tbourner Posted April 25, 2006 Share Posted April 25, 2006 I always thought it was turbo stall, and could only be done on singles because they can handle the occasional stall whereas stock twins can't. The descriptions of the noise are brilliant I have to say! Quote Link to comment Share on other sites More sharing options...
Ouch got me Posted April 25, 2006 Share Posted April 25, 2006 I wanted the chatter before I bought the car. No one could help. I fitted an HKS BOV a month ago and now get chatter at low boost lift off, I just get the shhhhhhhh on higher boost. Smile every time it chatter's around town:) Quote Link to comment Share on other sites More sharing options...
Terminator Posted April 25, 2006 Share Posted April 25, 2006 LMAO, one of the funniest threads for ages. Just love the sound descriptions. Quote Link to comment Share on other sites More sharing options...
supradibbs Posted April 25, 2006 Share Posted April 25, 2006 i used to get the sound on my stock twins with the hks ssq if i set the duty quite high??? Quote Link to comment Share on other sites More sharing options...
Seb Posted April 25, 2006 Share Posted April 25, 2006 I'm pretty certain it's turbo stall (compressor surge) as has been said, but with an SSQV I still get it - I reckon it just depends on how you lift off the throttle. Jump off and it dumps the air in one go, but lift off gently and you get the mutiple fluttering noise. Quote Link to comment Share on other sites More sharing options...
Lucifer Posted April 25, 2006 Share Posted April 25, 2006 Turbo Stall? Maybe read some more? Quote Link to comment Share on other sites More sharing options...
Seb Posted April 25, 2006 Share Posted April 25, 2006 Ready some more? What language is this?! Quote Link to comment Share on other sites More sharing options...
Lucifer Posted April 25, 2006 Share Posted April 25, 2006 Oops! Quote Link to comment Share on other sites More sharing options...
Lucifer Posted April 25, 2006 Share Posted April 25, 2006 A turbo by itself does not know how to regulate boost levels. Basically, a turbo system is a positive feedback loop meaning that the engine's exhaust spins the turbo which, forces more air into the intake making more exhaust which, in turn spins the turbo even faster. Without a way to regulate boost levels the turbo would keep producing higher pressures until the engine exploded. This is where the wastegate comes into play. The wastegate attaches onto the turbo header before the turbo. When you begin accelerating exhaust gas pressure builds inside the manifold and is forced through the turbo. This pressure continues to increase as the turbo spins faster (remember the positive feedback loop). When the desired boost level is reached the wastegate opens and vents pressure from inside the manifold so the turbo won't spin any faster. So how does the wastegate work exactly? http://www.turbosaturns.net/images/Wastegate.gif Above is a diagram of a typical external wastegate. Inside the wastegate is a diaphragm which creates a seal, and a spring which holds the wastegate closed. Spring rates vary depending on the amount of boost you want to run, typically they are given in a "bar" value for example 1 bar would be 14.7psi. This would mean that in order to open the wastegate you would need to excerpt a greater pressure than the 14.7psi spring holding the wastegate closed. In order for the wastegate to work you must have the compressor reference port hooked up to the compressor side of the turbo, if you don't have this vacuum line attached than the boost pressure will not be limited to the set spring pressure; it will build unlimited boost pressure until your engine is destroyed. Normally pressure from a spooling turbo pushes against the diaphragm (though the vacuum line attached to the compressor reference port) which in turn pushes against the wastegate spring. When the pressure from the spooling turbo exceeds the spring pressure the wastegate's plunger opens releasing the excess pressure through the dump tube into the exhaust after the turbo or to open atmosphere. Typically, if you use the wastegate to control your boost levels you will experience a decrease in power and spool times. Why? Although the spring fully opens at its set spring pressure it tends to begin opening before reaching the set spring pressure. This "pre-opening" leaks boost pressure through the dump tube before max boost pressure is reached resulting in a decrease in power mostly toward the top end. This can be corrected by using a boost controller. Boost controllers serve two functions; increase boost levels beyond the set wastegate spring pressure and reduce the "pre-opening" of the wastegate-controlled boost pressure. A manual boost controller will allow you to increase boost levels beyond what the wastegate spring is set. How does it work? Below is a diagram of a manual wastegate. http://www.turbosaturns.net/images/manual%20boost%20controller.gif In order to run a manual boost controller we need to tee off of the vacuum line which runs from the turbo compressor housing to the compressor reference port. The manual boost controller works using a spring and check ball, by screwing the adjusting screw into the boost controller you put more pressure on the spring which reduces the amount of airflow through the boost controller and into the boost controller port. Less airflow means less pressure will be assisting the spring to keep the wastegate plunger shut. The pressure in the vacuum line going to the compressor reference port will equal the pressure the turbo is producing. A boost controller will allow you to direct some of that pressure to the top of the wastegate diaphragm creating two opposable forces. By adjusting the spring pressure of the boost controller you can vary the amount of boost that the turbo will make before opening the wastegate's plunger. If you want to run a higher boost level than the wastegate spring allows you will need a boost controller. The manual boost controller is a very simple device that can help you make more power from your turbo setup. Here are three additional things to keep in mind about wastegates: Without a line running from the compressor housing to the wastegate's compressor reference port boost pressures will keep increasing forever. This will quickly destroy your engine! Run a wastegate as close to the desired boost pressure as possible this will help the boost controller handle the pressure better. You can't reduce your desired boost pressure lower than the spring rate. Quote Link to comment Share on other sites More sharing options...
Pig Posted April 25, 2006 Author Share Posted April 25, 2006 Lets talk somemore about my noise tonight boys and girls! Quote Link to comment Share on other sites More sharing options...
tbourner Posted April 25, 2006 Share Posted April 25, 2006 Yeah but Mr Lucifer what has all that got to do with the problem at hand? you seem to be saying that there is no such thing as turbo stall? And that if there was no wastegate or BOV the turbo would spin forever and never stall? So when you lift off and the throttle body closes, the reduction in air pressure in the inlet doesn't force the ECU to reduce the amount of fuel being put in then? And therefore reduce the amount of exhaust gases being produced? and therefore no longer 'power' the turbo? So the pressure now stuck in the intercooler and related pipery doesn't flow back through the weakest point (the now un-powered turbo)? Hence STALLing it? Quote Link to comment Share on other sites More sharing options...
Lucifer Posted April 25, 2006 Share Posted April 25, 2006 Yeah but Mr Lucifer what has all that got to do with the problem at hand? you seem to be saying that there is no such thing as turbo stall? And that if there was no wastegate or BOV the turbo would spin forever and never stall? quote] Ummm I don't believe I said that. Quote Link to comment Share on other sites More sharing options...
Seb Posted April 25, 2006 Share Posted April 25, 2006 That is all very intersting and makes sense, but like Tbourner said, I'm not sure what it's got to do with turbine stall/compressor surge? Quote Link to comment Share on other sites More sharing options...
Guest alexl Posted October 19, 2007 Share Posted October 19, 2007 sorry for dragging post back up but i came across on google and thought id try to help out. a BOV or dump valve are comletely different to wastegates. A wastegate controlls boost regulation, as lucifer said, by opening to allow exhaust gasses through without powering the turbo further when the desired boost pressure is obtained, otherwise the turbo would spin itself to destruction and boost levels would not be able to be regulated. This process deosnt cause the 'flutter' sound people hear. The purpouse of a BOV is to releive the boost pressure built up by the turbo after the throttle is let of, closing it. Some people remove BOV's so they can have the 'flutter' sound which is correctly called compressor stall/surge. this is basicallly as tbourner described it. the compressed air trys to force its way out of the system as it can no longer be forced through the closed throttle. The sound is the compressed air being forced through the turbo, and stalls the turbo as it is forced in the opposite direction to the turbos original rotation. On higher boost applications or where an upgraded BOV is fitted both noises can be heard. Higher boost applications still produce the noise usually if the BOV is not large enough to release all of the boost some stalls the turbo also. Sometimes when an upgraded BOV is fitted the noise is heard when the boost doesnt reach maximum, as when the throttle is let of there is not sufficient strength in the compressed air to open the BOV (dependant on set up) so it is forced back throgh the turbo. This is usually because the spring on these BOV's is stronger so a couple of psi isnt sufficient to open it. There is no such thing as wastegate chatter!! Theres mixed reports whether it damages you turbo to have this strain on it, i run mine without a BOV and have had compressor surge for a while now and have experienced no problems. It may wear the bearings more quickly, but nothing a rebuild cant fix nor do i think it is a substancial decrease in turbo life. Ive looked around for a while now to try and find some evidence that it severely decreases turbo life (thats how i came across this post), but have found none. Many people are severely opposed to people who alow ther car to flutter, but have no evidence or backing for what damage it causes. I have even spoken to a reputable company near me who specialise just in turbos, and the boss believes it doesnt do much if anything to reduce turbo life, unless your running a very high boost pressure application. in this case your likely to get the fluuter aswell as a dump anyway Im 100% the flutter noise is compressor surge, not an external wate gate, as a wate gate operates when the turbo is at the preset boost pressure therefore under acceleration/throttle NOT on let of (which will reduce gasses spinning the turbo therefore slowing it down meaning the wastegate will not be operating) as that is where the unused boost pressure is released. Quote Link to comment Share on other sites More sharing options...
edge Posted October 19, 2007 Share Posted October 19, 2007 I need one of these LINKY Quote Link to comment Share on other sites More sharing options...
fishman Posted October 19, 2007 Share Posted October 19, 2007 I need one of these LINKY ive seen that before somewhere Quote Link to comment Share on other sites More sharing options...
Guest mk47 Posted October 19, 2007 Share Posted October 19, 2007 :Dnice avatar Quote Link to comment Share on other sites More sharing options...
fishman Posted October 19, 2007 Share Posted October 19, 2007 :Dnice avatar lol, slightly different, i thought i was the only one Quote Link to comment Share on other sites More sharing options...
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