Julian Thompson

Chip; I think your reasoning is sound except that you have not taken into account the fact that the air around the spoiler area will be at a higher pressure than the static air in the engine bay and this will impact the density of that air which in turn will affect the power.

I will stand corrected on this as I am no physiscist (can't even spell it!) but am interested in this topic so thought I'd chuck in my 2p's worth.

914und993

If you could map fresh air velocities coming into the engine bay at speed with the spoiler up, and then put an intake snorkel into a position where it intercepted this air in it's zone of maximum velocity, you might get a ram air effect, but I think it would not be enough to notice. This would be something too easy for Porsche to do for a few extra ponies, and not likely to be ignored. OTOH, maybe they did do that, and the airbox intake stack is already in the best location for a little ram air. Note that this type of ram air effect will not occur at all on a stationary dyno, so it would be a bit hard to benchmark this.

Chip

Eli K

Searched all over couldn't find it. Would you have the link? The only Gruppe M systems I find are for Nissan, HOnda, etc....

IanR

It's here - second one down. Looks fantastic, but £650 for an air intake

Julian Thompson

Have a look at :

http://www.gruppemeurope.com/frc_porsche.html and this is the image;

Julian Thompson

Siberian; I don't think you could achieve "ram air effect." This is a common misconception I think.

I agree about mapping the high pressure areas for maximum air density but think about how much vacuum there is on full chat; to get ANY positive airbox PRESSURE you have to have more positive pressure than the engine is actually sucking - ie you have to be travelling at about 160 or so mph and have the intake designed cleverly to use that huge wind to your advantage. It is not going to happen away from a racetrack and certainly not at 964 speeds !

Put simply, then, there will be pressure hotspots (if any of you are bothered enough I have a very accurate digital air pressure meter and I could map the engine bay for you but it will take an hour or three!) and there will be pressure deadspots. Experience tells me that the base of the spoiler will be a huge pressure high spot and inside the engine bay tucked under the rear shelf where a "K&N" setup with no airbox goes will be a huge vacuum on full power! So I think that Porsche probably did not guess the location of their snorkel but looking at Gruppe M's one and working on the basis of those guys being performance kings I suspect there is no need to make one; just shell out for the Gruppe M one because this looks like a performance version of the Porsche design that is not as bothered about noise regs and any slight water ingress issues in favour of maximum power.

Eli K

Thanks!

Eli K

Nice filter set up as well.



I am pretty sure there is a way to fabrcate this without much expense... . I'll scour the local parts stores for ideas..