I don't think the 2g BOV's were a mistake.

[Gregory]

Hey everyone. I was just thinking about how everyone bashes on the stock 2g plastic bov, and was wondering why Mitsubishi engineers made this switch. Well, I actually always kind of had a suspicion that they did this for a reason. I have no proof, but I figure it is a nice safety feature for the engine internals. If any of the turbo management components malfunctioned and caused too much boost, the bov would leak it instead of it being forced into the engine. For example, arguments vary about how much boost you should run with the stock fuel system on a 2g. Most say 15lbs, but some say as low as 12lbs. Well, when I first threw on a 1g bov without a boost controller, my boost went from 13lbs (where the 2g bov leaked) to 16lbs (umb, too much). Now, this was with the boost solenoid restrictor removed, so don’t worry about the numbers. But I was thinking about how the 2g BOV kept me out of the dangerous range. I know this is solved with a boost controller, but I figure, theoretically, someone should want a bov that leaks just over the amount of boost they run. If you run 15lbs, you want it to blow at 16lbs. If you run 22lbs, you want it to blow at 23lbs. And when Mitsubishi engineers designed a car to run 11psi (or w/e the stock boost level is), they knew it was a good idea to have a bov that leaked at 13lbs. With that stock boost level below 13lbs, it not only seemed okay, but a smart way to protect your engine with a “leaky bov.” Of course, they are useless to anyone who wants to raise their boost, but on a stock car, it’s a nice safety feature, and a good idea. Just a thought… I heart dsms.
-Greg

 

[dave99gst]

i dont doubt that its intentional - they just leak at a point were we dont want them to.

They must be fine with the design seeings how they kept using it on EVO's (sept mr's)

 

[Apeximprt2nr]

I see what you're trying to say but yeah, I do'nt think that was the purpose of them. I believe they are just crap, and Mitsu. didn't see a reason to spend lots of money nor research to get a great holding BOV.

 

[zippyshoe]

The construction of the 2g BOV to leak at higher boost levels probably was intentional - if you look closely at the 2g BOV, you will see it contains a small opening through the center of the valve. This would act as a small passageway for pressurized air to bypass the valve, even when the valve is closed. This is probably a redundant safety feature to protect against an overboost condition (due to a wastegate malfunction, for example.) However, this "feature" seems to be unnecessary since protection from overboost is already provided by the ECU's fuel-cut feature - which removes fuel from the engine upon detection of an overboost condition.

So the leaky 2g BOV may be a useful redundant safety feature to protect against overboost on factory cars, but is a real detriment to anyone trying to run higher-than-factory boost levels.

 

[BrokenTsi]

I think its just mitsubishi contracting out to the lowest bidder in cheap parts.

 

[Defiant]

if you look closely at the 2g BOV, you will see it contains a small opening through the center of the valve. This would act as a small passageway for pressurized air to bypass the valve, even when the valve is closed. This is probably a redundant safety feature to protect against an overboost condition (due to a wastegate malfunction, for example.)

It's more likely to let it close more quickly.
They're plastic, and have a tendency to come apart. Mitsubishi never had the slightest suspicion we'd be keeping these cars running at the edge of their lives for more than twenty years. They thought better cars would be coming along.

 

[c4uldr0n]

It's more likely to let it close more quickly.
They're plastic, and have a tendency to come apart. Mitsubishi never had the slightest suspicion we'd be keeping these cars running at the edge of their lives for more than twenty years. They thought better cars would be coming along.

Well put! I don't think most manufactures of cars think their cars will last more than 7-10 years... most people don't even change oil at proper intervals for crying out loud.

As for the 2G BOV, like any manufacture of cars, when they bid out parts and can save $0.02 per part, they will go with it. It will save them millions.

-c4

 

[Talesin]

Er.. also, a boost controller won't let you turn boost down any lower than a direct line from the compressor outlet elbow to the wastegate actuator would.
Might want to check your vacuum lines to make sure they aren't cracked or leaking though.

 

[zippyshoe]

It's more likely to let it close more quickly.
They're plastic, and have a tendency to come apart. Mitsubishi never had the slightest suspicion we'd be keeping these cars running at the edge of their lives for more than twenty years. They thought better cars would be coming along.

I think I may have found a use for my old 2g BOV - I'm using it as a handy paperweight!

 

[housegsx]

I doubt they used the crappy bov as a safety feature. That is what the t-25 is for. You can't really overboost that thing. Plus, if it was designed to leak you'd have a major boost leak and be overspooling the turbo to make what little boost it can leading to turbo failure.

 

[DSMunknown]

I doubt they used the crappy bov as a safety feature. That is what the t-25 is for. You can't really overboost that thing.

You wanna bet?

 

[housegsx]

You wanna bet?

Past 5k rpm... yeah. haha. I think I spiked at 24psi once on the t25 when my boost controller was frozen. But that was probably at 3500rpm.

 

[wvturbo2]

If it was purposeful how come they used it again on Evo 8 and relized the mistake and only use metal bovs on Evo 9?