Gaaargh!!!

 

i still dont understand why it would cause bore wash. The re-circ air goes where exactly? because surely it would have to go through a meter again and be re-measured otherwise it will be innacurate?

 

havent checked the plumbing, but seems that way to me too

also that lovely waste gate flutter - anyone know how to emulate that safely - drove an esprit once where this was very loud - sounded great - looking for a more subtle (not heard so much inside) level of sound

Put the beer away guys - too early - experienced comments please!

 

The recirculated air goes back into the system AFTER the MAF sensor, but before the turbo. - therefore the MAF does not see that air (again), but the ECU bases its fuel calculations on that bit of air being in the system.

Richard

 

Correct!

AFAIK the chattering noise heard with WRC cars is a combination of the wastegate and the fact that they don't have dump valves. As the throttle is closed the compressed air hits the throttle and bounces back towards the turbo, ultimately stalling it. What you hear is the turbo blades chopping the air coming back of the closed throttle.

If you want to emulate this on your own scoob you ideally need a full decat and induction kit (to increase the noise) then remove the dump valve completely, blocking up the holes left by it.

The only downside is it may shorten the life of your turbo considerably Depends how strong it is

 

its not that i dont believe you but that too many vairables in it, there must be a way the computer calculates it more accurately

have to wait and see i guess

 

Ahhh... although Im sure I was told I didn't have one. Anyway, it's not high on my priorities anyway... unless they make jewel encrusted ones for that added bling factor LOL

 

got this from a respected company today

 

Yes, but when you put your foot back on the gas, the ECU will need to add fuel and it mixes it with the air mass it assumes is already there.

Fit one if you want, but it'll be hesitant and a bit lumpy on and off the gas.

 

...No offence intended, but don't you think that they might have told you this as they sell plenty of VTAs and think that you may be considering purchasing one?

 

Any beers left chaps????

ooooh and another corner

 

i had taken this into consideration lol but i had tried my best that i wasnt interessted in buying another i just wanted a decent technical opinion. (im still waiting for subaru to get back to me although i do have a friend that works right next door to prodrive.... )

 

Hum, thats quite not what happens and is not how a centrifugal compressor works. When you snap your throttle closed, their is a large mass of moving air. This runs in to the throttle plate and gives a pressure spike greater than the boost pressure, the air flow then turns and flows back up the inlet tract and hits the compressor. This reverse flow can slow the compressor and the shock wave can even break the compressor in the worst case.

The thing about blowers is, the greater the restriction to flow, the less power they take (at work we have 16 blowers rated at 10,000,000 Watts each, when you close the outlet guide vanes, the power drawn changes massivley).

With a DV you have to balance the requirement to dump the spike in boost pressure but not allow the compressor to expend energy pumping air about. Changing your DV to one that does not match your car can in theory actually increase lag.