The Cal-look Lounge

need some info

According to Jake Raby: DTM fan > Stock > Porsche style > Gol

I find his results interesting, if anything. I am really surprised that he found the 911 fan to work so poorly. Porsche spent a lot of time and $ in the early 1960's developing the axial-flow fan we all are familiar with on the 911....getting away from the less efficient radial-flow fan of the 356/912/Beetle. Even the expensive and very complex "dual" entry radial fan of the Carrera/Spyder motor was overlooked in favor of the 911 fan. Danny, I don't have the volume #'s of the VW fan, but the Porsche 911 fan (driven at 1.3x crank speed) pushes 1390 liters of air @ 6100 rpm. Porsche found the problem with the Beetle/356/912 fan was that it didn't cool both cylinder banks equally, and that is why it is offset to the right, but the axial 911 fan could be centered due to its design. Strange how the 906 (901/20) 210hp race motor was able to use an EVEN SMALLER 911 fan than the street motor, even though it was tuned to a higher level (210hp from 2000cc)
I wonder if the shroud design of the VW/911 fan kits are what makes them inefficient in Raby's tests. Or is it the finning style of the VW cylinders and heads? Or the tins under the cylinders are different than the 911's?

I think that his testing is very productive and informative, but I think there is more to the 911 system than he gives credit for.

I think very well spoken!

A lot of the current type 1 911 systems are however very poorly engineered (if at all) with regard to directional vanes or purposefull shroud forms. The GWD shroud still looks the best one to me in that respect as it has a distinctive form which shows there has been thought put into it.
The stock porsche deflector which is stock on the original 911 fan is almost always missing, just to name one aspect of most set-ups.
Also the type 1 engine case is even shorter than the type 4 case (on which engine it has been used very widely), which makes it even harder for the air on a type 1 engine case to reach the front two cylinders. The stock orientation of the fan housing and its rotation (right) makes the right bank cylinders cool much better than the left bank in most 'systems'..

Therefore, in most cases and imho, the stock doghouse system with ALL tin used and correctly mounted is usually best.

Regards,
Walter

thank you. I think you are correct, the directional ductwork just ahead of fan must make a big difference. I think also, the design of the cooling ware under cylinders of the Porsche is better designed than the VW counterpart. I remember reading somewhere that there is even a mod for the Porsche sheetmetal to improve cooling further.

I ran the DTM on my Type 1 engine, and compared to (complete and sealed) stock engine tin, the engine was running hotter with the mag case. The kit was designed for the widest engine possible, but there is no such thing as "one size fits all". With the aluminum case things did even get worse. This is not a critic to Jake Raby. (just my numbers). I will use my first DTM made by the inventor Joe Locicero on my T4 project, but this case is so much different than a T1 aluminum chunk of cast aluminum. If i ever would go the Porsche way then the GWD kit would be my first option. Just my 1 cent.

 We found out that the right Porsche fan gives the best cooling with less horsepower .  Porsche > 50hp with closed oilcooler doghouse > 30 hp .

udo

Udo, can you explain more please ?

First of all you must say that you need space for the air to get through cylinders and heads . that means small diameter cylinders and original heads to get the best cooling . If you close it with aftermarket heads like 044,superflow.. and big cylinders the air you push in the housing can not get out of it and the power the fan needs gets up . the porsche fan with a 5 blade needs less horsepower and makes a lot of air if you have the right pulley ratio and you can run this with more rpms on the belt .This is what we messured and works great on circuit track engines and german street engines that are driven hard on german streets with high rpms for a longer time . For this the housing must fit right . the 50 hp fan is designed for better cooling from VW factory , that is for shure , the 30 hp sometimes looks better and makes less cooling . On american streets were you can not drive fast may be you need more  cooling at lower rpms . Some porsche fans have a bad design and do not work well . The GWD you mentioned is ok.

Udo

I do not understand the 50hp fan verse the 30hp. and if you made some type of deflecter for the air inside fan shroud like stock would that help?

That is a good idea  :)

Udo

Porsche cooling must be very efficient as Eddie Remmele uses it on all his cars and these cars get driven real hard on the street and track. Most of his cars are powered by big type 4 motors up to 3.1 litres.
I know at one race at hockenheim his bug went on an 8 hour race with no problems.

Rob.

It's my understanding that there are more refined and better-developed kits in Europe versus the U.S.-produced (Bergmann, etc.) porsche fan shrouds/systems.  There was a discussion over on the CLF on this very topic, and as I recall even Jake Raby acknowledged that the systems could be more refined for better results, and didn't just dismiss them as junk (i.e., like the angle-cut shrouds and center mount fan shrouds with no internal vanes/external coolers only design).

We always had problems with too high oil and head temps with Porsche systems on type 1 engines, no matter what brand. Expept once when we stayed on 90,5 cylinders and Elliminator 2000 heads. That combo apparently gave us sufficient area to get enough air through the fins to get decent cooling compared to what the Porsche fan can actually deliver. (Of course the heads would eventually get too warm, but it took quite a while to get to that point.) When the type 1 DTM came out, I tried that one on a similar engine with 044 heads (2275 cc. 86B cam 10-1 CR etc.)  On a 20c. temperature day we could do a 85 mph cruise all day long (with a 3,88 R/P transmission) without extra cooling. And the oil temps never came above 100c. We did not measure the head temp, but they were fine, because we had no excessive valvetrain noise, not even after 2 hours on the freeway.
Even the best version of the 30 hp shouds IMO that would be Scat or CSP would NEVER be able to cool a constant load like that. The late model 50 hp shroud with the velocity ring, - maybe. But I doubt it.  Go fuel injected, and a whole new World opens in front of you.

I like the "simplicity of the DTM, type 1 or 4, meaning that you can cool significantly more compared to cheaper type 1 set ups or conversions, and STILL have the engine pretty compact.
T

I run a 1996 Mexican Beetle and drive it (very)hard.It doesn't leak and I think that it is mainly due to the fact that it is fuel injected.
Even after approx 1500km's at over 120kph(it still has the short transmission!),there is no dripping of oil.
Proper A/F ratio's lead to lower CHT's.

Regards,Arnoud