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Rb25det Free Boost?


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Yo! Whats goin on.. Jus sayin hi an postin my first Topic! haha..

Ok.. So I just got done talkin to a guy that works for Nismo.. I was pickin up a new nismo thermostat for my RB25 and we started talking about our cars.. I started talkin about the thread on here about runnin hi boost all the time by grounding the actuator solenoid but was stopped by him.. He said he knew a better way to get free boost and more of it, All you need is the stock BOV..

He stated that if you take the stock BOV and Indent the top of it you can get anywhere from 10-14psi..

Now it needs to be kinda cupped.. He said if you do it right it should look like a golf ball can sit right on top of it perfectly..

I removed the BOV and used a 3/4 open end wrench and a hammer to tap down the top of the BOV.

I just set the wrench on top of the BOV and tapped it with the hammer in a circular fashion until I ended up with a nice deep "Dish" shape on top of the BOV.. I dont know how much Boost Im actually pushing now ( since I have no gauge) But the throttle response is incredible now and my high end in 2nd, 3rd and 4th are insane! Just thought I'd share.. Once I install my gauge I'll let you all know exactly how much it's pushin now. ^_^

Also... Whats your take on doin the actuator mod and runnin on HI boost all the time with this??

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Been discussed before.... bit dangerous IMO cos you (unless you have an am boost guage) don't know what boost you're running.... also, what if you go too far. Guess it would be handy to have a spare bov sitting around

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Been discussed before.... bit dangerous IMO cos you (unless you have an am boost guage) don't know what boost you're running.... also, what if you go too far. Guess it would be handy to have a spare bov sitting around

I didnt smash the hell outta it or anything, Just put a nice lil dip in it.. But yeah. I agree on the gauge part.. I got one now I just have to install it..

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Whats the point of damaging your blow off valve for questionable gains in boost when to ground your solenoid you're looking at 10 minutes completely reversible work with a small piece of wire.

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Am I missing something? or am I just plain stupid?

How the heck does squashing the top of a stock bov restrict/bleed pressure from getting to the wastegate actuator thus making it open later? Wouldn't it just increase the spring tension in the bov?

I mean the wastegate actuator is being triggered by the boost solenoid which doesn't go anywhere near nor gets its pressure from the bov. Therefore the wastegate actuator shouldn't be hindered by the bov regardless of what you do to it.

Edited by KeyMaker
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I think it essentially adds more pressure to the spring that holds the valve shut.

hence will hold more pressure.

and - running without a boost guage.. are you crazy? the only time I would ( and I am now ) run with no boost guage is on a completely stock motor. I would get a boost guage in there ASAP

you dont want to be running your motor on an unknown PSI rating.. just asking for trouble if you ask me

Be sure you keep a keen ear out for detonation etc.

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squashing the top of the bov won't do a thing to boost pressure. it will mean that it doesn't leak as much (if it was leaking before) and that it will flutter slightly. plus if you are running higher boost it won't vent as well as stock because you are actually limiting the amount of travel it has.

and doing that mod to the wastegate won't work either. by squashing the front of the wastegate you may actually open the wastegate slightly. the spring in the wastegate is at the back of it.

so in short, that guy you were talking to is a complete wanker.

the hi boost mod has been done by many people on here succesfully.

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squashing the top of the bov won't do a thing to boost pressure. it will mean that it doesn't leak as much (if it was leaking before) and that it will flutter slightly. plus if you are running higher boost it won't vent as well as stock because you are actually limiting the amount of travel it has.

and doing that mod to the wastegate won't work either. by squashing the front of the wastegate you may actually open the wastegate slightly. the spring in the wastegate is at the back of it.

so in short, that guy you were talking to is a complete wanker.

I'm thinking along the same lines as you.

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damn, someone already made the complete wanker call :(

the mod is for increasing spring strength... thats all... if its leaking due to the high amounts of boost you are already running, and your all of a sudden too cheap to buy something new, then this is the mod for you! :)

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without a before and after boost reading you cant really tell how effective it is.

Well the stock is 5-7psi so I'll be able to tell the difference after I install my gauge..

Whats the point of damaging your blow off valve for questionable gains in boost when to ground your solenoid you're looking at 10 minutes completely reversible work with a small piece of wire.

Cause I got an new HKS SSQV sittin around I just got lazy and never made a adapter/flange for it.. So if the Stock BOV woulda got damaged then it woulda been ok.. And I can STILL mess with the solenoid if I want.. It's not like doing what I did is going to hinder my from being able to do that mod.. :pirate:

Am I missing something? or am I just plain stupid?

How the heck does squashing the top of a stock bov restrict/bleed pressure from getting to the wastegate actuator thus making it open later? Wouldn't it just increase the spring tension in the bov?

I mean the wastegate actuator is being triggered by the boost solenoid which doesn't go anywhere near nor gets its pressure from the bov. Therefore the wastegate actuator shouldn't be hindered by the bov regardless of what you do to it.

ok.. So I dont know exactly how it works or anything like that.. I just thought since I had a an extra BOV id give it a shot.. But ya know what?? IT WORKED! I may not know exactly how much boost I'm runnin But I KNOW that theres been an increase.. I can feel it.. It's pretty noticeable..

I think it essentially adds more pressure to the spring that holds the valve shut.

hence will hold more pressure.

and - running without a boost guage.. are you crazy? the only time I would ( and I am now ) run with no boost guage is on a completely stock motor. I would get a boost guage in there ASAP

you dont want to be running your motor on an unknown PSI rating.. just asking for trouble if you ask me

Be sure you keep a keen ear out for detonation etc.

Thanks and I'm installing the gauge today.. hopefully if time allows.. :blink:

squashing the top of the bov won't do a thing to boost pressure. it will mean that it doesn't leak as much (if it was leaking before) and that it will flutter slightly. plus if you are running higher boost it won't vent as well as stock because you are actually limiting the amount of travel it has.

and doing that mod to the wastegate won't work either. by squashing the front of the wastegate you may actually open the wastegate slightly. the spring in the wastegate is at the back of it.

so in short, that guy you were talking to is a complete wanker.

the hi boost mod has been done by many people on here succesfully.

the whole Hi boost mode mod is fine but only changes your dual stage from going from 5-7psi to 7 all the time.. No real increase in anything except in your low ends.. The BOV mod gives you an increase anywhere from 10-14psi ( so i've been told, and I cant verify till I gauge it.. Dont worry I'll do it soon..) but you cant really call the guy a wanker.. From your quick rant I take it you've never tried, done, or seen it so you dont really have a place to speak on it.. But it's fine.. everyones entitled an opinion.. :)

damn, someone already made the complete wanker call :(

the mod is for increasing spring strength... thats all... if its leaking due to the high amounts of boost you are already running, and your all of a sudden too cheap to buy something new, then this is the mod for you! :D

Im always open for FREE power power gains. Whats wrong with cheap if it works?? Not everyones got money to spend on everything so every little bit of Free gain helps us less fortunate tuners.. :yes:

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the whole Hi boost mode mod is fine but only changes your dual stage from going from 5-7psi to 7 all the time.. No real increase in anything except in your low ends.. The BOV mod gives you an increase anywhere from 10-14psi ( so i've been told, and I cant verify till I gauge it.. Dont worry I'll do it soon..) but you cant really call the guy a wanker.. From your quick rant I take it you've never tried, done, or seen it so you dont really have a place to speak on it.. But it's fine.. everyones entitled an opinion..

it isn't an opinion, it is a fact. the bov has NO affect on boost pressue unless it is faulty. i know people with aftermarket bov which have a higher spring tension than stock and it hasn't had any affect on boost. the bov is an open/closed item. if you squash the top of it you are just closing it tighter. it is like closing a car door. once it is closed if you make it close tigher it won't have any affect.

just so you know, here is a quick run down of how a bov works. as you boost up you have the boost pressure pushing on the bov from inside the intercooler piping, plus you have the same pressure pushing on the otherside from the little vaccum hose that runs to it. then you also have the spring tension helping it stay shut. now during this the bov is sealed shut (not letting any air through). when you back off and the throttle shuts, this creates a vaccum (negative pressure, so it is sucking) in the manifold. the top half of the bov is affected by this, so combined with the positive pressure in the intercooler piping, this over rides the spring forces the bov open and releases the air. by increasing the strength of the spring you have no affect on the boost pressure while it is boosting up. all it does is mean that it takes more force to open the bov when you lift off.

and yes i have infact squashed the top of my bov before, but only to prevent it leaking, and it had NO affect on boost pressure. i also know people that ran no bov. and guess what, when they put bov on it had no affect on boost pressure either.

the reason why squashing the bov cannot affect boost pressure is because the wastegate controls boost pressure. as boost pressure rises it pushes on a diaphram in the wastegate. this has a spring behind it the regulates what pressure it opens at. so no matter what you do to the bov it has ABSOLUTELY NO IMPACT on the wastegate.

a boost controller on the other hand restricts the amount of air that gets to the wastegate, letting it boost higher.

get it through your thick skull. the bov cannot raise boost. if you don't believe me then ring hks in japan, or topsecret and talk to one of their mechanics. they will tell you the exact same thing.

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I may not know exactly how much boost I'm runnin But I KNOW that theres been an increase.. I can feel it.. It's pretty noticeable..

Hahhahaaha, sure its not just the cold weather?

Dude you'll find out once you put your boost gauge on, it didn't change.

Unless your tampering with the wastegate actuator or BC, nothing would have changed.

Listen to mad082, he speaks truth.

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the way i see it is that because these stock bov's are all getting old now alot of them leak a fair bit and cause a power loss and cause the car to run rich as well.

So what this mod would do is simply keep the bov from opening which allows for no boost leaking from the BOV.

I can see how it works on a leaking BOV yes.

The next question i will ask is how many of us have had to replace leaking valves? i know a few people who have and this mod will just stop it from leaking which will make the car feel stronger.

Also if there is a increase in boost noticed from the stock level the reason why it would be happening is because of other mods done to the engine like bigger exausts and dump pipe and intercoolers which can cause the boost level to rise but it may not have been noticed before this mod because it was just leaking from the BOV anyway.

Seems easy to call someone a wanker when they make calls like this but when you think about it... in every day to day skyline's it could make a difference and probly does as mentioned here.

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