Blow Off Valves

[honkie]

hey guys.. i've been researching about bov's and apparently i found out that the blitz bov suit best for the skylines becos it just bolts straight onto the stock one... is that true?

what do u think about the turbosmart kompact dual port bov?

im deciding on which one to buy..

[Bonsai]

most jap brands will fit perfect like a glove, if its made for your model car. all sound different thats the only difference. HKS is the best IMO. again all jap ones are good quality. but you don't need one and they can be defected apparently. Saying that i got twin HKS hehe.

[Sheng]

hey mate, stick with the stock one best option.

plus have you tried to search the forum? theres kezillion thread like this..

http://www.skylinesaustralia.com/forums/Pl...amp;hl=best+bov

http://www.skylinesaustralia.com/forums/Bo...amp;hl=best+bov

http://www.skylinesaustralia.com/forums/BO...amp;hl=best+bov lol

http://www.skylinesaustralia.com/forums/Bo...amp;hl=best+bov

etc etc

[GTL05T]

ur just asking for trouble + fines. Stick to stock bov that way u wont get hassled too much.

BOV is just a wank factor but sup to u.

In regards to ur question, u can fit almost all bov type just need adaptor plate to suit. Best place to buy

is either autobarn or ebay (well thats we i look anyways).

[Lorg]

Turbosmart do an adapter kit for the r33 to bolt any of the type 2 or type 3 bovs also do an adapter kit for the plumback section too.

[Liz]

remove the bov.. block it up

flutter is the way to go!

wooo

[**RB2530**]

The factory BOVs always leak...They are designed to leak. Pull one apart and you will see what i mean..

I use a Bosch OEM BOV...You buy it as a SAAB or Porsche spare part for about $60-70 dollars. If you are keen I cab get the part No..They are plastic but will hold up to about 1.5 bar reliably...They are also a plumb back...Leave you factory one installed and just fit the Bosch one into the hose coming from the factory one..

No cost, no fuss, no vent to atmosphere, no fu(ked up air flow calculation at idle with stock ECU, no defects and NO NEGATIVE publicity to other skyliners for RICE SOUNDING BOV sounds...

[Xmetal]

remove the bov.. block it up

flutter is the way to go!

wooo

Spoken like a true 180sx owner.

[ignuz]

It's so worth it for shenanigans.. E.g someone else has one next to you and you just go tuuutuututututututu for the next 500m between each other for a laugh

[**RB2530**]

I dont own a 180. never have and never will....I hate stickers you see, and dont the 180s come with heaps of stickers as stock?...

On a serious note if you want some good advice on BOVs read my previous post...Running an expensive BOV is like running billet tyre valve caps...Just trying to give some good advice and stop some of the RICE modifications occurring to skylines...Anything to get the cops of our backs...

[TTT]

Your previous advice was not good advice at all.

Would you like me to tear it down?

[**RB2530**]

Yep no probs, tear away

[Xmetal]

On a serious note if you want some good advice on BOVs read my previous post...Running an expensive BOV is like running billet tyre valve caps...Just trying to give some good advice and stop some of the RICE modifications occurring to skylines...Anything to get the cops of our backs...

Agreed.

Leave the factory unit on, if you want it to make whooshing noises unplug the return line and put a cap over the return line so you don't get vacuum issues.

[TTT]

The factory BOVs always leak...They are designed to leak. Pull one apart and you will see what i mean..

I use a Bosch OEM BOV...You buy it as a SAAB or Porsche spare part for about $60-70 dollars. If you are keen I cab get the part No..They are plastic but will hold up to about 1.5 bar reliably...They are also a plumb back...Leave you factory one installed and just fit the Bosch one into the hose coming from the factory one..

No cost, no fuss, no vent to atmosphere, no fu(ked up air flow calculation at idle with stock ECU, no defects and NO NEGATIVE publicity to other skyliners for RICE SOUNDING BOV sounds...

1.) BOSCH do not make a direct fit bov for the RB series of engines. They will require an adapter, then a new return hose as the stock one will not reach.

2.) They are only good for about 15psi of boost after which they leak.

3.) the sotck skyline bov (mitsubishi unit) is designed to leak as you have said but not leak in the way you hae meant it. it is designed to leak a little to make the transition from on/off boost and off/on boost, smooth. so the car doesn't jerk when you boost up and back off a little but not completely, or when you are cruising then plant your foot.

The_Mafia - a user on here is using the stock bov on his RB25.

his car makes 314rwkw at 18 psi or some shit (he says it at every oportunity he gets but I still forget it).

There are numerous other cars that make a lot of power on stock bov.

if you are worried about the little leak hole in the stock bov used for smooth operation on/off boost, then you simply use a small screw to block it and it is the same as your BOSCH bov.

If you believe that you will make more power than the proen amount that the user above makes or use more boost, and you still believe that the bov will leak (even though it can't due to the fact that there is equal pressure on both sides of the bov piston while under boost), then you can use the backyard method of CRUSHING the top of the bov a little to help it hold more boost.

If you want to make even more power, then for the $70 you were going to spend on a BOSCH bov, you can purchase a single GTR bov (they have 2 standard and each is larger than the stock GTST one) and bolt that straight on to the stock GTST bov position.

R31_Nismoid on here makes over 350rwkw with 1 single GTR bov.

if you are going to make even more power than that, then the dual STOCK GTR bovs have been used in 600HP+ supras and even more powerful GTR's.

the pair will cost you about $150 but will obviously need to have a mount fabricated and return lines for plumback.

but at that level, that is small money.

so.

BOSCH is useless on a skyline.

they are good on SAAB, some Subaru's, Lancer GSR and some early Evo's.

[**RB2530**]

1.) BOSCH do not make a direct fit bov for the RB series of engines. They will require an adapter, then a new return hose as the stock one will not reach.

2.) They are only good for about 15psi of boost after which they leak.

3.) the sotck skyline bov (mitsubishi unit) is designed to leak as you have said but not leak in the way you hae meant it. it is designed to leak a little to make the transition from on/off boost and off/on boost, smooth. so the car doesn't jerk when you boost up and back off a little but not completely, or when you are cruising then plant your foot.

The_Mafia - a user on here is using the stock bov on his RB25.

his car makes 314rwkw at 18 psi or some shit (he says it at every oportunity he gets but I still forget it).

There are numerous other cars that make a lot of power on stock bov.

if you are worried about the little leak hole in the stock bov used for smooth operation on/off boost, then you simply use a small screw to block it and it is the same as your BOSCH bov.

If you believe that you will make more power than the proen amount that the user above makes or use more boost, and you still believe that the bov will leak (even though it can't due to the fact that there is equal pressure on both sides of the bov piston while under boost), then you can use the backyard method of CRUSHING the top of the bov a little to help it hold more boost.

If you want to make even more power, then for the $70 you were going to spend on a BOSCH bov, you can purchase a single GTR bov (they have 2 standard and each is larger than the stock GTST one) and bolt that straight on to the stock GTST bov position.

R31_Nismoid on here makes over 350rwkw with 1 single GTR bov.

if you are going to make even more power than that, then the dual STOCK GTR bovs have been used in 600HP+ supras and even more powerful GTR's.

the pair will cost you about $150 but will obviously need to have a mount fabricated and return lines for plumback.

but at that level, that is small money.

so.

BOSCH is useless on a skyline.

they are good on SAAB, some Subaru's, Lancer GSR and some early Evo's.

1. I never said that the bosch BOV is a direct fit...there is a hose tail on both ends and you need to run some tubing to it...If you've got money to burn and dont like tools buy a direct fit...

2. There is a version of the Bosch BOV that is good for about 20 PSI. Just like factory it has an actuator on the low pressure side fed by manifold pressure. ie the higher the boost, the greater the force on the diaphragm and therefore tighter seating inside the valve. Higher pressure version has brass button reinforcing diaphragm to cope with larger forces.

3. Stock BOV leaks in two ways. The way you have mentioned (BTW if you block of the small breather hole you better make sure the screw is in tight as the only place it will end up is in engine) AND it also leaks because the valve actually consists of an alloy disc seating on an alloy body. Not the best seal...

4. I have been using Bosch BOVs on my Skyline for 4 years without a drama!! I have been running around 260rwkW (1.1 bar) for the last 12 months and the BOSCH BOV is fine.

Sorry mate we dont agree....

[TTT]

I agree that we don't agree.!

after proof of one member with 314rwkw using stock bov, you still don't agree that there is nothing wrong with the stock item?

and you will still recommend a BOSCH bov over a GTR bov (same price if not cheaper) where at least one member has a proven 350rwkw using a single GTR bov?

Won't even bother comparing the stock Dual gtr bov to this comparo.

You say alloy to alloy is not a perfect seal.

what is your BOSCH bov made of?

the last one I bought many years ago, had a plastic body, and the sealing valve was also plastic and it sat ON TOP of the hole.. it didn't even have a seat for the valve like the stock skyline one does.

The version you are talking must be different to th one I had or replacement for stock SAAB item as they are shitty items.

they do not hold over 15psi.

perhaps you've got a pic of your one?

Edited February 25, 2008 by GTST

[**RB2530**]

I agree that we don't agree.!

after proof of one member with 314rwkw using stock bov, you still don't agree that there is nothing wrong with the stock item?

and you will still recommend a BOSCH bov over a GTR bov (same price if not cheaper) where at least one member has a proven 350rwkw using a single GTR bov?

Won't even bother comparing the stock Dual gtr bov to this comparo.

You say alloy to alloy is not a perfect seal.

what is your BOSCH bov made of?

the last one I bought many years ago, had a plastic body, and the sealing valve was also plastic and it sat ON TOP of the hole.. it didn't even have a seat for the valve like the stock skyline one does.

The version you are talking must be different to th one I had or replacement for stock SAAB item as they are shitty items.

they do not hold over 15psi.

perhaps you've got a pic of your one?

Yes the Bosch one is plastic body, with a rubber diaphragm mounted on a brass disc. The seal is plastic seat on rubber diaphragm. This creates a better seat than alloy on alloy for air at ambient temperature..Happy to get into a debate about material science and whether or not this is good engineering practice if you like...Plastic has its merits...

The version I use is a Porsche spare part but also used on some SAABs. There is a low and a high pressure version out there..About $10-15 bucks difference.

As far as proof that the stock BOV do work..of course they do!! I believe you. What I also believe is that with the example you give (314rwkW with stock BOV) a BOV that doesn't leak may indeed turn this into 320rwkW...

What I can firmly attest to is that when I first got my Skyline, I gutted the stock BOV, used the body as an adapter and put a Bosch BOV on.The car was completely stock and there WAS an improvement...The stock BOV was perfect apart from the leakage...

So in my mind, based on my experience Bosch BOVs DO work on skylines...If they work on a Porsche, SAAB, VW, AUDI etc they will work on a Skyline...

At the moment I am trying to find the money to buy a twin or triple plate clutch to hold the power I am making (with my Bosch BOV)..The 5 puck single plater cerametallic is not up to the task...Now if I had spent $600 -700 on a shiny BOV that can make 5 different pphhttt oooosh noises my clutch would be little bit further from reach than what it currently is....

[TTT]

Can I ask how you came to the conclusion that the stock one was leaking?

as in, the seal between valve and seat.

how did you test this?

are you sure the difference you noticed wasn't the fact that you went from a bov with the bleed hole (stock one) to a bov without this hole?

[**RB2530**]

Can I ask how you came to the conclusion that the stock one was leaking?

as in, the seal between valve and seat.

how did you test this?

are you sure the difference you noticed wasn't the fact that you went from a bov with the bleed hole (stock one) to a bov without this hole?

I was told by a very experienced Nissan mechanic that they do leak. And of course, there is the bleed hole. The bleed hole is there as you say to make the BOV smoother in operation and the difference I noticed was probably due to effectively removing this leak. Nonetheless it is still a leak. The actuation diaphragm that connects to the plenum is sealed and doesnt seal up the BOV. And when I say leak, I dont mean massively, but enough to make a difference because:

When the BOV leaks it passes air back into the compressor via plumback line. This is a waste of energy as you are effectively bleeding air you have already compressed / cooled, away from the engine. If you are running the stock GTSt turbo that is undersized anyway the last thing you want to do is make its job even harder..

Once again its only a small loss but when you add up all of the minor losses in any motor car they become substantial. Some you can reduce, some you can't. A leaking BOV is easily fixed. Thats why I did it...

To me a BOV is just a device to make life for your compressor easier..As long as it can hold boost pressure, can react fast enough and vent the pressure, its a winner...Doesn't matter what brand or what it costs as long as it does its job properly...If I can do it successfully with a cheap Bosch OEM part...good luck my team...

[TTT]

Fair enough.

I just thought that you may have tested with a compressor and pressure on both sides of the bov and seen the leak yourself instead of just taking the word of a very experienced nissan mechanic who I doubt had any part in the creation/manufacture of the Mitsubishi bov.

In the end, your bov works, is plumb back and doesn't cost much.

perhaps you could do up a DIY How To thread on what you did to use your stock bov flange to mount the BOSCH unit. and what the BOSCH unit part number is (as you said there are 2 versions), how much you paid for it and where others can purchase it from.