Aerodynamic penalty for removing factory muffler
 

I'm thinking of getting a single exit exhaust and won't be able to fill the gap left behind with any type of diffuser or paneling.

Do we know how much of an aerodynamic penalty there is when replacing the factory muffler with anything other than another OE shape/sized muffler?

Verus Engineering

https://i.imgur.com/EM3IIpe.jpg

It looks great and I would if I could but the class I want to run will not allow me to have this kind of mod.

Oh, race rules are involved. Well I can say many many people have ripped off their factory muffler, even racecars. I understand your concern about drag, but I believe the effects are minimal.

Right, primarily concerned about drag or if the rear-end starts feeling floaty at certain speeds. At the tracks I've been to so far, I can't see myself going higher than 110mph but I don't know if I'll end up at a higher speed track.

Could you make a coroplast flap that isn't a diffuser?

Do they let you cut the rear bumper? A lot of people cut that black plastic section off

Decent ideas, but those mods won't be allowed. I think I'll just assume that the weight reduction from a single exit outweighs any aerodynamic drag or lift that might be generated. :burnrubber:

Ya know, if the rear section of the factory heat shield beneath the trunk broke loose and got lodged against the bottom of the bumper....

It’s 6 of one and half a dozen of the other. Sure, there’s a penalty but judging by the trap speeds at the Runoffs, it’s negligible and removing that heavy muffler allows you to better distribute weight were it can benefit you more.

What rules? What class?

I'm going to be building around SCCA D Street rules but also plan on running OTA, a local time attack series which classes cars based on performance index points for mods.

You can probably accomplish both. The 70mm CSG exhaust gives you 2.75" of exhaust diameter (good) and retains a similar style OEM muffler to fill that gap. Then combine it with a 2.5" over pipe/front pipe combo and that will allow the engine to breathe well.

https://www.counterspacegarage.com/c...tition-exhaust

That may be the droid you're looking for.