Lightweight/modified fan/alternator

[Ole Petter]

Hi. I wonder if there is some way of lightening the fan/or modifying the fan/alternator to increase engine power.
Porsche used a fiber-glass cooling-fan in some applications didn't they?
I have never seen something like that aftermarket though.

Just a thought? The engine surely uses some horsepower to pull this combo...

[911pcars]

Not sure of the exact terminal designation, but if you open the field winding circuit, the alternator will stop charging and thus reduce electrical drag.

There are many ways of taking advantage of this for the small HP gained. One could install a manual switch to accomplish this or fabricate a micro switch mount on the throttle linkage to energize a relay to open the circuit. Some aftemarket ignition boxes have an rpm-sensitive function that could trigger the above relay.

I haven't seen a lightweight drive belt, but they do weigh something and creates some inertia.

Let us know what you decide.

Sherwood

[peter_soj]

Sherwood, I really like that idea of the switch for the alternator. Haha, the thought that I could have a "Magic HP" button is awesome. Just like NOS, except...1/10th? 1/20th of the gain?

Also I think I read something about a lightweight fan a few days back. I'll have a search and see if I can find anything.

Good luck

[dave231]

If you take the bulb out of the battery light in the dash gauge that will also disable the alternator. Make sure you plug it back in or you'll be walking home.

David

[MrPerkles]

Porsche made a smaller diameter fan/housing that was more economical and zapped less bhp form the engine for the specials.
I think Tuthills in the UK run them in some of the rally cars not sure which original models they were for.

[Elombard]

OF course lots of sprint race cars install a bearing in place of the alternator and run with out. Would not work on the street. With the alternator out of there you would get a lot more air flow and could maybe run a smaller fan? Maybe a 5 blade would be enough?

[Ole Petter]

The "Typ 911/72" engine 2806 cc, 308 HP at 8000 rpm used a fiberglass fan. As well as the 906, 907, 908, 917, 935... So it has to have something going for it?
Of course these were pure racecars, but that was in the sixties, and seventies. With "modern" production techniques it should be possible to make a fan out of carbon fiber...?

[Elombard]

Ohh that would be sexy in CF wouldnt it! Go and show!

[RWebb]

a while back, Jerry Woods had some motors "sittin' around" with horiz. CF fans on 'em...

A Brit. co. makes light wt. alternators. I checked but nothing for a 911.

[jwerion]

A CF fan sounds interesting does anyone make them?