911 Cooling Shrouds - Improving Internal Air Distribution

[eugene]

As promised- pisc of the klaus shroud of the 3rd generation. Note the complex shape on the back plus the mentioned internal air distributor. Sure some development went into this. The shroud uses a smaller porsche turbo like fan. 225/250mm diameter.

[Bad bug]

Eugene does you fan ring carry this code 901 106 101 5r on the fan ring. Why i am asking is because i think i have a turbo 911 fan and i am not sure. Also i need to change the fan it has some of the blades with cracks in them.

[eugene]

The ring is not an porsche item. Is made by Klaus so no OEM numbers. The outer diameter (250mm) is smaller than the turbo unit. I think the 11 blade fans are ok to be turned down to a smaller dia. and the twisted- end 12 blade are not because of drastic loss of air flow. I think GWD uses a turned down 12 blade fan(240mm). If you are planing to turn down a original porsche fan, you must buy a smaller ring from a tuner and have the fan rebalanced afterwards. I think it works this way.

[Wally]

Very nice Eugene! Thanks for posting!
Did you also got the special pully- and rear engine tin that seals of the engine compartment above the exhaust (and bell housing)?

[eugene]

No i did not. i have considered the pully cover but is quite expensive. i'll fab something from alu sheet metal. Klaus has some really cool things. Like his alu head covers and the central filter system. Clever design. If just money would be no problem.

[Wally]

Some pretty good info I found at our french sister-website www.germanlook.org :


Early 911 245 mm fan with 1.3: 1 pulley ratio 1390 ltr/sec @ 6100 rpm

1976-77 five bladed fan with 1.8:1 pulley ratio 1265 ltr/sec @ 6000 rpm

1978-79 226 mm fan with 1.81:1 pulley ratio 1380 ltr/sec @ 6000 rpm

Turbo fan with 1.68:1 pulley ratio 1500 ltr/sec @ 6000 rpm

964 fan with 1.6:1 pulley ratio 1010 ltr/sec @ 6100 rpm

New twin turbo with 1.8:1 pulley ratio 1210 ltr/sec @ 6100 rpm.

Early 911 245 mm fan with 1.3: 1 pulley ratio 1390 ltr/sec @ 6100 rpm


..................diameter (mm).........rpm.........pulley ratio....speed (ft/sec)

early 911................245..............6100.......... ..1.3 ..............334

76-77 5 blade..........245..............6100............1. 8...............462

SC.......... ...............226..............6100............1. 8...............426
.
930..........................245.............6100. ..........1.68...............431

964/993................... 279.............6100............1.6............... 468

993tt.........................279.............6100 ............1.8...............526


1965-74/75...... 110 mm crank..................95 mm fan pulley
1976-77... ........130 mm crank..................83 mm fan pulley
1978-79............130 mm crank... ..............80 mm fan pulley
1980-89............120 mm crank..................83 mm fan pulley

fan sizes / blades / air flow:

1965-74/75........245 mm / 11 pales.........1.3:1 ratio..1390 liters air/sec
1975/76- 77......245 / 5 pales..................1.8:1 ratio....1265 l/sec
1978-79............226 / 11 pales ...............1.8:1 ratio...1380 l /sec
1980-89............245 mm / 11 blade.........1.67:1 ratio...1500 l/ sec
964...............279mm / 12 pales......... 1.6:1 ratio..1010 l /sec (!)

And the best part:

An original 12-blade 964 fan uses only 8,1 hp at 6100 rpm!!
I say that is WAY less than a type 1 fan at that rpm