Anubis

Well my hks ssqv turned up the other day and am gonna fit it tomorrow but its come with the re-circulating adaptor too, so i have the choice either to have it vta or re-circulating. So its probably been asked before but i was wondering what is best either vta or re-circulating?

Mt cars a 03 wrx sti type uk, hasnt got anything done to it apart from a hks pannel filter.

thanks andy

DonNedly

iTrader: (10)

http://www.enginemapper.co.uk/Tuning...ide%20V1.1.pdf

Page 9

ilogikal1

Re-circulating would be better, unless you're going to get the car re-mapped after fitting in which case it depends if you want the noise or not essentially.

bigsinky

Fitting an externally venting dump valve, or a vent to atmosphere, (VTA), valve will cause a number of problems when you lift off and general engine running, as that dumped air has been measured by the MAF, but is then not used by the engine, although it expects it.
The other main issue regarding externally venting dump-valves and MAF sensors, is that the dumpvalve will always open under vacuum, i.e when not is boost, (positive pressure). This means that on idle and cruise, an external venting dump valve will always be letting in extra air post MAF, (essentially an air leak). This means that initially it will run leaner than it should until the ECU learns some corrections, (standard ECUs only). This problem is not applicable when running a mafless ECU,
like a Simtek, Syvecs, Link etc.
My advice; on a standard ECU stick with a recirculating dump valve for drive-ability and general integrity of the engine management control systems. As said before, if you are running mafless, then running an external dump valve won’t matter or not.