not a good BOV experience

steptoe · Post by **steptoe** » Sat Jan 25, 2014 2:56 pm

Anyone got good hands on experience in BOV / recirculation valve set up ?

I have, but its not good.

The Forge brand look alike, styled on a Bosch unit found on Falcons, SAAB, Porsche etc came off ebay US, no real instructions with it at all - may have been some on the ad. Comes with two other springs for stronger boost than what I am using, so sticking with the one inside it -weakest one. Also comes with shims for more accurate tuning .

After the fluke positioning of it on the EA82T non spidey set up, nncoolg TIG WELDING SERVICES, did a fine job of welding in an outlet on the alloy crossover, the outlet side of the BOV is vented back into the air intake pre turbo, post fuel metering devices so no rich mixtures should be encountered.

The BOV inlet and outlets were both 25mm OD.

The third orrifice is the reference line coming off inlet manifold below the throttle. I used a fitting already in place that was for the previous auto trans vacuum signal. I used a steel vacuum pipe or brake fluid line ? as the intermediate pipe between manifold fitting and BOV. I now realise I did not give the BOV the same ID from BOV to inside manifold - may be my problem

OK, not driven for six months, so my first drive last week took a little re-acqaintance time. Just did not feel right driving it. Squirt did not seem to occure until 3500 to 4500 rpm unlike pre BOV the best squirt was between 2500 and 3500 rpm.

Not consistent either, when it hit was like a crazy power surge at about 8- 10 psi boost.

Put 300kg of trailer on the back and it was worse than driving an EA81 with trailer !!

I was seeing boost light, boost on the gauge, just not feeling it, until that wicked power surge which was pathetic in the wet. 4WD lever fixed that a little. Still, gutless until the surge. Fuel efficiency has gone to the crapper by about 20 - 25 % !

I pulled the BOV and its bits off, went back to having what may sound like Maria Sharapova https://www.google.com.au/search?q=shar ... 920%3B1200 under my bonnet every gear shift, with her intimidating exhalation as she serves up. man, imagine having her under the bonnet every time you look in there

I can only suspect . as nncoolg says, leaks off some boost...the BOV has taken its liberties a little too far with our friendship

I have my torque back between 2500 and 3500, pulls like it used to, tows real good - just ask the bloke in his Triton this morning who thought he was gonna pass me before lanes merged

So, who has experience in tuning these little BOV's ?

I read that the reference line to inlet manifold is not just for vacuum - as i realised when I thought about it - under boost, this line has boost pressure same ? as inlet of the BOV so should hold even. Too small ID of this line may just cause the delay and trouble I have ?

Not going for stronger internal spring as my recollection is that next one up is for 15 to 20psi, then the next is even stronger.

Then also have found this ....

http://forum.n12turbo.com/viewtopic.php ... 251436ff1d

tambox · Post by **tambox** » Sat Jan 25, 2014 9:14 pm

Buy a Bosch one.

steptoe · Post by **steptoe** » Sun Jan 26, 2014 6:47 am

but they are plastic, supposedly have issues, the one we aimed for is no longer available - you selling yours?

Gannon · Post by **Gannon** » Sun Jan 26, 2014 7:04 am

I have the same one, black aluminum bosch copy. I havent done much road testing as my rx isnt registered but it seems to operate like a factory unit. Are the genuine bosch ones alloy or plastic?

Pull it apart and make sure the mechanism moves easily. If there is too much friction it could be causing the delay. Maybe just oil it. I doubt the vac pipe size it too small, the diaphram would be lucky to hold 2 ml of air.

steptoe · Post by **steptoe** » Sun Jan 26, 2014 7:56 am

plastic, and their must be a number of them to suit things from SAAB, Porsche to our BA turbo Falcs.

I rockd up to the local Bosch agent with a part number to be told by an honest face who not knowingly BS me, that no longer available. Maybe one from Ford may do ?

Her is a few words pointed out by the mailbox welding service nncoolg

"Theoretically, you can actually hold more boost if you are not recirculating. When you recirculate, the BOV outlet recirculates into the pre-turbo intake pipe. During acceleration, the pre-turbo intake pipe is under vacuum. This can subject the top or side of the BOV/CBV piston to vacuum on some BOVs, trying to pull it open. This is what causes some BOVs to leak at lower boost than our website recommends them for. "

Took a while to get my head around it, until looking at the subjects to realise , yep, likely to be the case with my set-up - some sort of vacuum could well likely be here , so directing BOV exhaust to further upstream, immediately before my LPG mixer will be next thing to try.....or a dirty big one way valve ?? And to think I nearly tossed them !! I got a few air pump/air injection reed valve doo dads from Ford Laser type stuff to copy Steve Rising Suns EA82T blow through LPG set up.
The collective brains trust at work in here !!

Gannon · Post by **Gannon** » Sun Jan 26, 2014 8:42 am

Would a lot of your issues be fixed by converting to injected lpg?

Im assuming that your bov vents between the mixer and the turbo? Does the mixer have a venturi and create a restriction to the airflow?

Venting pre mixer would only cause the air to be double fueled and be overly rich.

Where would you mount the one way valve? I cant see where it would work

steptoe · Post by **steptoe** » Sun Jan 26, 2014 6:41 pm

Not going down that injected track , trying to avoid computers has been the aim of the exercise. Yeah, was, being the operative word, venting between mixer and turbo, and mixer is a restriction as such, but not when have 5.0 litres, even 5.8 litre donks running off these 200 series mixer and mine is just 1.8 litres. There is likely something going on in the area.

The one way reed valve would go from BOV to same place, just with the reeds preventing any signals coming up to BOV.
This would help isolate the problem to see if it is BOV needing tuning or a reed valve to stop unwanted signals

And yep, vent just before mixer would be momentary rich, just how rich would have to run it on the analyser. Pre mixer exhausting - not path I would be happy with - only for experimentation , have to read the Standard to see how it would be interpreted too, but not even sound like good practice.

Love it the way it is - Sharapova under the bonnet - no BOV !!

tambox · Post by **tambox** » Sun Jan 26, 2014 7:40 pm

Maybe thats the hint, no improperly set up BOV is better than having one.

Gannon · Post by **Gannon** » Mon Jan 27, 2014 8:51 am

Have you read these from Autospeed.com?
The $70 Electronic Blow-Off Valve

The All-Electronic Blow-Off Valve!

steptoe · Post by **steptoe** » Mon Jan 27, 2014 8:58 am

First was a pretty quick read.....in the middle of engine fitting - typical quality Julian Edgar sort of stuff. I lost interest about the time I realised I think , could be wrong (of late

) this is shutting off the reference line to the inlet manifold ?? And learning elsewhere that the reference also uses boost to push against the BOV from behind with boost pressure from below the throttle ????

I'll take it up again when I have time and no mess about me, the drive to see it right.

Thanks fer yer input fella's

stenno · Post by **stenno** » Mon Jan 27, 2014 9:16 am

Has the vacuum reference line got a built in one way valve somewhere? But yeh maybe try the stronger spring or plumbing in the blow off valve upstream of the mixer so as to not run rich maybe

steptoe · Post by **steptoe** » Mon Jan 27, 2014 12:38 pm

according to one trusted site ....frozenboost ? that vacuum reference line you refer to gives it both ways - assistance to keep thing shut during boost, and vacuum to pull it open on gear shifts. So, a one way valve in that line might be a no no

Gannon · Post by **Gannon** » Mon Jan 27, 2014 2:49 pm

I was referring to the electronic valve, hook it up to a throttle switch or a pressure switch so its closed when on boost and no chance of leakage.
But really, do you need a BOV in your case?

ktmtragic · Post by **ktmtragic** » Mon Jan 27, 2014 4:32 pm

These guys are a customer of mine. https://www.gfb.com.au. Give them a try. John knows Subaru/ Mitsubishi back to front. Sure they can help.

steptoe · Post by **steptoe** » Mon Jan 27, 2014 4:34 pm

OK. I've just read the article on full electronic control. Stoppin' right there. Done fiddling with cars for while. It started out as being a possible $30 part to bung in and try....

Bloody tambox put me up to it !

Do I really need one? Dunno, thought it might increase longevity of the turbo due to the alleged benefits. And was hoping to lose a doughy pedal after shifting up a gear as fast as it will shift. Was not chasing PSSHHHT sound - already got it - the BOV silenced the Sharapova sound from the intake!

But you are right, the electronic one sounds good in theory. I guess when I pick this thing up again it will be just to try a reed valve on the exhaust side to see if any pulses from under the LPG mixr were contributing to things.

Gannon · Post by **Gannon** » Mon Jan 27, 2014 4:49 pm

Im skeptical that the downsides to not having a BOV are as bad as BOV sellers make out.
From reading workshop manuals, the main benefit to having a BOV is to silence the noise, and contray to what BOV sellers say, it is beneficial to have the spring soft enough so that the valve is open at idle to allow the air to circulate though the turbo and back through the BOV, this allows for the best turbo response

steptoe · Post by **steptoe** » Mon Jan 27, 2014 7:37 pm

Information overload is the 'net on this topic me thinks

Mmmm, the idea of tambo's was to keep this thing spinning freely between gears so power is at the ready as I take next cog.

This baby was made in 1985 and is still the original turbo from the way things look, and got there without a BOV. Probably didn't get the caning RX's got being an auto, so maybe a contributing factor ....

Mr nncoolg has pointed ou in slow, clar English, that to put a reed valve so air blows only one way, will still allow vacuum to get through to possibly disturb the BOV.

The way I understand

a blow off valve might work , should not open a smidge until it getsa the vacuum signal. I was driving ., towing and was almost a nightmare, no bost/power where it was before, and then suddenly would come in and slam me at 8 or 10 psi

Greg says get a Bosch one - that is where I started.

Nice little learning experience - unresolved

tambox · Post by **tambox** » Sat Feb 01, 2014 8:13 pm

Thats cause you have'nt got the Bosch one.

I cut my intercooler down several times to get rid of a lag, then the Boooosch valve let the motor give a "kick" when changing gears when performance driving (hooning) the car, with the turbo was often.
Maybe it was just a mix of the two that worked out well, BUT, Jonno, it was petrol, not LPG. In theory it should give you the same result, except for the explosion factor.