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Rear Window Engine Air Intakes

Richard Pottle

Richard Pottle

PCGB Member
Member
Hi

I have noticed in 911 and P World that a couple of cars have air intakes/ducts fitted to the rear windows that then feed into the engine via holes in the rear parcel shelf.

Has anyone considered this and does people think that they would be effective or merely for show?

I think www.GT-racing.com sell the ducts but the way (go to the windows section in the product listing)

Cheers

Rich
 
Effective? Not unless you have intercoolers sitting on top of the engine that need good cool air supply. You have probably seen turbo cars with this set up.
 
When it rains or when you wash the car does the water just get funneled straight onto the engine and electrics?
 
ORIGINAL: Richard Pottle

My car has no spoiler so I think it would benefit from another source of cold air - can't harm it at least?
Click to expand...

What makes you think your car needs more cold air? The cooling fan sucks thousands of cubic feet of air into the engine bay. There is no difference in power output between spoiler and non-spoiler equipped cars.

Richard
 
I expect there would be a gain to be had in saving weight - plexi glass is lighter than a laminated screen. One for the CS boys perhaps. [8|]
 
When my car had the spoiler it was noticeably cooler ie at least half the temp that it is at the moment - hence my curiosity around these ducts.

Surely a cooler engine will prolong life and reduce intake temps etc
 
ORIGINAL: Richard Pottle

When my car had the spoiler it was noticeably cooler ie at least half the temp that it is at the moment - hence my curiosity around these ducts.

Surely a cooler engine will prolong life and reduce intake temps etc
Click to expand...

Do you mean the engine/oil temperature was cooler - was it really half the temperature? If so, I would seriously start looking for other causes. The std non-spoiler grill allows the fan to suck plenty of air in. Remember, the air cooling of the engine is fan cooling not aerodynamic cooling - regardless of spoiler. This is the first time I have heard of a significant rise in engine temp from reverting to a non-spoiler tail, so I really doubt it is the cause.

At the very least, I would check the fan belt for slip and make sure the thermostat, engine oil cooler and front oil cooler are in good condition and working properly. Also check the hard oil lines for dents or crimps that may block flow.

Certainly a cooler engine prolongs life and heat is bad - I just think you are looking in the wrong place for the cause.

Richard
 
What a ridiculous subject.

Unless you're off to the desert, I don't see any purpose, reason or otherwise to mess with the original 911 cooling system. I will comment however, that these rear window intakes were probably some form of ram-air for the carbs, certainly not to cool the engine.

With regards to a cooler engine prolonging life - ??? quite the opposite actually!

Removing the rear spoiler should have no effect at all on the engine cooling - other than in the case of the intercooler position. The 911 fan moves some 1500 litres per second at 6000 rpm - that's a lot of air.......

What are you trying to do ....... if you want a hot-rod, go and buy one.
 
Not a ridiculous subject at all. If the product is sold on the open market (admittedly primarily in the US) then why can't we discuss it and its related topics??

Thanks to Richie B for the structured comments and advice by the way.
 
ORIGINAL: carreraman

What a ridiculous subject.

Unless you're off to the desert, I don't see any purpose, reason or otherwise to mess with the original 911 cooling system. I will comment however, that these rear window intakes were probably some form of ram-air for the carbs, certainly not to cool the engine.

With regards to a cooler engine prolonging life - ??? quite the opposite actually!

Removing the rear spoiler should have no effect at all on the engine cooling - other than in the case of the intercooler position. The 911 fan moves some 1500 litres per second at 6000 rpm - that's a lot of air.......

What are you trying to do ....... if you want a hot-rod, go and buy one.
Click to expand...

Easy tiger. It wasn't that bad a question. And as a side effect he is now closer to getting an answer regarding the real problem of heat.

BTW, I think the most common application is for the late 935 style intercooler set-up. Some of these cars had intercoolers (or even water jacketed heat exchangers to cool the intake charge) protruding thru into the back seat. The only way to get air is thru the side windows :rolleyes:

RB
 
Okay - I'll take my tongue out of my cheek for a moment then ...... ridiculous in terms of after-market additions which arguably do little or nothing, if not detrimentally effect, the original well engineered 911 package.
 
where did the figure of 1500 litres per second come from tony?, that seems a very high figure for such a small fan.
 
1500 ltr./sec at crankshaft speed of 6000 rpm ...... comes directly from the Porsche official Technical Data - 911 Carrera VIII 1987
 
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