Alright, BOV question for you all...

Ok all you engineering smart types, I got a question for ya. Say you have a car, a Lexus IS300 for shits and giggles sake, with a 2JZ-GTE swapped in. Now then, your running about 2Bar of boost and something north of the 700 mark at the rear wheels. Now here comes the question. You rev the car, and bang, the BOV just blows out the front of the hoost, and causes some damage to the FMIC and other good stuff. What exactly would cause a BOV, that has been perfectly reliable till now, blow up and out of the car?

MAybe it wasnt rated to take that amount of pressure, or the welds or however its bunged into the intercooler piping just couldn't handle it.

but a turbo IS eh? pretty sweet. I demand pics.

you do realise that you don't even need a BOV? turbo'd race race don't use them. they have something similar called a pop-off valve which is an over-boosting fail-safe.

BOVs are a street car thing.

and i would imagine that the welds or mouting were the weakness that blew off the BOV.

Well race cars spend very little time not at WOT, in other words, with the throttle plate closed. A BOV running 2bar of boost is a very good idea on a street car, otherwise you can surge the turbo and severely damage or even destroy it. A street car only running 6-8 pounds of boost doesnt need one, but 30, yes.

the wastegate prevents any problems, bypassing all the exhaust gas away from the turbine means it's not making any boost, no boost means no problem with a closed throttle plate. there's no need for a BOV if you have a wastegate, whether it's internal or external.

Not really. The wastegate is designed to bleed off excess exhaust gasses to control the boost while under load, so that the turbo wont exceed a certain amount of pressure. They are almost always vacuum controlled by the intake pressure. The purpose of the BOV is to release the sudden and intense spike in intake pressure when the throttle plate is suddenly closed. If CassiesMan didnt' even have the BOV to begin with in that motor, the best that would have happened would be that one of the intake hoses after the turbo would have popped off, the worst would be that it didnt, and the turbo would have surged, likely ruining the turbo at those pressures.

Here, I'll post the vid, you can all take a watch see and argue some more.

Clicky to see video (http://www.youtube.com/watch?v=U_XzMgU6vwA)

Now, watch the video, and take a look at this here pic.

http://www.visionboy.com/images/full/is300motor.jpg

If you look in that pic, and then in the video where they look inside the engine bay, the BOV, as well as that silver/black cylinder thingy are both missing...

Which silver black thingie? Theres lots of them under there, and you cant really see too much in the video.

Just to the left of the BOV, on the other side of the piping, has GReddy written on it. Last time we looked at it, we thought it was an oil catch can.

NOt exactly sure, but my guess would the the valve assembly for the boost controller. It looks like the vacuum lines go the the turbo wastegate.

what was that flash of light right before the BOV flew off?
looks like an explosion happened inside the BOV possibly.
is it possible that the BOV was malfunctioning when a backfire found its way into the turbo and created a spike in boost?
the other thing is in the video, the BOV flew off and blew a hole in the front of the car near the splitter or whatever, but in the picture, teh BOV looks to be a lot more near the top of the engine. is it the same car in the picture?
whatever it was, it was pretty cool, but sad at the same time.


edit:
just realized that you wouldnt have seen the backfire, so i guess that wouldnt have been it.
either way, it has to be related to having too much boost.

either the welds sucked and thats why it failed, or too strong of a spring was used in an attempt to run more boost which exceeded the capabilities of the cheap BOV.

after looking at the vid more, it seemse to me that you would need a lot more than ~ 30 psi to launch that thing thru the front of the car and into the air. i suspect that more like 3+ bar or so of boost was going at the time. just a hunch

Thats what me and my friend were thinking, that he had a massive over boost. Like, for that one heart beat, that briefest of brief seconds before all hell broke loose, he was making like, 1000psi and a few thousand horsepower. Then the car said fuck you. If any of you want to see the car in action it is the Visionboy IS300. Tons of videos out there of it doing its thing...before it blew up.

Thats what me and my friend were thinking, that he had a massive over boost. Like, for that one heart beat, that briefest of brief seconds before all hell broke loose, he was making like, 1000psi and a few thousand horsepower. Then the car said fuck you. If any of you want to see the car in action it is the Visionboy IS300. Tons of videos out there of it doing its thing...before it blew up.

Err... i don't think so. a pressure like that would blow out tubing connections and a lot more.

and yes, the polished silver thing is a catch can.

oh, i was looking at the thing by the fuse block.

Err... i don't think so. a pressure like that would blow out tubing connections and a lot more.

I see that sarcasam is not your strong suite...

Anyways. So, now we have an oil catch can and a BOV blowing off. Literally. What causes this general catostrophic malfunction.

hehe, is this a question or just bragging?

The reason it blew off is because you used the $20 Kmart special BOV. Get one that actually has a bolt on flange instead of that rediculously cheasy pinch bolt setup, and I promise you, it won't blow off anymore....even with your amazing 1000psi capable engine.

Of course, that would ruin the bragging rights eh? :D

I see that sarcasam is not your strong suite...

1,000psi is almost 70 times atmospheric pressure, the silicome hoses couldn't stand anything like that, and neither could much of the solid piping.

does that catch can blow off? i can't see any reason it would, i think it was probably just the BOV firing out from near the grill and buggering everything around it.

1,000psi is almost 70 times atmospheric pressure, the silicome hoses couldn't stand anything like that, and neither could much of the solid piping.



It was sarcasm, your supposed to laugh ;)

After watching that Video, are you sure it was only the BOV that came off?

There was a LOT of orange flame and pressure released when it popped.
Looked more like the head tried to make a break for freedom.

Alright, I just watched a higher res video on the visionboy website.

The BOV deffinitly came out the top of the engine, the bonnet was lifted off and flexed around the hinges and front catch.
There is also considerable fire damage to the front of the bumper, the paint is well and truly toasted.
When the bang happens there is a large orange fireball in the right front corner, where the BOV is located, this appears to cause the fire damage to the bumper, and also appears to cause a lot of flex in the side of the bumper. I would assume its this fireball that also dislodges the BOV and throws it out of the engine bay through a gap in the flexed bonnet.

Now either thats one f-ing big blow back through the intake, or, note the location of the oil catch can, and the fact that it's missing after the explosion. :)

Now either thats one f-ing big blow back through the intake, or, note the location of the oil catch can, and the fact that it's missing after the explosion. :)

Thats what I've been saying. The only problem is VB hasn't listed anything on his website about it at all, and I and my bud have gone to a bunch of IS/2JZ forums, and again, nothing.

Generaly when a race car has a major accident, the owener tends to be very reluctant about sharing with the world why.
There is a huge amount of pride involved.

It looks to me like the oil catch can blew up.
The cause of ignition, and explosive vapour is open to speculation, but thats what it looks like.
Its not the first time Iv seen it happen either.

Love to see some pics under the hood now. While it's certainly possible to blow the BOV off with a hell of alot of pressure at 2bar... (I shot a pressure tester across a garage and dented the wall 12 feet away at 1 bar) ...that doesn't explain the explosion.

Is his intake down below the passenger headlight...looks like it. It appears that the explosion was below the oil catch can. Pics of the damage would help. But I'm gonna guess one hell of a blowback.

No pics of the damage besides the ones in the vid, sorry. Guess we just have to leave this one up in the wind?

I will officially put my stance on gremlins.
http://tesla.liketelevision.com/liketelevision/images/toonfest/lowrez/bugs4212.jpg

^those ones.

if you watch the video, at about 56-58 second in, the engine "looks" different to how it does in the photo on the site. by that i mean it has the plastic cover on and you can see the air filter, i think the catch can was added after the video was shot.

you do realise that you don't even need a BOV? turbo'd race race don't use them. they have something similar called a pop-off valve which is an over-boosting fail-safe.

BOVs are a street car thing.

Have you never seen or heard a WRC car?
Big turbos, as much boost as they can pull through the restrictors and blow off valves which chirp loudly every time the throttle is closed.

from what i was told by some guys who work at my college and a merc dealership, that's the wastegate, and some noise is made by vibrations in the inducted air bouncing back and forth when the throttle plate is closed.

on top of that, in the pictures i have of various rally/race engines, they don't have BOV, only pop-off/surge valves.

all race cars have BOV. Depending on the model of BOV, they can also act as a "pop off valve" (ie, over-boost protection).

Basically any turbo engine that has high boost wants a BOV to prevent surging and also keep the turbo spooled when closing the throttle. Only time I would recommend not having one is if you had a very low boost setup, IE, under 10psi.

Only time I would recommend not having one is if you had a very low boost setup, IE, under 10psi.

Or if you've got a diesel with no throttle plate.:grinyes:

It cracks me up how the ricers go out and buy the loudest BOV they can for their 5 psi of boost to make it sound impressive.
Especially fitted to cars with a MAF on the airbox, you see them go so rich they spew black smoke just after the BOV opens.

ah yes, I should have mentioned that about diesels.

The thing about those annoyingly loud BOV, they often flow less than GOOD BOV because they are restricted by the whistle outlet, so (depending on the parameters) they are compromising the effectiveness of the BOV to make that annoying noise.

As for the MAF, all you need is a BOV that bypasses back to the turbo intake....assuming its a draw-thru anyway. Often called a bypass valve, but its the same thing

As for the MAF, all you need is a BOV that bypasses back to the turbo intake....assuming its a draw-thru anyway. Often called a bypass valve, but its the same thing

Yes most of the ricer cars here with factory turbo come plumbed up with a recirculating BOV.
Of course the aren't anywhere near loud enough, so a venting one is the first mod these turkeys do.

The second is usually a 3-6" tip for their 2" exhaust.

The third is a set of wheels which don't match the car and take them four years of HP to pay off.:screwy:

I finally watched the video, I can't see crap in the video, although its obvious there was an explosion in the intake track. It could be this setup has alcohol injection post-turbo and thats why the explosion was so violent, but its really immaterial....something bad happened, thats about all you can tell from so little

well that, and his taste in music sucks. thats in my opinion of course, so its possible that MY taste in music sucks.

that is an awesome explosion tho

well that, and his taste in music sucks. thats in my opinion of course, so its possible that MY taste in music sucks.

that is an awesome explosion tho

No, you're right; his taste in music does suck.

it sucks he sold his IS, fixed it after the explosion and then got rid of it, no more visionboy