question? why does the US delivered EVO get a plastic diverter valve when the JDM version gets the metal version (MR BOV) ?

 

The stock Valve on the 1G, & 2G DSM's, 1G & 2G 3000GT, GVR-4, EVO VIII and EVO IX are partially open at idle.... this is not a "leak" problem. They are designed this way with a low spring pressure to give ultra fast response for throttle lift from a part throttle acceleration condition.

This is why someone trying to vent the stock BOV to atmosphere will run pig rich at idle, and it is also why most aftermarket valves that vent to atmoshere "flutter".... they have a stiffer spring to hold the valve closed at idle (preventing the pig rich at idle problem), so they do not open up as easily from a throttle lift durring a part throttle acceleration condition. Even when closed at idle an aftermarket BOV that is vented to atmosphere will cause an extremely rich condition on shifts.

Later,

Keith

 

Once my clutch install is finished I will be doing a write up on my stock diverter valve modification. It's basically a variation of the "stop leak mod".

So far it seems to hold and release fine with no issues, the object here is to have the valve hold boost as well as it would if it were backwards but at the same time evacuated boost (recirc), esp at part throttle boost, just like stock configuration

My setup consists of a OEM DV with an extra nipple tapped into port that goes to the "open" chamber of the diagram. This port see's charge pressure whenever manifold pressure is below 10.5psia (via differential pressure switch) which is the same as normal configuration. But when 10.5psia is ahieved the switch is made allowing ground for a solenoid (used an extra FPsol) that routes charge psi into the manifold DV tubing and the open chamber air is vented to atmosphere.

 

Mike @ Forge, I have the JDM MR valve installed on my EVO, with the stock turbo it held 24psi with no problems. Recently I added a gt35r in place of the stock turbo and now the BOV is giving me some problems.

Whats happening is during light throttle inputs in 5th gear the car will occasionally buck. It feels like not all the pressure the turbo is producing is getting out of the intake track and gets sent back to the compressor when the throttle plate closes. I think its due to the stock valves inability to open wide enough/fast enough to allow the amount of CFM this larger turbo is producing to escape in time.

What is your opinion and would one of your valves eliminate this problem?

 

I'm sorry for being away from this thread for so long.

I'm not here solely to promote our valves, so I'll just say that any valve with enough flow volume for a 50 trim turbo (at least a 34mm inlet and outlet) should be sufficient considering flow-volume, but as for recirc. or atmo. that is entirely up to you.

Since you will still be using a MAF based setup, a recirc. valve is your best bet to maintain 100% driveability. A VTA valve MAY be able to be used if you absolutely must have the sound associated with it, but you will still encounter a rich fuel condition off throttle that MAY cause you some problems, even with the UTEC.

As I mentioned much earlier in this thread, valve fluttering is a common occurrance at partial throttle or partial boost and it is not really a problem.

While the OEM Mitsu. valves utilize the channel up the spine of the valve to equalize the pressure differential accross the sealing surface of the valve and help eliminate partial throttle valve fluttering, this only works within certain pressure ranges considering the flow-volume of the valve and the turbo and the volume of pressure between the intercooler piping and the intake manifold.

Since you are now using a much larger turbo than stock, and you are flowing a significantly larger volume of air through the system, that tiny channel up the back of the valve will have a much more difficult time equalizing the new pressure differential of the higher volume of air of your particular application.

Our valves do not utilize a pressure-equalizing channel at all, so they do not have the ability to minimize partial throttle fluttering in the same way that the OEM valves do, but we would have various valves that will do many other things much better than the OEM valve. Feel free to call us with any other questions.

 

Mike,

Have you guys ever contemplated on designing a valve with this pressure-equalizing channel?

I remember years ago on my DSM, I used the Greddy Type-S valve, which offered a second port for this purpose. It would virtually eliminate part throttle backoff fluttering and gave the ability to nicely blowoff even after lifting to part throttle from WOT. I simply tapped the upper IC pipe or the connection to the second port, as close the the TB as possible, to try to get a pressure as close to IM pressure.

The Gus modded 1G valves go one step futher and use use a valve to completely shut off the second port at WOT so the valve stays closed at even higher boost pressures. With DSMLink, we were able to do this ourselves, via control of the FPR solenoid.

Anyway, I was just wondering if you were ever considering a similar design, as in my experience, this offered the best drivability and performance in all situations.


Eric

 

This is not a feature able to be incorporated into our valve designs.

 

Bump so more people see and read this.

 

nope

 

just read ur thread for the 1st time..nice info..i always install either a dsm 1g bov/forge 007 units on my installs..recirc is prob the best way to go on maf cars..

 

yea "prob"

 

stick with diverter valves if you ask me. i will never give up sound over performance. in fact after i installed my forge DV and got the DV tuned just right i get better fuel mileage. i was getting 18-23 mpg avg. now im getting close to about 24-26 mpg around town and almost 28 mpg on the highway. "that is if keep my foot off the peddle.... LOL

good write up mike at FORGE..


you guys make anything for SEMI-TRUCKS !

I own 2 - 2008 volvo 880`s look up the spec`s on these bad boys!!!!!!!!!
can you sayD16 600 hp / 2050 lb-ft

and thats at 2200 rpm

 

WTF?! You don't have any choice but to use a diverter valve...otherwise you'd get compressor surge with every let-off of the accelerator...

 

That's completely untrue in every possible way.

For a better understanding of what IS and ISN'T compressor surge, read this thread:

https://www.evolutionm.net/forums/sh...d.php?t=285733

 

Semantics aside---sorry to use the wrong term--w/ no diverter valve where is the boost pressure going to go when the throttle plate closes? It's got to go somewhere and if there's no release it's going back to the compressor...is it not?