3 port boost solenoid?
 

Good afternoon,
I don't mean to seem daft but can people explain to me what a three port boost controller does over the stock controller and the reasons I should change it when building a modified car?
Cheers,
Andy.

Better able to control boost apparently. Not required as stock or even lightly modified cars. All parts have limits and once you start reaching the limits of the OE solenoid you upgrade. Of course you can't just upgrade to one without a remap.

Cheers for the reply. I'm building a track day toy and although I am running a standard turbo and TMIC I am fintting equal length tubular header, decat up pipe, decat down pipe, a different exhaust, panel filter, 255lph Walbro fuel pump and larger injectors. I'll get it mapped to suit so was wondering if it is worth me fitting a 3 port boost controller now and get it mapped together?
I'll be fitting a larger turbo and FMIC in the future and I want to go Simtek in the future as well.
Cheers,
Andy.

For the cost definitely worth adding one in 😊

a 2port solenoid is just a bleed valve - it bleeds off an amount of air that would normally be pressing against the wastegate which has the effect of increasing the pressure required to open the gate. Generally the wastegate will work as if the bleed valve isn't there - more like a much stronger wastegate spring.

With a 3port solenoid, air pressure is allowed through or can be blocked entirely from hitting the wastegate - this allows for an improved turbo spool up as the gate can be held shut better. This means target boost can be achieved sooner and with less overall wastegate duty.

Say for example your current 2port solenoid is running around 85/90% duty cycle to achieve your 20-22psi target boost. You could fit a 3port and then reduce that duty to maybe 60% to get the same boost levels - if you don't adjust the map though you'll end up overshooting the boost target by quite some amount. This leads to you constantly overshooting and undershooting your target boost as the ECU tries in vain to control it.

Once it's mapped though the 3port will give quicker spool and more fine grained control over the boost curve.

Thanks for the reply bludgod, that makes the boost solenoids job much clearer!
I know there is always an element of personal choice but are there any recommended 3 port boost solenoids to go for?
Cheers,
Andy.

The 3 port Denso off a classic Subaru are pretty much the best. Around £30 second hand mate so worth the money.

i have a classic 3port on my bug and it's been grand - but a tactrix/grimmspeed/prodrive 3port is a better unit. It depends how much boost your looking to try and make. If you're only just on the limit of the 2port then the classic 3port will get you that little bit more. If your trying to build 400hp then don't cheap out and get a new, quality one.