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Originally Posted by strang3majik
(Post 11335050)
Plus, lets not forget the back pressure in the exhaust playing a part. In the exhaust manifold before the turbine, there's usually double, sometimes more, pressure than the boost level your running at (thats why backpressure isn't a problem in turbo cars, and large exhaust is best). There is no pressure on the turbine when you let out of the throttle... |
Originally Posted by Turbo II Rotor
(Post 11335749)
Most ignorant post I've read all day.
Originally Posted by seandizzie
(Post 11335774)
There is no pressure on the turbine when you let out of the throttle...
Exhaust manifold pressures are often in excess of 30 or more psi. Evacuating a pressurized exhaust manifold of its contents over the turbine is no different than whats happening on the compressor side. When the throttle plate is closed the pressure is not sustained, correct, but its still following the path of least resistance. Over the exhaust wheel. While on the compressor side, compressed air is following the path of least resistance, over the compressor wheel. Due to the pitch of the compressor wheel, it is in turn putting an opposite force than the exhaust side. At the same time. Draw. |
hmm... the compressor is creating the pressure and the turbine is being driven by the exhaust port. No throttle= No exhaust flow= no pressure on the exhaust side. The compressor is still spinning( pumping) and flow has gone to 0 so it goes into surge ( as seen on the compressor map and the fluttery noise happens) but since the turbine is not being driven it's not the dangerous type.
So yes it is different. As the Compressor is pumping and the turbine is being pumped |
conquest with no BOV
Originally Posted by strang3majik
(Post 11335050)
1983-1989 Mitsubishi Starions/Chrysler Conquests did not have BOV or BPV. Vehicles driven hard experienced turbo failures in under 50k miles. Very seldom does one get over 100k out of a stock turbo with no BOV on those cars. This was in the early age of turbos on street cars. It was an experimental stage and much was learned from mistakes.
And that being said, I installed one on my completely stock car and noticed a significant difference. Without a BOV, that car had horrible compressor surge. I'd lay back into after every gear and it would need to spool back up every time. After installing the BOV, it hit full boost almost instantly once I layed back into it. Turbos spin well in excess of 15k rpms...some much much higher. When there's no BOV/BPV, air finds the path with the least resistance, and thats back the way it came, or popping a hose off. When it goes back over the blades, depending on boost levels and compressor speeds, I've seen cases of compressor blades actually bending. You're taking something from spinning at 15k rpms to a halt almost instantly. With a BOV you're giving that compressed air somewhere to go, therefore its not forcing the turbine to a stop allowing it to more or less free wheel until the next gear gets it back to its full rpm or until it gets down to its idle speed as you shut down after a run. Yes it evacuates all the air out of the system, but the turbo remains spooled, therefore will make boost as soon as the throttle plate allows air through the engine and out the exhaust. Without a BOV your also taking all the air out of the system, but now your stopping the turbine so it has to rebuild its RPM damn near completely. Plus, lets not forget the back pressure in the exhaust playing a part. In the exhaust manifold before the turbine, there's usually double, sometimes more, pressure than the boost level your running at (thats why backpressure isn't a problem in turbo cars, and large exhaust is best). Now thats trying to continue on its journey outward while the air on the compressor side is also trying the same. Therefore the compressor stall, or surge since they're forcing it in opposite directions...also causing severe heat. And BOV/BPV serve no real emissions purpose. Car companies don't put them on for nothing. They install BPV/BOV from the factory because they don't want to have to replace turbos under warranty. A penny spent now is a dollar saved later. Running without a BOV is no different than shutting your car off everytime after a run without letting it cool down. There's no instant effect (usually), but overtime the effects are obvious. But just like this topic, many swear with modern turbos you don't have to let it cool down. Kinda like double clutching versus shoving it in reverse and dumping the clutch between every gear. They make setups for some cars now that cut timing so you can stay full throttle between shifts and it limits your revs to keep the turbo spooled fully. Thats the best way to go. |
Oh and double clutching,,,,,,,,,,someones been watching fast and the furious again.
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Originally Posted by TheROVER
(Post 11336664)
Oh and double clutching,,,,,,,,,,someones been watching fast and the furious again.
thewird |
Originally Posted by GoodfellaFD3S
(Post 11166666)
You won't get a 'rash of shit' for being a DSM guy, but you will get laughed at mercilessly for saying absolutely retarded crap like the above.
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Originally Posted by TheROVER
(Post 11336664)
Oh and double clutching,,,,,,,,,,someones been watching fast and the furious again.
Because double clutching a trans with synchros is neccesary :D And guys, I've called every autoparts store and no one can get me rod bearings for my RX7 :( |
I might have some...
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Originally Posted by thewird
(Post 11336667)
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Reworking my engine bay this winter.... Plan to run 25psi with preturbo on my new BB TD61. SERIOUSLY considering ditching my Tial 50mm.
We shall see.... |
haha love this thread, just goes to show there are so many paranoid people out there.
Back in the 80s all the turbo F1 cars running 50+psi never used shitty BOV's |
I think the main function of a BOV isnt necesaarily safety of the turbo.. (which I feel having a BOV will help prolong turbo life)...but moreso to minimize "lag" if you will, between gears and in ,on,off, and on thottle again, instances...
By releasing excess boost pressure the turbo keeps spinning at higher speeds...ie.. Ready to start building boost as soon as throttle is reapplied..... If not released pressure slows/stops the turbo when the throttle is closed..thus taking longer to get back up to boosting speeds when the throttle is reapplied... My 2 cents |
Originally Posted by zaridar
(Post 11385317)
I think the main function of a BOV isnt necesaarily safety of the turbo.. (which I feel having a BOV will help prolong turbo life)...but moreso to minimize "lag" if you will, between gears and in ,on,off, and on thottle again, instances...
By releasing excess boost pressure the turbo keeps spinning at higher speeds...ie.. Ready to start building boost as soon as throttle is reapplied..... If not released pressure slows/stops the turbo when the throttle is closed..thus taking longer to get back up to boosting speeds when the throttle is reapplied... My 2 cents |
How much money do you think that it costs to produce a bov?
Lets just say 10 dollars because I do not know. Now lets produce one for every Dodge SRT-4 (25,000). $250,000. Why do manufacturers spend hundreds of thousands of dollars on parts they don't need? Its easy, they don't. I do agree that for a course of a few years the wear does not begin to show itself. |
Dodge does it for the sound lol. And for the very same reason as all the replies in these post. Some people think it need to be because that is what people tell them. So bottom line is do what you want in your own car. The title of the post was just saying his results of not running one. Not saying to throw them out. I shared my results.
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they produce and install them for the people who do not want to hear the compressor surge on factory cars. it's purpose is to minimize noise and not enhance it like the aftermarket blow off valves.
you may be surprised at what people will complain about when they buy a brand new car and shell out over $30k for it will be bothered by. why do some diesels not come with anti surge turbo housings also? because they are quieter. yet you see people in modded up trucks "whistling" happily down the street. aftermarket these are attention getter devices, so that people know you have a turbo and it's doing something, at least making noise anyways. overall i find them to be efficiency reducers, why dump all that boost when you may need some of it to spool the turbo for the next stab in the next gear? oh, and turbos spin more in the range of 100,000-120,000 RPMs. 15k? not even close. |
Originally Posted by RotaryEvolution
(Post 11386249)
they produce and install them for the people who do not want to hear the compressor surge on factory cars. it's purpose is to minimize noise and not enhance it like the aftermarket blow off valves.
close. |
most logical that i worked as a factory tech for a decade.
most logical that i haven't used a blowoff valve for about the past 3 years with no problems. neither have most of the people posting in this thread who aren't running blowoff valves and have properly running setups. there's so much BS in this thread that it started to stink many pages ago. |
Originally Posted by RotaryEvolution
(Post 11387309)
most logical that i worked as a factory tech for a decade.
A turbocharger should last twice that length of time. It could increase wear by 10% and you would not know in your time frame. Realize I am not saying one way or another because there is no public scientific research of it. Just opinions from people who conclude from there own logic. |
I blew 2 different Precision turbo's without a BOV. I really think its just Precision that sucks but I'm going to try one more time with a Garret GTX4202R on the 20b I'm building. If the Garrett blows, then I'll know why and stop wasting my time with no BOV :). I track my car seriously, its not a show and shine queen or waste my time doing simple highway pulls.
thewird |
btw even though diesels have no throttle plate, when one lets off the throttle the engine slows more quickly than the turbo... thus the same effect.. but maybe not as abrupt... also diesels run much more boost than gas motors, if i could generalize, so therefore the effects are still noticed..
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Originally Posted by zaridar
(Post 11387651)
btw even though diesels have no throttle plate, when one lets off the throttle the engine slows more quickly than the turbo... thus the same effect.. but maybe not as abrupt... also diesels run much more boost than gas motors, if i could generalize, so therefore the effects are still noticed..
thewird |
Originally Posted by thewird
(Post 11387446)
I blew 2 different Precision turbo's without a BOV. I really think its just Precision that sucks but I'm going to try one more time with a Garret GTX4202R on the 20b I'm building. If the Garrett blows, then I'll know why and stop wasting my time with no BOV :). I track my car seriously, its not a show and shine queen or waste my time doing simple highway pulls.
thewird however they are great for the money. and all that jazz, but i like OEM manufacturers like Garrett and Borg Warner. i ran no BOV on a tII stock turbo in a RX3 but hated the sound of the surge as i thought it was damaging my turbo. so i put a bov on it. ( this was years ago) now i plan to run no BOV with my S366. because if it messes up EVENTUALLY they only cost $650 now |
Originally Posted by thewird
(Post 11387668)
Might wanna look at this (towards the end)... Turbos change speed extremely quickly. When the guy lets off it drops from almost 100k to 50k between shifts almost instantly. Video Link: https://www.youtube.com/watch?v=B196nyntLbQ thewird |
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