flat fan verses vertical fan
 

Hi everyone, I really would like to see a decent resolution to this. so where are we with this option that"s been driving me around the bend. I have read most of the threads about this and the pro's and cons on it all but surely there must be a solution. A flat 11 blade fan set up must be way more efficient with equal air flow over all 4 cylinders than the vertical one. Why is it soo difficult to make an angle drive system as the 935 or a better solution than the problematic fan dual pulley scenario? Also I would have thought there must be an electric light weight fan thats just as efficient now? I am asking because my new engine is going need one. Regards Brent:D

Hello Brent,

Not suggesting I have it all figured out, but the gear driven 935 system can be had as an aftermarket solution for 911 6-cylinder engines. If you see the costs of that, you'll also deduce - like I did - its probably indeed rather difficult to make as a reliable 'system'.

Otoh, I am not sure the upright 911 fan systems can not be made to cool evenly (enough). There is a centrally positioned upgraded 911 fan system from MSS that promises that and has some research done on it. Also if your handy with GRP, you can copy Robin's 4-outlet system he did on a 911 upright fan on his type 1 turbo engine with Street Eliminator heads to create a forced, perfectly evenly divided cooling system.

Wrt electric cooling fans, a calculation on what electric power would be needed to really cool as well as a pulley system (the draw on hp on a dyno from a(ny) fan would be a good start), has ruled that out for me completely for street/circuit use.

You'd be better of looking into building an engine that can dissipate heat better imo. So, if you considering (the extreme costs of) gear driven 911 fans, but are not using aluminium cylinders in the first place already, start over ;)

Hello Walter

do you have a link of Robin's 4-outlet system ? really would like to check this

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Dimitrios

How about in type IV app?

Wow! at least impressive I could say, thanks a lot Walter

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Dimitrios

Thanks for your input, well because of the massive undertaking to build a reliable and efficient flat fan system it would take many hrs and cost loads i have decided to stick with me 11 blade and fiddle with the shroud and consider building some internal dividers . FYI.. I did a load of research and found the old ELVA porsche race cars that ran the quad cam 4 cylinder carrera engine also ran a unique flat fan system, same sort of ideas as the 935, and even though there were only half a dozen race cars built i found a guy in the states that actually has a complete original fan complete unit off an ELVA porsche, :lmao: I emailed him to find he wanted a mere 12K USD for it!!!... well that blew that idea out the window. but if some one wanted to invest there is a opportunity to replicate it and probably would be a good demand on selling them.