How to make your 2g blow off valve not suck

[turbo BMW]

Allright first off I realize this is not the right forum to be posting this but because of the forum rules I am not allowed to post anywhere else. If someone who is an established member would like to steal this and put it in the Turbo Tech Forum, that would be great.

Okay so we all know that the 2g DSM blow off valve are notoriously crappy and hold no boost at all so I decided to get my hands on one and play around with it to see if I could make it hold more boost pressure without leaking. Here's my crappy drawing of a 2g BOV.

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A DSM friend of mine gave me one for free to play with so I started to do some bench testing with an air compressor. I made an addapter so that I could hook the bottom port of the wastegate directly to the compressor tank and an extra line with a release valve to use for the top port of the diaphram. I started bench testing it just as it was and found that it was actually leaking at 3 psi of pressure!

Heres why, there is a hole drilled through the center of the valve which allows boost pressure to travel up the valve and inside the wastegate can under the diaphram. Under boost the pressure is equal above and below the diaphram so it relies totally on the spring pressure to hold it shut. With any amount of boost pressure at all the valve is forced open and it leaks.

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So why is the hole there? When you let off the throttel manifold vacume sucks all the air out of the top of the wastegate can which combined with the boost pressure under the diaphram forces the valve open and venting the excess boost pressure.

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So whats the fix? This is a trick that has been used on the 1g bov's for years, it just takes some creativity to addapt the trick to the 2g's. What you need to do is shut off the supply of boost going to the bottom port of the wastegate can. So just simply find something to plug the hole in the center of the valve. In my case I coated a nail with epoxy and simply stuck it in the hole. Then you need to make a hole to be vent the pressure out of the bottom part of the wastegate can when the valve moves. I drilled a small .100" hole in the can from the outlet port of the wastegate. Make sure you put the valve in in a vise or something to push the valve open to make sure you don't drill into the diaphram when you do it.

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After you have done this the wastegate will work as follows

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I again bench tested the valve to make sure it works so I filled the air tank with about 20 psi of air and the valve stayed tightly shut. Then I removed the pressure line from the top of the wastegate and the valve instantly vented the entire air tank even without a vacume source. The valve does not have a very good seal so it never seals up compleatly but the amount of leakage is minimal and won't affect performance, you can barely feel it on your hand. Next I started increasing the pressure to see what would happen. I eventually increased the pressure up to 50 psi and the valve still stayed firmly shut. Again I increased the pressure a bit and the valve blew compleatly off the connector from the pressure! So I made one final check to make sure the diaphram was still intact after seing 50+ lbs of pressure and it was. To test it out I put it on my BMW which runs 15 lbs of boost. It never leaked and vented quickly. Becouse I removed the boost source under the diaphram the valve doesn't open quite as easily as before, but it still opens redily at any pressure above 2 psi or so. So if your a cheap ass like me there is a way to make the bov on your 2g capable of holding some boost pressure without throwing it away and getting a new one.

 

[95fwdtsi18psi]

Wow, really good thoughts you have here. The only time I could see people doing this though would be if they couldn't fork out enough money for a 1g BOV. It's a really nice article, but it's just not practical when we can get a 1g BOV off this site for like 10 bucks. I really respect what you accomplished though.

 

[knochgoon24]

Not bad

 

[fox4]

Very nice job man. This is the kind of thinking that makes this site very useful to all that use it!

 

[DyNamiC]

Good job, excellent write up too!

 

[ricktb]

sounds like it really could work, cool pics btw

 

[Calan]

Nicely done. Hopefully a mod will see this and move it to the articles section and throw some chiclet points at ya

 

[97gst_spyder]

Great thinking...

I'm trying this, this weekend.

 

[Defiant]

Nicely polished turd.

Now you can solve the weld failure between the pressure chamber halves. Oh, that's been done.

By buying a 1G BOV.

The "crappy" 2G BOV was meant by Mitsubishi to leak. It reduces the boost to the engine, reducing engine stress and lowering the number of warranty rebuilds Mitsubishi would have to do when they were new.

 

[turbo BMW]

Nicely polished turd.

Now you can solve the weld failure between the pressure chamber halves. Oh, that's been done.

By buying a 1G BOV.

The "crappy" 2G BOV was meant by Mitsubishi to leak. It reduces the boost to the engine, reducing engine stress and lowering the number of warranty rebuilds Mitsubishi would have to do when they were new.

Even if thats the case, just because the bean counters decided it was a good idea doesn't mean it is. Thats what overboost protection is for. Boost leak is bad for a couple reasons, 1-it forces the turbo out of its efficiency range and thus leads to higher charge temps, 2-because it forces the turbo to work harder it increases backpressure, 3-on a MAF vehicle it is leaking metered air.

The 1g leaks pretty bad too unless you perform the same modification. I did the same mod on a 1g valve a couple years ago. When I was bench testing it beforehand it leaked horrably at 10psi and up. Either way they both leak, the 1g just leaks less.

 

[bling5tatus]

I believe this has been coined the "Dodge Garage Mod" (google it). It is a good idea and has been known to work very well... I will also warn you that there's a lot of people here that will preach to recirc your "bypass" valve. Lot's of people w/ maf's that don't know what they're doing will vent their bypass valve because it sounds cool.... not realizing the negative effects it's having on their tune.

Either way, good write up. I seem to remember the casing for the 2g bov's is plastic or no?

 

[rush2252]

I believe this has been coined the "Dodge Garage Mod" (google it). It is a good idea and has been known to work very well... I will also warn you that there's a lot of people here that will preach to recirc your "bypass" valve. Lot's of people w/ maf's that don't know what they're doing will vent their bypass valve because it sounds cool.... not realizing the negative effects it's having on their tune.

Either way, good write up. I seem to remember the casing for the 2g bov's is plastic or no?

The Dodge Garage Mod isnt the same. That mod allows the BOV to have a quick release function in no way the same as this. Its a good write up but a waste of time. The 1g BOV can be crushed if done correctly and has been tested upwards of 30+ psi.

Also note Ive seen more mitsu 1g BOV on other vehicles than any other brand. Still not sure why people spend 200USD on greddy etc.

yes the 2g turd is plastic... they suck period

 

[bling5tatus]

Well, I don't want to get into a debate about the dg mod here because that's not what this thread is about... I will link here and let others determine for themselves if this is the same thing (it really looks like it is).

DDG- Talon BOV mod for HIGH BOOST

In the last paragraph it says, "Now pressure from the uicp cannot reach the lower part of the bov...."

Oh... and crushing bov's may work and it may get so and so to hold 35psi boost... but it's really an unexact "science" (if you want to call it that)...

 

[turbo BMW]

yeah thats the one ^^^ I did that to a 1g a long time ago, worked great. This is just a way to do the same thing to the 2g. Take it as you will, if you don't like it don't do it.

 

[RedTurboEclipse]

Another alternative and DIRECT INSTALL for stock 2g pipe.. EVO VIII, IX BOV. Just don't make those EVO guys find out its an upgrade for us like their fuel pumps or else they will inflate the price

turbo BMW, thanks for your efforts, you might want to submit this into the articles and let the website host the image via attachment so images are not broken down the rode.

 

[Dsmj89]

It's a really nice article, but it's just not practical when we can get a 1g BOV off this site for like 10 bucks.

+1 to that.

Another alternative and DIRECT INSTALL for stock 2g pipe.. EVO VIII, IX BOV.

Gotta love those bov's. They can be had for cheap, drop right in the stock pipe, and hold boost better than any 1g or greddy bov.

Great write-up though and props for the effort.

 

[RedTurboEclipse]

The IX is actually the better of the 2. The VIII I believe is still plastic, but actually holds a lil over 20+ compared to the craptastic 2g. The IX is what steel/metal?

 

[Dsmj89]

I had the 9 bov on my previous gst, i believe it was steel, same material like the 1g bov, just a waaaay better spring by a long shot. Really stiff.

 

[JusMX141]

The Dodge Garage Mod isnt the same. That mod allows the BOV to have a quick release function in no way the same as this. Its a good write up but a waste of time. The 1g BOV can be crushed if done correctly and has been tested upwards of 30+ psi.

I hate to seem argumentative, but the Dodge Garage Mod is exactly the same.

What's done here is he's capped off the hole in the center of the shaft leading to the quick-release chamber at the base of the diaphragm, the same as one would cap off the hole on the base of a 1G valve when performing the Dodge Garage Mod.

 

[bling5tatus]

^^You're right, I just didn't want to get into it with another person on this site that thinks they're correct.

Again, good write up and thanks for helping push people that may read this in the direction of doing things the practical way instead of doing what everyone else says is good or works. It's new thinking that pushes the sport, not old.

 

[97gst_spyder]

What did you use to plug the hole? Also, how did you drill the hole at that angle?

 

[ricktb]

So whats it sound like with this mod.. without quick release would it be like a whoosh instead of a chirp?

 

[Defiant]

No, you aren't going to hear a difference. BOVs are not musical instruments. Any sound they emit is a circumstance, not a goal.

 

[bling5tatus]

No, you aren't going to hear a difference. BOVs are not musical instruments. Any sound they emit is a circumstance, not a goal.

Amen to this. People need to stop venting w/o the proper air metering setup (clue: your stock maf/ecu setup is NOT the right setup). It doesn't make you cool and it doesn't make your car faster, in fact it makes your car SLOWER because of the jacked up fuel trims you get.

 

[bling5tatus]

What did you use to plug the hole? Also, how did you drill the hole at that angle?

You didn't read the entire post? He says what he filled the hole with in the description. Also, you can drill a hole (at any angle) .... with a drill. Get a 2g bov in your hand and look at it and I'm sure the answers will come to you.