Anyone tested the Drag caused by swapping exhaust?

robones · 04-10-2012, 08:24 AM

Notice how the Z's exhaust is designed, it's engineered so that the air passing underneath the car curves through the bends of the exhaust through the rear diffuser in a smooth way. This causes less drag at high speed.

By changing the exhaust to a two piece set up, i.e: Fast Intentions, Berk, etc. you are are creating essentially a parachute on the rear of the car. I would think drag is significantly increased by this design.

When you remove the CAN design, the rear bumper gets exposed and creates a huge gap which traps air underneath the car just as its exiting through the rear.

The better designs would be exhausts similar to the stock setup and/or the nismo setup. Stillen, Greddy have similar designs which leave less of a gap in the rear bumper.

Your thoughts?

osbornsm · 04-10-2012, 08:42 AM

You are absolutely correct... much like the square back of a VW golf creates a vacuum. However unless you are looking for absolute top speed of the vehicle, this may be just an academic observation.

LakeShow · 04-10-2012, 08:59 AM

Interesting point, never really thought of that. Significant to affect necessary performance, not really.

robones · 04-10-2012, 09:07 AM

Well just imagine how much drag you are creating at higher speeds? The higher the MPH the higher the drag your car is creating. I would think that any significant HP gain from these two piece setups systems would be offset by the increase in drag they create?

I know the two piece setup sound nice and looks cool from the back but not much engineering thought is put into these systems IMHO.

wheee! · 04-10-2012, 09:08 AM

But the car goes much faster while standing still with the HKS style exhaust setup

robones · 04-10-2012, 09:13 AM

Quote:

Originally Posted by wheee!

But the car goes much faster while standing still with the HKS style exhaust setup

DarkJak · 04-10-2012, 09:32 AM

I've noticed that too. It's such a huge gap, and the back is mostly solid. There are several aftermarket exhausts that still use a setup similar to OEM though, like Invidia, Akrapovic, Ark DTS Type 1 (did that ever go into production?), and probably a couple more I can't recall.

One could probably just put a flat piece over the entire area to cover it up if the drag really is significant.

UNKNOWN_370 · 04-15-2012, 09:58 AM

Quote:

Originally Posted by DarkJak

I've noticed that too. It's such a huge gap, and the back is mostly solid. There are several aftermarket exhausts that still use a setup similar to OEM though, like Invidia, Akrapovic, Ark DTS Type 1 (did that ever go into production?), and probably a couple more I can't recall.

One could probably just put a flat piece over the entire area to cover it up if the drag really is significant.

You can't forget the GOD of OEM style exhausts...

GT HAUS Meisterschaft.

wheee! · 04-10-2012, 09:34 AM

I haven't noticed any issues at speeds around 240km/h....

TerribleONE · 04-10-2012, 09:35 AM

I see the difference being extremely minimal..

robones · 04-10-2012, 10:37 AM

Quote:

Originally Posted by TerribleONE

I see the difference being extremely minimal..

if you are trying to shave seconds of your best lap... why would you want to hinder your chance at going faster?

Same argument people make on this forum when a member gets new shoes for their car... "HOW MUCH DO THE RIMS WEIGH"??? Now why would people care about the weight of their wheels?

TerribleONE · 04-10-2012, 10:39 AM

Quote:

Originally Posted by robones

if you are trying to shave seconds of your best lap... why would you want to hinder your chance at going faster?

Same argument people make on this forum when a member gets new shoes for their car... "HOW MUCH DO THE RIMS WEIGH"??? Now why would people care about the weight of their wheels?

I personally dont think that drag will make a difference even on the straightest of tracks... Plus the power you gain would make up for it anyways. As for weight of wheels, that seems like a retorical question...

robones · 04-10-2012, 10:42 AM

Quote:

Originally Posted by TerribleONE

I personally dont think that drag will make a difference even on the straightest of tracks... Plus the power you gain would make up for it anyways. As for weight of wheels, that seems like a retorical question...

You may be underestimating the importance on minimizing drag as much as possible specially if you track your car. LOL yes, about the weight of the wheels; definitely a retorical question.

Nick911sc · 04-10-2012, 09:59 AM

I'm going to sell my exhaust now and revert to stock. I need to make sure I'm as aerodynamic as possible.

TerribleONE · 04-10-2012, 10:02 AM

Quote:

Originally Posted by Nick911sc

I'm going to sell my exhaust now and revert to stock. I need to make sure I'm as aerodynamic as possible.

04-10-2012, 08:24 AM	#1 (permalink)
robones Enthusiast Member Join Date: Mar 2011 Location: Miami Posts: 357 Drives: 2011 - Nissan 370 M6 Rep Power: 14	Anyone tested the Drag caused by swapping exhaust? Notice how the Z's exhaust is designed, it's engineered so that the air passing underneath the car curves through the bends of the exhaust through the rear diffuser in a smooth way. This causes less drag at high speed. By changing the exhaust to a two piece set up, i.e: Fast Intentions, Berk, etc. you are are creating essentially a parachute on the rear of the car. I would think drag is significantly increased by this design. When you remove the CAN design, the rear bumper gets exposed and creates a huge gap which traps air underneath the car just as its exiting through the rear. The better designs would be exhausts similar to the stock setup and/or the nismo setup. Stillen, Greddy have similar designs which leave less of a gap in the rear bumper. Your thoughts?

04-10-2012, 08:42 AM	#2 (permalink)
osbornsm A True Z Fanatic Join Date: Jun 2011 Location: WHAT Posts: 2,551 Drives: 2018 Camaro SS 1LE Rep Power: 423	You are absolutely correct... much like the square back of a VW golf creates a vacuum. However unless you are looking for absolute top speed of the vehicle, this may be just an academic observation. __________________ 2018 Camaro SS 1LE (455hp) - 2011 Nissan 370z (333hp) - 2004 VW R32 (240hp) - 2000 Civic Si (160hp)

04-10-2012, 08:59 AM	#3 (permalink)
LakeShow A True Z Fanatic Join Date: Dec 2010 Location: L.I., NY Posts: 5,307 Drives: Everything Rep Power: 25	Interesting point, never really thought of that. Significant to affect necessary performance, not really. __________________ \|2013 Audi S4\|Ibis White/Black\|S-Tronic P+\| \|2013 370z\|PearlWhite/Persimmon\|Touring/Sport/Nav\|F.I. CBE 18" CF\| \|Sold\|2011 370z\|Gun Metallic\|Touring/Sport/Nav\|

04-10-2012, 09:08 AM	#5 (permalink)
wheee! A True Z Fanatic Join Date: Sep 2009 Location: Mod Capital of Canada Age: 57 Posts: 7,354 Drives: cars. lots of cars. Rep Power: 40181	But the car goes much faster while standing still with the HKS style exhaust setup __________________ H&R / Stillen / Berk / HKS / Swift / Michelin / UpRev / SPC / Amuse Rep / Seibon / Fringe XVO / TWM / more... My Journal

04-10-2012, 09:34 AM	#9 (permalink)
wheee! A True Z Fanatic Join Date: Sep 2009 Location: Mod Capital of Canada Age: 57 Posts: 7,354 Drives: cars. lots of cars. Rep Power: 40181	I haven't noticed any issues at speeds around 240km/h.... __________________ H&R / Stillen / Berk / HKS / Swift / Michelin / UpRev / SPC / Amuse Rep / Seibon / Fringe XVO / TWM / more... My Journal

04-10-2012, 09:07 AM	#4 (permalink)
robones Enthusiast Member Join Date: Mar 2011 Location: Miami Posts: 357 Drives: 2011 - Nissan 370 M6 Rep Power: 14	Well just imagine how much drag you are creating at higher speeds? The higher the MPH the higher the drag your car is creating. I would think that any significant HP gain from these two piece setups systems would be offset by the increase in drag they create? I know the two piece setup sound nice and looks cool from the back but not much engineering thought is put into these systems IMHO.

04-10-2012, 09:32 AM	#7 (permalink)
DarkJak A True Z Fanatic Join Date: Jun 2011 Location: Madison, WI Posts: 1,391 Drives: 2009 370Z Rep Power: 13448	I've noticed that too. It's such a huge gap, and the back is mostly solid. There are several aftermarket exhausts that still use a setup similar to OEM though, like Invidia, Akrapovic, Ark DTS Type 1 (did that ever go into production?), and probably a couple more I can't recall. One could probably just put a flat piece over the entire area to cover it up if the drag really is significant.

04-10-2012, 09:35 AM	#10 (permalink)
TerribleONE A True Z Fanatic Join Date: Jan 2009 Location: Socal Posts: 10,203 Drives: WOT Rep Power: 5850	I see the difference being extremely minimal.. __________________ 638WHP 541WTQ @ 13.5PSI Build thread

04-10-2012, 09:59 AM	#14 (permalink)
Nick911sc A True Z Fanatic Join Date: Feb 2009 Location: Long Island, New York Posts: 1,698 Drives: 2010 Nissan GT-R Rep Power: 20	I'm going to sell my exhaust now and revert to stock. I need to make sure I'm as aerodynamic as possible.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Accidents Caused by Blind Spots - Seriously, ..anybody?	EazyD	Nissan 370Z General Discussions	32	02-27-2012 08:57 PM
Swapping out oil is it ok	sonic370	Engine & Drivetrain	3	02-09-2012 09:47 PM
Injen intake caused s-mode to turn off	Dingo	Intake/Exhaust	7	08-25-2011 07:26 AM
What caused this?	Big J	Nissan 370Z Warranty / Scheduled Maintenance / Servicing / Repairs	7	07-24-2011 11:27 PM
SO what is the Best tracked tested Oil cooler?	GZ3	Track / Autocross / Drifting / Dragstrip	12	07-07-2010 08:35 AM