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'twittering' dump valves

  • Thread starter Thread starter doctorpotford
  • Start date Start date
D

doctorpotford

does anybody know what sort of dump valves 'twitter' rather than 'hiss'?
this ones got me scratching my head :?
cheers
stu
 
I believe its a group 'A' dump valve ya want. Sound kinda cool, a bit like wastegate chatter, and a bit different to the Whooooosh you usually get.
 
My car has some dodgy setup with a standard bailey dump valve and a stand recirc valve that now vents to air and it makes the rally style dump noise.
 
if you want loudness?

get one drilled into the throttle body housing,thats where my forge motorsport group A one is,right above the throttle body,its mega loud,and i have compared it with others,top place to put it,but you have got to get the housing drilled/treaded,so get someone to do it with proper tools,air tight
 
DUMP VALVES THE MYTH AND RUMOUR...

Ok here goes guys.....

a) There is no such thing as a 'flutter' valve you can only buy a dump valve or blow off valve. Both of which will whoosh/hiss, this is all they are intended to do.

b) The flutter noise you refer to is caused by either compressor stall within your turbo resulting in any boost the dump valve cant deal with coiming out via the air filter.

Example, ive got a grp A Forge on my 21, and ive got a grp A in my toolbox off a Escort Cos from Collins. Put ya thumb in the Forge one and I can freely push the d/v open, do it to the Collins one and I break my thumb. Buy yourself a soft spring, your dumpvalve will go off at at 3mph in slow traffic, buy a tough spring it will just flutter even at high speed, cos YOU WONT BE PRODUCING ENOUGH BOOST TO FORCE THE SPRING OPEN. Therefore the boost cant go anywhere, it causes slight compressor stall within your turbo and the flutter you hear is the wastegate opening and closing really fast emitting via your air filter.

It really dont matter whether you buy a grp A,B or Z.....if the spring is right it'll go off, if it aint it will flutter.
That said I can make my 'LOUD' Forge one flutter by reducing the internal diameter of the take off pipe, if I use a take off pipe of equivalent size to the dump valve stem, it'll produce a loud whoosh, if I use the narrow one supplied by Samco, I get flutter.


I know ive gone on a bit, but thats the truth of the matter, it bugged me when I became a 21 owner, cos a Halfords boy told me to buy a 'Butterfly valve' lol and having never seen one, I thought i'd do my homework.

Me
x
p.s Blow off valves are basically expensive dump valves, although they are adjustable and often incorporate a dump and recirc method, thus avoiding compressor stall completely in ya 50psi roller bearing Skyline. Andy Francis (a 21toc member) recently fitted a ?297 Scooby blow off valve to his 21, it was a little more high pitched than my ?60 Forge one. The Scooby owner agreed it wasnt worth ?297.
 
'butterfly valve' LMAO :lol: :lol: :lol:

Well thats cleared that up.

My mates got a hyundai coupe turbo 1.5 no intercooler, no dump valve just a nice air filter. so i gave him one of my old uno turbo intercoolers to get fitted.

But anyway when he changes gear it goes 'CHHHaaarrrr' very weird but i told him thats the charge coming back out the filter. Not to good for the turbo, stallin it an all.
 
amazing

:D amazing what some of you people know, i thought i was the only 21t owner in a raincoat holding a notepad till i join this club :lol:
 
Chaaaar....

Sounds the same as the old Alfas to me.....the Alfa 33 does the same when you change gear, its basically the air filter taking in a deep breath in anticipation for more right foot action.......... 8)

Me
x
 
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