BF951

Is there a better cooling effect through the radiator and Interooler with or without the undertrays. I'm sure there are some effects relating to backpressure but I don't know what the pros/cons really are.

TIA.

Techno Duck

Better cooling with them on. Creates a low pressure zone in the engine bay, so air flows through the radiator, into the engine bay and out better.

BF951

Many thanks !

BF951

How about the black ductwork from the nose to the interooler?

Black51

Backpressure??

I think you meant to say 'drag'?

Now I'm not an engineer or anything so someone correct me if I'm wrong, but I believe race cars have a flat underbelly to reduce drag. But I don't think that is the real purpose of that tray, per se. Although it probably does have a small effect on reducing drag when installed.

Cyberpunky

Patrick is going through this process with his race car, in that he is trying to balance aero, drag, downforce, lift and heat management. With his car being aimed at time attack his heat management/ cooling requirements are completely different to an endurance racer for example. Patricks beast is extreme to say the least and he is going about it in an almost semi-professional manner.

I don't race but have put the undertray back on(my car came without it), although plenty of people run there cars fine with out them, because I figure the aero guys at Porsche know way more than most, and put it on for a good reason(and that may just be stability at 150 MPH for example). It may have little benefit at the suburban speeds I drive at, but I am confident it does benefit the overall CD of the car, and so my save some fuel on long interstate drives etc if nothing else.

If I did race I would keep it on because I think any slight weight penalty it presents would be overcome by better aero/cooling benefits and also if I ran off track, it provides some protection to engine bay. The flow of air and heat management under the bonnet of any car is complex and our cars clearly had a lot of effort put into it by some of the finest engineers of the era, so without some serious data acquisition/testing/engineering I am skeptical that improvements could be made easily and leaving it off throws out a lot of work by those engineers.

Anyway just my $0.02 worth and I am not an engineer and I don't race these cars either
peace
Cyberpunky

blade7

When I last changed the belts/tensioners on my turbo I decided to leave the undertrays off until I had re-tensioned the belts, a little while later I was enjoying the speed when the steering started to feel very light . The undertrays were refitted PDQ.

Willard Bridgham 3

The undertrays affect both the cooling and handling of the car, that's why they are there.

Iridium

The tray is worth a few mph at the end of longer straights for me. I replaced mine with a flat sheet of aluminum actually. One advantage of having that is if you go off in gravel or whatever its much harder to push the radiator back into the belt assembly, which is a disaster.

964-C2

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