Cut away body work to let out higher pressure behind the car is pretty cool. Not a new development in the aero world but certainly looks unique here. I was curious as to the lack of the rear diffuser though. Is there a reason for just the small flip up in the back instead of the larger venturi style? Due to the engine size/placement perhaps?
That undertray only floats about 1/4-3/8" from the bottom of the new engine in that car(A91, no longer the metzger design)
Very interesting. Reminds me of the cutouts on the 458 GT3 but obviously much larger. The 458 looks to use a similar style “flip up” as well.
:dunno I’m super intrigued by all this stuff but beyond some basic physics principles and what I’ve read in RCE all this aerodynamic stuff is way over my head.
so it sounds like the porsche’ packaging doesn’t allow for an effective diffuser out back then.
the 458, i believe they are expanding the air over the top of the tray flip up, and therefore it may be a bit deceiving in that picture.
Somewhere I have some shots of an A91 powered RSR with the tray off. will dig them out.
i’m pretty sure if it needed a rear diffuser to make it handle better and stay within spec… porsche would have done it. that rear bumper is most likely VERSION 89.03
It is that rendition, good eye.
The A91 engine is Porsche new design that has integral cylinder sleeves(like a Subaru engine). No longer using the old Metzger design(gt1 case) that has a separate cylinder water jacket that contained the sleeves independent of the engine case. All Porsche cases up through the 997.1 gt3’s used a case design similar to the old aircooled Porsches. Actually have 964 part numbers cast into them.
New engine is a step beyond 40 some odd years of Porsche engine design. Sits lower in the bay because there no longer an intermediate shaft driving the camshafts, which itself sits in the belly of the engine case. Allows the entire engine to sit some odd 3" lower in the chassis. Quite a feat really.
GT1 cylinder set design:
A91 cylinder design
