blow off valves ?
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sjr2531
- Posts: 23
- Joined: 23 April 2010
- Year and Model: 1998 saffron V70R
- Location: Portland, Oregon
blow off valves ?
What is the opinion of BOV on a 1998 V70R. when i had my P2 i was told that the Ecm is expecting to get the cooled air returned back to the motor so it is not needed. is this the same for the older platforms like my v70? are they beneficial after you've done some power mods. I'm not looking for the sound effect, but if these are helping the the process then should i maybe get one ? anybody done these yet any CEL? anyone's input would be great...
2002 s60 T5 manual 98,000 miles
(R.I.P 12-26-2010 112,000 miles)
1998 Saffron V70 R 109,000 miles
"My Precious"
(R.I.P 12-26-2010 112,000 miles)
1998 Saffron V70 R 109,000 miles
"My Precious"
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jimmy57
- Posts: 6694
- Joined: 12 November 2010
- Year and Model: 2004 V70R GT, et al
- Location: Ponder Texas
- Has thanked: 4 times
- Been thanked: 320 times
I wouldn't explain it that way.
The blow off valve is opened on lifted throttle as the flow under pressure in intake system through intercooler and hoses is abruptly stopped and the pressure wave will effectively bounce off throtle and go backwards through turbo. This causes stress on turbo and can go backwards through MAF sensor. MAF registers the flow either direction so the ECM could get a signal and meter additional fuel and create a momentary over-rich condition if throttle is not completely closed (completely closed cuts off injectors on closed throttle, no fuel delivered, not rich). The BOV lets air get dumped to inlet side of turbo and the turbo pulls that in again and it effectively creates a temporary recirculation to stop the backflow. This also allows turbo to keep its speed up so a re-application of throttle results in faster boost build again.
If you do performance mods that increase boost you can go past the capabilities of the stock integrated BOV and you add a higher capacity external one. The external are louder but if the mods aren't done it won't be louder as there really isn't enough airflow for the hissing noise or whooshing sound. Some use a poppet valve that blows off the air to the oustide and those are the REALLY noisy ones but can give overrich problems.
The blow off valve is opened on lifted throttle as the flow under pressure in intake system through intercooler and hoses is abruptly stopped and the pressure wave will effectively bounce off throtle and go backwards through turbo. This causes stress on turbo and can go backwards through MAF sensor. MAF registers the flow either direction so the ECM could get a signal and meter additional fuel and create a momentary over-rich condition if throttle is not completely closed (completely closed cuts off injectors on closed throttle, no fuel delivered, not rich). The BOV lets air get dumped to inlet side of turbo and the turbo pulls that in again and it effectively creates a temporary recirculation to stop the backflow. This also allows turbo to keep its speed up so a re-application of throttle results in faster boost build again.
If you do performance mods that increase boost you can go past the capabilities of the stock integrated BOV and you add a higher capacity external one. The external are louder but if the mods aren't done it won't be louder as there really isn't enough airflow for the hissing noise or whooshing sound. Some use a poppet valve that blows off the air to the oustide and those are the REALLY noisy ones but can give overrich problems.
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sjr2531
- Posts: 23
- Joined: 23 April 2010
- Year and Model: 1998 saffron V70R
- Location: Portland, Oregon
perfect explanation. that was the info and clarification i was needing to read. Thank you jimmy57
2002 s60 T5 manual 98,000 miles
(R.I.P 12-26-2010 112,000 miles)
1998 Saffron V70 R 109,000 miles
"My Precious"
(R.I.P 12-26-2010 112,000 miles)
1998 Saffron V70 R 109,000 miles
"My Precious"
so, if I do my ecu upgrade I should probably do a blow off just to be safe too. was plannning on doing something with exhaust ( just straight pipe from back?) IDk don't wanna spend 900$ i don'e have but want to upgrade now LOL like us all.
Ne way I should start a new question what mods to do before ecu upgrade or at same time
lol im newb fell in lov with volvo 6 months ago wish i bought the volvo i fell in love with 99 s70 hpt awd 80k , but the second one was pre ford and rare 98 c70hard top hpt110k wish i could change that but yeah rite.
lol at my ramble any reply appreciated.
Ne way I should start a new question what mods to do before ecu upgrade or at same time
lol im newb fell in lov with volvo 6 months ago wish i bought the volvo i fell in love with 99 s70 hpt awd 80k , but the second one was pre ford and rare 98 c70hard top hpt110k wish i could change that but yeah rite.
lol at my ramble any reply appreciated.-
Alecw81
- Posts: 172
- Joined: 31 January 2011
- Year and Model: S70 GLT 1998
- Location: Wilmington, NC
- Been thanked: 1 time
First: Would it kill you to at least attempt to communicate in an clear manner? I can barely understand what you're trying to say.
A Blow-off-valve is unnecessary unless you have done EXTENSIVE modifications, which you haven't. So just forget about it.
Spending $900 on an exhaust is dumb as hell too.
Go to a local exhaust shop and have them make one for ya. You should be able to get a Full 3" turbo-back for less than $600.
A Blow-off-valve is unnecessary unless you have done EXTENSIVE modifications, which you haven't. So just forget about it.
Spending $900 on an exhaust is dumb as hell too.
Go to a local exhaust shop and have them make one for ya. You should be able to get a Full 3" turbo-back for less than $600.
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