Notices
General Miata Chat A place to talk about anything Miata

is there any point in running 3" exhaust from my bell 2.5" dp?

Thread Tools
 
Search this Thread
 
Old Jul 7, 2007 | 11:14 AM
  #1  
hustler's Avatar
Thread Starter
Tour de Franzia
iTrader: (6)
 
Joined: Jun 2006
Posts: 29,085
Total Cats: 375
From: Republic of Dallas
Default is there any point in running 3" exhaust from my bell 2.5" dp?

If its already bottle necked there, will the 3" from the dp back help at all? I know bigger is better in this respect, but its not going to get any better with this dp...right?

I'm looking at the 3" enthuza w/cat.
Old Jul 7, 2007 | 11:20 AM
  #2  
Mach929's Avatar
Elite Member
iTrader: (3)
 
Joined: Oct 2004
Posts: 2,494
Total Cats: 0
From: lansdale PA
Default

i thought the bell dps were 2.75" but anyway it can't hurt, only reason not to go 3" would be for noise, but with a proper muffler and a resonator should be decently quiet
Old Jul 7, 2007 | 11:24 AM
  #3  
hustler's Avatar
Thread Starter
Tour de Franzia
iTrader: (6)
 
Joined: Jun 2006
Posts: 29,085
Total Cats: 375
From: Republic of Dallas
Default

Originally Posted by Mach929
i thought the bell dps were 2.75" but anyway it can't hurt, only reason not to go 3" would be for noise, but with a proper muffler and a resonator should be decently quiet
64mm i.d.
Old Jul 7, 2007 | 01:48 PM
  #4  
y8s's Avatar
y8s
DEI liberal femininity
iTrader: (8)
 
Joined: Jun 2005
Posts: 19,338
Total Cats: 574
From: Fake Virginia
Default

pipe size is measured by OD...

and go with the 3". less back pressure downstream is still good.
Old Jul 7, 2007 | 07:14 PM
  #5  
TurboTim's Avatar
Elite Member
iTrader: (9)
 
Joined: Jun 2006
Posts: 7,035
Total Cats: 425
From: Chesterfield, NJ
Default

If Enthuza's 3" fits without banging into anything and isn't too loud for you, they I agree with Y8S, 3" instead of 2.5" post turbo should give you a hp or two.
Old Jul 7, 2007 | 08:27 PM
  #6  
Braineack's Avatar
Boost Czar
iTrader: (62)
 
Joined: May 2005
Posts: 80,552
Total Cats: 4,368
From: Chantilly, VA
Default

do it!
Old Jul 7, 2007 | 11:52 PM
  #7  
Al Hounos's Avatar
Senior Member
 
Joined: Oct 2005
Posts: 1,168
Total Cats: 0
From: Knoxville
Default

3" is the hotness....2.5" is so 2003.
Old Jul 8, 2007 | 12:08 AM
  #8  
LunaticDriver's Avatar
Junior Member
 
Joined: Apr 2006
Posts: 457
Total Cats: 0
Default

so a 2.5" ID is a what OD?
Old Jul 8, 2007 | 12:10 AM
  #9  
RusMan's Avatar
Senior Member
 
Joined: Jun 2005
Posts: 507
Total Cats: 0
From: WA
Default

about 2.75 I think.

But yeah 3" is the only way to go if you're turbo, not much louder than 2.5" and it's just so hot and gives you some more horses
Old Jul 8, 2007 | 12:15 AM
  #10  
hustler's Avatar
Thread Starter
Tour de Franzia
iTrader: (6)
 
Joined: Jun 2006
Posts: 29,085
Total Cats: 375
From: Republic of Dallas
Default

Originally Posted by Braineack
do it!
its done. Now I just have to pick up my $350 torsen swap, then decide if I need the 57mm rad or not...then there is nothing I need to buy.
Old Jul 8, 2007 | 01:33 PM
  #11  
reckless_abandon's Avatar
Junior Member
iTrader: (1)
 
Joined: May 2007
Posts: 93
Total Cats: 0
From: chilliwack, bc
Default

Originally Posted by Al Hounos
2.5" is so 2003.

clearly
Old Jul 8, 2007 | 03:53 PM
  #12  
cueball1's Avatar
Elite Member
iTrader: (13)
 
Joined: Nov 2006
Posts: 3,875
Total Cats: 2
From: Tigard, Oregon
Default

Has anyone dyno'd a car swapping a 3" for 2.5"? I just got my 2.5" and it looks huge for our tiny motors. Just wondering if the gain is proven or theory.

Not only do I drive a Miata, now I have to feel even less manly with my little 2.5" exhaust.
Old Jul 8, 2007 | 04:43 PM
  #13  
LunaticDriver's Avatar
Junior Member
 
Joined: Apr 2006
Posts: 457
Total Cats: 0
Default

Originally Posted by RusMan
about 2.75 I think.

But yeah 3" is the only way to go if you're turbo, not much louder than 2.5" and it's just so hot and gives you some more horses
oh... so i guess i have 2.5" ID Turbo Back
Old Jul 8, 2007 | 05:30 PM
  #14  
Al Hounos's Avatar
Senior Member
 
Joined: Oct 2005
Posts: 1,168
Total Cats: 0
From: Knoxville
Default

FM, BEGi, and their supporters have always said it doesn't make any difference, but BEGi's new DP is a 2.75".... it probably isn't necessary on little turbos like the Greddy turbo and the gt2554r, but any bigger, and I'd run a 3".
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
EricJ
Suspension, Brakes, Drivetrain
7
Sep 11, 2021 11:10 PM
Tony the Tiger
Miata parts for sale/trade
63
Dec 29, 2016 02:23 AM
patsmx5
General Miata Chat
46
Jun 6, 2016 10:27 AM
chrisn
Race Prep
27
Oct 16, 2015 05:12 PM




All times are GMT -4. The time now is 10:45 PM.