Shailan

iTrader: (1)

Is the standard re-circ valve good enough for 300 or so bhp.

What I mean by good enough is are there others people have used?

Am looking for re-circ valve not a dump valve.

I already have a dump valve but want to go back to re-circ.

myblackwrx

iTrader: (1)

Yes

34srm

definately

MrNoisy

iTrader: (28)

Like they said...

scooby72

iTrader: (6)

Thats good to know - can you tell me though why the denso valve wont clamp boost as well as say a bailey or blitz??
I seem to lose about 0.1 bar when running the standard.

Petbeemer

turn it round

scooby72

iTrader: (6)

TURN IT ROUND????

Petbeemer

Which re-circ is it, if its the plastic type with 2 outlets just reverse it, that way more pressure will keep it closed rather than forcing it open

jameswrx

iTrader: (4)

Amen to that.

I've done it on every evo I've owned and they all hold more boost afterwards.

I also ran a reversed evo 4/5/6 dump valve on my type r with 20G

Petbeemer

And if you use the latter evo type (alloy) there even better and people give them away!

scooby72

iTrader: (6)

Ive never heard of this before - are there any implications in doing this?
are you effectively running without a valve by doing this??

Petbeemer

works just the same but holds more boost pressure

scooby72

iTrader: (6)

Ok I'll give it a go - its the denso plastic one that sits in-line from the cooler pipe back to the air inlet. it does have a directional arrow on to show the airt flow direction back to the inlet - so i'll wap it back on in reverse and check it out.

japjunkie

iTrader: (3)

i reversed the recirc valve on my evo 4 and it did not cause and problems and i gained wastegate flutter too. basicly you not running a dump valve like this.

The rookie

iTrader: (1)

"Wastegate flutter" otherwise correctly known as compressor surge is indicative of a valve that isn't opening (working)......

Simon

scooby72

iTrader: (6)

Right - so my first thought was correct - the valve dosent work it just clamps closed and stall the turbo......!!??
Now I understand that the TD05 will kinda cope with this but my thought is thast SUBARU didnt spend millions on designin the Impreza and put a recirc valve in for no reason eh????

The rookie

iTrader: (1)

'Stall the turbo' no compressor surge, the turbo keeps spinning quite nicely!

The stock valve should cope fine (Sti is 280ps....) but yours may be a little tired, so why not get a like for like replacement - the Bosch valve used by VAG (Golf/TT etc) is very similar and I have been told fits and can be had from Bosch agents for about £28 (VAG charge £116 for the same part!).

Simon

scooby72

iTrader: (6)

Okey dokey -Cheers!

jameswrx

iTrader: (4)

The bosch one for VAG cars is too small for a direct fit and much worse than the stock jap one.

Imran21

iTrader: (5)

Hi guys,

I have a version 3 type R with a VF34 turbo and a Forge recirc DV. The boost is fine in gears 1, 2 and 3 (1.2 - 1.3 bar) but in 4th and 5th i get a lot of turbo flutter (compressor surge??) at about 1.1 bar. Sometimes after the fluttering the boost settles back to 1 bar.

Could this be due to weakening of my DV?? And why does it only happen in 4th and 5th gear??

Cheers,
Imran

The rookie

iTrader: (1)

As per your other post and my reply, nowt to do with your DV at all. James thanks for correcting what appears to be eronous info.

Simon

kingmikeyuk

'Stall the turbo' no compressor surge, the turbo keeps spinning quite nicely!

How can the turbo keep spinning nicely if the air is trying to get back past it because it has no other way out, does not sound logical to me ....... i am always willing to be educated if i am wrong........?

Mike D

The rookie

iTrader: (1)

Because you read and believed all the usual forum bull I'm afraid (which then gets repropogated by people that believe it - just like the Whiteline ALK reducing front end lift!).

During compressor surge the air doesn't go back past the blades at all, surge is when the airflow over the blade stalls (like a stalling aircraft wing) and as such seperates from the back of the blade, boost pressure drops as efficeincy goes out the window, blade unstalls, boost builds until it goes into stall condition again, the turbine assembly keeps spinning, you know from when you floor the throttle that it can't go from spinning slowly to full speed fast enough to match the ch-ch-ch-ch-ch-ch noise you get in surge, the frequancy would be much lower!

This can happen at high boost lowish engine speed (therfore low flow - why do you think compressor maps have a line labelled the surge line!) as Imran is getting (see his thread) or (more usually) when lifting off without a mechanism for dumping the high boost pressure with very low flow (throttle shut) like a dump/recirc valve.

Simon

kingmikeyuk

Ok i can understand the compressor surge lecture , but that does not explain where the air goes to when you take your foot off the pedal and the butterfly valve in the throttle body slams shut, you then have high pressure air with nowhere to go and a turbo thats not being driven by the exhaust fumes , maybe you might get away with this if your going up through the gears extremely quickly otherwise i dont see how this will help and may damage the turbo if its not built for it ..

Mike D

i eagerly await the next lesson .

Glowplug

iTrader: (8)

This thread may helppeople understand a little more


https://www.scoobynet.com/general-te...han-noise.html

The rookie

iTrader: (1)

Well the throttle isn't shut (the engine wouldn't idle otherwise) and the idle speed control valve is open, so the airflows through into the intake, at a reduced rate, but still flows, the pressure between turbo and throttle cycles over a small range either side of the surge line until the turbo has slowed enough that it can no longer boost over the surge line, boost continues to decay as the turbo slows (as there is little turbine flow now as the throttle is closed to the idle postion) until it reaches its idling speed for the turbine flow that still exists.

Simon

Shailan

iTrader: (1)

So, the debate continues.

Let me share my driving experience after re fitting the standard re circ.

generally the car feels much smoother with the re circ when changing up gears.
In 5th gear the acceleration feels more powerful especially from 90mph, also cruising feels more responsive as there air is being circulated rather than dumped to atmosphere.

In terms of overall performance I donlt think it makes a difference, but an RR run could prove otherwise.

In terms of drivability car feels smoother.

In terms of noise - I am still waiting for the whoosh when I change gears. - LOL

I prefer the standard re-circ, my opinion.

wiganwayne

i have a my96 uk model fitted with a baileys dump valve, are you saying it will run better/smoother with the standard DV fitted. if so how easy are they to put back on? i purchased the car with the baileys already fitted.

Shailan

iTrader: (1)

yes, mine definitely runs smoother.

I am not sure on a 96 model.

Mine was straight forward to change. Its a 2005 and the DV is on the intercooler.

Where is the DV located on the 96?

wiganwayne

mine isnt on the intercooler but is in that region, i think im going to have to get this done, im not too bothered about the silly noises that a BOV make,