Alright, BOV question for you all...

CassiesMan · #1 02-12-2007, 12:57 PM

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?

Steel · #2 02-12-2007, 01:02 PM

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.

2.2 Straight six · #3 02-12-2007, 01:37 PM

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.

Steel · #4 02-12-2007, 01:42 PM

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.

2.2 Straight six · #5 02-12-2007, 01:46 PM

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.

Steel · #6 02-12-2007, 02:00 PM

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.

CassiesMan · #7 02-12-2007, 03:28 PM

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

Clicky to see video

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

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...

Steel · #8 02-12-2007, 03:56 PM

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

CassiesMan · #9 02-12-2007, 04:40 PM

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.

Steel · #10 02-12-2007, 05:50 PM

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.

GreyGoose006 · #11 02-12-2007, 06:17 PM

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

CassiesMan · #12 02-12-2007, 06:35 PM

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.

2.2 Straight six · #13 02-12-2007, 09:39 PM

Quote:

Originally Posted by CassiesMan

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.

Steel · #14 02-12-2007, 10:27 PM

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

CassiesMan · #15 02-12-2007, 10:38 PM

Quote:

Originally Posted by 2.2 Straight six

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.

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