I'm currently running the common 3-port MAC valve, and I'm suffering with poor throttle modulation. When I'm in the zone where the car will make boost (3500RPM and above), it's difficult to modulate the power. Either I get next to none or just about all of it. I'm currently running a 9psi WG spring and 15psi max boost. I'm controlling boost through my ECU. I can setup boost MAPs based on a number of different parameters, either open loop or closed loop, but the min pressure of 9psi is still too much for some situations.

I'm told that I can get the best of both worlds with a 4-port valve. It will allow me to run a less forceful spring in the WG (maybe 3psi) for better modulation, but still allow me to boost to higher levels (20psi +) for power.

1. Is anybody using one?

2. Any downsides?

 

The 4-port will allow a broader range of boost levels by controlling pressure to the top and bottom port of the gate. I just don't understand what your issue is; what you're attempting to fix and how you're going to fix it.

 

The issue is this: When I launch the car with my current 9psi spring, I light up the rear tires uncontrollably in 1st and 2nd gear. If I back off on the throttle, I don't get any noticeable reduction in power unless I back off so far I don't have any boost.

I want to setup a boost table based on throttle position and RPM that will give me more boost as I feed in more throttle. To make this useful, I need to be able to run less than 9psi at small throttle openings and still be able to run upwards of 15psi at WOT. I can't do this with a 3-port.

What frequency do you recommend with the 4-ports?

 

That I understand. Let me know if you need one.

You can run them 25-45hz.

 

I decided to go ahead with the change to a 4-port solenoid. The first thing, however, was updating my plumbing.

Material: Since I run dual WGs with a short runner setup, some of the hoses run close to the exhaust. I was running silicone hose with reflective heat shield over them, but I was always concerned they would fail. Since everything is mounted to the engine, I decided to run 1/4" stainless hard line. It's relatively inexpensive, and it shouldn't have any durability issues.

WG Banjos: I have TiAL 44s, and I had one of them back off a couple of years ago. A friend had the same problem on his car, too. I decided to get stainless 10mm banjo to -4AN adapters and attach them with stainless banjo bolts that I could safety wire in place. This seemed like an easy way to go until I found out that all that stuff was really designed for brake applications, so the passages are very small -- too small for good airflow. So I drilled out all the passages -- banjo bolts and banjo adapters to a diameter that matched the ID of the stainless tubing.

 

Here are more pics -- I ran hard line for the BOV and WG. Since the stainless can withstand the heat, it made routing a lot cleaner.

Harness: The solenoid came with unterminated wire, so I added a Deutsch connector, similar to the one that came on my 3-port solenoid. It plugs right into my existing harness like the old one.

Wastegate: I changed from my old 9 PSI springs to 3 PSI ones, which required disassembling the WGs. It was a good opportunity to check the condition of the diaphragms. Fortunately, both of them were in good condition.

Tuning: The logic is the same as my old setup, but it should give me better modulation of power. I will set up a boost table based on throttle position that gives me progressively more boost with wider throttle openings. It will also allow me to run more than 18 PSI if I dare.

 

Im interested in the results once you get your tuning done. Keep us posted! nice engine bay by the way. Would love to see more pics of that as well. sub'd thanks

 

Sounds like a decent project, personally I'm more of a fan of having boost set by gear rather than by throttle. Still want to see how it turns out for you.

 

"Im interested in the results once you get your tuning done. Keep us posted! nice engine bay by the way. Would love to see more pics of that as well. sub'd thanks"

ditto.

it has always seemed to me a 4 port config has advantages... let's hear from others who run 4 ports.

 

Found that a 4 port with a lite spring works best with a speed sensor. Then every gear has it's own boost pressure.

 

I've been running 4port valves on my car for some time now and they work very well. I recently had the car on the dyno and made over 40psi of boost (unintentionally) with 10lb springs on dual 44mm tials. With the controller off it makes around 14psi.

 

My ECU allows me to set up boost as a function of:
- RPM vs. Throttle Position
- RPM vs. Speed
- RPM vs. Gear
- a few others

For RPM vs. Gear, it calculates the gear using RPM, final drive ratio, and gear ratios. So . . . to implement RPM vs. Speed or RPM vs. Gear, I need a vehicle ground speed input. It's best that it not be tied to the drivetrain in case I want to add traction control at some point.

I know I could add ABS tone wheels to my front spindles, but as a path of least resistance, I considered a GPS speed sensor --> http://www.summitracing.com/parts/iz...FexcMgodOiEA9g

Does anybody have experience with these? Do they react quickly enough? Any issues with lapses in coverage?

 

I just made some open loop boost control runs to set a baseline; here are the results:

0 - 30%DC = 5 psi (I guess those 3 psi springs were off a little)
40% DC = 7 psi
50% DC = 8 psi
60% DC = 10 psi
70% DC = 14 psi
80% DC = 20 psi

At the higher duty cycles, the boost would hit the psi, then decay. At 80%, the boost hit 20 psi, then decayed to about 15. The lower the boost, the less the decay.

These values are off of my mechanical boost gauge, which has typically correlated fairly well with my ECU.

Ideas?

 

For what it is worth, I run much lower DC% in order to hit 12-15psi. For example, for 13.5 psis, the DC is set to 18%.

I am running a 4 port mac from C.Ludwig, on a Haltech PS1000, open loop boost control, dual 38mm tial wastegates on 9 psi springs, and T04S turbo.

 

I had a 3 Port Solenoid my car didnt go past 18 psi. With the 4 port I just do whatever I want. I also run close-loop I just tell the ECU give me 15, 20, 25 or whatever the case maybe and thats what I get.

 

I need an ecu like that lol

Been playing with the closed loop control in the haltech, its nice, but not "tell it 15psi and get 15psi" nice (that or I have a long learning curve to go)

 

Well ok lol you need to have the right PID Setting. I running a PS1000. That how cloose loop should work. You tell ECU give me 20 target boost and the ECU should do its best to give you the 20. But again needs the right settings.

 

Haltech has a step by step setup process in their help section, it shouldn't take more than 3-4 passes or a few pulls to get one boost level dialed in. If you are doing boost by gear or varying boost it will take a little longer to get the start duty cycles dialed in.

OP, those DC do seem a bit high to me as well. 25% got me about 20psi, 45% was over 44psi

 

Yeah, the DCs do seem high. What WG spring pressure are you running? My first thought is that my low 3psi spring pressure requires more DC to keep the WG closed.

Also, what size exhaust are you running? Since my boost is decaying, I'm guessing that the backpressure in my 3" exhaust is pushing the WG open.

 

That's entirely possible, backpressure is not an issue with me. I am running 10lb springs in dual 44mm gates. I'm running a T6 1.32 turbine with a 5" dump out of the side of the car.

How do you have the valve plumbed? Where are you pulling pressure from?

 

I also have dual 44mm WGs, but they're plumbed back into the exhaust about 18 inches downstream of the turbo outlet. I have the valve plumbed just like the diagram I posted (attached again below), and I'm pulling pressure from the intake tract, just upstream of the throttle.

I know that dumping to atmosphere is preferable, but I drive on the street as much as track, and I'm concerned about the noise.

 

3lb springs may be a little low, i would recommend a spring that's maybe 2lb less than the lowest boost you plan on running. You may also try pulling pressure straight from the compressor housing. I don't know what ECM you are running but it could also be possible to play with the control start points and the start duty cycles. IE you can have it where it starts the boost control 3psi before the target and enter a start duty cycle appropriate for a lower than target boost. Doing that would start the control sooner and bring it in more gradually. hope that makes sense.

 

More pics.

 

Man that thing looks nice.

 

Did you just input the duty % across the hole table and see what boost it ran?