robbie2883

air still bypasses the throttle plate...it never closes 100%. if it did your motor would stall out.


also just b/c the air is injected before the turbo doesn't mean that it's not back in the system. it's still a one way system and air is only moving in one direction especially under vacum. air is not recirced back into the airbox though....it recircs back to the piping between the box and the

robbie2883

simple explination.....if you took a water hose and and ran it with a constent say 30 psi water pressure (standard home water pressure) and put a capped off tee tee in the middle of it.....if you then uncapped the tee would water pressure drop at the end of the hose? now, if you took that tee and ran a hose off it and put it back into the original line what would happen to pressure. it would stay the same....no matter where you put it back into the system. pre pump, post pump....where ever.

Evo_Jay

iTrader: (17)

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Evo_Jay

iTrader: (17)

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robbie2883

but it's not BAD for your car.....the whole thing started when you said it was BAD for you motor. which it's not. then you said it doesn't effect spool up. which it does effect spoolup after a shift. and you have yet to back anything you've said with any facts. just "go read you'll see"

I don't need to read to know what years of real world experience has taught me. not to mention the basic mechanics of a motor and EFI systems.

anyway, i don't want to argue with you anymore.

back on topic. if you want a bov as i first stated...**** the dumbasses who make judgements on you for putting a bov on your car. most of those guys are haters plain and simple and need to criticize to satify their own insecurities......you shouldn't care what anyone else thinks anyway. no they won't hurt your car. mod away for your own reasons!

Mojito

iTrader: (1)

No, the air doesn't bypass TB, if it did there wouldn't be any point in having the TB. There's only that much air that is coming through the closed TB regardles of what has been measured by MAF before the open BOV.


Oh yes, it makes a big difference if its recirculated before or after turbo. And since it's recirculated before the turbo, it can even be blown out of the system without affecting turbo spool.

First of all, you don't just uncup the tee, you cap the hose after the tee. And secont, it's not a constant pressure pump, turbo only pumps when trottle is open. When you close the throttle, there are no exahust gases to spool the turbo.
And in this situation of course the pressure would drop (if you mean the end downstream of the tee). That's the whole point of the BOV.
That would depend on were you put the hose back in, before or after the pump. And let's remember that we capped the hose at the end (the trottle is closed), only a few drops are coming through regardless of the pressure.
No, there's big difference.

Anyone else could care explaining the MAF thing?

robbie2883

you obviouly have no concept. air has to bypass the throttle plate.....when at zero throttle at ALL time there is either a flutter in a DBW throttle plate, a BAC or an IAC adjusting the amount of air bypassing the throttle plate. not to mention the fact that an thottle plate NEVER closes all the way. period. if you didn't have an adjustmeent in the amount of air that passes the tb plate then you would NEVER have a stable idle when the temp and humidity and altitude change. go do some more research man. i'm not just typing for the hell of it. it's a fact.....check out EFI 101 if you care to learn more

as for the pre and post turbo...i'm sorry bro...but at idle...it doesn't matter...the whole system is in VACUUM. or can you not understand that concept?

Evo_Jay

iTrader: (17)

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robbie2883

i think you're misunderstanding me evo kid. i do not agree that a BOV can increase spoolup (unless the old bov was leaking) but a vta bov will actaully slow down spool between gears. this is a fact. as for what i've stated, i've explained the principles of EFI and maf. i think that's quite eough fact and not just say so.if you had any experience with installing and tunign stand alone ecu's you'd understand. if you don't believe me then take the clases. everything is determined on tune and LOCATION of the maf. i.e. drawthrough maf vs blow through maf. i am not speaking from just import experience....i am a mechanic an a tuner and have worked on MANY motors, pioneered one motor and tuned a ton of cars. what i'm saying isn't my opinion, it's facts taught to the masses in any EFI tuning class. you can learn alot right here

http://www.efi101.com/




Having a MAF has NOTHING do with it man. or a map, or any other kind of air flow/pressure/volume sensor. it's all about the location of the MAF as related to the BOV. period. point of fact. i've stated why this matters and so have some others in this very thread. go back and read it and you'll understand

Evo_Jay

iTrader: (17)

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Mojito

iTrader: (1)

I'm not a native English speaker, but I happen to understand the meaning of the word bypass in pipeline system. Bypassing the TB would mean running a hose around the TB into the intake manifold or, as more relevant example, having the BOV vent into the intake mani. So, there's a terminology issue. With that in mind, what you are saying is correct and I agree. But that just illustrates my point that I don't see how VTA with a closed (or nearly closed) throttle can affect the mixture in this very moment.


Who says anything about idling? We are discussing BOV here and that's relevant for the closed throttle under boost situation. There it makes a difference.

Anyway, thanks for trying to explain. Obviousely, I must be missing some nuance which would explain why VTA BOV is bad for MAF cars. But you couldn't give the explanation. In fact, it seems you are not even getting my point. So, I would suggest that you sit nex to me and wait until someone with knowledge comes and gives some good explanations.

Evo_Jay

iTrader: (17)

BOV are great

thj17

Hi guys!
I'm writing just cuz I want to understand and reading this post just makes me even more confused...there are people totally against VTA on EVO or MAF based cars and others claiming to have absolutely no issues running 'em on their EVO X...So I'm trying to understand why? BTW my english might be bad I'm speaking french...
Don't want to make anyone hangry...just want to know if a VTA could work on the EVO X...no other car
I never had a turbocharged car...but I want to understand it better and know the possibilities before getting the EVO

This is what I understand about BOV and I might be wrong if I am...please explane me why while not beeing frustrated...I need constructive explanations

In a VTA type...when the BOV open for let say a seconde(the time is not really important could be ms, doesn't matter for what I want to explain), the air is going out because of difference between pressure levels inside the intake system and atmosphere (just like if you open a door in a plane)
This causing the air flow to accelerate...this is the drop pressure that seems to be the cause of the venting and this is what explain a higher flow to me
a higher flow measurement by the MAF sensor(placed before the BOV, I guess)...the ECU seeing the higher flow compensate with more fuel...this is where the too rich AFR is coming from

In a recirc type...I'm not sure really to understand how the BOV works but this is what I think I got
The BOV open and by the pressure in the intake system is venting with less air volume than a VTA causing not a really high drop in pressure levels...since the air stays in the system the pressure remains almost exactly the same...???
this let the air flow virtually unchanged and so for the fuel
I don't see what's the job of the recirc BOV( could someone explain) probably my view of a recirc BOv is wrong

Anyway I think I understand why you can't use a VTA BOV on a maf car..I might don't get everything, but enough to understand that it's not really a good idea...

BUT for the EVO X...why people claims tho have no issues, and why a big brand like HKS would sell a special kit ofr the EVO X...OK beeing that big doesn't necessarly mean your have the best products...
in this particular case the EVO X is even more complex than other cars having the MAF but also the MAP (manifold absolute pressure)
So by having the MAP...maybe the ECU see an anormal drop in the pressure level enterring the manifold causing to back off from increasing fuel level...????
TO me, when you have 2 sensors, there's one dominating the other and in that case that should be the closest to the combustion...I guess

This is a lot of speculations and personnal toughts...
So please don't be rough on me...I just want to understand
and sometimes you have to admit in real life that you might be wrong...
maybe a VTA can really work with almost no issues on this particular vehicule
maybe it's really not a good idea...
but I'm not convinced by either of the 2 point of view
I just want to understand and find out what's really happening in both situations

Thanks a lot guys!!!

evoxdreamz

iTrader: (2)

lol this is all very confusing. there are a HUGE AMOUNT of cars that run VTA bovs with ABSOLUTELY ZERO problems with their car. I thought that since the MAF sensor on the intake is close to the intake filter and away from the vent the bovs vented air will not effect the MAF sensor. the turbo is jus sucking in the air thats being thown at it with the recirculation bov.

I think we need a professional to chime in on this like vivd racing, perrin, and all those who have more knowledge than all of us.

Volatile

Agreed. So far all we have are theory's, petty squabeling, and confusion.