"The BIG BOV thread" (Where all bov question threads get merged)

[BigClunke]

it should move if you have a decent torch to help the process...
you will probably have to dent it, but in a space that small, i think it would be alot more work. if you dont think it will bend, how do you expect to get a clean dent with the header already installed?

[burrito007]

hey, at least i have intelligence and a willingness to accept fallibility working on my side...

Honestly, i don’t know how to respond to your post be cause it was such a vague flame, i can't even choose a coherent sentence to respond to.
Haven’t you noticed a very technical discussion occurring between dark_rex and myself for quite a few posts in this thread?
Its not easy stuff and is fairly detailed; even for me and i spent weeks in auto labs learning how these sensors work.
I fail to see your correlation between me, a person with a formal education in automotive classes and someone entirely new to cars?
(Just incase you were wondering, Noob is not short for Nubian princess. its a slang internet term that means one is new to something; ignorant, etc. with time, the spelling has gotten increasingly further from the original, newbie )
like i said, there is a seperate post for this topic, please take it there.

you still never responded to my argument. you just keep dancing around it. the precat will heat up to be hotter than the tolerances for the lining. what do you have to say about that... thats all i really care about at this point and you just keep ignoring it. forget your discussion about the lag between shifts and performance of a bov its all been discussed and is trivial. what really matters is if its going to hurt the car.

[burrito007]

can you inform me of which type of "glue" subaru uses on its cats? it would also be helpful if you would post the equation so that we can check the work.
(sorry if this is a n00b question )

Both conditions can cause converter damage like this. Converter substrate will melt between 1600 oF and 2000 oF. So lean running (High EGTs) can cause this. But, running rich will cause unburned fuel to burn in the cat. Ignition failure (weak spark, retarded timing) will also let unburned fuel into the exhaust. This can cause the substrate temperatures to soar over 2200 oF. This is how 99% of cat meltdown happens. Either rich mixture, or ignition will definitely do it. The stealership is going to blame the rich condition caused by the BOV. Now, on the other hand, if you had a defective O2 or ignition problem that was covered by warranty, all subsequent damage from the failure (including turbo) should be covered. All they need is a good excuse, and unfortunately BOV is a good excuse. Sorry, man.

[burrito007]

also, all of the stuff you asked and commented on on the first page is pretty much answered in the nabisco bov faq

[adam3482p]

clearly, i have a very good idea of how an engine works, i wouldnt have been able to write all of that if i hadn't. just because i was alittle unclear about forced induction dosent mean i dont know what im talking about at all
thank you for contributing positivly to this thread

Sorry bout that. I get a little carried away sometimes. I remember before I ever had turbo, talking to people on the street and wonder what a wastegate was.

[adam3482p]

I wondering where this post came from......

If you was refering to me quoting it.....It came from his 2nd post in this thread...First line.

[StarquestAndyR]

Actually, I'm pretty sure the turbine doesn't just *stop* between shifts. Even if it just spinning a little, this with the vacuum from the engine will likely create a negative pressure in the intake. That shoud draw the re-vented air back towards the turbo, keeping the MAF readings correct. ALso, remember that the biggest reason for the re-circ is to preserve the MAF readings. So having the vented air burp back out through it would cause the same problem as having an atmo. BOV.

Of course it doesn't just stop, but it does lose momentum without the throttle being open. The BOV dumping into the intake tube allows it to keep spinning easier without expending energy to draw that air through the filter. Thus, the spooling is slightly quicker after shifting.

And as far as causing problems with air burping back out through the MAF, that would totally depend on the factory tuning. Who knows whats in that ECU when it comes to the BOV... hehe

[StarquestAndyR]

I'm reading all this and despite the hundreds of words there doesn't seem to be any actual conclusions based on anything besides opinion. The biggest point the 100% atmo bov "haters" seem to be making is that the car runs rich momentarily (true) as it shows up on a wbo2. However, put it into context where you are actually driving. You are ending 2nd gear, shift (woosh) you run rich. Common knowledge dictates that running rich = less power. This loss of power though comes in between shifts. As soon as you are on the gas again after the shift the small amount of time that you were rich is over. It wouldn't matter if a car is making 1000 hp in between shifts because it isn't power that will ever see the pavement. Any problems that I've ever heard of coming from BOVs seem to be guilt by association or OE. I have never once had the engine stutter after a shift or bog due to the BOV. When installed correctly and adjusted properly you get a very nice noise maker with no effects anymore adverse than a silencer delete.


+1 opinion reply

Like I said in my post originally, the bogging comes from the DSM's that I am used to working with. That was my way of saying that if Subaru designed the BOV to recirculate, then they also tuned the ECU to read the air when the BOV purges into the intake tubing. On DSM's it causes them to bog. I dont know what it does to WRX's, but you can bet that it does something even if it is a momentary rich fuel condition.

That is above and beyond the direct affect of the turbo losing momentum between shifts due to no exhaust pressure on the exhaust turbine, and the fact that it has to draw air through the filter while it spins on its own power.

[kessler89]

<<<not about the argument i wanna see some before after results!!!!!!!! wheres those dyno sheets!!!

[BigClunke]

Very short-lived rich conditions are really not detrimental to your engine or catalytic converts. Turbo engines need to be rich to maintain temperature. The optimal a/f ratio is about ~13:1 to 14:1 (A: F). Now this should get you thinkin...
Hey! That would cause catastrophic failure on our engines!
That’s right! So how do we manage the heat? Run very rich ~10:1-11:1 (*even 8:1 in some cases)
If cats were extremely sensitive then our cars couldn't use them anyways.
Here is where the misconception stems:
The more rich a a/f mixture the more work a catalytic converter has to do, this creates more heat and wear on the cat because it is processing more. Cats also don’t usually shatter apart when they are spent, they usually clog/restrict and smell awful. That will hurt performance but it should really never reach that point until many years of operation have past. Catalytic converters are not a wear item to be replaced frequently; they are pretty strong and last quite a long time under normal circumstances.

the breakdown of unburnt fuel is part of the normal function of a cat....
if you dont know how a cat works, this is more info than you will ever care to know.
http://auto.howstuffworks.com/catalytic-converter.htm
the reason i did not directly answer that question is because i already have. it is a bull**** excuse for weak cats on SOA's part. i see no validity to that conclusion and that is why i was asking for the chemical compound of the "glue" you mentioned in the other post. so that i can analyze the melting point and aprove or disprove of that conclusion. i am trying to map out every detail so that a real conclusion can be reached on the issue.
(you really have to stop assuming i dont know what i am talking about. my credientals look better on paper than some tuners/mechanics you wouldn't even think twice about paying thousands to. no one knows everything, but an educated man will be resourceful enough to give you a meaningful conclusion.)

[BigClunke]

All they need is a good excuse, and unfortunately BOV is a good excuse. Sorry, man.

i dont accept it as a good excuse and seek to disprove it.
that is why i was asking for the chemical compound of this "glue."
what you have detailed is not specific to the wrx, thats how catalytic converters work; therefore, my discussion of a/f ratios and their affect on the cat was touching on that exact point. I also introduced reasonable doubt to that analysis, through comparing the difference of NA engines to turbocharged engines. i need to know what subaru used to hold the catalysts togather. the pictures of the failed cats dont look like they failed due to meltdown of the "glue." they look like the first catalyst actually broke apart. i would think subaru would be hard pressed to explain why they didnt engineer a catalyst that would withstand "normal" heat ranges for turbo applications. i mean think of what a problem this could be 10 years down the line, even for a stock car.

[burrito007]

the breakdown of unburnt fuel is part of the normal function of a cat....
if you dont know how a cat works, this is more info than you will ever care to know.
http://auto.howstuffworks.com/catalytic-converter.htm
the reason i did not directly answer that question is because i already have. it is a bull**** excuse for weak cats on SOA's part. i see no validity to that conclusion and that is why i was asking for the chemical compound of the "glue" you mentioned in the other post. so that i can analyze the melting point and aprove or disprove of that conclusion. i am trying to map out every detail so that a real conclusion can be reached on the issue.
(you really have to stop assuming i dont know what i am talking about. my credientals look better on paper than some tuners/mechanics you wouldn't even think twice about paying thousands to. no one knows everything, but an educated man will be resourceful enough to give you a meaningful conclusion.)

you can't say that the rich condition is not a danger to the cats (which are probably weak) i don't care what you want to assume. if you want to think a bov is good and just want to ignore all of the bad things it can do to a stock car then fine.

also i wouldn't pay a tuner to think for me... as a mechanical engineer from an ivy league institution i can do that on my own... i would only pay them because i don't have the time to install the parts or do research in between lawschool a masters program and a full time job.

just because you've taken classes at lincoln tech doesn't mean you know everything, or even something. i said "glue" because i assumed you didn't know the word substrate.

[dark_rex]

get this thread on topic or i'm shutting it down.

dR

[BigClunke]

also i wouldn't pay a tuner to think for me... as a mechanical engineer from an ivy league institution i can do that on my own... i would only pay them because i don't have the time to install the parts or do research in between lawschool a masters program and a full time job.

just because you've taken classes at lincoln tech doesn't mean you know everything, or even something. i said "glue" because i assumed you didn't know the word substrate.

actually, if you pass any class it does mean you know something, one might argue, at least 70% of the material or more...

I also know the word substrate is the wrong word to call the catalyst... (Technically the substrate is the un-burnt fuel. anyone at an ivy league school with a background in some science should have a good understanding of these terms ) I would hope that they use metal (welds?) to secure the catalyst, not glue. Also, the material securing the catalyst to the pipe is very different that the actual catalyst. I expect you wont be confusing the two anymore.

It was mechanical engineers with degrees that poorly designed the cat in the first place. Clearly, credentials don’t mean everything (and other times they do)...

I defiantly don't know everything (or even most things), but i know enough to think for myself and not directly quote post from other message board and take credit for it (especially when the info is incorrect)...

I have tried to get this argument moved to a different thread but, you seemed pretty quite over there

*I’m only going to try to assist people with header issues in this thread from now on.

You can keep this up but there is defiantly a point in which you need to accept defeat and move on.
I feel like I am beating a dead horse at this point and I’m sorry I have wasted this much energy on this off-topic issue.

[subaru prelude]

Do recirculate valves ever let air back into the atmosphere or just back into the intake charge. Cause it seems if you are under a very large amount of boost, then the recirculate pipe can still casue compressor surge, it will just take a bit longer, because the turbo is still pulling air into a closed in space. Also why not move the stock MAF sensor to after the turbo and bov? Then you can stil have your bling without the lose of performance.