BOV/DV placement

[Efini82]

right on my fd3s, i bought it with a hks BOV on it.  now on every turbo\'d car ive had ive fitted the dumpvalve (dv) as close the inlet as possible as it makes the most sense. on mine at the moment its fitted BEFORE the intercooler, and to me thats just pointless.

in fact i feel it makes perfect sense for it to be nearest the inlet cuz where it is the air has to hit the closed throttle body (during gearchanges) then go back thru the intercooler and THEN dumps out.

anyone elses views???

and y will some of u say recircs are better???surely they only put hot air from the intake system in to the cold air system ??   i guess someone will say because they keep ur car standard and there is less of a shock to the engine if the air dumped is immediatly replaced with more air, as in dumped right back into the airbox.

BUT if the engine isn\'t getting any more air because the inlet is shut as ur changing gear it wont matter if theres air going back into the intake system anyway.



think wot im tryin to say is that I think the hks one i have at the moment is hindering acceleration as i feel its in the wrong place (before Intercooler - not as close to the inlet as possible). it feels ever so slightly sluggish after a gearchange...

anyone like to help with my confusion.  (iv forgotton which bit im confused over now...)

Justin

[kev-yorks]

Got mine between the turbo and inter cooler. Not saying my thinking\'s right but look at it this way the BOV\'s job is to vent air as the throttle is closed to keep the turbo impeller spinning to reduce lag. The closer the BOV is to the turbo the easier and faster it is to vent the excess pressure in a closed throttle situation. Think of a garden hose at home if its only a foot long turn on the tap and water comes out instantly, if its a full length hose pipe there\'s a delay from the tap being turned on until you get water coming out. Bit of a extreme example but the easiest way i could think to describe it.
Kevin

[Efini82]

ok.

from a different angle i guess. so ur saying that a BOV is dumping the boost that is created after the throttle is closed (from directly out of the turbo), whereas i was saying im thinking it should dump the boost that is already in the intake system, nearest the inlet.  i see ur point and dont know which would be best to get rid of, the excess boost already made, or the boost made after the inlet is shut.....

anyone else?


Justin

[Efini82]

right, still confused on this issue. on my inlet elbow, theres a bit right near the trhottle body that is blanked off. wots this for?? as i said before,mine came with an hks bov fitted



cheers

justin

[kev-yorks]

Need to see a pic really is the elbow stock or a after market one. The elbow is a favorate place for mounting additional injectors, it could be that ones been on then removed for sale and blanked off. If its on the body itself it could be the secondary butterfly thats removed or on the underside of the elbow theres the air temp sensor.
Kevin

[memski]

Bov placement is best close to the TB imho. Recirc bov on our cars wont have any advantage as far as I know; these are useful on maf metered cars as the unmetered (dumped) air messes with fuelling in some cases. Ours is map metered so you can dump to your hearts content

[Martiny]

Ok, the BOV vents to keep revs on the Turbo.

Is another important function of the BOV this - to prevent damage to the turbo, because without it, you would get a huge buildup of pressure, (resistance to the turbo actually) as you closed the throttle, and thereby stressing the turbo?

[Fish]

But if not running a BOV you get the rally sl4g chatter.

Fish

[kev-yorks]

Ok, the BOV vents to keep revs on the Turbo.

Is another important function of the BOV this - to prevent damage to the turbo, because without it, you would get a huge buildup of pressure, (resistance to the turbo actually) as you closed the throttle, and thereby stressing the turbo?

Thats why mines close to the turbo martin as soon as it gets a negative boost signal from behind the throttle butterflys (first place to get a negative vacuum) the BOV opens and being next to the turbo vents it that much better. Also if its good enough for mazda it will do for me as they mount there BOV close to the turbo\'s as stock.
Kevin

[LeedsLad]

Ok, the BOV vents to keep revs on the Turbo.

Is another important function of the BOV this - to prevent damage to the turbo, because without it, you would get a huge buildup of pressure, (resistance to the turbo actually) as you closed the throttle, and thereby stressing the turbo?

with out dumping the pressure it is possible to get compresser surge (similar to gas turbine engines) putting huge stress on the turbo

[ro284]

I think they are designed to go straight on to the Y connector from the turbo and mine came with a right angle rubber tube total length about 3 inches to fit in this position with a bracket also, but mine was second hand,think there is a thread on here somewhere Justin.
Bob

[Efini82]

so im guessing its where u think is best then? as some think closer to turbo, others think closer to TB - and both valid arguments for why they have theirs placed where they are. :p  will leave mine where it is for the mean time.however, i saw the ENDLESS rx7 and (after winding my tongue in)im pretty sure that it has the blitz bov placed in the elbow in the straight bit before the curve to the TB....



ok next question to debate over.....

wot make of BOV/DV??



i have an hks one on the rexy at the mo. had a bailey one on my last turbo\'d mota and also have a TCC Works adjustable BOV.


im not keen on the hks 1\'s noise, its not aggressive enough (the car still snaps peoples necks when i hoof it but isnt as naughty as my the bailey one i had.lame aint i? haha i have the performance i wanted, now to make it sound dirty!)


the blitz ones sound nice, a mate has one on his mr2 turbo, similar to the bailey\'s as theyre a higher pitched noise :Thumbs-up rather than my big PTUUUUSH that i get with the hks one.

i know the hks one and my tcc works one are adjustable. not sure no the blitz (think they are) but the baileys arent. i found that the bailey was fine on my last turbo\'d car even tho it was running at around 1.2/1.3 bar, the valve still held firm until left foot came, quick high pitched ptish/quick gear change and into the next gear,no lag, straight in with the boost (and on to the next petrol station asap!)

\'spect u all think im nuts.... :Hammer




hi bob, i\'l have a search for the thread.got a nearly new cat coming tomorrow hopefully. will let u know if this fixes my idling if not i\'l be takin a trip down ur



Justinway i think to see someone in that place in bournmouth.