Most fascinating flat six

[silverc4s]

Over the years, like many here, I have seen some really unique and interesting Porsche engines. Just ran across this photo on a well-known Swiss gentleman's site (elevenparts.com) and I can't stop looking at it.
There is a new, interesting detail everywhere I look:
Flat fan with "factory" drive
MFI pump on right bank
Twin plug system
Alternator mounting
Etc..
What do you see here for the first time??

[jmshepard]

2.9 liter?

[BRPORSCHE]

917 1/2?

[Early_S_Man]

2.9s were a high-end Andial set of Mahle big-bore pistons & cylinders for the Mg case 2.4 & 2.7 engines.

Revised MFI pump mounting location was used on several Turbo racing engines of the '70s, including 'Baby,' the 2.14 '74-only RSR, and some 935s. Most likely scenario is that a wasted 935 engine donated parts for the fan, alternator, MFI pump mounting, plastic injector lines, and twin-plug distributor for the street engine.

[jmz]

you don't hear much about the 2.9 p/c set. How were they in that 7R case as compared to the 92mm 2.8 set?

[skinnerd]

Super cool engine....
Don't you wish a flat fan set-up was available today for a "reasonable" cost???

[randywebb]

Originally posted by skinnerd
Don't you wish a flat fan set-up was available today for a "reasonable" cost??? [/B]

No - it's not as efficient and wastes power. There is an old thread on this if you search.

IF you want to go against everything the marque stands for... there is an Aussie place that sells the conversions I think.

[silverc4s]

Originally posted by randywebb
No - it's not as efficient and wastes power. There is an old thread on this if you search.

IF you want to go against everything the marque stands for... there is an Aussie place that sells the conversions I think.

Randy,
I do recall reading that the drive system for the flat fan was quite complex, but isn't the main purpose to provide more evenly distributed airflow across the cylinders/heads, therefore permitting higher hp/cylinder of output?

[skinnerd]

certainly a right angle drive is more complex (and inefficient) that a straight through approach

i guess i just like the "cool factor" about them
looks for sure
and they sound incredible....the whine they make

i'll have to put this on my to do list when i retire
building my own version of this

[Dan in Pasadena]

Okay, I'm gonna get lambasted for even suggesting this but here goes:

I admittedly know NOTHING about the flat fan setup other than I agree with skinnerd that it does have a high "coolness" factor having nothing to do with how well it cools. Corvairs had flat fan setups with a right angle drive. Back-in-the-day did anyone ever try adapting or using parts off a Corvair system onto a Porsche flat six? I know nothing about hte Corvair system either but I've GOT to think that some tinkerer at least made some measurements and maybe tried it.

Okay, I'll go back into my hole now!

[Scott at Pelican Parts]

Originally posted by silverc4s
Randy,
I do recall reading that the drive system for the flat fan was quite complex, but isn't the main purpose to provide more evenly distributed airflow across the cylinders/heads, therefore permitting higher hp/cylinder of output?

That's right. I happened to be reading the chapter on the '74 RSR Turbo the other day (Excellence was Expected) and this is the first time they used the flat fan setup on a 911-derived motor. Cylinders/heads 3 and 6 weren't getting enough cooling using the regular fan.

[randywebb]

right -- so do you have a cooling problem?

We have to reach back to our Puritan past and enforce some discipline... otherwise, we'll end up with things that look like higher performance but are actually _reducing_ performance (cf. Ant Farm's critique of tail-fins on a Cadillac)

I admit - it looks cool.

[klaucke]

Originally posted by Dan in Pasadena
Back-in-the-day did anyone ever try adapting or using parts off a Corvair system onto a Porsche flat six?

Its been asked and discussed before Dan, so no worries for asking. The issue is the Corvair system uses two idler pulleys and a longer belt that simply "bends" the right angle over the idler pulleys (i.e, the idler pulleys are mounting perpendicular to the engine pulley, or parallel to the rear wheels). The system was not engineered extremely well for any high performance application; it is prone to throwing the belt off (no cooling!). The Porsche system used extremely tight tolerances and spiral bevel gears in order to put up with the suprizingly large amount of power transmitted to the fan at high revs. A belt in the Corvair configuration is simply not up to the task.

[Shaun @ Tru6]

why not use an electric fan connected to some sort of potentiometer to regulate speed against revs?

[skinnerd]

I would bet that kind of fan would pull unbelievable amps....
Pullin' high G's is OK.....pullin' high amps, prolly not
I am not for sure though

[Early_S_Man]

Has anyone out there heard that Porsche was a consultant on the Corvair engine??? I heard that rumor years ago, but I don't know if it is true or not ...

I think an electric fan [motor under the hub] is the real solution to a horizontal engine cooling fan ... shouldn't have to pull more than 15 - 20 Amps!

[dd74]

Don't the new Porsches have a an electric fan - but connected to the decklid?

[Dantilla]

Maybe the "e-Ram" guy could try an "e-Fan".

[TRE Cup]

So.. this is a normally aspirated "935" engine. All those goodies is what the 935 used

nice stuff

[Bill Verburg]

Originally posted by dd74
Don't the new Porsches have a an electric fan - but connected to the decklid?

new Porsches are water cooled and yes, they have electric fans.