What mods to Porsche shroud to use in Type 1?

[wallace lee]

Jake,
in the other forum you mentioned that the Type 1 engine is 1/3 too small for the airflow of an 11 blade fan and unless the shroud is modified, too much airflow can be released resulting in power draw and ineffective cooling.

may i ask what mods are needed to be done to the shroud? Does this apply to the shrouds from Sharpbuilt,CSP etc? I thought they were bolt on.

[Massive Type IV]

It aplies to any shroud..I started cutting on mine whle it was on the dyno. It really helps to clean the head castings up well and make sure that youget as much air through the fins as possible.

[Oliver Knuf]

Best way to get the shroud designed is to use temprature tape bits on all the important positions of an engine. Only with these small bits you can get a safe shroud and air at the points, where it is needed.

Even if a 4-cylinder engine is no 6-cylinder, even if the air amount is higher through a Porsche fan, it depends on the way, how you gear the fan and how you route the air through the shroud. There is no "OVERCOOLING" when you do it correctly!

[Ephry73]

What if(with all that has been, said, done, and tested) one could find a smalled fan assembly?

Wouldn't that in itself produce less Mass of air? Then again, the shroud and housing would have to be modified for the smaller unit...But, could it be done? I've seen Jetski turbine propelors that look very similar to a 911 5 finned fan ( 9 fins if I'm not mistaken) and about 1/4 to 1/3 smaller in size as well...


Just adding to the fire

Regards,


Ephry

[Oliver Knuf]

If you want it small, you can get it. A German shop produces a 240mm (ring diameter!) system for the aircooled engines, that's nearly 20mm less the diameter that is originally used on Volksporsches. Our 254mm system is also smaller, as the original fan diameter is 260mm and our ring diameter (od.) is just 254mm!