greenlightracer

just wondered if anyone knew what it is that gives the scooby or the flat 4 engine in it its unique sound ?

No prizes sorry ! but it'd be nice to know

m4rk4765

[QUOTE=greenlightracer]just wondered if anyone knew what it is that gives the scooby or the flat 4 engine in it its unique sound ?

No prizes sorry ! but it'd be nice to know [/QUOTE

i think you will find its the unequal length header pipes...i only know this as im looking at buying some stainless steel headers at the moment, and when using equal length pipes ,it says that you lose the subaru rumble.

mark

greenlightracer

ah intresting never thought of that , thanx !

is this right or anyone got any other ideas ?

Also, is it right that a cylinder on each side of the engine is always closed so u have 2 cylindrs closed and 2 open at the same time ?

timmyajmy93wrx

iTrader: (27)

no he's right mate, the unequal length headers give it that great rumble!

JohnD

iTrader: (5)

It's a shame that the distinctive sound is due to inefficient design/production constraints!
JohnD

greenlightracer

JohnD please explain ? ?

RAF1

iTrader: (5)

A mate of mine has a STi4 with Equal Length Headers fitted - it doesnt half feel funny driving along in it without the flat four sound.....

Raf.

greenlightracer

i bet ! but surely itot the sound of the flat 4 then is it just the header part

JohnD

iTrader: (5)

The most efficient layout would be to have equal length headers, as mentioned in this thread. The cost of equiping a standard prodution car with these would be prohibitive. The simple cast iron production item is easy to produce, transmits less noise and gives adequate results. Aftermarket equal length manifolds are very expensive but would need to be considered if you were contemplating a big horse-power project.
JohnD

finnie

I hear the burble costs you 10% in power. Then again who cares when it sounds this good around town!

greenlightracer

yeah whocares i just love that noise !

Thanx for explaining JohnD just one thing though , so are u saying all production cars have un equal length headers as its to prohibitive to give them equal ? if thats the case why dont they all make the noise a scoob makes ?

New_scooby_04

iTrader: (4)

I believe that some companies do offer more efficient unequal length headers, not as efficent as equal length ones, but an improvement on std and retains the lovely burble!

NS04

flat4_ire

i have full zero sports decat system with equal length headers and it doesnt lose the flat 4 sound really, sounds deadly! its just the beats are a lot closer ya kno?
wudnt change the sound of mine for anyting! thumbs up for equal length headers

TonyBurns

iTrader: (3)

Thus the reason the JDM STi's from 2003 onwards have these fitted
And it sounds awesome

Tony

greenlightracer

okay o if its NOT the headers then why the noise ? ? ?

buzzard

its the unequal length.
the end.

heh heh.

Chelspeed

Scoobies with unequal length headers burble because the engine is flat four. Other cars with unequal length headers don't do it because they're in line four engines not flat four.

Think of the layout, two cylinders on the left and two on the right, turbo down by the right hand cylinders. So big long headers from the left hand cylinders to the turbo, short headers from the right cylinder to the turbo.

So where does the burble come from? At certain revs the exhaust pulse from a left cylinder will take so long to get to the turbo down the long header that it arrives at the same time as an exhaust pulse from a short right cylinder header. Sounds arriving together add together. Then big gap in time until the next exhaust pulse from the other left cylinder arrives just at the same time as the next exhaust pulse from the other right cylinder.

So normal four cylinder engine:

bop, bop, bop, bop, bop, bop

Impreza standard headers:

........BOP, ...........BOP, ...........BOP

Equal length headers delay the pulses from the right cylinders by the same length of time so they all arrive at the turbo at equal intervals, hence no burble.

SCOOBYD00

been out in STi's with both options. un-equal & equal... TBH I would rather have the burble.. Like other cars I've owned (GTR, VR6, 1.8T, STi etc etc) they all have a character... on a Sunday afternoon on your fave B roads nothing like hearing that note.. the VR6 deep induction note IMHO made the experience and with the stock airbox was flat.. The point being the burble for me drew me to scoobys in the first place and still draws me to the old TVR V8's.... maybe I should just hook up a cd changer with different engine notes and buy a Mondeo.... maybe not Just my 2p.

greenlightracer

deffo dont get a mondeo , pleeese !

thanks chelspeed for you're lengthy reply all makes sense now sorry if i bored anyone but if sumoone wants to know now at least i can tell them !

thanx guys

buzzard

any engine can be made to sound like the subaru burble . i have heard it on 2 hondas and a couple of 200sx's and its very odd.....but nice.