Hey guys,

Let me start by saying that I have found TONS of useful info here from you guys, and thanks alot for that! I had a ralliart, and have since picked up the IX, this is my first turbo car, and im just learning about the engine, turbo etc after alot of reading, here and elsewhere. Now on to my question:

I took The recirculation hose off my BOV to see what all the fuss was about in regards to the (dare I say it) WHOOOOSHH sound LOL.. and I plugged, or should I say duct taped the return hose on the intake. Dont get me wrong im not getting all ricey on ya, I just wanted to see what it sounded like. I have since recirculated it. Anyway what I experienced brought a question up. Since I could hear the BOV fully while VTA I noticed that at high RPM's I could hear air coming out of the BOV BEFORE I switched gears, and BEFORE I let off the gas. I also had a loss of power at that point. So my question is, is there a possibility that this may be happening when it is recirculating, but I just dont know it cause I cant hear it? Is this whats considered a boost leak? Or is the valve engineered that way that the boost tapers off at higher RPM's? The car is stock so I would think the stock BOV should be able to hold the stock boost.. Any help is appreciated.. Oh yeah, and I have my FLAME SUIT on.

Thanks guys!

 

Were you at part-throttle when you heard the air leaking out, or were you at full WOT/full boost? The boost is designed to taper as controlled by the ECU, but it should not taper because it's leaking out through the BOV. The BOV should not open at all until you close the throttle plate, but if you drive at part-throttle (anything less than 100%), you likely are causing it to flutter, and maybe you just don't notice when it's recirculated.

 

ive tried the same thing. under load at the threshhold of boost, like in 4th gear, the bov will open and you will hear a huge leak and you will lose all power.

Don't VTA a DV that is meant for recirc. if you want the whoosh, get a VTA, but dont come crying when the car stutters when you are in low boost in high gears.

 

+1 as this is a good point.

But FYI for the thread originator, is what Warr said isn't the case... The stock BOV on all USDM Evo VIII's leaks like you explain after 16psi. Now supposedly the stock IX BOV is improved and doesn't leak until twenty something psi, as proven by leak tests done by board members. No this isn't concidered a boost leak, and it is detrimental, but not to the extent of actually showing a dramatic increase in power when replaced with one that doesn't leak.

So basically i'm just here say, do SOME of the IX BOV's have a problem with leaking still? Spring just isn't stiff enough, or something?

 

KO, it's not "supposedly" stronger. The two BOVs are completely different. One is plastic and one is aluminum. If you look at both, you know immediately. The IX bov is the same as the JDM MR DV, which has been used a great upgrade on the VIIIs for years now. There is always the possibility of a bad valve, but it's not likely. My stocker opened up as early as 13psi when doing a leak test, but my JDM MR DV didn't open until 24-25psi.

 

I have to agree, Ive seen the VIII BOV's and they are garbage compared to the stock IX, in appearance anyway, the IX looks much stronger, and well made compared to the plastic VIII. When I heard it leaking out was when I was accelerating, I would guess around 5000 RPM's RIGHT BEFORE I switched gears and still partly on throttle, and this happened through a few gears. As soon as I heard the "leak" as I would call it or it "tapering" down is when I got the power loss as well.. It was like pull pull pull <sound> drop in power. The best way to describe the drop in power would be like when you hit the rev limiter on a motorcycle, or car.

Also, the whole time, I got a pretty bad smell coming from the car.. Not a rich smell (I got that too) But another weird smell. I am still breakin the car in, and am staying below 5,000 RPM's for now, but it was almost like the smell of a new engine when you push it a little (I wasnt pushing it at all). Not sure this had anything to do with anything LOL, but figured I would mention it. I definatly was not WOT.

Oh by the way, these guys that run a VTA have to be NUTZ to sacrifice that much power and drivability man!! I mean if you run VTA and get it right, all the power to ya, good for you, but thats just not for me unless there was a way to perfect it.

By the way, I just got back from the store, and I have it hooked up the original way (recirc) and I highly doubt there is anything wrong with the BOV because this car PULLS like a mother!! Must be something with the VTA. Or possible there is no back pressure on the outlet side so it leaks out? Im guessing here

 

Well, if you're not going WOT when doing this stuff, then the valve is probably opening. You need to be at full throttle for it to remain completely closed and work properly. However, there is no immediate drop in power when you do part throttle boosting/acceleration and get fluttering. What you are describing is almost like what happens when people forget to fasten down their stock intake snorkel, which causes it to get sucked up against the hood and cut off the air supply. That usually doesn't happen until 6k rpm, though, so I wouldn't think that was your problem. Just to humor me, have you taken off the intake snorkel before (the inlet that attaches to the front of the engine bay and sends air to the airbox)? If so, did you fasten it back down with both clips? Just curious.

There shouldn't be anything that causes a major loss of power right around 5k rpm. If you are just exaggerating, then it means you're feeling the point at which we first lose that initial surge of boost/acceleration, which is when the boost starts to taper (naturally), and the tune goes mega-rich. When our cars are stock, we have a flat spot in the 5000-5500rpm range that feels like the car is dying a little, but then at 6k rpm we get another bump, then it pulls hard to 7k before dying off again. I was disappointed in my Evo when it was brand new, because I wasn't going all the way to 7k and thought the car felt kinda slow. Once I opened it up and let it go all the way to 7k, it was a whole new ballgame. Then, when you get tuned, you remove that flat spot and make linear power all the way to 7k.

 

OMG Warrtalon, you are the man!! That is INDEED what I did, I thought the Snorkel wouldnt move so I DID NOT fasten it down for the test ride!!

Mystery solved!! Thanks so much!! Man, you have some Evo knowledge eh?

PS, could the snorkel being sucked against the hood cause a pretty nasty smell as well? Not a rich smell..

 

Freakin psychic this guy is.

 

Ok, I went through this whole debogle for the 2nd time today, burnt fingers and all . Basically this is the deal:

boost starts bleeding off at mid to 3/4 throttle at almost exactly 5,000 rpm's 1-3 gears, 4th not so much from what I could tell when I could get the rpm's there, and of course I couldnt test 5th at 5,000 unless I want to be doing 140mph lol.

My conclusion? VTA blows.. and not to the atmosphere LOL!

I really dont think there is anything wrong with my BOV because when it is recirc'ing its FINE, pull pull pull! The VTA bov FORCES you to switch gears at 5,000 or less, otherwise its BOG CITY.

Im my opinion after testing the VTA im POSITIVE that 2 evo's side by side, one venting the other not, wouldnt even be a race. It just KILLS the drivability, because you are not able to squeeze that extra juice from the powerband way up high in the rpm's. Recirc for me. Thanks for all that gave their input!

 

So, with the BOV recirculating and the snorkel fastened down, everything runs fine?

As for the VTA, I am a huge VTA antagonist, but I am not too sure that the problems you encountered are normal for trying VTA with a properly sealed system. Maybe your duct tape method was still releasing air and causing problems. You're supposed to use a plug that completely seals off the opening in the intake, but I don't know why I'm even bothering, since I hate the whole concept of trying to VTA on a MAF-equipped Evo just for sound.

 

I agree pal, on both the VTA front, as well as the duct tape front.. I was thinking that too. Yeah who really cares, my main point was that I just wanted to make sure that the BOV wasnt leaking, and I just couldnt hear it when it was recirc'ing. But the way the car runs I highly doubt it could be leaking. Thanks again.

 

Wow, Warr. Nice call!

 

Yeah i know... I was going more with the bad valve route on this one.