mario_82_ZXT Posted June 12, 2005 Share Posted June 12, 2005 Does a fluttering intake indicate a leak?? I just finished installing my large NPR intercooler and if it is boosting and I shift gears I get a flutter. I don't have a BOV install, and am using the stock recirc valve. I can't tell if the turbo is overrevving mostly because I can't hear it at those rpms due to the open DP. Thanks in advance, Mario Quote Link to comment Share on other sites More sharing options...
lifegrddude Posted June 12, 2005 Share Posted June 12, 2005 It's compressor surge, not a leak. I noticed it became more audible when I went to a fmic setup as well. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted June 12, 2005 Author Share Posted June 12, 2005 What can I do about it? Install a BOV? (I thought the stock VCV was supposed to account for that) Will it be Ok if I run it like that? How much PSI can you run without a BOV or good recirc? Thanks again, Mario Quote Link to comment Share on other sites More sharing options...
AnTmanS130T Posted June 12, 2005 Share Posted June 12, 2005 Sounds like compressor surge.. that extra air is being pushed on your turbine wheel causing it to put a lot of wear on it and slow it down. Buy a b.o.v. and weld it on the cold side pipe. The only thing that is going to happen is the life of your turbo will decrease. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 12, 2005 Share Posted June 12, 2005 VCV is designed for stock inlet volume, and stock pressures. You have upped the pressures and more than likely at least DOUBLED the captive volume in the pressurized side of the intake system. Either add a second VCV, or put a blowoff valve on the piping to dump pressure during drop-throttle. I have used dual VCV's successfully to 17psi on the stock J-Pipe, but the pricing on decent BOV's is half what it was when I set that up... So there is no real reason to not get one. Though the Dual VCV is a very stealthy, quiet setup (as is a BOV if you pipe it properly!) I like quiet, stealthy cars... Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted June 13, 2005 Author Share Posted June 13, 2005 Disclaimer: It is only temporary! The pipes are ABS plastic, but it will all change in a few months to nice shiny Aluminum ones. I used 4 90* bends, but that will also change when I use Al pipes. If I cut and swivel the connections on the endtanks I am fairly sure you can get away with only one or two 90* bend. This was my first attempt so don't laugh http://www.mafoose.bobos.ca/IC/IC.htm Mario Quote Link to comment Share on other sites More sharing options...
Clifton Posted June 14, 2005 Share Posted June 14, 2005 Will it be Ok if I run it like that? How much PSI can you run without a BOV or good recirc? Thanks again' date=' Mario[/quote'] You should hear mine, T66. I don't even need to make boost just be close. I've never had a BOV on any car. I run 24 psi. You'll be fine Quote Link to comment Share on other sites More sharing options...
CruxGNZ Posted June 14, 2005 Share Posted June 14, 2005 This was my first attempt so don't laugh http://www.mafoose.bobos.ca/IC/IC.htm Mario Oh man, if those pictures make it out of here, you'll probably see them posted on all the car sites of what some "ricer" did. But they will never know they were just temporary. !M! Quote Link to comment Share on other sites More sharing options...
sims76 Posted June 14, 2005 Share Posted June 14, 2005 Not bad Mario. When those pipes are metal instead of plastic people will definitely give you great comments. Looking good. Quote Link to comment Share on other sites More sharing options...
sims76 Posted June 14, 2005 Share Posted June 14, 2005 I've run a BOV from day one, but I have run around with it disconnected. I get compressor surge very very bad. It's bad enough that I won't drive the car like that. Mine flutters too, but I don't think I have any leaks. Quote Link to comment Share on other sites More sharing options...
hat1324 Posted June 14, 2005 Share Posted June 14, 2005 i would never drive w/o the bov or some type of re-circ. flutter is a sound heard with a bov, and is the air coming back on itself and slowing the turbo down and putting force on the shaft in reverse. 24psi? no recirc, pop off, or bov? good luck on that lasting. HKS SSQV. is what ill be going with, Ill have a ford motor, but gotta keep the rice in me.. and if you arnt making the pipes your self, plastic is a great Idea.. make the pipes, and take them to a shop.. say "make these". Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 14, 2005 Share Posted June 14, 2005 What about getting a fluttering sound WITH a BOV? I'm running a DSM BOV, and I've verified that it works by putting my finger on the valve and feeling it open and close as I attach and remove the vacuum hose with the engine running. It's installed on the pipe between the I/C and the throttle body. So I SHOULDN"T be getting compressor surge. Funny thing is, I don't remember ever hearing it make that flutter sound until after I installed the I/C and turned up the boost. It doesn't always do it either, sometimes I get the more usual pssssssssh sound, but sometimes if I get on it briefly, hit full boost and then let off again rapidly I get that fluttery sound. Quote Link to comment Share on other sites More sharing options...
Clifton Posted June 14, 2005 Share Posted June 14, 2005 24psi? no recirc' date=' pop off, or bov? good luck on that lasting. [/quote'] I have about 10 years on my L28's turbo at 22 psi with no BOV either and it's just a standard shaft T4. A little surge on a shift is one thing, running a turbo in the surge area under load is another. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted June 14, 2005 Share Posted June 14, 2005 bastaad525 the reason why you STILL hear a flutter, with a BOV, is because the spring for the BOV could be too tight... When its really tight, or your DSM BOV was crushed, the spring will open and close, open and close, and open and close really fast. If the spring was loose, the valve will stay open untill the vacuum tells it to close. The Greddy Type S BOV allows you to adjust the spring tension.. and with it really tight, you will hear it flutter, with it loose you will simply hear a Pshhh. I personally LOVE flutter sounds, reminds me of the old Audi Quattro Group B rally car, and the older Subaru WRX's in the WRC =) Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted June 14, 2005 Author Share Posted June 14, 2005 and if you arnt making the pipes your self, plastic is a great Idea.. make the pipes, and take them to a shop.. say "make these". Exactly what I plan to do! Oh man, if those pictures make it out of here, you'll probably see them posted on all the car sites of what some "ricer" did. But they will never know they were just temporary. I will probably edit the pictures to say this.... I will put a BOV on the car, but I need to do some datalogs first because the car cut out twice yesterday under full boost at 4000 rpms (something it has never done before, even right after the install). I think somethings wrong with one of the sensors, or I have a boost leak under full boost. Thanks for all the replies and suggestions, Mario Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 15, 2005 Share Posted June 15, 2005 bastaad525 the reason why you STILL hear a flutter' date=' with a BOV, is because the spring for the BOV could be too tight... When its really tight, or your DSM BOV was crushed, the spring will open and close, open and close, and open and close really fast. If the spring was loose, the valve will stay open untill the vacuum tells it to close. The Greddy Type S BOV allows you to adjust the spring tension.. and with it really tight, you will hear it flutter, with it loose you will simply hear a Pshhh. I personally LOVE flutter sounds, reminds me of the old Audi Quattro Group B rally car, and the older Subaru WRX's in the WRC =)[/quote'] I crushed the cap down but only VERY slightly, this was when I was trying to run it open to atmosphere before I knew any better I was trying to get it not to leak at idle. I didn't notice a real difference in the tension when I tried to open the valve by hand. I mean it was less than 1mm that I crushed the cap. Ah well... I do kind of like the flutter sound too... it doesn't always do it sometimes it just goes psssssh. Well mostly I was just worried that the comrpessor might still have been surging, but I guess that's not it. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 18, 2005 Share Posted June 18, 2005 What about getting a fluttering sound WITH a BOV? I'm running a DSM BOV' date=' and I've verified that it works by putting my finger on the valve and feeling it open and close as I attach and remove the vacuum hose with the engine running. It's installed on the pipe between the I/C and the throttle body. So I SHOULDN"T be getting compressor surge. Funny thing is, I don't remember ever hearing it make that flutter sound until after I installed the I/C and turned up the boost. It doesn't always do it either, sometimes I get the more usual pssssssssh sound, but sometimes if I get on it briefly, hit full boost and then let off again rapidly I get that fluttery sound.[/quote'] Read my post above detailing the volume issue. In a centrifugal compressor, the VOLUME of air a vavle can release is JUST as important as the fact that you ae dropping the pressure. If you take a graph, and on the lefthand side, draw the line straight up, and call it a "pressure" axis, then on the botton, from origin draw the line to the right calling it "flow" you realize when you dump throttle, your point of work on the turbo goes INSTANTANEOUSLY both UP (rising pressure) and to the LEFT (lowering flow) making the compressor cross a diagonal line drawn from origin up at an angle designated as a "surge line". This is when a compressor surges. (Surge can also be said to be the REVERSE FLOW of air thorugh a centrifugal compressor) The higher up you operate on the Vertical axis (pressure), the more important the ability of the valves FLOW capacity comes into play. When you lift throttle EVEN SLIGHTLY the ability of the blowoff valve to keep a minimuim flowrate through the compressor and keep that operating point to the RIGHT of the surge line becomes more critical. When you TOTALLY lift the throttle, that operating point of the turbo goes STRAIGHT UP immediately while the valve reacts, unless you duct the diaphragm to ASSIST the BOV in opening quickly it lags behind the flow requirements ofthe turbo, and the result is intermittent surge. Basically you are above the flow characteristic of the valve, that is why you are getting surge flutter some times, but not others. I am now in the third week of hand in hand programming of a Modicon PLC to control the surge characteristics of a 2500 HP Centrifigual Machine, and the programmer is trying to TOTALLY control via a bypass valve blowing to atmosphere ONLY. I am trying to make her understand that throttleing the INLET of the turbo allows the control PID Loops to be set FAR more stable so they are not blowing $10,000 of electricity to the atmosphere in the form of compressed air every time there is a minimal process upset. But they bought this PLC for only $3000, and that was FAR CHEAPER than our dedicated Compressor Control System with SIX different control loops, depending on the operating state of the compressor.... I digress. Hope that made sense! LOL Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted June 19, 2005 Share Posted June 19, 2005 hmmm all I have to fall back on here is the article that was in Sport Compact Car quite a while ago, which I think actually contributed to the popularity of the 1st gen Eclipse BOV. They did a very thorough test of several BOV's/Bypass valves, to see how quickly each one reacted or how much surge they allowed. The 1G DSM performed VERY well, actually beating out quite a few of the aftermarket BOV's, responding VERY quickly with only the tiniest spike of pressure. I think there was only one other BOV that outperformed it which was the Greddy Type S, though my memory might be off on that. This article alone convinced me that the DSM BOV was a GREAT unit especially considering how cheaply they can be had. I got mine for $50. So I don't think that fluttering sound I'm hearing is surge, I'm more inclined to think Proxalamus has it right with his reason. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 20, 2005 Share Posted June 20, 2005 My blowthrough triples setup would "flutter" but that was a simple function of the intake manifold and it's strong pulses. The flutter and surge sound completely different. My surge sounded like someone hitting a tin pan with a hammer rapidly in succession. But that was a max flow natural surge and not a throttled surge, which have two distincly different audible characteristics. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted June 20, 2005 Author Share Posted June 20, 2005 I'm thinking I should post a clip. It flutters even when not in boost if I let go of the throttle. Its very noticeable at full boost with the full crappy exhaust back on (since the car is so quiet). Mario Quote Link to comment Share on other sites More sharing options...
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