blow off valve

[mwolfe1969]

I bought a used PTE front mount intercooler, my question is do you have to use a blowoff valve. What are some off the advantages or disadvantages of using one, driveability, etc. Thanks.

 

[BlackMetal]

No type of intercooler would require you to use a blowoff valve.

Advantage of a blowoff valve is when you get off the gas and the throttle blade snaps shut, the air has a way to escape the intake piping instead of making it's way all the way back to the turbo, slamming into the turbo blades, and causing the turbo to suddenly reverse direction and spin backwards.

Many guys have run turbos for years and years on these cars with no BOV and the turbo doesn't fail, but it doesn't hurt to run one either. They serve a bigger purpose on manual transmission cars where you loose boost pressure during every shift and need to spool the turbo quickly again. It would be a lot harder to spool the turbo up again if there was air coming backwards through the intake and pushing the wrong way on the turbo. So the air is released during shifts and then boost builds up again. Don't have to worry about that on an automatic trans.

No real driveability concerns if you install it correctly, my engine doesn't stumble or anything when the BOV goes off.

 

[vader87]

Personally I would use it. As stated above They are normally used for standard shift cars. Here is why I use one. When I am turning 6000 rpm and only God knows how fast the turbo is spinning, I let off the gas and hit the brakes, that compressed air has got to go somewhere. It is forced back through the turbo. I don't care what anyone says, THAT CAN'T BE GOOD ON THE TURBO'S BEARINGS! My turbo was $750 dollars and that was cheap, but I still don't care to replace it too soon!

 

[BlackMetal]

Personally I would use it. As stated above They are normally used for standard shift cars. Here is why I use one. When I am turning 6000 rpm and only God knows how fast the turbo is spinning, I let off the gas and hit the brakes, that compressed air has got to go somewhere. It is forced back through the turbo. I don't care what anyone says, THAT CAN'T BE GOOD ON THE TURBO'S BEARINGS! My turbo was $750 dollars and that was cheap, but I still don't care to replace it too soon!

Yup, a lot of guys try to live by the rule "if Buick didn't put one on from the factory then I don't need it", but let's face it, we put a LOT of stuff on these cars that Buick never did themselves, so that rule goes out the window. Just because some guys can run a turbo for years with no BOV and say it still runs good doesn't mean that there isn't a benefit to having one.

 

[Dreamcar86]

Yup, a lot of guys try to live by the rule "if Buick didn't put one on from the factory then I don't need it", but let's face it, we put a LOT of stuff on these cars that Buick never did themselves, so that rule goes out the window. Just because some guys can run a turbo for years with no BOV and say it still runs good doesn't mean that there isn't a benefit to having one.

That is a very good point!

 

[mwolfe1969]

thanks

Thanks, for the info what size and best place to order one from. Thanks, mike

 

[blackmonte]

Any pictures of that HKS bov? Did you mount it to the up pipe?

 

[BetMinesFaster]

I will be adding a BOV within the next week or 2, on my car if you accelerate fairly heavy around 15 psi boost and gently back off the gas to maintain speed the turbo sneeze causes some surging, its not major but noticable, with a BOV im certain i wont have this problem.....

 

[1991syclone]

OK I am putting on a BOV also, but who makes a connection between the TB and the inlet pipe. My up pipe is a thin alum. and the connector for the pipe need to be welded on (then you "bolt" the BOV to it). It would be nice to have a SS piece that goes between the TB and the up pipe, with welded nuts or bolts (so you never have to worry about the lock nuts coming loose). Does someone make an install kit???

 

[Stage 5]

I have a blitz super sound blow off valve in the parts for sale section, brand new never used in box with pics.

 

[BlackMetal]

Any pictures of that HKS bov? Did you mount it to the up pipe?

Here it is mounted on the uppipe...

Only downside is that I recently noticed my engine only pulls about 12" vacuum and it's possible that the vac leak may be related to this because I can't think of anything else. But I will try to hunt it down soon as maybe there's a leak somewhere else...

 

[turbojimmy]

Here it is mounted on the uppipe...

Only downside is that I recently noticed my engine only pulls about 12" vacuum and it's possible that the vac leak may be related to this because I can't think of anything else. But I will try to hunt it down soon as maybe there's a leak somewhere else...

It looks like you have a blow-thru MAF arrangement? I set my MAF up that way to cure a stumble when I moved to my BB70 turbo. I am now considering a BOV and would like to put it where you put yours but I'm afraid that I will re-introduce the stumble by putting the BOV after the MAF in the air stream. Do you have any trouble with yours?

Jim

 

[White Out]

I don't have a bov on my GN. On my STi I run a TiAL 50mm bov. It is a great piece. They come in all different colors also.

Nick

 

[Turbo1dr]

Venting a blowoff valve to atmosphere after the MAF will cause the engine to rich very rich until the turbo winds down.
If you have a BOV mounted in the up pipe it's best to let it vent back in between the MAF and turbo inlet.

 

[headstrong3157]

Here it is mounted on the uppipe...

Only downside is that I recently noticed my engine only pulls about 12" vacuum and it's possible that the vac leak may be related to this because I can't think of anything else. But I will try to hunt it down soon as maybe there's a leak somewhere else...

Is there a bolt that you can tighten and loosen to adjust how tight the valve is? If there is loosen the nut you would to adjust it and put some teflon tape behind the nut and then tighten it back down. I have a HKS bypass valve on my buick and it leaked until I put the tape on it then no more vacuum leak from there.

 

[87GNSteve]

BOV is not needed on these cars.
Save your money, the "benefits" seem to apply to the manual transmission 4 cyl imports, this reasoning has infected the new comers to the TR world.

Furthermore, of all the automotive turbo applications Porsche, Audi, GM, Ford, Toyota, Nissan, Dodge, Mercedes, BMW.
Of all the Heavy duty applictions International/Navistar, Cummins, Mack, Cat, DetroitDiesel, Mercedes, etc. None were offered with a "BOV".
Why? Its simply not needed, the original design of the CRHA's fully floating bearings with oiling provisions, and the newer ball bearings are able to function in either direction and provide support, because they were designed to function in a severe enviroment.
Once again look at the above manufacturers and see how many did come with manual transmissions and do not have bovs.
Its just a shame to see junk science, seperate people from their money.

 

[Turbo1dr]

Personally I would use it. As stated above They are normally used for standard shift cars. Here is why I use one. When I am turning 6000 rpm and only God knows how fast the turbo is spinning, I let off the gas and hit the brakes, that compressed air has got to go somewhere. It is forced back through the turbo. I don't care what anyone says, THAT CAN'T BE GOOD ON THE TURBO'S BEARINGS! My turbo was $750 dollars and that was cheap, but I still don't care to replace it too soon!

You have A LOT of common sense.

BOV is not needed on these cars.
Save your money, the "benefits" seem to apply to the manual transmission 4 cyl imports, this reasoning has infected the new comers to the TR world.

Its just a shame to see junk science, seperate people from their money.

Some people don't have any.

 

[turbojimmy]

Venting a blowoff valve to atmosphere after the MAF will cause the engine to rich very rich until the turbo winds down.
If you have a BOV mounted in the up pipe it's best to let it vent back in between the MAF and turbo inlet.

My MAF is in my up pipe. It looks like in the picture above of Turbo6Chicago's arrangement, that the BOV is after the MAF mounted in the up pipe. I can't see the MAF, but if you look close there is a silicone hose in the up pipe which makes me think that that's where the MAF is. Since his BOV is after the MAF I'm wondering how that's working out. EDIT: I take that back. I can see his MAF is on the inlet side of the turbo. Oops.

I can mount a BOV before the MAF in the up pipe, too.

Jim

 

[BlackMetal]

Venting a blowoff valve to atmosphere after the MAF will cause the engine to rich very rich until the turbo winds down.
If you have a BOV mounted in the up pipe it's best to let it vent back in between the MAF and turbo inlet.

I have a question about that. So you're saying the engine will run rich because the air is already accounted for by the MAF sensor, and the ECM will provide fuel for that air, but the air is being shot out the BOV to atmosphere. Makes sense. But when you get off the gas and the throttle blade snaps shut WITHOUT a blow-off valve, all the air that the MAF measured STILL isn't making it into the engine to be used for combustion, so regardless of having a BOV or not, if the MAF measured a certain amount of air and then you snap the throttle shut, isn't the car going to run rich either way? Whether the air is vented to atmosphere with a blow-off valve, or shot back the "wrong" way through the intake piping until it slams into the turbo and sneezes out your air filter, in either situation the air isn't making it to meet up with the fuel that the ECM provided for it. I'm not saying that you're wrong, I'm just providing you my train-of-thought and hoping you can explain. I figured the air isn't entering the engine regardless of which way it finds its way out, any time you snap a throttle blade shut you will momentarily run rich...

Is there a bolt that you can tighten and loosen to adjust how tight the valve is? If there is loosen the nut you would to adjust it and put some teflon tape behind the nut and then tighten it back down. I have a HKS bypass valve on my buick and it leaked until I put the tape on it then no more vacuum leak from there.

Thanks very much for that tip! Mine does indeed have an adjustment screw and does not have any form of sealant on it, perhaps it is leaking there. I will add that to my list of suspected locations for my vacuum leak.

EDIT: I take that back. I can see his MAF is on the inlet side of the turbo. Oops.
Jim

I was about to ask you why you thought I had a blow-through set-up, but I see you caught your mistake. :tongue: I actually wanted to do blow-through for a long time but then I got alky injection and I'm sure my MAF sensor wouldn't enjoy taking a methanol bath every day.

 

[White Out]

BOV is not needed on these cars.
Save your money, the "benefits" seem to apply to the manual transmission 4 cyl imports, this reasoning has infected the new comers to the TR world.

Furthermore, of all the automotive turbo applications Porsche, Audi, GM, Ford, Toyota, Nissan, Dodge, Mercedes, BMW.
Of all the Heavy duty applictions International/Navistar, Cummins, Mack, Cat, DetroitDiesel, Mercedes, etc. None were offered with a "BOV".
Why? Its simply not needed, the original design of the CRHA's fully floating bearings with oiling provisions, and the newer ball bearings are able to function in either direction and provide support, because they were designed to function in a severe enviroment.
Once again look at the above manufacturers and see how many did come with manual transmissions and do not have bovs.
Its just a shame to see junk science, seperate people from their money.

Audi:
A4
A6
S4
RS4
RS6
TT

bmw:
335

Bugatti:
Veyron

dodge:
SRT4

lotus:
Espirt
Exige S

mazda:
rx7

mercedes:
65 series cars

nissan:
300ZX TT
skyline GTR - I6 & V6

pontiac/saturn:
Solstice GXP0/Sky Redline

toyota:
supra, soarer - I6

Volvo:
850 - GLT, T5, R
V70 - GLT, T5, R
S70 - GLT, T5, R
S60 - GLT, T5, R
S40 - GLT, T5

VW:
Beetle
Cabrio
GTI
Jetta
Passat
Rabbit

"japanese four cylinder"
Mitsubishi:
Evoloution 1-10
Eclipse 1 & 2

Mazda:
mazdaspeed3
mazdaspeed6

Nissan:
Sylvia
Skyline (non-GTR)

Subaru:
baja turbo
forester XT
forester STi
legacy GT
WRX
WRX STi
STi

Toyota:
MR2

Nick