Anyone tested the Drag caused by swapping exhaust?

TerribleONE

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robones

[QUOTE=phelan;1651002]Oh dear, the mythbusters correlation.

Okay, there is a question of scaling here. QUOTE]

LOL I know but I made the reference only to make a point. Agreed, definitely much less air is directed through the bottom of the car then on the top.

TerribleONE

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robones

AWESOME ZED!!!! HAHAHAHA

ZMan8

Just some observations:

1. Kenchan is right, there is not much air going under the car
2. we have front spoilers
3. the differential is almost as low as the rear bumper therefore it will block off some of the air approaching the bumper "parachute like" area
4. If someone really wanted to, plug in an airflow sensor right behind the bumper between two cans and measure how much airflow there really is.

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2015 Mazda6 | 370ZChicago: Chicago Area Cars & Coffee

ZMan8

I'm not sure if this is relavant:
Quick and very dirty CFD run on the Z

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2010 370Z 40 Anniv., 6 MT | Fast Intentions | Swift Springs | SPC | Z1Motorsports | JWM | Redline Oils | 35% Window Tint
2015 Mazda6 | 370ZChicago: Chicago Area Cars & Coffee

stratburst

Two words... "Flux Capacitor" Solved!

Skeeterbop

IMO, the impact is negligible at best. There simply isn't enough airflow in that area to worry about. If i could get hold of a cheap air flow meter and find out i would.

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Phenix

I don't think it's really an issue of drag as much as it is lift, or reduction of lift. Remember the 370z is designed to have zero rear lift. This is probably done with the spoiler and flat (err... flat enough ) bottom. The fact is that none of us likely have the resources Nissan has in order to determine what effect there is from the various styles of aftermarket exhausts. All I know is from most of the articles and papers I've seen regarding race car aero, airflow underneath the car is at least as important as airflow above the car, if not more important. Just look at some of the supercars coming out now that generate hundreds of pounds of downforce without using a wing. Of course they usually have a completely flat bottom along with a bunch of other specific design considerations, but you get the idea.

That said, I think anybody really concerned with the issue would probably also think to buy or build an exhaust that's tucked up as high as possible in order to leave room to build a custom diffuser. Since we don't necessarily have the wind tunnels or computer modeling at our disposal, we really would have to stick to the academic. My gut says that messing with the exhaust in any way risks creating some rear-end lift. If that's a concern then you should plan on adding a rear diffuser.

But, I really think the only folks that ought to be concerned with it are those that heavily track their cars and want to do so with no rear wing or one as small as possible.

delusional

looks like i'll be doing the same

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Skeeterbop

if you look at the Nismo 370z RC you will notice they didn't worry about tucking the muffler. Heck it has other items hanging down into the airflow. If they weren't worried about it then why should i be??

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robones

Well did you guys purchase a sports car or not? lol seriously though all these issues are equally important when it comes to changing dynamic characteristics of a well balanced sports car. Our car is amazing and handles incredible and I am afraid of making changes that will alter the amazing balance just for looks. Nissan has Hundreds of Engineers who spend thousands of hours designing every component that goes into our cars. Including the exhaust. They must balance performance, cost, and practicality. For me, dual exhaust cans bent in a 45 degree angle is not a practical design. It lowers the pipes so low in the rear center of the car that it exposes it to road debris and bumps. A few members here have been unfortunate enough to have dented their cans because of it.

delusional

honestly, the amount of difference it actually makes is so minimal as everyone has been saying. the pro's far outweigh the con's with an aftermarket exhaust. and as much as nissan tried their best to design every component of this car, its still at the end of the day only a $30k sports car. not every angle and aspect of the car is going to be perfectly engineered. and as kenchan has said, barely any air flows under the car especially with the front sports chin spoiler. so worrying about this is like worrying about the weight of my center caps causing me to lose time on the drag strip

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_ace_

On the OP's question, I for one wouldn't worry about it at all.

If you want sound and a small amount of power, get an exhaust. If you care a lot about drag, add a diffuser under the body. You could also remove the spoiler, but I wouldn't. If you care about lift/downforce, get a (bigger) wing for the back and something for the front, and expect to increase drag.

Also, the change top speed due to additional drag from any reasonable source is a complete non issue for those of us that use the stock ECU and gearing. The governor is at ~155 mph regardless of what the car can do.