280Z Turbo Posted August 10, 2008 Share Posted August 10, 2008 What are everyone's thoughts on crushed 1G DSM BOVs? Do they still work okay? I'm having a hard time finding 1-1/4 hose for the BOV recirculation. I know that you're technically not supposed to vent to atmosphere with a MAF setup like mine, but running a big fat hose looks like a real pain even if I do find one. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted August 10, 2008 Share Posted August 10, 2008 Let it vent! That way when it goes south on you, you can hear it! How do I know this well, because I used one on my car and got tired of the hose routing and just vented it to atmosphere one day. That is when I noticed it was leaking, badly. Oh yea it was crushed so that I could run 15 psi. Before when it was a recirculation BOV I did not know that it leaked so bad. I ended up replacing it with a Tial 50 mm BOV. No more leady BOV anymore. Hope this helps. HB280ZT Quote Link to comment Share on other sites More sharing options...
big-phil Posted August 10, 2008 Share Posted August 10, 2008 this is a very old video but at 2:20 you see my crushed B.O.V. at the time it worked very well! I just kept crushing the top little by little until it no longer leaked at boost. Also let it vent, the worst that will happen is the car will go rich for a split second because the MAF reads the air going in, tells the ECU how much fuel to give. When you vent, the ecu still thinks that air is there, so the fuel stays the same. Which will be a bit rich. Thats how I understand it any how. Quote Link to comment Share on other sites More sharing options...
Challenger Posted August 10, 2008 Share Posted August 10, 2008 Is it worse on the stock afm? I dont want my car to almost die in the middle of autox everytime I lift the throttle. Also how do you determine what psi the bov will vent at? How do you determine how much to crush it? Quote Link to comment Share on other sites More sharing options...
280Z Turbo Posted August 10, 2008 Author Share Posted August 10, 2008 Is it worse on the stock afm? I dont want my car to almost die in the middle of autox everytime I lift the throttle. Also how do you determine what psi the bov will vent at? How do you determine how much to crush it? It should not vent under boost. It's supposed to vent under vacuum. Quote Link to comment Share on other sites More sharing options...
Challenger Posted August 10, 2008 Share Posted August 10, 2008 Shouldnt it vent right after the TB closes and there is a increse in pressure in front of the Tb? If there was vacume it wouldnt really vent air out rather in... Quote Link to comment Share on other sites More sharing options...
280Z Turbo Posted August 11, 2008 Author Share Posted August 11, 2008 Shouldnt it vent right after the TB closes and there is a increse in pressure in front of the Tb? If there was vacume it wouldnt really vent air out rather in... As I understand it, when you lift off, it goes to around 20 inches Hg of vacuum, sometimes more. That makes it easy for the excess air in the intake pipe to push it's way out of the valve. If it leaks under boost, you've got a problem. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 11, 2008 Share Posted August 11, 2008 Shouldnt it vent right after the TB closes and there is a increse in pressure in front of the Tb? If there was vacume it wouldnt really vent air out rather in... In reference to manifold vacuum. Quote Link to comment Share on other sites More sharing options...
rvandivort Posted August 11, 2008 Share Posted August 11, 2008 Hi, Please expain "crush" for the rest of us idiots...with all do respect. Quote Link to comment Share on other sites More sharing options...
280Z Turbo Posted August 11, 2008 Author Share Posted August 11, 2008 Hi, Please expain "crush" for the rest of us idiots...with all do respect. It's when you put more preload on the spring in the BOV so that it's harder to open up. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 11, 2008 Share Posted August 11, 2008 Hi, Please expain "crush" for the rest of us idiots...with all do respect. You literally crush the BOV, most common way is to place in a vice and "crush" the top this way, to, as said, add more pre-load to the spring. Quote Link to comment Share on other sites More sharing options...
rvandivort Posted August 11, 2008 Share Posted August 11, 2008 And, if You lift off You have residual pressure on the intake wanting to go somewhere..thus the Bov and with the closed system..putting that stuff back in front of the intake turbine to keep it going. I don`t see the vacuum thing ..doesn`t make any sense. Quote Link to comment Share on other sites More sharing options...
rvandivort Posted August 11, 2008 Share Posted August 11, 2008 Hey, thanks for the answer! Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 11, 2008 Share Posted August 11, 2008 And, if You lift off You have residual pressure on the intake wanting to go somewhere..thus the Bov and with the closed system..putting that stuff back in front of the intake turbine to keep it going. I don`t see the vacuum thing ..doesn`t make any sense. When the throttle is closed, the intake manifold creates vacuum. This is how your "vacuum asisted power brakes" get thier vaccum. There is a hose that attaches between the plenum (manifold) and the "upper" part of the BOV, that will apply vacuum to the diaphram and either lift the plunger or help lift the plunger. Quote Link to comment Share on other sites More sharing options...
rvandivort Posted August 11, 2008 Share Posted August 11, 2008 True enough, but that is on the inside of the intake manifold. We are talking about the input at the throttle valve..on the outside--big difference. Quote Link to comment Share on other sites More sharing options...
Challenger Posted August 11, 2008 Share Posted August 11, 2008 Well If you look at the DSM bov there is a small ~1/4 hole and then a larger one. The larger one is to be vented back into in front of the turbo and then the smaller one goes to a vacume bung on the manifold, as you can see in the pictures. Quote Link to comment Share on other sites More sharing options...
rvandivort Posted August 11, 2008 Share Posted August 11, 2008 Hey Derek, Where are getting the DSM from? I`d like to see it so I can respond. Quote Link to comment Share on other sites More sharing options...
Challenger Posted August 11, 2008 Share Posted August 11, 2008 ' Shot a picture of mine. Quote Link to comment Share on other sites More sharing options...
rvandivort Posted August 11, 2008 Share Posted August 11, 2008 OOps, I do not know much about this, but the small inlet may not go to the intake manifold at all. Just guessing...Why would it? It`s controlling the input pressure. Why would MAP have anything to do with it?....just wondering.. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted August 11, 2008 Share Posted August 11, 2008 OOps, I do not know much about this, but the small inlet may not go to the intake manifold at all. Just guessing...Why would it? It`s controlling the input pressure. Why would MAP have anything to do with it?....just wondering.. Come on man, I just explained it..... The MANIFOLD VACUUM pulls the diaphram up, lifting the plunger off the seat, or in the case of a crushed BOV, applies vacuum to the top of the diaphram, to allow the high pressure in the intake tract to push against the plunger to lift it off the seat to vent excess pressure. I assure you, that "small inlet" does indeed get attached to the intake manifold. Do some research on BOV function, it will help you understand it's purpose and functionality. Quote Link to comment Share on other sites More sharing options...
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