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

    • Hello, just just bought an 1999 enr34 with a stock rb25neo and I'm looking to upgrade the engine to 500whp I know some basic things but wondering if there are things I'll need to do to upgrade the stock block and all the bits and pieces to achieve this.
    • Thanks everyone for the replies and suggestions. Got the seats out (hoping I could find some existing grommets but no such luck). By tapping and measuring etc. I could figure out where I could drill through if needed. But first I borrowed an inspection camera and managed to go through factory holes in the chassis rail and could see that the captive nut was holding steady which is why it could retighten. So it was indeed a stripped section of thread, so I applied downforce by levering the bolt head with a screwdriver and went slowly back and forth until it came out. Camera helped a lot cos I could monitor that the captive nut was holding tight. Now I just have one very seized main subframe nut to tackle 😅
    • BOVs do have a purpose, if you ever log pressure before and after the throttle body, you will see a spike pre throttle on lift off from a WOT condition. Enough to bend throttle blades / damage e-throttle motors or simple assist in blowing off cooler pipes. FWIW, the above on really applies to those running at least 2 bar of boost. OP shouldn't have an issue, on the other hand, here are some videos of my shit box over a decade ago with some succulent dose with the airbox on and off. That shit box is unrecognisable these days 🫠    
    • I've tried all different combinations of BOVs/ no BOV and stock bypass valves over the years, on gear changes the stock bypass valve seems to get the car back on boost quicker because in part the turbos wheel speed isn't being slowed down by reversion, although they have issues holding boost much over the stock setting. Most aftermarket BOVs you can adjust the spring, tighter will make it open later and close sooner, but in my experience it'll cause a bit of flutter at low load/rpm anyway. I've also got some input into this whole no bov causing turbo wear, never had an issue on any on my turbos HOWEVER, I got my R33 GTST with 200k kms on it, with from what I can see still has the original turbo, no lateral shaft play but has about 4-5mm of play in and out which to me seems like a worn thrust bearing from years (100-150k kms?) of turbo flutter running no bov, so maybe there is some truth to it in the long run. But that'll never stop me loving the Stutututu while I have the car.   OP just wants to know if he can run a atmo vented BOV with no major issues and the answer is YES, plenty of people do it, there's no harm in installing it and seeing how it runs before spending $$$ on an aftermarket ecu, last time I bought a Nistune it was $2400 for install and a tune , unsure of todays prices but you get me. Crazy money to spend just to fix the minor inconvenience of stalling that can be overcome by letting the revs come down to near idle before putting the clutch in or a little bit of throttle to avoid it. You're better off leaving the ecu and tune for after a bigger turbo/injectors have been installed to take full advantage of the tune and get your moneys worth.   Let OP have his Whoosh sound without trying to break his bank haha
    • I see you missed the rest of the conversation where they have benefits, but nothing to do with avoiding breaking turbos, which is what the aftermarket BOV made all the fan boys, tuners, and modders believe was the only purpose for them...
×
×
  • Create New...