Airtrek Turbo vacuum pressure at idle

[limaynard]

Hi, I am going through the process of making a few upgrades to my Airtrek and I was wondering what the range of vacuum pressures were at idle.

Mine has been at around 12 InHG (-6 PSI) since I fitted the boost gauge many years ago but having recently fitted the Evo metal BPV I want to make sure that is correct as the BPV needs vacuum to operate.

I am told that the Evos are at around 18 InHG (-9 PSI) so I was concerned that I may have a vacuum leak and that the BPV may not open early enough causing a boost spike - actually since fitting the TD04HL-19T I am experiencing a spike of auto gear change...

Thanks...

 

[stutzedward]

My idling was around -0.5 bar while using stock TD04. I've not checked after changing to TD05. But boost spike during gear changes was normal for me on the stock turbo. As for TD05, it's more stable without any spike.

 

[limaynard]

Thanks, on stock BPV it was fine but it was leaking. -0.5 BAR is about where mine is.

The new turbo is a ported 19T so needed the new BPV...

Thanks.

 

[stutzedward]

Why not use blow off valve? Worry of stall engine or the authorities?

 

[limaynard]

I don't really like the boy racer 'pssst' and also being a MAF based system the Airtrek needs to have the metered air returned to the intake (as you know) to keep the AFR correct.

It will be fine once I can tune the boost curve. I need the Evodroid to log properly :)

 

[stutzedward]

Ahh okay. :) Understood.