Why No Blow Off Valve?

[williamsGN]

I think BOV describes most the mouths in this thread.. venting a bunch of unwanted air.

 

[jskarateka]

I think I just BOV'd myself.

 

[~JM~]

I think I just BOV'd myself.

I hope your seperator is in operation. Nothing worse that Sharting in your shorts.

~JM~

 

[RIFF RAFF]

First BOV I ever saw was on a small block Chevy with a Powerglide. This car was an easy 9 second Malibu. The same Malibu that was on PINKS that ran against an early big block Camaro out of Canada. I was told that it was to prevent damage to the throttle blade when the throttle closes. I didn't know that it was a ricer part at the time.

Oil Man, Is your name Richard, or is that just your state of mind?

~JM~

NO MY NAME IS ONRICO..

 

[RIFF RAFF]

I think BOV describes most the mouths in this thread.. venting a bunch of unwanted air.

but ..

 

[~JM~]

NO MY NAME IS PAUL & IM COUNTING THE SECOND'S TILL YOUR NEXT STUPID QUESTION .. TRY THE SEARCH OPTION .. OVER THE YEARS THERE HAS BEEN ALOT OF GOOD INPUT ON BOV'S BUT IT HAS BEEN MUDDED UP BY PEOPLE TO LAZY TO SEARCH FOR THE ANSWER .. BUT I DO UNDERSTAND WHEN LOOKING THRU 50 PAGES OF CRAP TO GET SOMETHING USEFULL .. THATS HOW I DO IT .. GIVE IT A TRY .. YOU HAVE BEEN THE JOKE OF THE WEEK AT T6P.COM .. GO AND LOOK .. P.S. RICHARD IS MY LINE GET YOUR OWN .. TRY A SEARCH FOR A NEW ONE .

...and you have been the ass of the week here so I guess that evens the score. Do you actually have any knowledge or talent or are you just another safe behind the keyboard punk? I'm betting on the latter.

~JM~

 

[DR BOOST]

ive never experienced compressor surge, isnt that caused by a small turbo and large intake volume between the turbo and throttle? the only reason ive used bov's is to protect the turbo when i get off the throttle.

Whats up oilman!

 

[RIFF RAFF]

...and you have been the ass of the week here so I guess that evens the score. Do you actually have any knowledge or talent or are you just another safe behind the keyboard punk? I'm betting on the latter.

~JM~

YOU COULD CALL ME WORSE THINGS ..

 

[RIFF RAFF]

ive never experienced compressor surge, isnt that caused by a small turbo and large intake volume between the turbo and throttle? the only reason ive used bov's is to protect the turbo when i get off the throttle.

Whats up oilman!

well ..

 

[williamsGN]

edited.. not worth the effort.

 

[forzfed]

I was told that it was to prevent damage to the throttle blade when the throttle closes. I didn't know that it was a ricer part at the time.
~JM~

Maybe things have changed since I last studied Fluid Mechanics. Water hammer is a major concern on valves. Is air hammer? Your not boosting when the valve closes, and the pressure is considered low. It's not like it is over 1000psi, if you put it into perspective it is really low pressure your talking about. The air takes the path of least resistance which is out your filter.

 

[notacarlo]

I have a stick in the SVO. I bought a new set of throttle actuators at Footlocker last week......work great. Says on the box "works for automatics". Car is 25 years old on the original turbo runing 25 psi. No recirc, no BOV. Running like a champ with the mid-eighties turbo lag.

Do what you want. Will it hurt....naw....prolly not. WIll it help......naw...prolly not.

 

[RIFF RAFF]

edited.. not worth the effort.

Yuuuup !

 

[RIFF RAFF]

I have a stick in the SVO. I bought a new set of throttle actuators at Footlocker last week......work great. Says on the box "works for automatics". Car is 25 years old on the original turbo runing 25 psi. No recirc, no BOV. Running like a champ with the mid-eighties turbo lag.

Do what you want. Will it hurt....naw....prolly not. WIll it help......naw...prolly not.

WILL YOU NEED A SHOT FROM A DOCTOR ? PROLLY..SVO & BOV

 

[spooledyou]

Absolutely correct that the BOV will not cure surge in any way when the throttle is open. The only way to reduce this is to use a ported shroud or try to introduce some prerotation to reduce the losses to the suction eye of the impeller (other methods are also available...). Kidglok, you are also referring to the same phenomenon of surge when you talk about the stalling of the compressor. If you imagine what a compressor map looks like, the surge line determines when the compressor will surge. To the left of this line, it will be surging. At zero flow (throttle blade shut) and essentially any pressure ratio, you will be surging the compressor. This can also happen if you are operating the turbo under throttle and your flow vs pressure ratio falls left of the surge line.

Yes, oil starvation is another failure mode of this equipment, but it is certainly possible that failure could also be caused by surge.

Also, the valve does not have a "set point" either like I saw a few posts back. It operates based on a pressure differential between the volumes of air before and after the throttle blade. The spring inside is there only to keep the valve shut against the motor vacuum (throttle blade shut, motor creates vacuum).

I hope that people find some of this information helpful.

please forgive my retaredness, but what do you mean ported shroud? are you talking about the turbo inlet houseing? port that?? im confused. and yes all this info is very helpful, thank you..

 

[turbo nasty]

Nothing wong with running a blow off valve, running high psi's with alky for instance IMO its smart......dont get into a pissing contest with these guys or let em get to you.......just let it go...

Heres a pic of ported shroud

 

[jskarateka]

Is there a BOV trophy on this new forum?

 

[turbo nasty]

No particular person gets it but, this thread does.

 

[RIFF RAFF]

DARTH VADER .. we have your shroud at the lost and found ..

 

[RIFF RAFF]

Here's what we know..... This arguement will never be resolved to everybody's satisfaction, why? Because proponents of BOV's will forever argue in their favor, and those apposed will argue in agianst them.

What are the facts? Can they help save a turbo's life. No definative proof, but I'll give ya a maybe. Were they designed for that? No.
Can they help cars with standard tranny's keep the turbo spooled up during shifts? Yes. Were they designed for that? Yes.

I'm not going to speak to whether they are good for the longevity of a turbo, because I've never suffered a turbo failure due to the lack of a BOV. The 44 on my 86 has been there having the snot beat out of it since the early 90's....STill going strong.
The 49 on my 87 has been there having the snot beat out of it since the early 90's.....Still going strong.

As a matter of fact the ONLY turbo failure I've EVER suffered was not due to the absence of a BOV, but rather debri from a Champion spark plug that came apart and went through the turbine. That was on the 87 and the reason the 49 got replaced way back in the early 90's by another.

As for the arguement that virtually the entire automotive industry is using them, hogwash, and B.S. Ford is now the largest nameplate that's turbo'ng (over half their automotive line), show me their BOV's. Diesel trucks...also none.

I choose not to run any for common sense reasons. Those of you that like them, spend away.

.. the only comment in this thread that made any sense to me .. thanks dave .even tho you said you would'nt comment.