor airflow. Factor in that I don't really drive it when the ambient temperature is under 45*, and I'm a LOT more concerned with rejecting as much heat as possible, than I am with getting to operating temperature more quickly. That means a DTM with no flaps.

I've read the Gospel according to St. Gene as well, and I've always marveled that when God gave St. Gene the rules of high performance VW-ing on Mount Baldy, he was apparently very specific. 12-15% seems like a pretty exact number, and one not easily arrived at without divine revelation. I wonder if it would be heresy to question how St. Gene came up with it? What exactly does 12-15% more wear look like?

I've got a VW engine with a Scat 36 hp Doghouse shroud, modified for a Type 4 cooler, and set-up with the flaps and bellows sitting on a 2110 for the bus. It probably does almost as well as the DTM in the heat of summer, but I'm not taking the chance with my Speedster engine.

It's possible I'm looking at this wrong, but this is how I'm running it and it's worked just fine so far. Your mileage may vary.

I agree!