turbo thought

[b8er]

so i was sitting around explaining what a BOV does to a friend of mine then i thought....


instead of letting the BOV just relase the air out into nothing, could you re-route the excess air back into the turbo, i figure you would have to re-route it to the intake side of the turbo, from what i can see this would reduce turbo lag inbetween shifting, the downside i see is that you wouldnt get the cool pshhhhhh sound

am i just a complete moron or is this possibe, has it been done before

[88eyeguy]

i don't know much about turbo's, but that sounds like a recirculation valve. not sure though...

[A20A1]

Well Factory systems usually reroute the air charge to keep things quiet... but I dunno if they will route it back into the intake stream since it's hotter then ambient air.

[w00tw00t111]

If you re-routed the air wouldn't you cause pressure surges? I mean think about it if you all of a sudden increase the pressure of air in the intake tube by severl si's wouldn't you cause a spike? Seeing as though the turbo would all of a sudden have full power but then when it runs out of the BOV air it would drop back down to what the it did have in air supply. That makes sense to me but, maybe my turbo knowledge is lacking.

[A20A1]

Hmm, or would the air be cooler cause it decompresses when it is released?
I think it could be released back into the intake... but maybe further away from the turbo intake?

[b8er]

everything you guys are sayng is making sence to me but i cant say if one thing is right or wrong, i know the basics of turbos and whatnot but i think we need a more experience turbo'd guy to give his 2 cents. my only thought was that it would reduce turbo lag inbetween shifts, it was just a thought but if it leads somewhere then cool, im still thinking if you were to re-plum the BOV would you plum it to the intake side of the turbo or back to the exhust portion of the turbo, if you went to the intake you may run into a problem with the turbo since the intake side is designed to have air sucked through not to have air forced throught it but if you plummed it to the ehaust side you may run into a problem with exhaust gases flowing up to the BOV but i guess you could just through in a one way check valve or somthing,

anybody else got a thought

[88eyeguy]

http://www.geocities.com/MotorCity/3...josboost1.html

not the best description, but i'd say it's pretty close to what you were asking. i believe that the 300zx TT's had recirc valves OEM.

[w00tw00t111]

I agree w/ b8er about the intake side. That's what I've been trying to say. If you were to put it on the exhaust side of things I think that you might be on to something. Although I would be worried about the whole boost surge but maybe since your going to make more exhaust after those first few firings from the forced boost then it would compensate. Kinda like the guys using insanely large A/R on their turbo's but, don't have any lag b/c they shoot a bit of the funny gas every time they take off and just shift insanely high. Might be the same principle just for free. *no re-filling of nitrous tanks*

[turfnnsurf]

Hey guys Take a look at any stock 91-99 Turbo DSM, they all recirculate the BOV back into the intake track before the turbo. It serves two purposes: 1. All the air that enters through the MAS is counted by the ECU in needs to stay in the system for the car to run properly. 2. It also helps keep the turbo spinning/spooled between shifts.
My DSM had this setup until I upgraded the intake and BOV and MAS to allow proper venting of the BOV to atmosphere.

[Accordtheory]

just about all factory turbo cars have recirculating blow off valves. it doesn't affect the turbosystem in any way other noise reduction over an open atmosphere system, obviously disregarding the mass airflow sensor

[AccordEpicenter]

the bov doesnt have too much effect on the lag wether its recirculated or open air, it might be a little quicker if its recirculated, but youre taking the already pre-compressed and heated air and heating it again by looping it back through again, i say just vent it open air unless youre going for a sleeper car, or get a quiet bov. Maf equipped cars tend to stall or stumble if you vent the blowoff valve to the atmosphere, because the computer thinks that that air is going into the engine, instead its being released into the atmosphere. Blowing off to the atmosphere helps keep the turbo spooled almost as much as recirculating because youre removing the compressed air that puts a load on the turbo, slowing it down, without it the turbo will keep spinning, but if you didnt have a bov, the pressure will spike like crazy in the charge pipes when you slam the throttle shut and may cause a pressure wave that will try and stop the compressor wheel from turning and may actually try to turn the compressor wheel the other way or at least slow it down untill it cant hold the compressed air in and it will fall back through the compressor housing, this is known as compressor surge, and its basically when the compressor is compressing more air than you can use and it tries to stop the turbo. Its damaging to the turbo and creates a lag between shifts

[b8er]

alriht, thanxs for all the info and clearing up my questions, i thought i was onto somthing neat but i guess i should have knowen its been done before, ahaha, anyways i felt smart for a bit

[Hash_man_Se_i]

Its called a recirculating BOV... Mostly used on cars with mass air sensors because if you use a BOV that vents to the atmosphere in those cars it will dump the fuel in for the air registered before the BOV but when the air isnt there it just has a ton of fuel... I think accord epicenter basically summed it up... but ya, unless your car has mass air there is no need for a recircuilating BOV

[smufguy]

well like Brad said it, all stock BOVs are recirculated into the intake tract. but where is the question.

On all turboed cars, there are two sections of the charge pipe. a pipe that comes from the turbo's compressor housing and goes to the Intercooler and then another comes from the intercooler and goes to the Throttle body.

The BOV is situated in pipe between the Intercooler and Throttlebody and the air it vents out is routed via a pipe and joins the pipe between the Turbo and the intercooler to be cooled.

The air that BOV vents is not warm since it has passed thru the intercooler already. only the air that is compressed by the turbo is warn.

like Brad mentioned it, they do that cause most of the cars that came in turbos had MAF sensors and they had to do it so that the computer wont go crazy, because the MAF sensor is located before the turbo. On map sensor equipped cars, the sensor reads the pressure/vaccum on the intake manifold and do not care how the air gets into it or how much so u can suck in lets say 20psi of air and only10psi of air into the intake manifold and the car will be fine. but on the maf sensor equipped car, the car would just bog and die.

(( The psi was just an example so that you can understand it by looking at the gauge and stuff, but technically its the volume of air that the MAF sensor records, Mass Air Flow is thus its abbrivation))

[b8er]

ah thats cool guys, thats for explaning