Jump to content
SAU Community

Recommended Posts

imo, what does 3m of 2.5" pipe have to do with it when in the end its just into the atmo,

i mean basically having say 4" full exhaust (just to make it plane obvious) thats basically the same as the air being dumped straight into the atmo.. i dont get how it could be easier to have air "sucked out" when it all ends up in the atmo in the end.

  • Replies 98
  • Created
  • Last Reply

Top Posters In This Topic

Just opening up the exhaust is not necessarily the answer. The extreme would be to remove the exhaust system altogether but, for those of you who have experienced it, if the exhaust breaks near the manifold, all power is lost.

For a normaly aspirated (non-turbo) engine in particular it is important to retain a certain amount of back pressure. The reasons for this are all to do with exhaust scavenging which is to do with negative pressure pulses reflected back up the exhaust manifold to remove the last of the exhaust waste from the engine.

Hi [D4RKS1D3],

How much it set you back? Which one is it from this list..

http://www.magnaflow.com/02product/shopdis...one=main&id=386  

Anyone know whats happening with that group buy?

cheers

chicane

http://www.magnaflow.com/02product/shopexd...one=main&id=764

Thats it there. cost about 450 for the muffler, and about 300 for the rest of the install. i do however have a feelin that i got a bit ripped off on the price of the muffler, but i didnt realli mind cuz the bloke rushed me thru and had it all installed in a couple of hours the following day.

The group buy has fallen thru i think. Not enough interest and communication problems with the supplier i think.

my car had an HKS dual dragger when it was imported, far too big and far too loud - absolutely useless, it was more suited to a GTR or GTST...

needed to change it for compliancing so I had a stock exhaust put in (still have it today) and the stock exhaust sounds absolutely CRAP, but it definately isnt quiet.

illusiVe - I've already posted a link to this site in this thread http://www.miata.net/garage/KnowYourCar/S4_Back.html Go and read it and learn all about scavenging

As for my muffler, I have a universal, large bodied, mild steel, 2.5" straight through muffler. Cost me $110 fitted and have proved (on the dyno) that it produces the same amount of power as my old TRUST muffler.

Have spent sometime reading throught this thread, as I have been thinking of changing my current exhaust, to a more straight through system. Currently I have jasma approved system with extractors (6,2,1), 2 1/2" stainless exhaust system with no cat and two very large mufflers (not the straight through sort). I was thinking of putting in a couple of resinators and a straight through type muffler, in the hope that it might improve the flow of exhaust gasses.

A friend sent me this article which I found quite an interesting read, looking into the importance of exhaust gas flow and looks into the back pressure thing too.

what size is the standard NA exhaust?

Mine was 2 1/4 inch from the factory i think. So basicalli you open it up 1/4 of an inch when movin to a 2.5 inch system. The onli thing that realli holds back your exhaust is the mechanical(?) muffler which is meant to baffle sound via redirecting exhaust fumes.

i think thats what the standard muffler is called. It just has the air looping back and forth thru a series of tunnels. if that makes any sense. where as a with a straight through muffler, its just a straight tunnel.

_________________

| _______________|____

| ( __________________ <-----exhaust

|_(____________ ) |

_______________) |

|________________|

In a standard exhaust then the fumes are "baffled" through a "mechanical" eexhaust and this results in restrictions.

__________________

| |

|_________________|__

____________________ <----- exhaust

| |

|_________________|

In a straight thru exhaust their is no restrictions to exhaust

nice ascii work [d4rks1d3] hehe.. ;)

check http://auto.howstuffworks.com/muffler3.htm ppl.. some go around in the fashion like d4rk mentioned, some go thru a more 'inline' series of sound absortion material/chambers etc, but the gist of it is the same.

I spoke to an exhaust shop (perf exhaust in ringood) about a muffler today. I told him how I want to go to a quieter (ive got a noisy rev-flow muffler on there now, and 3" pipe from bends to the muffler) one and he said a canon style (round) won't be the ideal one. He recommended an oval style one. Also quoted about 380 for a maganaflow oval one, but im not thinking only maganflow, but any good brand (post if you can recommend) which will quiet it down a bit, but not strangle it (and have _some_ noise when on the throttle).

Cheers :D

chicane

  • 2 weeks later...

anybody else care to reply to this thread and mention anything I should look out for when getting a new muffler on my R33?

Cheers,

chicane

------------------------------------------------------------------------------------------------

An internet forum is only as good as the quality which is contributed..

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Nope.    Grab a varex and turn it down as you get close to home, win win? 
    • So, I've had my V36 for about a month now and have already copped an "excessive exhaust noise" notification from QLD TMR, reported by someone in my local area. It's a twin as per the original, and can have a bit of a throaty note to it when idling cold 😄 and if I do get up it a bit, it can be noisy, but it did pass a roadworthy inspection before sale, so.... ... but in the interest of being a good neighbour, I do want to quieten it down a bit. Is anyone here running a quiet aftermarket cat-back on their V36 or 370Z? And the big, bold question: does an aftermarket cat-back really make much of a performance difference on these cars?
    • The wiring diagram for the R33 RB25 is freely available, and is essentially the same same as most other RBs (just with differences as to which pin # does which job). To get the ECU to power up, you just need to provide power to the ECCS relay, and have the other power feeds that come in from the top left of the wiring diagram (wrt the ECU) that give perma power to the fuel pump relay, the ECU itself, etc etc, all connected. When you put power on all these it will just come to life. It's pretty clear from the diagram what needs to happen. Just follow the lines from the 12V + supply stuff in the top left over towards the ECU. I've even posted snips of such diagrams (not for vanilla 25, I think for Neo and 26) to various threads here in the last few months, talking about what it takes to get the fuel pump and FPCM up and going. Search these up and they will help get you started on doing the same with the vanilla 25 diagram. Hell, for all I know, I've done the same with that one in years past and have forgotten.
    • Yep...so unless someone posts up the answer you will need to probe from the ECU connector to the dash plug with a multi meter in continuity mode to trace the wires.  Note the ECU has multiple - and + (and across different key settings - Battery, IGN and Start) and most likely the power is fed from the connector(s) that is normally near the left hand headlight.
    • Thanks Duncan, I am actually just trying to get the Rb turning and running with the RB25DET S2 original loom itself  I am just trying to get it going outside the body and not thinking about the S15 or trying to match anything to the S15 loom at all I am only trying to see if anyone has done this and what pin they found to be the ignition trigger and ECU+/- on the dash connector, that's about it. Thanks  
×
×
  • Create New...