When I bought my Scoob it had an atmospheric dump valve fitted.
While I like the noise some people have told me these don't work as well as a re-cirulating valve.

Anyone know if changing to a re-circulating will make any difference at all?

Its a 94 WRX if that makes a difference

Cheers

 

it has been said that recirc is best but don't think you would notice much of a difference. VTA might make it run slightly richer from what I have been told.
If you like the sound stick with the VTA.
ken

 

It depends what you mean by a difference... it will stop your bores being washed due by the over-fueled intake charge but it wont sound as good in McDonalds carpark. Whilst its a lot better for the car; I wouldnt expect to see any difference in performance by re-fitting the original re-circulating dump valve.

Simon

 

Use the "search" facility, this has been discussed many many times previously.

 

I have both...a Forge re-circ and a Forge VTA (not fitted at the same time ). I use the re-circ daily as the car "feels" better - acceleration is smoother and it recovers from a gear change quicker. The VTA I fit when I want to scare grannies and animals

 

Guess I shoud have searched first...sorry!!


Running a bit richer can't be a bad thing for a turbo car can it? Don't the imports run a little lean anyway?

Does an ADV make you a boy-racer???

 

all scoobs tend to overfuel at high revs unless remapped

 

Thats reassuring!! My mates always have issues with running lean with their modified Fords at high revs, usually with pistons melting down the inside of the blocks....

Nice to know I don't have that problem, which is nice!!

 

I thought that most scoobs run very lean at high revs/speed???

 

Dammit....now I'm worried again!!!

 

Thats what I have been told anyway. With a VTA, you only run rich momentarally, ie, when you lift of and re-apply the throttle. However, over time, there is the possibility of increased engine wear. This is due to bore wash which is where the extra fuel washes the oil off of the cylinder and piston lining. However, this is only in theory, and why the extra fuel doesn't get burnt along with the rest of it, beats me
I did have a vta for a while on my sti 4. Changed back to standard due to there being 'increased' turbo lag. I put this down to the intercooler having to be re-primed with metered air. A re-circulating dumpvalve, dumps the excess air back into the intercooler ready to be used again.
Bit of a p&ss take when these companies say that VTA's reduce turbo lag!

 

with a vta the reason your fuel doesnt get burnt it that you have vented the air so the fuel cant burn as there isnt enough air for that split second until it grabbed some more clean air, if it was recirculated it would burn in that air.

 

What air... the recirculated air doesn't go in the engine either tho does it. It goes back into the inlet pipe. The fuel is in the engine.... the recirculated air in the inlet pipe. Even with a recirc DV your engine shows rich on lift off for the above reason.... i have wideband logs which show this rich condition when lifting off (when on throttle etc the DVs make no difference to fueling)... and the difference between VTA and recirc is so small it doesn't concern me. Bore wash needs a lot of overfueling, a VTA simply won't do this unless it is faulty.

Tony (currently running a recirc due to it being a bit nicer on/off throttle).