The Rig

iTrader: (13)

As title really

i have to run the system with the bung in and have always wondered if im losing stupid bhp or only 5ish bhp ?

anyone evr dyno`d with/without ?

its an unmapped car with only a few minor engine mods so any thoughts

cheers

muttleyturbo

iTrader: (5)

I'd lose the bung unless you drive off boost, can cause back pressure in the exhaust and turbo spike

The Rig

iTrader: (13)

Hmm,never heard that before,interesting.

I cant drive it without the bung in,my and my kids ears wouldnt last,hence the question to help me to decide if i should ditch the nur spec for another system.

not had any running issues,regarding this back pressure and use the boost alot LOL
although i do get a fume/crankcase kinda smell when i come off boost from full throttle,not linked tho i guess ?!?!?!?

cheers

Martin 2010

iTrader: (9)

By bung is that the bit that goes in the back box? as im running with mine in didnt seem any difference when i took it out just got a lot of bad looks from neighbours lol and if it is that i cant seem it causing that much back pressure?

The Rig

iTrader: (13)

yeah,thats the bit.
I think it sounds better with the Bung IN, for some reason,with it out, its just a droning load of noise,with the Bung in,you can hear the burble more i find.

scottydouk

iTrader: (3)

Makes big power difference when i use myn! Maybe better off buying a different back box.

neil1980

iTrader: (2)

just quietens it m8 had 1 in my skyline pal sort of restricts fumes not loads tho just remove it for the pure sound lol.

Martin 2010

iTrader: (9)

yeh i agree with that mate does just sound really loud and deep throughout the car and droney. i still dont get how it makes any difference and it keeps the bore size the same pretty much just slides in to it and changes the size of the very end tip bit. i may be wrong but i cant see it making much difference, and a different back box will surely be no different as if its quiter then again it will be due to being restrictive?

The Rig

iTrader: (13)

Yeah,like you say,the tube part just slides inside the backbox which is the same diamter internally as the bung tube and it then meets the piping at the end of the backbox.

i was thinking of removing the bung and cutting off the tube part so i was just left with the end part,that way,the backbox still does it thing,its just a reduced exit from the 4.5" to the 2.5"ish bung bit to quieten it down,but,at £49 a pop for the bung,a costly experiement LOL

midnight

iTrader: (10)

The bung does make a difference when inserted, as the basic principle of speed is how much air you can get into an engine and how fast you expel the exhaust gases.That is the reason why many people find a 10+ bhp increase when going from the std peashooter to a larger backbox.If you increase back pressure,you are restricting the flow of the exhaust gases. I asked the question to my mapper when i had the bung inserted before my remap; and was told: when normal driving it is ok as the engine is running like a n/a engine ,but would not recommend when giving it some hammer unless the car was mapped with the bung inserted.

midnight

iTrader: (10)

Also the bung makes a big difference on a car with a fully decatted system & a afterburner vortex - hardly any noise for 1,and a big difference in the way the car pulls.

Martin 2010

iTrader: (9)

might be worth a try but i cant see it making any difference personally. and oops ive got a hole through mine for my sprk plug ( flame kit ) never mind lol still works ok. i might take it out for a bit see if it makes a difference its just so much louder im worried bout being pulled as ive got no cat and the 3" blitz al the way through. lol

The rookie

iTrader: (1)

Nothing to do with the standard exhast having a triple pass with baffles etc and the aftermarket being straight through of course....oh sorry yes its all to do with that.

Depends on the bung, some are restrictive, some not, if you have a 2.5" system with a 4.5" tailpipe and insert a 2.5" bung, guess how restrictive that will (not) be........

Simon

The Rig

iTrader: (13)

Makes sense i guess.

The thing with the bung is,maybe i am looking at it wrong, but the tube attached to the bung is the exact same length as the backbox,the exact same diameter as the tubing inside the backbox and the exact same size as the tubing leading upto the backbox.

without the bung,the gases get to circulate inside the backboxwhich has its wadding etc

with the bung,its going straight thru it and out,the gases not touching the backbox as such.

If i were to cut the tube off the bung,so the fumes circulated inside the backbox yet only came out of the bung end piece,would this help with less backpressure,more umph ? Or would it create the noise again as its using the backbox not the tube of the bung ?

The Rig

iTrader: (13)

well, i did it LOL

i removed the bung, cut the tube off of the bung (it can be welded back on easily as i cut it off flush with the 4.5" part of the bung if it is too loud) and refitted it,it is louder,but now its in between no bung and the bung so still sounds good,but now its alot more free flowing as its not restricted by the whole tube of the bung,just the end part of the bung that fits into the 4.5" tailpiece

we`ll see,took it round the block so havent been down bypass/70+ yet LOL

cheers

The Rig

iTrader: (13)

well,took it for a blat down the bypasses,not too bad,70 is abit loud but someone mentioned if i lined the boot under the carpet,back seat area with loft insulation,will reduce the cabin noise,hmm ??

joz8968

iTrader: (13)

Get a Simtek and get the 2 maps done: one w bung; the other w/o.

That way you know you can go to a trackday, fit the bung, choose the 'bung' map, and hoon with a free mind/no anxiety...

Jolly Green Monster

iTrader: (4)

Bung makes a bigger difference the higher the power output.

Done a simtek twin map one with bung and one without couple lf months back 450 and 350bhp!!!

The Rig

iTrader: (13)

would like to get a new ECU etc,just the reddies that stop me !

Jolly,on that basis,if my output was near standard, 280ish,would the bung reduce my output to 200 with the bung,if so eeek !!!!

Jolly Green Monster

iTrader: (4)

No i would hope to see 280 with bung and full potentisl without. It gets worse thr higher the power/exhaust flow.

The Rig

iTrader: (13)

Well,as i have removed the tubing part of the bung and have just been left with the reducer partthat fits in the tail pipe im hoping it wont be as restrictive ??

its certainly louder so i have done something LOL Ha ha you dont find out i guess until you try.
im going to fit some boot soundproofing anyhoo just to see if that helps,it has to i guess,as theres nought at the moment,just a sliver piece of carpet lining the floor

ive listened to other exhausts and they just dont sound as good,so will do all i can to get a happy medium of inner cabin sound and performance etc

cheers