eecsdude

There seem to be plenty of exhaust offerings that bypass the center muffler and the side mufflers for weight and sound, but I'm surprised if people are going that far, why not change out the lower bumper altogether? Similar to the 911 RSR, they moved the engine to the middle to make room for a larger diffuser, if instead of bypassing the center muffler, you remove it completely and rely on side exits, wouldn't you be able to fit a diffuser where the center muffler occupied?

I'm sure there are reasons for this, but just curious because I see akrapovic offering a full race exhaust system with a replacement carbon "diffuser" which is essentially just a cosmetic change to the lower part of the rear bumper. Just seems like there's so much more potential to do more...

GrantG

Even without the exhaust, the engine extends too far rearward to make a much better diffuser. In the RSR, they moved the engine in front of the rear wheels...

FourT6and2

Ask yourself if someone driving a street car (even on a race track during HPDE) will see benefits from a larger rear diffuser. Outside of bragging rights, that is.

Also the stock center exhaust is part of the diffuser... A lot of people don't realize this. When they remove it to put in an aftermarket center bypass, they are removing aero.

eecsdude

Yeah you're right. Looking at photos from other threads of the exhaust area, the center muffler is pretty thin. Probably not enough area to make a big difference if the cavity were exploited for a diffuser.

IPSA

i have heard that before and you can see the continuation of the angle of the end of the diffuser and factory center section but the angle is so shallow I suspect the pressure change is nominal. You could argue that eliminating the factory part actually steepens the angle and thus creates more downforce but the air is more chaotic so probably not.

Anybody have a windtunnel...


Cheers

ilovecarbs

there’s this, although bumper needs to be cut and exhaust needs to be tucked:

s4corrado996tt

Wow! That's plenty of work needs to be done! Thanks for sharing anyway!

drdonger

Our cars have enough grip in the rear. We need more front grip. No point in doing a more aggressive diffuser, especially for a street car.

GrantG

I agree with this generally, but for a track focused car it could be pretty cool. You could set the sway bars or alignment to favor rotation (oversteer) that would be effective at low speeds (where you want that in tight corners) and then have added high speed stability on fast sweepers from the additional rear aero.

Assuming this diffuser extension actually works as intended.

Of course you can also achieve the same thing with the high downforce position of the rear wing, but this causes some drag...

mdrums

If driven on the street a more aggressive diffuser will get trashed...plus you will not feel any benefits I will say. At the track on 120mph sweeping corners...then you will feel benefits is the diffuser is properly designed in an air tunnel to take advantage of air flow under the car.

eecsdude

This picture shows exactly what I was initially wondering. If you remove the center muffler and just let the exhaust exit straight out from the cats, you can clear our the entire center section. The extended diffuser from the photo looks like the diffuser in open flap mode from a 488 But if the center muffler were removed, you can imagine a more aggressive diffuser profile.

As folks have said, our cars probably have enough rear grip, but perhaps for the wingless GT3s, this might be an option to make up for the loss of a wing?