People with aftermarket canister style exhaust system, do you have any system to stop the air flow from building up under the body and behind the bumper? If you look at the stock muffler, they have a wedge built in for max flow and minimum drag. If you look under the car, there's a huge space to catch air and create major drag.

I'm thinking of building some kind of diffuser with metal sheet. Any ideas?

 

Not sure if you'd really feel the drag unless you're driving at an unreasonably high speed. But when I swapped to my fuji it did cross my mind. I tried to find a way to move over the original one, but figured its way too much trouble. I mean, the canister is round anyways. If anyone does happen to make one that'll fit a fuji or a generic bolt on, i'd be interested... =p

 

Found something while looking at the APS site. They have a true dual canister cat-back exhaust that has bolt on location for the oem wind scoop. Might be of some interest...

http://www.airpowersystems.com.au/35...st/exhaust.htm

 

Never even considered it until you mentioned it. But yes it must have some effect of airflow at the rear.
You need to crudely fabricate the shape of the original muffler and somehow attach it where the orginal muffler went. Thin stainless should do the trick.
G/L
C.

 

You probably have too much time on your hands to worry about such things.
G35 will hit the speed limiter before benefit of making any kind of shield will be measurable.
Why not switch to 155 width tires on front wheels?

 

wow, good catch. I think it's a great point. If the engineers decided that is was cost effective to fabricate and install a diffuser on the stock muffler then it must make a significant impact to the undercar aerodynamics. If it didn't do squat do you think the manufacture would actually spend the extra money to install it? Manufactures are always looking for ways to cut their costs, say it costs them $25 to fabricate and install this part, multiply that by 60k vehicles and that comes out to $1.5M (of course I'm just throwing out numbers). it's a big business and they wouldn't simply add on additional parts for no apparent reason, every penny they can shave of the production cost adds up. That's why they don't add on the rear underbody diffusers as a standard item, it's part of the aero package. You can't see it, as it doesn't make a visual difference, but there is a benefit to it.

 

I'm glad someone here understands my point.

Hey obender66, its not that I have too much time on my hands. Unlike you, I prefer to understand the tech. side of things and not just leave it as it. May it the engineering in me since I am an engineer

But if you don't think it matters, pay attention cars on the road who's bumpers are loose or damage (especially cars with body kits and not properly installed, ie. rear bumper) See how much is moves do the the wind drag. We might not feel it or will it affect our everyday driving, but I'm sure it affects our fuel efficiency and performance some what.

Also, novice drag racers who can't afford to fabricate a chassis would cut holes in the rear bumper to help with air flow and reduced drag.

Just my $0.02 and observation.

 

I think it will also create lift, whereas the air flowing smoothly and easily under will create less lift. Lift is dangerous at not so high speeds. The G has fairly low lift (Infiniti claims zero), which is part of the reason it feels so stable at higher speeds compared to say... a Malibu.

So yeah, I don't agree with dismissing the concern. I'm with you Sidewy8.

 

agreed, please inform us when you make something to replace the makeshift air diffuser

 

I too, agree w/ Sidewy8.