ENVY-T CNUTOX Donating Members 3,098 Member For: 22y 1m 14d Gender: Male Location: Not sure? Posted 31/05/06 09:52 AM Share Posted 31/05/06 09:52 AM Well if Simon says you don't need one.. Of course you don't!!←If you know so much, why did you have Nick tune your car?? You should have done it yourself.So if Simon or the 280 odd people that have stage 2 Nizpro kits without blowoff valves are so wrong why hasn't he blown any turbos?If you don't have it you get a flutter, do you really think ford would release a car that makes all the noise? NO So they recirculate to make it silent. Link to comment Share on other sites More sharing options...
IH8TOADS Silver Donating Members 3,618 Member For: 19y 7m 12d Gender: Male Location: OZ Posted 31/05/06 09:54 AM Share Posted 31/05/06 09:54 AM time will tell!!! I have a atmo valve because I'm a brat who loves to scare pedestrians.......I also use puddles to spray bike riders though!! Link to comment Share on other sites More sharing options...
IH8TOADS Silver Donating Members 3,618 Member For: 19y 7m 12d Gender: Male Location: OZ Posted 31/05/06 10:01 AM Share Posted 31/05/06 10:01 AM Well if Simon says you don't need one.. Of course you don't!!←If you know so much, why did you have Nick tune your car?? You should have done it yourself.So if Simon or the 280 odd people that have stage 2 Nizpro kits without blowoff valves are so wrong why hasn't he blown any turbos?If you don't have it you get a flutter, do you really think ford would release a car that makes all the noise? NO So they recirculate to make it silent.←If you disconnect the BOV on a std T (I have done it) you wont hear bugger all with the std filter (same noise level as with the std BOV). Put a pod on and its a different story though guys!!see this linkhttp://www.fordxr6turbo.com/forum/index.ph...pic=24608&st=18 Link to comment Share on other sites More sharing options...
81CJH Member 204 Member For: 19y 5m 3d Gender: Male Location: Brisvegas Posted 31/05/06 10:02 AM Share Posted 31/05/06 10:02 AM Your turbo is spinning at thousands of RPM, when you back off your throttle WITHOUT a BOV the turbo is stopped suddenly. Continue with this for a few years and your turbo isn't going to last. I don't care what anyone says.Lets not forget we're talking about air here, at relatively LOW pressure.How much pressure does your air compressor in the shed build up in that huge tank with a single piston 5HP "engine"? 100psi?...and how many more, much larger pistons did we have turning that small compressor wheel in the turbo, which is pushing less than 20psi!Lets not forget, air compresses fairly easily, since it's a gas. That compressor wheel you mentioned, which is spinning at "thousands" or RPM's, isn't going to grind to a screaming halt in the time it takes you to change gears.That bit about the rally cars made me laugh concidering that the turbo's are replaced just about every race. Short term it's ok, long term = bye bye turbo.←...like I said, they don't have them because they replace engines (yes, and turbos) so often, and I imagine having no BOV means you keep the intake pressurised and therefore have kickass throttle response - which is I'm led to believe is fairly high on the checklist of "things we'd like" in WRC. Link to comment Share on other sites More sharing options...
ENVY-T CNUTOX Donating Members 3,098 Member For: 22y 1m 14d Gender: Male Location: Not sure? Posted 31/05/06 10:53 AM Share Posted 31/05/06 10:53 AM If you disconnect the BOV on a std T (I have done it) you wont hear bugger all with the std filter (same noise level as with the std BOV). Put a pod on and its a different story though guys!!←That is correct from in cabin, but outside it is more audible.Now try the above with 13.5 psi and a bigger cooler...ULEH sounds great in and out, it's a turkey sneezing under there Link to comment Share on other sites More sharing options...
Paradoxx Colossal Member Member 5,049 Member For: 20y 5m 27d Gender: Male Location: Perth, WA Posted 31/05/06 10:59 AM Share Posted 31/05/06 10:59 AM Just a question about compressor surge... I have had the noise for ages even under stock boost levels... that gobble gobble sound... now if the BOV is designed to vent the excess pressure then why does my car make this sound? Wouldn't it be a sudden rush of air?? Does this mean my BOV is either A) not venting the air sufficiently, or B) not venting at all? Link to comment Share on other sites More sharing options...
gogo Member of team Kittens Member 609 Member For: 20y 11m 28d Location: Melbourne Posted 31/05/06 01:15 PM Share Posted 31/05/06 01:15 PM (edited) If just about EVERY mass produced factory turbo car comes standard with a BOV then you can be sure it's there for a very good reason.←So why didn't the VL Late model camira turbo come out with one?And in more recent history - well because the EPA cares a little more about emissions, and perhaps because the marketing department said to...There are some small 4cyl turbos with small shafts that have bent the shaft when used without BOV. It doesnt seem to worry the big shaft turbos.←The comment on the shaft diameter is a good one... Again lets think about this...The consequence of back pressure on the inducer side is it will act to try and spin the turbo in the reverse direction (as it does during normal operation when the car is on boost). The difference during a gear shift is, as has already been pointed out, is that there is low exhaust flow, so low energy on the exhaust side of the turbo trying to drive it.In very small turbo's the inertia of the rotating componant of the turbo is lower, and often boost pressure on small engines using small turbos is high. This increases the likelihood of actually stopping the turbo completely, or even spinning it in the wrong direction...Then the gear shift has been completed, and the cars is brought back on full noise. For the sake of creating a worst case scenario, lets ignore the fact that there is only a very small amount of air mass in the piping between the turbo and the engine on the induction side (just as an aside, this also helps the cobra stage II kit - as the volume of all the pumbing is much lower than the stock plumbing, hence much lower mass flow back through the turbo is required relative to stock to acheive the same reduction in pressure).This means the turbo suddenly is being spooled up, and if rotating the the wrong direction, could result in very high pressure on the exhaust side momentarily as the initial high pressure exhaust flow is commpresser further by the rotation of the turbo. The exhaust side is more likely to be fine, as it is being accelerated through the direct action of the exhaust gasses, but the force required to accelerate the inducer is transmitted by the shaft.Now from memory (and lawsy or any other engineer or knowlegable person might like to correct me here as I don't have any reference material in front of me, and it has been a long long time since I did any calculations of stresses in shafts but... ) the stress in a shaft from torsional load is proportial to the diameter to the fourth power. This means, for the same torsional load, a shaft half the size will be subject to around 16 times the stress...hence to my mind it is perfectly logical that if ever a turbo charger was to be subject to this kind of failure then it would be on turbos with smaller shaft sizes...Bottom line though the XR6T's run quite a large turbo, with relatively high inertia, beefier shafts, and relatively low boost pressures - all of which should limit the likelihood of any damage.Regardless, this would most likely exhibit itself as shaft or bearing failure, not bend vanes on the impeller. Provided the shaft and bearing have been sized correctly, and there are no cooling or lubrication issues, these should provide a long and safe operating life, as per the comment about this failure not seen in turbo's with larger shafts...There are some small 4cyl turbos with The BOV keeps the turbo spinning a bit better during gear changes.←True, but not having one helps retain presssure in the inlet side, so you have more 'instant boost' which will help cover while the turbo spins up, and help spin it!Just for the record, I have a stage II cobra kit, and no BOV... Cheers Ben. Edited 31/05/06 01:21 PM by gogo Link to comment Share on other sites More sharing options...
SAMSXR6T Member 685 Member For: 20y 10d Gender: Male Location: CENTRAL COAST Posted 31/05/06 01:27 PM Author Share Posted 31/05/06 01:27 PM Sorry guy’s car was running 285rwks... Last Friday I had a new actuator installed... told by my tuner that I needed a new actuator so that the tune I was getting today would maintain the boost from the turbo (a consistent line)... it was pointed out to me last Friday that the turbo was on its last legs, and I would need to replace it.. In his words he said that all the fins were bent and that the damage came from the BOV... I was hoping the turbo wasnt damaged but what can I do.. I have had some quotes today by a couple of people in sydney and they are asking around the $1500 to $1900 depending on the damage on my turbo.. (standard garrett xr6t) Link to comment Share on other sites More sharing options...
Master G Donating Members 511 Member For: 21y 3m 29d Gender: Male Location: Sydney NSW Posted 01/06/06 01:21 AM Share Posted 01/06/06 01:21 AM Jeez and I was just about to say I thought you might have sucked up a pidgeon at cruising altitude, that would certainly dent the blades.... I think at times you got to take a light hearted view at things, as for whether a BoV is needed, opinions are like a$$holes everyone has one. RegardsM G Link to comment Share on other sites More sharing options...
loopism Tractor Driver Member 709 Member For: 19y 10d Gender: Male Location: Sydney Posted 01/06/06 01:33 AM Share Posted 01/06/06 01:33 AM <much snippage>←Damn ... that's a post to rival Lawsy if ever I saw one. Link to comment Share on other sites More sharing options...
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