Benefits of a Flat fan ie 934, 917, etc

[Darkclaw13]

I was just wondering what, if any, were the benefits of having the cooling fan flat on the 934?

[wp935]

It's all about the look, nothing more, nothing less

[Axeman]

Originally Posted by wp935

It's all about the look, nothing more, nothing less

Damn that looks hot!

[safe]

Originally Posted by Darkclaw13

I was just wondering what, if any, were the benefits of having the cooling fan flat on the 934?

Better, more even cooling. A must above 700hp

[86911cab]

Originally Posted by Axeman

Damn that looks hot!

Isn't the fan used for coolin'?



Mommy told me I was her special lil' boy

[zithlord]

It creates more even cooling and more air(travels from the grill 90 degree into the fan, not a 180 degree turn from grill to fan)

John

[TRE Cup]

Read some place years ago that the flat fan set up sucks 35 hp from the motor. Cool when you are making huge turbo power

Maybe someone here has the stats on what a standard fan takes to drive ?

[RWebb]

Here ya go, Dave...

from Ludvigson, EXCELLENCE WAS EXPECTED, 1st ed., Ch. 16
On the 1963 911, the cooling fan took only 4.7% of the 901's gross engine output - p. 402

-- a LOT less in other words

too many gears & shafts with frictional losses in the horizontal fan I guess

[jcge]

According to Mezger's 917 tech paper...

"The cooling blower is arranged horizontally above the
engine. It has a diameter of 330 mrn (13 in) and supplies
the cooling air for the engine at a rate of approximately
2400 l/s at the rated engine performance. The blower is
driven via bevel gears at a ratio of 17: 19 of engine speed.
As already mentioned, at maximum engine power the
power input to the blower is 17 hp, i.e. 2.7 per cent of the
engine performance. Of the entire cooling air volume
65 per cent is used to cool the cylinder heads and 35 per
cent for the cylinders."

He cites the 3 litre 8 cylinder race engine (908) as absorbing 14hp.

[RWebb]

hmmm, somebody do a scatter plot of the data

[juicersr]

Originally Posted by wp935

It's all about the look, nothing more, nothing less

Thats a 962 IMSA motor i believe.

In fact, its a lot more than about the look, as the factory did nothing if it didnt help their motors last longer for endurance racing. As John mentioned, and as we know from installing brake cooling ducts, air hates to travel around corners, esp for cooling purposes. Much more efficient to draw air across the engine vertically vs horizontally. Does look bad-ass cool tho

For a mere $8500 or so (depending on the strength of the Rand) you can put one on your motor http://www.baileyedwardscars.co.za/FOR_SALE.HTML You then gotta get the ITBs and custom IC if turboing.

Keep your eyes peeled for an install of this fan kit coming to a location near you

[TheMentat]

Originally Posted by jcge

According to Mezger's 917 tech paper...

"The cooling blower is arranged horizontally above the
engine. It has a diameter of 330 mrn (13 in) and supplies
the cooling air for the engine at a rate of approximately
2400 l/s at the rated engine performance. The blower is
driven via bevel gears at a ratio of 17: 19 of engine speed.
As already mentioned, at maximum engine power the
power input to the blower is 17 hp, i.e. 2.7 per cent of the
engine performance. Of the entire cooling air volume
65 per cent is used to cool the cylinder heads and 35 per
cent for the cylinders."

He cites the 3 litre 8 cylinder race engine (908) as absorbing 14hp.

I'd imagine that the horizontal fans in race applications are geared to push a lot more air at a given RPM, hence the seemingly high numbers...

[rouxroux]

Hmmmm. flat-6 engines with top-mounted "flat" magnesium cooling fans?

Heresy, I tell you...HERESY! (no, not Klipsch)

[Laneco]

Ohhh... A 110 and a 140! Never seen a 110 with air - cool!

I always wondered what the HP loss was for the Corvair setup. Some of which is obviously mitigated by running the alternator off the same belt.

We often threw our belt though at high RPM on our Corvair. Kept a spare all the time. Well, that and a fuel pump rebuild kit because that failed about every six months...

angela

[daepp]

Originally Posted by Laneco

Ohhh... A 110 and a 140! Never seen a 110 with air - cool!

I always wondered what the HP loss was for the Corvair setup. Some of which is obviously mitigated by running the alternator off the same belt.

We often threw our belt though at high RPM on our Corvair. Kept a spare all the time. Well, that and a fuel pump rebuild kit because that failed about every six months...

angela

Angela can identify various Covair motors - very, very impressive

Were there non-air cooled Corvairs?

[Rot 911]

Originally Posted by daepp

Angela can identify various Covair motors - very, very impressive

Were there non-air cooled Corvairs?

I think he was referring to the AC on the 110 hp Corvair.

[The Gaijin]

Originally Posted by Darkclaw13

I was just wondering what, if any, were the benefits of having the cooling fan flat on the 934?

The flat fan is for aerodynamic purposes to keep the motor (and car) as low profile as possible?

[s2per]

Oh man, that 140 brings back memories! A '66 Corsa, with all those factory gauges. The first motor I ever rebuilt and the joy of Unisyn-assisted carb tuning. Also, an early indoctrination to the belief that "all cars leak a little oil, somewhere...."

[911pcars]

The Corvair setup reduced the inertial mass by spinning just the mg fan. The alternator has a separate drive pulley (and drive ratio).

I don't think the 90 deg. drive belt arrangement has drive issues that can't be mitigated by modern technology.

Sherwood

[dw1]

Interestingly, the advantages of using a similar horizontal fan and housing can be found in other products.

Either that, or this new Antec "Skeleton" PC enclosure was designed by a rabid Porsche racing car enthusiast.



Seriously. This is a new product from a well-known maker of PC enclosures and power supplies. http://www.antec.com/Believe_it/product.php?id=NzA0