Stock EVO X BPV Modification
Jan 4, 2010, 04:36 PM
#1
Stock EVO X BPV Modification
I know many people are having issues with many BOV's not working correctly or not well enough.
I already have gone through two BOV's a Forge RS and GFB Steath FX. The Forge RS produced harsh driving conditions on the highway causing fluttering issues under part throttle. The GFB is not too bad with the flutter when it hot, but has many issues when it gets really cold. Like in the single digits F...
The GFB and RS both held boost great in the higher PSI ranges. But they did not produce the stock like driveablity.
So I began a hunt for a solution. The stock BOV is perfect, except for one flaw it leaks boost in the upper psi range for most people, but not all. Some did get a freak stocker that holds 28 psi all day long.
So after some searching. I found two solution. One was the "GUS MOD" and the other the Dejon Tools Mod.
The "GUS MOD" covers the reference hole on the bottom of the BOV. Then creates a new orifice that sits on the side of the BOV that is VTA. What is does it prevent the bottom of the diaphragm from seeing boost and there for open prematurely. What it also creates is driveability issues... especially on DECEL.
However, the BOV does hold more boost. You can hook up the new reference hole to a boost source and have the valve work like stock again.
The "Dejon Tools Mod" goes one step further. It does the same thing as the GUS mod, but also add a mechanical solenoid that closes at 15 psi of boost. This makes the BOV hold more boost. But, work like the stocker below 15 psi of boost. I am sure you could create this with a electronic solenoid and hobbs pressure switch (similar to meth injection). Set the switch to XX psi and it will close the solenoid. I would guess it would create a smoother transition than a mechanical valve.
The original Dejon tools mod is a step above the Gus Mod. But works on the same principle. I think if someone wanted to try to run a hobbs pressure switch the turns on a solenoid to close would be pretty sweet. But I have no idea how well it would work. The solenoid would have to react very quickly.
This brings me to my idea...
Now my theory.
The GUS MOD works by blocking the reference hole completely so it is air tight. No air gets to the bottom of the diaphragm to push it up early. But it also causes driveablity issues.
So why not create a new MOD... I will call if the KRIS MOD... I know creative.
The reference hole is 4.6mm wide...
If I drill through the set screw with a 5/64 drill bit I create a 1.98mm hole... Reducing the reference hole by more than half...
In theory it creates a restriction... less air can get through the reference hole... to the bottom of the diaphragm to pop it open in a given amount of time. It works the same as a "BOOST PILL" limits the amount of air a solenoid see's at a given time thus typically lowering boost level with a smaller hole. Once the hole is enlarged you gain boost pressure. Same idea holds true here. Limit the size of the hole, limit the amount of boost that is transferred to the bottom of the diaphragm. I doubt I can go much smaller than 1/16 without fancy machinery. If you make the hole about 1/16" then you reduced its size by ~66% from stock. Much less boost gets to the diaphragm to pop it open early.
I am sure in theory you can add another restrictor... or a combination of a large and small resistrictor.
One Restrictor == - ==
Two Restrictors == - == - ==
I sure that if you add another restrictor instead of just one the boost holding would increase a bit more.
Try a combination of 5/64 and 1/16 restrictors or two 1/16 restrictors for more boost holding ability.
Therefore, should hold a bit more boost for longer and alleviate the drivability issue.
I will also test the bov with a 1/16 hole, but currently testing the 5/64 hole.
Items needed for this MOD:
10/24 NC Screw Tap (home depot, local hardware store)
10/24 x 1/4" Set Screw (home depot)
5/64 COBALT (metal) drill bit (home depot made by RIGID)
Bench Vise
Drill
Blue Loctite
Procedure:
1. Take apart the stock X BOV.
2. Use 10/24 Tap on reference hole (pic from 1g DSM BOV). Clean out the burrs well.
3. Put set screw in vise and drill the hole. It is a royal PITA to drill. DO NOT GET HARDENED STEEL set screws. The home depot ones are SS, not hardened. I drill them from the side that use a allen key to screw in the set screw. It is easier to drill from the top rather than bottom. Remember to use oil and low drill speed, otherwise the drill bit snaps... DO NOT DAMAGE the threads in the vise.
4. Loctite the set scew with the hole and screw it in. Let the loctite settle for a hour or two.
At the end should look like this... except with a small hole in the middle of the set screw.
5. Reassemble the BOV. Lube with grease the bottom O-ring on BOV cap.
I am currently testing if this will work as it is supposed to... I will update as I find out how well it holds boost and how the driveability is after a few days.
I already have gone through two BOV's a Forge RS and GFB Steath FX. The Forge RS produced harsh driving conditions on the highway causing fluttering issues under part throttle. The GFB is not too bad with the flutter when it hot, but has many issues when it gets really cold. Like in the single digits F...
The GFB and RS both held boost great in the higher PSI ranges. But they did not produce the stock like driveablity.
So I began a hunt for a solution. The stock BOV is perfect, except for one flaw it leaks boost in the upper psi range for most people, but not all. Some did get a freak stocker that holds 28 psi all day long.
So after some searching. I found two solution. One was the "GUS MOD" and the other the Dejon Tools Mod.
The "GUS MOD" covers the reference hole on the bottom of the BOV. Then creates a new orifice that sits on the side of the BOV that is VTA. What is does it prevent the bottom of the diaphragm from seeing boost and there for open prematurely. What it also creates is driveability issues... especially on DECEL.
However, the BOV does hold more boost. You can hook up the new reference hole to a boost source and have the valve work like stock again.
The "Dejon Tools Mod" goes one step further. It does the same thing as the GUS mod, but also add a mechanical solenoid that closes at 15 psi of boost. This makes the BOV hold more boost. But, work like the stocker below 15 psi of boost. I am sure you could create this with a electronic solenoid and hobbs pressure switch (similar to meth injection). Set the switch to XX psi and it will close the solenoid. I would guess it would create a smoother transition than a mechanical valve.
The original Dejon tools mod is a step above the Gus Mod. But works on the same principle. I think if someone wanted to try to run a hobbs pressure switch the turns on a solenoid to close would be pretty sweet. But I have no idea how well it would work. The solenoid would have to react very quickly.
This brings me to my idea...
Now my theory.
The GUS MOD works by blocking the reference hole completely so it is air tight. No air gets to the bottom of the diaphragm to push it up early. But it also causes driveablity issues.
So why not create a new MOD... I will call if the KRIS MOD... I know creative.
The reference hole is 4.6mm wide...
If I drill through the set screw with a 5/64 drill bit I create a 1.98mm hole... Reducing the reference hole by more than half...
In theory it creates a restriction... less air can get through the reference hole... to the bottom of the diaphragm to pop it open in a given amount of time. It works the same as a "BOOST PILL" limits the amount of air a solenoid see's at a given time thus typically lowering boost level with a smaller hole. Once the hole is enlarged you gain boost pressure. Same idea holds true here. Limit the size of the hole, limit the amount of boost that is transferred to the bottom of the diaphragm. I doubt I can go much smaller than 1/16 without fancy machinery. If you make the hole about 1/16" then you reduced its size by ~66% from stock. Much less boost gets to the diaphragm to pop it open early.
I am sure in theory you can add another restrictor... or a combination of a large and small resistrictor.
One Restrictor == - ==
Two Restrictors == - == - ==
I sure that if you add another restrictor instead of just one the boost holding would increase a bit more.
Try a combination of 5/64 and 1/16 restrictors or two 1/16 restrictors for more boost holding ability.
Therefore, should hold a bit more boost for longer and alleviate the drivability issue.
I will also test the bov with a 1/16 hole, but currently testing the 5/64 hole.
Items needed for this MOD:
10/24 NC Screw Tap (home depot, local hardware store)
10/24 x 1/4" Set Screw (home depot)
5/64 COBALT (metal) drill bit (home depot made by RIGID)
Bench Vise
Drill
Blue Loctite
Procedure:
1. Take apart the stock X BOV.
2. Use 10/24 Tap on reference hole (pic from 1g DSM BOV). Clean out the burrs well.
3. Put set screw in vise and drill the hole. It is a royal PITA to drill. DO NOT GET HARDENED STEEL set screws. The home depot ones are SS, not hardened. I drill them from the side that use a allen key to screw in the set screw. It is easier to drill from the top rather than bottom. Remember to use oil and low drill speed, otherwise the drill bit snaps... DO NOT DAMAGE the threads in the vise.
4. Loctite the set scew with the hole and screw it in. Let the loctite settle for a hour or two.
At the end should look like this... except with a small hole in the middle of the set screw.
5. Reassemble the BOV. Lube with grease the bottom O-ring on BOV cap.
I am currently testing if this will work as it is supposed to... I will update as I find out how well it holds boost and how the driveability is after a few days.
Last edited by Clipse3GT; Jan 5, 2010 at 01:01 PM.
Jan 5, 2010, 09:32 AM
#4
Well, first results are in.
The BOV does not open up prematurely on DECEL when in vacuum. There is no jerking on DECEL. The release is very smooth. (I'm not sure if it didn't make the BOV quieter, it's been a while since I had a stock BOV on, might be not used to it.)
The most important part is the the car now spikes to 27 psi each pull... before with the GFB the car used to spike to 25.5-26 psi. I might have gained a PSI. The release up top is smooth and fast.
Highway tests pending due too snow covered roads...
If anyone try's this let me know how your results pan out.
EDIT: I will be hopefully testing this on a stock EVO X with only a tune and DIF. I hope within the next few days see what the results are.
I might try it with a 1/16 hole (1.56 mm) compared to the 5/64 (1.98 mm) hole difference of 0.42 mm. I doubt there would be a difference in results. But then again, I am not sure.
The BOV does not open up prematurely on DECEL when in vacuum. There is no jerking on DECEL. The release is very smooth. (I'm not sure if it didn't make the BOV quieter, it's been a while since I had a stock BOV on, might be not used to it.)
The most important part is the the car now spikes to 27 psi each pull... before with the GFB the car used to spike to 25.5-26 psi. I might have gained a PSI. The release up top is smooth and fast.
Highway tests pending due too snow covered roads...
If anyone try's this let me know how your results pan out.
EDIT: I will be hopefully testing this on a stock EVO X with only a tune and DIF. I hope within the next few days see what the results are.
I might try it with a 1/16 hole (1.56 mm) compared to the 5/64 (1.98 mm) hole difference of 0.42 mm. I doubt there would be a difference in results. But then again, I am not sure.
Last edited by Clipse3GT; Jan 5, 2010 at 09:45 AM.
Jan 5, 2010, 09:55 AM
#5
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a couple noob questions for you man, what BOV is that? I have a forge I plan on putting on my car soon (X) along with FMIC UICP, LICP and turbo back exhaust. I am hoping not to have an issues with changing out the stock BOV, but it seems the computers are not liking mods at all.
Where you drilled the hole, I take that goes thru the inner portion of the BOV? When you say spiked, do you mean it just goes to full boost ASAP? or that it went over your preset boost settings?
Where you drilled the hole, I take that goes thru the inner portion of the BOV? When you say spiked, do you mean it just goes to full boost ASAP? or that it went over your preset boost settings?
Jan 5, 2010, 10:05 AM
#7
a couple noob questions for you man, what BOV is that? I have a forge I plan on putting on my car soon (X) along with FMIC UICP, LICP and turbo back exhaust. I am hoping not to have an issues with changing out the stock BOV, but it seems the computers are not liking mods at all.
Where you drilled the hole, I take that goes thru the inner portion of the BOV? When you say spiked, do you mean it just goes to full boost ASAP? or that it went over your preset boost settings?
Where you drilled the hole, I take that goes thru the inner portion of the BOV? When you say spiked, do you mean it just goes to full boost ASAP? or that it went over your preset boost settings?
The next two pictures are a 1G DSM BOV ( I borrowed the pictures off another website to illustrate what to do)
The main part is to tap the reference hole, then make a 1/16 or 5/64 hole in the set screw. Then loctite the set screw hole in the BOV reference hole.
The point is to limit the amount of air going through the reference hole, in turn this limits how much air is seen by the bottom of the diaphragm. If you limit or eliminate air coming to the bottom of the diaphragm then in turn it should take a bit longer for the BOV to open prematurely at high boost levels.
What I meant is the PSI peak at 26 psi previously on the GFB BOV and now peaks at 27 psi. I gained ~1 psi of pressure from doing this mod and changing BOV. I did not modify and other parameters of my car or ECU map.
The car is tuned for 26 PSI. So now I gained about 1 PSI on stock BOV.
I used a FORGE RS bov before it would flutter and throw a limp mode for me not matter what setting on spring hardness.
Last edited by Clipse3GT; Jan 5, 2010 at 10:19 AM.
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Jan 5, 2010, 10:33 AM
#8
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sorry, ive never done anything like this before, so if I start having some issues I might try this out as well. Just want to make sure I have it all right in my head thats all lol.
Jan 5, 2010, 11:26 AM
#10
I still think this method is better initially. I have not done all the testing due to weather. But I will do some logging and see. I might borrow a unmodified valve and see if there is a difference in the logs.
