Straight through exaust

Engines, Transmissions & Final Drive questions and answers

Moderators: timk, Stu, -alex, miata, StanTheMan, greenMachine, ManiacLachy, Daffy, zombie, Andrew, The American, Lokiel

olboy
Fast Driver
Posts: 204
Joined: Tue Sep 22, 2009 7:28 pm
Vehicle: NA6 - Turbo
Location: NSW South Coast

Straight through exaust

Postby olboy » Wed Sep 23, 2009 9:09 pm

Anybody ever tried doing away with the cat and muffler and running a straight through system on an na6. good idea or not, its on a race only car.
olboy

User avatar
bruce
Speed Racer
Posts: 7772
Joined: Fri Apr 25, 2003 11:00 am
Vehicle: NA8 - Turbo
Location: Victoria
Contact:

Straight through exaust

Postby bruce » Wed Sep 23, 2009 9:13 pm

I think it would sound absolutely crap.

olboy
Fast Driver
Posts: 204
Joined: Tue Sep 22, 2009 7:28 pm
Vehicle: NA6 - Turbo
Location: NSW South Coast

Straight through exaust

Postby olboy » Wed Sep 23, 2009 9:19 pm

don't beat around the bush give it to me straight

User avatar
StanTheMan
Forum legend
Posts: 6824
Joined: Thu Apr 24, 2003 11:00 am
Vehicle: NA6
Location: Balgowlah

Straight through exaust

Postby StanTheMan » Wed Sep 23, 2009 10:23 pm

No back pressure. Not sure if that's real good. Yes it will probably give you a slightly better Dyno reading But I feel Patchy likes a little back pressure. Mine was almost like what you describe. It idles better with some extra back pressure. As well my transient throttle seems to be less obvious with a little extra backpressure
Satans Ride called F33nix the resurrected NA6

User avatar
Boags
Speed Racer
Posts: 3533
Joined: Thu Nov 10, 2005 6:25 pm
Vehicle: NB SP
Location: Brisvegas
Contact:

Straight through exaust

Postby Boags » Thu Sep 24, 2009 9:20 am

olboy wrote:Anybody ever tried doing away with the cat and muffler and running a straight through system on an na6. good idea or not, its on a race only car.
olboy


I have no cat on my NA6 racer. The system goes 4-2-1 extractors>2.5" press bent pipe>hot dog resonator>2.5" press bent pipe>straight through muffler>2.5" press bent pipe tip.

The sound is raspy but you can tell there isn't much restriction to breathing. Much better than stock. Comes in at 98db at Lakeside.

No power figures as the car came with a side exit muffler that was bashed and rooted (being so low, it's no surprise). I replaced it straight away.
Spartan Motor Sport : http://www.SpartanMS.com.au

User avatar
Boags
Speed Racer
Posts: 3533
Joined: Thu Nov 10, 2005 6:25 pm
Vehicle: NB SP
Location: Brisvegas
Contact:

Straight through exaust

Postby Boags » Thu Sep 24, 2009 9:23 am

Oh, another thing. There used to be a flexy bend at the end of the extractors. That busted after a short detour on the grass at a race meeting so we ran without any rear section for the rest of the day.

NO top end power due to car pinging its head off. I'm guessing that had a lot to do with the O2 sensor being so close to the outside world. Maybe a bit of back pressure helps the sensor work properly. Your Miles May Vary.

Boags
Spartan Motor Sport : http://www.SpartanMS.com.au

manga_blue
Forum Guru
Posts: 4897
Joined: Mon Apr 24, 2006 7:27 pm
Vehicle: NA8
Location: Moruya, NSW

Straight through exaust

Postby manga_blue » Thu Sep 24, 2009 10:33 am

I've seen one NB running with just a hotdog to a side exhaust. Blackflagged for noise. I don't think it gave it any gains anyway.
’95 NA8

User avatar
16bit
Speed Racer
Posts: 2346
Joined: Wed Nov 29, 2006 1:51 pm
Vehicle: NB8A - Supercharged
Location: Brisbane Southside

Straight through exaust

Postby 16bit » Thu Sep 24, 2009 10:52 am

i just got rid of an exhaust that had an empty cat and muffler. more power but less torque. and it was very very noisy and annoying. don't do it.
98 evo gold - rotrexed and loving it.

This post has been printed using recycled pixels

User avatar
bruce
Speed Racer
Posts: 7772
Joined: Fri Apr 25, 2003 11:00 am
Vehicle: NA8 - Turbo
Location: Victoria
Contact:

Straight through exaust

Postby bruce » Thu Sep 24, 2009 11:56 am

It would just sound like a huge raspy fart at nearly 100db. Cop magnet.

User avatar
16bit
Speed Racer
Posts: 2346
Joined: Wed Nov 29, 2006 1:51 pm
Vehicle: NB8A - Supercharged
Location: Brisbane Southside

Straight through exaust

Postby 16bit » Thu Sep 24, 2009 1:51 pm

very raspy and much louder then 100db. mine was 101 at 5krpm. would have got to 110 easy.

here's mine.

http://www.youtube.com/watch?v=Gn_UEYWNrX4

in a tunnel though.
98 evo gold - rotrexed and loving it.

This post has been printed using recycled pixels

User avatar
AJ
Speed Racer
Posts: 4349
Joined: Sun Oct 30, 2005 8:27 pm
Vehicle: NC
Location: Gold Coast

Straight through exaust

Postby AJ » Thu Sep 24, 2009 3:41 pm

Boags wrote:Maybe a bit of back pressure helps the engine work properly.
Boags


rectified & quoted for historical purposes :wink:

maybe I should quote your comments in mIRC for hysterical purposes Boags???...........no??? :P :lol:
Image
Don't worry about what people think, they don't do it very often
XMX5 Rogues

User avatar
Boags
Speed Racer
Posts: 3533
Joined: Thu Nov 10, 2005 6:25 pm
Vehicle: NB SP
Location: Brisvegas
Contact:

Straight through exaust

Postby Boags » Thu Sep 24, 2009 5:50 pm

AJ wrote:
Boags wrote:Maybe a bit of back pressure helps the engine work properly.
Boags


rectified & quoted for historical purposes :wink:

maybe I should quote your comments in mIRC for hysterical purposes Boags???...........no??? :P :lol:


Bite me. :lol:

PS: you are wrong. :mrgreen:
Spartan Motor Sport : http://www.SpartanMS.com.au

RG.net
Racing Driver
Posts: 1692
Joined: Thu Apr 06, 2006 7:48 pm
Vehicle: NA6
Location: Sydney
Contact:

Straight through exaust

Postby RG.net » Fri Sep 25, 2009 1:24 am

bruce wrote:It would just sound like a huge raspy fart at nearly 100db. Cop magnet.


olboy wrote:its on a race only car.
olboy


didnt know there were any cops on the track :lol:
http://Run-It-Hard.com - We're here to have fun!

rascal
Racing Driver
Posts: 1783
Joined: Fri May 16, 2008 1:39 pm
Vehicle: NB8A
Location: FarSE Melbourne

Straight through exaust

Postby rascal » Fri Sep 25, 2009 9:35 am

MXHEVN wrote:
bruce wrote:It would just sound like a huge raspy fart at nearly 100db. Cop magnet.


didnt know there were any cops on the track :lol:


Well there is the sound police! Can't exceed 95db at most tracks otherwise you get booted off. (At least you dont get a ticket, but you also cant race again till you quieten it down..)

RG.net
Racing Driver
Posts: 1692
Joined: Thu Apr 06, 2006 7:48 pm
Vehicle: NA6
Location: Sydney
Contact:

Straight through exaust

Postby RG.net » Fri Sep 25, 2009 3:03 pm

ah touche! :lol:
http://Run-It-Hard.com - We're here to have fun!


Return to “MX5 Engines, Transmission & Final Drive”

Who is online

Users browsing this forum: No registered users and 2 guests