Does plumbing a 4 port MAC valve like a 3 port increase effective % resolution?

Re tuning my 6258 EFR using the 4 port MAC valve I've been running for years (Trackspeed), and thought now would be the right time to redo it if needed. Not limiting myself to TT3 this year so a can be a more aggressive not being HP limited in TTU.

Hooked up as a standard 4 port MAC my resolution is very tight. FYI 20% is 186KPA and 34% is 243KPA. Its even closer together in low RPM areas.

Always had a heck of a time tuning out initial and shift boost spikes, both open and closed loop. Seems to me the small resolution say 25% for 203 KPA and 30% for 220 KPA doesn't help.

Would venting to atmosphere the backside line double my resolution while running Turbosmart GenV Twin Port Internal Wastegate (IWG) Actuator?

Discussion, Ideas, results and photos would be awesome.

 

Yes.

 

Kinda brief but OK. Does it effectively double it?

For some reason when I went from MS 1.4.0 to MS 1.6.1 to add my CAN EGT it added a few things like Min/max range and my tune got way more sensitive to overshoot?

Eased it by changing frequency from 39Hz to 19.5Hz & turning Max duty cycle from 80 to 50 but that seems like a band aid? Update also added upper limit delta and max rate with descriptions that don't seem to match what it does.

 

Yes, been amore than a decade since I derived all the math, but is is basically the difference between (1+d)/(1-d) (4) and 1/(1-d) (3)

For d=0.25: (4) 1.25/0.75 = 1.67x spring, (3) 1/0.75 = 1.33x spring

6.1 has a new field I am not familiar with (upper limit delta, I think that may actually have been my request). Set lower limit delta to 25 and see if that helps.

Honeslty, "simple" works nearly as well as advanced for most installs and is easier to tune. Min DC should be between 20 and 30% depending on a bunch of factors.

19.5% can "flutter", but increasing frequency costs you some resolution and dynamic range.

My preference is to size the spring appropriately (1.5-2.25x for max target) and run a 3 port at mid 30s

 

Thank you.
Will try plumbing as a 3-port, re bin and re try out "simple".
A bit frustrating as I had it almost perfect before new motor and firmware update depending on wather.
Florida's new "Super Speeder" law makes street tuning iffy, and rules out 1 to 1 pulls to 7800 RPM with 3.63 gears .

 

OK while sitting at work without my car in front of me, my brain is hurting as the ports use completely different labeling terminology between 3 and 4 port.
Am i just removing the backside hose and venting to atmosphere/filter the backside of the WG and plugging port B on solenoid?

 

I suspect none of those is what you want. You probably want the configuration with the vacuum T between the source and the actuator. IIRC you block 1 of the ports on the 4 port to turn it into a 3 port. This has to be in a thread on here someplace. It has been way too long for me to remember the details.

 

So pretty sure this is the configuration still having a bit of a problem figuring the ports as it seems you are bleeding pressure instead of adding pressure?

Would it just be better to buy a 3 port as the reading I've done seems to indicate due to valve movement the 3 port has more resolution?

 

When actuated the top pressurizes, when not actuated the top depressurizes. The "4th port" is blocked with a plug. Look up the way these valves work on humphrey or granger.

It is simple really. When actuated the two ports on the right are routed to the two ports on the left. When not actuated, the connected ports swap. You want the pressure source port to be routed to the blocked port when not actuated, and to the WG top line when actuated.

The resolution is a hookup configuration thing, not a valve thing (well mostly, I did characterize several different valves and there are minor differences).

 

Thought I would add an update.
Still not done tuning due to time but changing from 4 port to 3 port did reduce sensitivity and increase resolution by approx.40%.
Made boost curves in closed loop less spikey and more predictable, which should lead to a better Bias duty table.
I'm a bit old fashioned so I graphed them out by hand which makes seeing things easier for my analog mind.

 

Right on, maybe post your solenoid and line connections for the future people?

Also from the plots above it looks like you have a pretty dramatic RPM dependent situation going on. Might be worth running the reference line to the volume after the IC but before the TB. If you are on VVT, make sure you are pulling advance after about 4200-4500, if you have VICS change the toggle to see if there is a causal impact. This could also be from a dramatic change in AFR or timing at that inflection point.

Edit: NVM just looked at an old log, wastegating does decrease with target at around that point on my setup.