The facts directly from Porsche prove otherwise. I love how you go into every thread and post meaningless false crap, usually not even related to the discussion. Get a life WWEST!

Here is proof Reid in this very thread. Post #31. Get a grip man.

[QUOTE=Ronnie's.930;7515313]They move MUCH less air according to Porsche

Only some less, most of the loss is due to the pulley ratios, 1.6:1 vs 1.8:1.

(as published in Bruce Anderson's book) and were used only to comply with noise reduction mandates. Note there is an error where 997 is used in place of 993.

Turn the curved blade fan at the same rate =

Sorry, numbers don't "jell".

1500 FPM w/1.6:1 ratio = ~1333 FPM w/1.8:1, not 1210 FPM...

Regardless of "some" or "much", the point I was trying to make was that your statement that engine cooling was improved on the 964 was not accurate - the fan design, pulley ratios and under engine paneling (all implemented to reduce noise) actually lessened engine cooling efficiency.

Oh, okay....the engine cooling was only IMPROVED on an as needed, as required, dynamic. The cabin heating blower/fan was used only when needed for "make-up" engine cooling capability, and for "after-run" cooling requirements.

he doesnt get it. Its why he shows a pic of a SPAL fan on a deck condenser in which he likens it to the 993 when discussing engine heat, when the 993 didnt even have a condenser in the engine bay. so its not a valid comparison. the circular arguments are baffling.

Well, if nothing else, at least all this "off topic" blather is sure to piss Reid off - ha! :D

This thread makes me glad I did an a/c delete on my 911.;)

[QUOTE=wwest;7515389] wwest, I looked at the fan data again, and just noticed something that addresses your question in this post:

Turbo fan (which is the fan that is on most 911s from 1980 on) - 1.6:1 pulley ratio =1500 L/sec at 6000 RPM and the 964 fan - 1.6:1 pulley ratio = 1010 L/sec at 6100 RPM. Now wouldn't you say that this is a significant difference in air volume between the two (same pulley ratio as well)?

C'mon... the 964 fan only moves two-thirds as much air. Rounding error! :D

But porsche supplemented with the heater fan. LOL

all those 964 owners need is a few SPAL fans and a trinary switch.

That's too funny! Yes, Porsche's "rounding" of the fan blades was indeed an air volume error - ha! :D

Ha! I haven't looked up the L/sec to CFM conversion, but I guess you would need more than one SPAL to make up the 490 L/sec difference (and maybe a dozen trinary switches) - ha! :p

Pulleys...parallel...fishes I'm getting confused...where is Catpain Slow and his capital letters to explain this to Joe Public?

Numbers do not "jell"...

The engine pulley is always larger than the fan drive pulley.

early 911 - 1.3:1 - 1,390 liter/sec - 6,100 RPM (fan = 7930 RPM)

1976-77 - 1.8:1 - 1,265 liter/sec - 6,000 RPM (fan = 10,800 RPM)

1978-79 - 1.8:1 - 1,380 liter/sec - 6,000 RPM (fan = 10,800 RPM)

Turbo fan - 1.6:1 - 1,500 liter/sec - 6,000 RPM (fan = 9,600 RPM)

Same fan - 1.8:1 - 1,210 liter/sec - 6,100 RPM (fan = 10,980 RPM)

Shouldn't that 1,210 liter/sec be 1687 liter/sec ...???

964 fan - 1.6:1 - 1,010 liter/sec - 6,100 RPM (fan = 9760 RPM)

wwest - I guess I am too dense to understand the formula you are using to determine fan speed but it does look like there is a discrepancy for the reported 993 Twin Turbo fan output. However, I was really just noting a comparison between the most used 911 fan (the turbo) and the 964 and I assume that you agree that the 964 fan moves a lot less air at the same pulley ratio? Or are you suggesting that all of the published numbers are wrong given the apparent 993 turbo error?

There was a thread this week were a guy decided to make a 964 fan work on a 911 engine because he did not like the noise of the 911 fan. He did some type of air volume measurement and also noted that the 964 fan, even with his custom pulley setup, moved much less air (he was not concerned with this, however).

I don't wish to say one way of another but I've always been under the impression that the curved, "swept wing" blades were more efficient at moving airflow due to the lower turbulence, NOISE, factor.

Found the thread, wow..a lot of work.

He cut the 964 fan down in 2 dimensions to get it to fit the 911 shroud and still got 80% of the original 911 fan airflow rate. Makes those numbers really look suspect.

Did you also notice that he did not say what size fan pulley he made? And wouldn't trimming length off of the curved blades make them more like the straight blade 911 fan (some of the most curved portion was removed). Regardless, even after all that, it still moved significantly less air . . . I can't speak for anyone else, but I consider 20% less air flow, considering the massive volume that the fans move, to be a huge number.

But what would the fan have moved not trimmed..?