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Aaron, you think we should tune my car on ecu boost rather than an MBC to net more boost out the top?

OP I like where you are going with the wanting a super low boost map, but even on our crap *** 91, you can still run like 12-14psi of spring in the gate. Saves you the added complexity and tuning quibbles the 4 port could possibly bring.

 

I just installed my 4port. Nothing fancy, but I will start tuning it tonight/this weekend.

When dsport did there test going from a 3port to a 4port they saw ~100ftlbs improvement at 5k on there GTR. I know it is not apples to apples, but if I can pick up even 30-40ftlbs then it is way worth it.

 

I am interested in how these do on Evos. These are all the rage on Hondas because guys need to run a 3 psi spring to get traction but then can ramp up the duty to make over 20 in higher gears....I have a friend who runs about 6psi (wg pressure on a 3 pound spring)in first and then uses the 4 port to ramp it up to 26psi which is 670whp lol. They also help like you said to keep the wg from cracking early especially on cars with lots of VE that like to blow the gates open which gives big torque in the midrange.

With the traction and motor differences of Evos I wonder if it will be worth it since they tend to be a little more fickle to tune

 

i will keep close tabs on this thread, interested to see if you guys gain midrange over the 3 port.

 

We run them on the Lease Locator Racing evolutions. It can make a difference in certain situations but normally they are more for altitude induced problems or traction. For perspective we can run 75psi on the Eclipse with a 3 port easy enough. Then again it leaves the line at 34-36 psi normally so there isnt much need to get low spring pressure down low.

 

So just an update on this thread. I have been running a 4 port for quite a few months now. So far I would say the results would match a properly setup 3 port.

Here is where it sucks. The resolution is really low.
Duty Cycle info
17.4psi == 30%dc
20.3psi == 33%dc
23.2psi == 35%dc
26.1psi == 37%dc
29.0psi == 39%dc
31.9psi == 40%dc

Using a 10psi spring the resolution is so small that a 1-3% change will results in a 2psi change. This makes it very hard to control a very tight boost profile, even with feedback. Also as weather conditions change even a .5% change in DC will result in a huge change in boost profile.

So in closing, the 4port has worked very well for me, I was able to run a small spring and have a wide boost range, but the resolution that I am missing out on makes tuning a longer process, and requires a lot more feed back to control the boost profile.

I am going to ditch the 4port and move back to a 3port and see if get the results I am looking for.

More or less I wan to see 5%dc increase will result in 1.5psi more boost even if I can get it to 5% makes 2psi that will be a huge improvement over the 1%=2psi.

The area that became very cumbersome to deal with was 5th gear on the freeway an flooring it. If you start at 3k, it will spool up super quick, this makes the feedback have to work crazy hard, and sometimes I would even hit my 7psi over boost protection. So 5th gear would spike to 39psi and hit boost cut before the feed back could get it under control.