john banks

When connecting this:

Unpowered solenoid connects compressor outlet to wastegate
Powered solenoid vents wastegate and seals compressor outlet

Is there any need to actually vent the third port anywhere since it seems OK to have the wastegate at atmospheric? The duty cycle is switching between compressor outlet pressure and atmospheric then which seems OK to me.

Clearly there are a few ways of doing this. Bob suggested no restrictors anywhere.

brickboy

Volvo & Saab turbos vent the third port back into the inlet, after the MAF and before the turbo. Presumably this ensures that the engine actually sees all the air that the MAF has metered -- although the actual amount of air must be minimal.

I would guess the risks of splits / leaks from punching a hole into the inlet pipe outweigh any possible benefits of "recycling" the air from the solenoid -- probably best to attach a length of hose and let it just exhaust to atmosphere.

Chris.Palmer

On the Pre M97s with 3 port solenoids it vents back into the airbox and there is a restrictor in that pipe.

Probably doesn't need to go back to the airbox - I snapped the airbox connector off & ran for a couple of weeks venting to atmosphere (with no adverse affects) before I finally got round to repairing it.

I'm guessing that the restrictor is used to prevent boost oscillation.

I think I have a spare one of these pipes. If you want a free one to play with then email me.

Regards,

Chris

dowser

John,

I run mine without restrictors too. This is metered air you're talking about atmo'ing (although I guess not much in the big scheme of things, you will be richening the mixture on full boost ), I recirculate it.

Richard

john banks

There is never any connection from compressor outlet to atmo though - just the boost in the pipe between the solenoid and the actuator? I can recirc it no problems I suppose. I'll see how I get on with the plumbing in daylight

dowser

Yep - just as much air that can escape from the tube at whatever boost/duty you're running

As a percentage, it's gotta' be pretty low - be nice to quantify though......could be used to negate a bad tank of gas if the knock sensor's not listening (mine never seems to anymore)....

Richard

john banks

It is quite good in some respects Not quite the kick in the back of the Dawes, but the top end boost is easier to control since you can alter the maximum duty cycle permitted. Does a very good impression of decent closed loop boost control now. Will be able to loosen off the actuator a bit since the 3 port will hold better top end boost than the Dawes would at sensible midrange - 19 PSI at 7000 RPM is yummy (and probably too much but very limited time to map it today), however, the 550s are not resting on their laurels since they are getting over 80% IDC already, but it is still rich. Must find time when it is not freezing cold to hookup the WB lambda and see just how rich.

hades

John/Richard - Do I take it that the 3 port solenoid will work fine with a normal ECU/ECUTEK remap, or do you need something a bit more exotic to control it? Am curious about maybe doing this when I get my MY02 ECUTEK'd in the near future.

Cheers

john banks

Could be done with a custom map, but wouldn't work with a standard Tek "one size fits all" map since these are designed around the factory 2 port. Unless it becomes a popular option of course.

hades

Thanks John.

In your opinion, would the three port give a worthwhile improvement in boost control on a fairly mildly modded car? (Up-pipe and full APS sports cat system, ITG filter) If so, I might shortly wave the magic plastic at Bob - you're a very long drive for a custom map!

john banks

I'd use a Dawes personally with a cheaper off the shelf map. If you start getting weird and fitting lots of strange kit to your car it might be different. However, my 3 port only cost £25+VAT from a breakers It is more the time to map it that you would pay for compared to an off the shelf map. Bob gets very good results with 3 ports.

Mr J

JB ...only £25+VAt...that's even less than a Dawes...
What is the catch ??

/Jan

carlos_hiraoka

John how did u end up plumbing the 3 port solenoid ????? ..... recirc or vent ?????

Carlos H.

john banks

I recirced it. Had some Samco lying about courtesy of T-uk for the joint from the solenoid to the wastegate actuator.

The catch - not sure, it has worked for a few days now

Mr J

Ok..no catch..then...
But what are the differences with the one you got and..the 3-port that I could get from Bob.. PBM ..Scoobymania for ~+£100???

/Jan

john banks

Just need to clean it up for a few minutes whilst laughing at the money you saved Dealer quoted me £150 + VAT

It is the same model number.

Pavlo

just a note to say, if you plumb the bleed into the inlet after MAF, you will be bleeding to max vacuum (enough to collapse samco inlet) , so getting more effect than just bleeding to atmosphere.

Restrictor should just smooth out things, might try mine without.

Paul

carlos_hiraoka

What would be the problem with simply venting to the atm. ?????

Carlos H.

john banks

Nothing much, but I had the hose to recirc it so I did. Small amount of MAF metered air would leak?

Mr J

What year of the Impreza used a 3-port...??

So I know what to look for...
Or maybe you have a spare one JB

/Jan

john banks

No spares. 16102AA013