Is it ok to run without a bov?

[Tom]

I took out my stock bov and blocked up the pipes to test if the stock bov is leaking, I haven't yet taken the car over 4k but on lift off I get a chatter sound, I take it that's the wastegate? So is it ok not to run a bov? If I find out that the car boosts fine now that it's removed, is it ok to leave it that way?

btw the walking stick end's are absolutely perfect for blocking up the pipes!

[terawua]

um, I thought that the BOV stopped turbo stall due to back pressure as the throttle closes.... surely not having a way for the pressure to escape is bad, at least long term...

[hadyn]

i know people with 200SXs who run without BOVs @ 15psi plus, didnt seem to cause any problems apart from the lovely pidgeon wastegate chatter noise :)

[Jake]

Tom,
Chris Wilson is of the opinion that they aren't really needed but others disagree.
I found the (quite old but the points are still valid) thread I was thinking of, have a read mate, it's very interesting.
http://www.mkivsupra.net/vbb/showthread.php?p=111033&#post111033

--
Jake

[Ian C]

They are great on a road car as a) they stop turbo stall and b) they allow the turbo to keep spinning between gearshifts rather than it stopping dead due to backed up boost pressure. Because we shift gears a lot slower than a race sequential box ;)

I blocked off my stock BOV once when trying to diagnose a stalling problem, and I got the rat-rat-rat-rat noise on lifting off, which is turbo stall, not the bloody wastegate. It's a nasty sound to anyone with mechanical sympathy, and it was doing this just by stationary revving, so a full-chat 1.4bar would have been horrendous :eek:

-Ian

[Terminator]

I think Mr Toyota stuck it there for a very good reason as above.

[paul mac]

I think Mr Toyota stuck it there for a very good reason as above.
yep i'me with termy, Mr Toyota does not put things on his cars that are'nt needed as he likes to make a profit, anyone who says you dont need a BOV is very misguided

[Jake]

Hi Paul
Did you take a look at the thread I posted above and see CW's reasoning as to why a BOV may not be necessary? Some things are on cars for reasons other than performance or reliability. (I'm not saying either view is (in)correct, I really don't have an opinion, but I'm not going argue with CW)
:shrug:

[paul mac]

Hi Paul
Did you take a look at the thread I posted above and see CW's reasoning as to why a BOV may not be necessary? Some things are on cars for reasons other than performance or reliability. (I'm not saying either view is (in)correct, I really don't have an opinion, but I'm not going argue with CW)
:shrug:
Yes Jake i did read CW's thread but have also done a lot of reading myself, Chris is talking about race engines that basically last a race, i am sure when turbos were used in F1 all those years ago no one seriously beleives the turbo was re-used for the next race, i stand to be corrected but i'me sure the thing will have been junked, as stated the BOV stops the turbo stalling, that stall equals spinning at 70'000 + rpm to 0 rpm in less than a second, if someone wants to bin there BOV and report back here in 6 months to share their findings there welcome, but i aint taking mine off, is CW right or EVERY car manufacturer that produces a road going turbo charged car - the choice is yours

[Tom]

Ok, how do I test if it's the stock bov leaking if it's bad to run without a bov?

I've put it in TTC so that turbo's are not used for the moment.

[paul mac]

http://www.mkiv.com/manual/manualtt/turbo_inspection/index.html

[paul mac]

sorry mate forgot the message, i checked mine at work years ago when i had one, we had vaccuum pumps but i think you can suck enough (oo er missus) to get it actuate

[Chris Wilson]

IMO perfectly OK. I never run a BOV on even truly radical turbo engines.

[Ian C]

Chris, just to get this straight, you use no recirculatory valve at all? So when you close the throttle plate, the turbo just stalls, yes?

-Ian

[Chris Wilson]

I use no valve at all. The turbo doesn't stall.

[Ian C]

Well, I'm intrigued :) Where does all the boosted up air go when you close the throttle plate? The way I see it, it's in the system, it's pressurised, and suddenly it can't go anywhere, so what happens?

Not being funny or arsey about it, just interested in learning more :thumbs:

-Ian

[Chris Wilson]

Get a cylinder vacuum cleaner, put your hand over the OUTLET duct. Listen to the fan speed... :)

[C4 SUP]

They are great on a road car as a) they stop turbo stall and b) they allow the turbo to keep spinning between gearshifts rather than it stopping dead due to backed up boost pressure. Because we shift gears a lot slower than a race sequential box ;)

I blocked off my stock BOV once when trying to diagnose a stalling problem, and I got the rat-rat-rat-rat noise on lifting off, which is turbo stall, not the bloody wastegate. It's a nasty sound to anyone with mechanical sympathy, and it was doing this just by stationary revving, so a full-chat 1.4bar would have been horrendous :eek:

-Ian

Hi, I have a HKS BOV fitted in the stock position and my car makes the "rat-rat-rat" noise on lift off. Does that mean the BOV is not working or does it just need adjusting?
Any help very much appreciated.
ps I have twin hybrids running at about 1.2 bar but don`t give it a lot of stick.

Ian

[Ian C]

Get a cylinder vacuum cleaner, put your hand over the OUTLET duct. Listen to the fan speed... :)

Sounds like a good idea but are the systems comparable? What boost does a hoover run? :D

I see what you are saying. Thanks for confusing me on an issue I previously had straight in my head :) You always said to read the books by Corky Bell and the other Bell chap (Alex?) which I have, a few times each, and they say the BOV/recirc valve is a good idea, for the exact reasons I've shamelessly parroted on here (although I've heard turbo stall on the hybrid twins for myself so some fo it is experience ;) ). Now I'm not saying they get everything right in those books but I'm also not assuming you get everything right either, because anything like that is a naive assumption. I've no idea at the moment how to test things though, to see if a recirc valve is a good idea or not. Maybe a boost measurement pre-throttle plate datalogged with the usual boost measurement post-throttle plate, it'd show what boost curves are like with and without a BOV and give an indication of what's going on...

-Ian