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BBSC BOV Help....

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I know that this has been talked about in other posts, but I haven't seen any specific answers. I'm running an aftercooled BBSC system and have some questions about the diverter/blow off valve. Excuse my ignorance! Is there a difference in the two, other than one vents to atmosphere, and the other back into the intake? I want to change the current Bosch unit with something that functions properly, and looks a little nicer. I've looked at the Forge units and they seem great, but what one do I need? The "closed loop diverter" (http://www.forgemotorsport.com/content.asp?inc=product&cat=0006&product=FMCL007P ) seems to look the same as the Bosch, although I'm not dumping back into the intake, so why couldn't I use the "dump valve" ( http://www.forgemotorsport.com/content.asp?inc=product&cat=0006&product=FMCL007P )
And then there's the "blow off valve" ( http://www.forgemotorsport.com/content.asp?inc=product&cat=0006&product=FMDV004A ) The BOV seems as if it may be the best option.... So what will work the best?

What direction should the current Bosch valve be installed. ( which end attaches to the aftercooler? )

Should there be air constantly excaping from the valve?

At what time shouldn't there be air excaping from the valve?

I've had a hell of a time with making boost, and this seems to be the only variable that may still be affecting this.

Please advise.....
 
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I am also setting up my aftercooler with a BBSC. Make sure you replace the original basch rubber couplers with silicone. The latter will leak. Get good T-clamps. You have to tighten the hell out of the belt.

The original Bosch units are prone to failure and are a source of boost leak.
We require a blow-off; these function to divert (blow-off) residual boost to the atmosphere when the throttle plate closes. The SC is still turning and producing some boost and it has to go somewhere when you come off the pedal.

As far as I can tell, they are all basically the same device. There are numerous manufacturers-some of the main players are HKS, Forge, Tiel (spelling?), Apexi, Greddy,....Some choose one over another for the characteristic sound produced on blow-off. I will never here it over my cat-less exhaust and do not care.

The basch aftercooler is a 1" pipe and none of the aftermarket will fit as is. You will have to weld a flange and may have to modifiy the fitting. I just ordered Aprexi. No good reason other than apparent configuration seemed to be best for my configuration.
 
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Tail sport would be the best way to go....IMO.

And I would stick it either where the original one was or embetween the cooler and charger, to dump the hot air.

if its open at "cruise" its ok, same deal with a turbo set up, will not affect anything. Your motor souldnt be under boost at idle or cruise any how LOL wouldnt be to good for it.

As soon as you open the throttle, your engine vaccum will decrease causing the valve to close and off you go.

Air will release as soon as you let off the throttle, depressurizing the charge system..

if your local and need a flange welded on, PM!

Hope this helped you out.
 
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while i agree Tial is the better BOV, what the BBSC uses, and most SC system use is NOT a blow off valve, it is a recirulation/diverter valve. it is sometimes very difficult to swap one out for the other....

I would stay with the diverter style of boost release.... try a porsche unit or a forge unit...
you can pick one of them up at www.ecstuning.com
 
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lets not forget, a diverter valve and blow off valve are the same thing..

DVs and BOVs are in essence the same. It's simply the nomenclature which is different. They both perform the same function, which is to protect the compressor from surging when the throttle plate closes.
 
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lets not forget, a diverter valve and blow off valve are the same thing..

DVs and BOVs are in essence the same. It's simply the nomenclature which is different. They both perform the same function, which is to protect the compressor from surging when the throttle plate closes.

not really true....using your statement a disc brake and a drum brake would be in essence the same, they are both slowing the wheel with friction........

lunch this week?
 
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while i agree Tial is the better BOV, what the BBSC uses, and most SC system use is NOT a blow off valve, it is a recirulation/diverter valve. it is sometimes very difficult to swap one out for the other....

I would stay with the diverter style of boost release.... try a porsche unit or a forge unit...
you can pick one of them up at www.ecstuning.com


The early BBSC does not divert. The Bosch unit on my install vented to atmosphere. It is my understanding that MOST FI set-ups do not recirculate.
 
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The early BBSC does not divert. The Bosch unit on my install vented to atmosphere. It is my understanding that MOST FI set-ups do not recirculate.[/QUOTE]

this is not true....most aftermarket, sure maybe...

lets think of it like this....audi, VW, and porsche without a doubt have the largest number of cars on the road that have FI. think about it...they have been consistantly running turbos for 30+ years and you can get a FI engine option on almost every car they make. except for very old models...they all use the bosch style diverter valve. I am 99% sure the new turbo bmw does also....but i could be wrong here. even the comptech SC for the S2K uses the diverter style. all the Dinan SC systems for a bmw use the diverter style as do all of the Vortec SC systems.


so while it mat be true that most aftermarket systems use a BOV, most factory systems use a diverter.

while you are just venting to atmosphere...there has to be a reason that mark basch used that style...maybe its the size? maybe its the ease at which it opens...? who knows maybe its was just a cheap solution...i do know that I have never, to the best of my memory ever seen a true BOV on a BBSC....there has to be some reason for this considering how custom most have gone with it.

let us know what you end up doing
 
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this is not true....most aftermarket, sure maybe...

....so while it mat be true that most aftermarket systems use a BOV, most factory systems use a diverter.

while you are just venting to atmosphere...there has to be a reason that mark basch used that style...maybe its the size? maybe its the ease at which it opens...? who knows maybe its was just a cheap solution...i do know that I have never, to the best of my memory ever seen a true BOV on a BBSC....there has to be some reason for this considering how custom most have gone with it.

let us know what you end up doing


All true. My post was intended to reference most aftermarket applications as this is the relevant thread.

In regards to the bosch unit used by MB; I do not believe that Mark gave it much thought; it was simple and cheap. Unfortunately, they have not proved very durable and are prone to leak. Many have changed this out for typical BOV (HKS, etc). My original install had the Bosch blowing out to atmosphere.

Does it matter if the BOV is positioned before or after the aftercooler? Install after would be simpler.
 
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All true. My post was intended to reference most aftermarket applications as this is the relevant thread.

In regards to the bosch unit used by MB; I do not believe that Mark gave it much thought; it was simple and cheap. Unfortunately, they have not proved very durable and are prone to leak. Many have changed this out for typical BOV (HKS, etc). My original install had the Bosch blowing out to atmosphere.

Does it matter if the BOV is positioned before or after the aftercooler? Install after would be simpler.[/QUOTE]

in theroy it should be as close to the throttle body as possable
 
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not really true....using your statement a disc brake and a drum brake would be in essence the same, they are both slowing the wheel with friction........

lunch this week?



BOVs and DVs serve the same purpose, they vent excess boost from the intake tract. The difference being that a BOV vents the extra boost pressure out into the atmosphere so you are loosing that boost, a diverter valve however blows the extra boost back into the intake before the turbo so it is used to keep the turbo spinning reducing lag. Some people will argue that you don't want the boost recirculating because it is blowing hot air back into the turbo and you want cool air from the outside. Most cars that originaly were equiped with a diverter valve seem to perform better when you stay with the diverter valve. It seems most peoples argument for a BOV is they like the noise it makes.

A wastegate is similar to a BOV or DV except it is between teh exhaust manifold and the turbo. It opens to allow exhaust gasses to bypass the turbo. it does this to keep the turbo from spinning beyond its intended RPM maximum.

courtesy of a full-race tech.....LOL


and no thanks on lunch, I'm full.
 
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BOVs and DVs serve the same purpose, they vent excess boost from the intake tract. The difference being that a BOV vents the extra boost pressure out into the atmosphere so you are loosing that boost, a diverter valve however blows the extra boost back into the intake before the turbo so it is used to keep the turbo spinning reducing lag. Some people will argue that you don't want the boost recirculating because it is blowing hot air back into the turbo and you want cool air from the outside. Most cars that originaly were equiped with a diverter valve seem to perform better when you stay with the diverter valve. It seems most peoples argument for a BOV is they like the noise it makes.

A wastegate is similar to a BOV or DV except it is between teh exhaust manifold and the turbo. It opens to allow exhaust gasses to bypass the turbo. it does this to keep the turbo from spinning beyond its intended RPM maximum.

courtesy of a full-race tech.....LOL


and no thanks on lunch, I'm full.


sounds correct to me aswell.
 
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BOVs and DVs serve the same purpose, they vent excess boost from the intake tract. The difference being that a BOV vents the extra boost pressure out into the atmosphere so you are loosing that boost, a diverter valve however blows the extra boost back into the intake before the turbo so it is used to keep the turbo spinning reducing lag. Some people will argue that you don't want the boost recirculating because it is blowing hot air back into the turbo and you want cool air from the outside. Most cars that originaly were equiped with a diverter valve seem to perform better when you stay with the diverter valve. It seems most peoples argument for a BOV is they like the noise it makes.

A wastegate is similar to a BOV or DV except it is between teh exhaust manifold and the turbo. It opens to allow exhaust gasses to bypass the turbo. it does this to keep the turbo from spinning beyond its intended RPM maximum.

courtesy of a full-race tech.....LOL


and no thanks on lunch, I'm full.

I concur with this statement!:biggrin:
 
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guys,
take off your egos.

whatever you want to call it, what we want to do is relieve the intake track of pressure from whatever it is we're presurizing it with. call it whatever you like, but when you drop throttle, the pressure needs to go away.

on a turbo it's because it can send a backpressure wave to the turbo. with a turbo on a stick like a vortec or procharger, it can do the same thing, but to a lessor degree because it's belt driven. on a roots type, like a comptech, even less so. HOWEVER, none of these forced induction units like boost shoved back up their ass.

a turbo will soon ruin its bearings and the others will also fail, but not quite as quick.

but what's being left out is the type of engine management.

until 2005, all hondas have been speed density. that means they use a pressure sensor or MAP (manifold pressure sensor) as the load calculation. in 05, the accord started to use both, but the MAF (manifold air flow) was the main calculation method. most oem's use maf.

the big difference is that on a map system, the ecu doesn't give a shit what you do with bleed from the boost when you drop throttle. HOWEVER, on a maf based system, the MAF has actually measured, not calculated, the airflow. so when you drop throttle on a maf, the bypass MUST be recirculated into the intake.

ALL nsxs are map based, so when you have whatever type of boost, no matter how you make it, and you drop throttle, it can vent to atmosphere and all's good.

this is why the comparison to VW is not correct. VW (like i said, most oems) uses MAF. honda doesn't.

think of it like this. all you keyboard experts can blow off all you want and the honda ecu doesn't give a shit.....:)

btw, same for aem and fic.
 
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guys,
take off your egos.

whatever you want to call it, what we want to do is relieve the intake track of pressure from whatever it is we're presurizing it with. call it whatever you like, but when you drop throttle, the pressure needs to go away.

on a turbo it's because it can send a backpressure wave to the turbo. with a turbo on a stick like a vortec or procharger, it can do the same thing, but to a lessor degree because it's belt driven. on a roots type, like a comptech, even less so. HOWEVER, none of these forced induction units like boost shoved back up their ass.

a turbo will soon ruin its bearings and the others will also fail, but not quite as quick.

but what's being left out is the type of engine management.



until 2005, all hondas have been speed density. that means they use a pressure sensor or MAP (manifold pressure sensor) as the load calculation. in 05, the accord started to use both, but the MAF (manifold air flow) was the main calculation method. most oem's use maf.

the big difference is that on a map system, the ecu doesn't give a shit what you do with bleed from the boost when you drop throttle. HOWEVER, on a maf based system, the MAF has actually measured, not calculated, the airflow. so when you drop throttle on a maf, the bypass MUST be recirculated into the intake.

ALL nsxs are map based, so when you have whatever type of boost, no matter how you make it, and you drop throttle, it can vent to atmosphere and all's good.

this is why the comparison to VW is not correct. VW (like i said, most oems) uses MAF. honda doesn't.
think of it like this. all you keyboard experts can blow off all you want and the honda ecu doesn't give a shit.....:)

btw, same for aem and fic.



actually if you would have READ my post you would have read that i was not comparing honda to vw, just stating that the OP's comment that most FI systems use a BOV was not true.

damn brandon...you'll agree with anything stmpo says anyway :(


hey thanks for the keyboard expert line too....considering you dont really know anyone here, or what their experiance level is or isnt....
 
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damn brandon...you'll agree with anything stmpo says anyway :(


hey thanks for the keyboard expert line too....considering you dont really know anyone here, or what their experiance level is or isnt....

leave brandon alone...... he agreed with me aswell

a never ending argument......

sounds to me you really dont know other peoples experiance levels either!!

and the keyboard expert is me. lol
 
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sorry, guess i gave you guys too much useful info.

bov and divertor are the same. you are just making them different because of how the air is account for by the ecu.

yes, the germans has been doing turbo forever. their management systems use a mass aif flow or maf to determine the air going into the engine. the divertors or bovs on these cars vent to the intake track AFTER the maf. that's because the air they blow off, has already been accounted for by the ecu. if you were to disconnect it (many do because the bov can sound cool) and vent it to atmosphere, it will cause a rich condition, enough to stall the engine as it returns to a lower rpm after the sudden throttle closing.

dsm, toyota, nissan and many other use a maf because of its accuracy vs speed density.

like i said, no nsx used a maf, just a map sensor. if you take a look, the map sensor is mounted in the throttle body. so in this case, venting your bov to atmosphere is no problem because the load is determined AFTER the bov and not before, like the maf cars.

not many cars use map, but unlike a maf, there's no restiction on the inlet (where the maf is located). it's also much cheaper and works very well. no big power supra, TT vette, etc, uses a maf.

if you still think i'm just typing, look at the setup on a german car and then find an srt4. it's a factory map style turbo. it's bov vents to atmosphere.

for ALL these nsx setups, venting to atmosphere is what you need to do. put it back into the intake and the map sensor will read it and a bump in airflow will have to be accounted for in the tuning. any of them will work. since you can vent to atmophere, you can get one that sounds cool (if you like that) when it opens. an option the maf cars don't have.
 
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leave brandon alone...... he agreed with me aswell

a never ending argument......

sounds to me you really dont know other peoples experiance levels either!!

and the keyboard expert is me bitches!! lol


actually he didnt agree with you....you both agreed with Dave (stmpco):rolleyes:

your in az also huh....you work @ aap also?
 
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sorry, guess i gave you guys too much useful info.

bov and divertor are the same. you are just making them different because of how the air is account for by the ecu.

yes, the germans has been doing turbo forever. their management systems use a mass aif flow or maf to determine the air going into the engine. the divertors or bovs on these cars vent to the intake track AFTER the maf. that's because the air they blow off, has already been accounted for by the ecu. if you were to disconnect it (many do because the bov can sound cool) and vent it to atmosphere, it will cause a rich condition, enough to stall the engine as it returns to a lower rpm after the sudden throttle closing.

dsm, toyota, nissan and many other use a maf because of its accuracy vs speed density.

like i said, no nsx used a maf, just a map sensor. if you take a look, the map sensor is mounted in the throttle body. so in this case, venting your bov to atmosphere is no problem because the load is determined AFTER the bov and not before, like the maf cars.

not many cars use map, but unlike a maf, there's no restiction on the inlet (where the maf is located). it's also much cheaper and works very well. no big power supra, TT vette, etc, uses a maf.

if you still think i'm just typing, look at the setup on a german car and then find an srt4. it's a factory map style turbo. it's bov vents to atmosphere.

for ALL these nsx setups, venting to atmosphere is what you need to do. put it back into the intake and the map sensor will read it and a bump in airflow will have to be accounted for in the tuning. any of them will work. since you can vent to atmophere, you can get one that sounds cool (if you like that) when it opens. an option the maf cars don't have.

exactly my point....
There is no need to put the air back into the intake stream with a speed density car.
There for, they are the same, your just redirecting the air flow back to the mass air sensor....
So that makes them both the same. period! end of discussion.
 
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actually he didnt agree with you....you both agreed with Dave (stmpco):rolleyes:

your in az also huh....you work @ aap also?

RLMAO!!!
mark your cracking me up...
and no i dont work at aap?!?!
you will never give up the argument anyways so its pointless to continue.

and its stmpo dork
 
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Everyone is entitled to there own opinion, so just settle down, I as of 4-18-08 no longer work for AAP, which is not a bad thing, AAP has been a great shop, but it has come time for me to venture into a new Company. As far as the topic of discussion, any info negitive or positive is good info, MR. Burner knows his stuff, I have the right to agree with him If I want too. Thanks Brandon.

p.s. who is Dave with STMPO racing?
 
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