Guest bastaad525 Posted November 7, 2005 Share Posted November 7, 2005 Not Z related, sorry guys. This is an SRT-4 question and a general turbo question. AND it's gonna be another one of my signature long posts... sorry guys there's a lot of details involved and I really need a good answer on this... it could be the difference between enjoying a 20 extra cheap hp, or destroying my turbo I upgraded the WGA on my SRT, the stocker is VERY weak so this is usually one of the first upgrades SRT guys do. Unfortunately, because the turbo is SO small and so easy to spool, when you take computer control out of the equation, you get full boost at anything more than 1/3 throttle above 2500rpm. Now... some people might think that's great, but on the SRT, when you exceed about 5-7psi at part throttle, there is this fluttering noise, and the car kinda shudders along with that noise. The fluttering, to me, sounds like when you have a BOV that has been adjusted too tight, and doesn't go pssssssshhhh in one sound but instead flutters Pshpshpshpsh, sometimes called a 'turkey gobble' or compared to a laughing hyena. My BOV does this I don't think I've ever heard compressor surge but I dont think it sounds like that rapid fluttering hiss sound. But I'm worried that using this WGA is gonna be doing harm to the turbo over time if it IS surge. The shop that sold me the WGA says it's the wastegate flapping, but that doesn't make sense since the WGA is much stronger than the stock WGA, yet you NEVER get that sound with the stock WGA. I think he just doesn't want me to return it So this sound happens when boost get's pretty high at moderate throttle levels and the rpm is slower than 4000rpm. It also happens if the boost gets higher than 19-20psi at WOT. One other thing I need to mention, what *I* think the sound MIGHT be. The BOV on this car is controlled by the computer. There is a line from the intake that goes to the BOV, but it passes thru a computer controlled solenoid. It regulates vacuum/boost pressure to the BOV this way. Now, the computer doesn't expect there to be much boost at part throttle... with the computer controlling boost you wont get much more than 5psi unless you push the throttle more than 80%. So maybe the computer, not expecting boost, is not supplying pressure to the BOV to keep it closed, so when pressure builds up it's forcing the BOV open, bleeding off a bit of boost, slamming shut, boost builds instantly, forcing it open... rapidly cycling and causing that flutter sound. I have no idea how strong the spring in the BOV is on it's own, but I know I do get the flutter at different levels of boost depending on what rpm and gear I'm in... sometimes it flutters as low as 7psi, sometimes it doesn't flutter at anything less than 12-13psi. So what do you guys think, is this compressor surge? And can someone PLEASE describe what compressor surge SHOULD sound like? Quote Link to comment Share on other sites More sharing options...
pjo046 Posted November 7, 2005 Share Posted November 7, 2005 I don't think this is compressor surge. I had compressor surge on my previous car before I installed a BOV on it. And that sounds more like a shwooop sound, like when closing a door that has a lot of pressure coming out of it. It's, weak at the beginning, then becomes stronger and stronger and suddenly stops. Takes about 1.5 seconds Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 7, 2005 Share Posted November 7, 2005 You typically get surge at lower rpms and when the turbo is too big for the engine. A smallish sized turbo shouldn't even get the chance to operate in the surge zone. Look at a turbo map for that turbo and map out the engine rpm and cid to figure out if surge is even a possibility. I think you have some other issues with the BOV. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted November 7, 2005 Share Posted November 7, 2005 remember that video I posted not too long ago?? It sounds like a FLUTTER.. so when you let up off the gas you hear a Pshh Pssh Pshh Pshh Pshh really fast... like a turkey call Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 8, 2005 Share Posted November 8, 2005 Could be a loud "WHUMP!" could be something that sounds like a hammer banging on your engine in rapid succession---all depends on the turbo and where it is on the compressor map when you surge it. In many cases people with these "hard dump" BOV's are getting a sound much LIKE surge because they are very near lthe surge point. A BOV should make a "sigh" when relieving the pressure. Letting pressure build to a point and then dumping it is running a pressure spike close to surge before dumping it. The bigger the compressor section, the lower it sounds. It can be bad, very bad. In the old days, one good surge at full pressure could snap the blades of the compressor causing a big mess! To witness Garrett's test cells testing compressors it makes someone like me cringe. But happy at the same time, since I realize casting and blade designs have really greatly improved their strenght and integrity... Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 8, 2005 Share Posted November 8, 2005 Sounds like turkey gubble but 10 x louder and it happens in low VE area. Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 8, 2005 Share Posted November 8, 2005 If you have a decent boost gauge the needle will fluctuate when you hear the fluttering if it is surge. This would happen at part throttle with boost. If its WOT and the revs are up you are not having surge especially if it is a small turbo like you say. Have you posted this on a SRT board? I'm sure it is common enough that they would know. Quote Link to comment Share on other sites More sharing options...
AnTmanS130T Posted November 8, 2005 Share Posted November 8, 2005 This being said, I have had a surge problem while I was on the dyno.. I thought it was my blow off valve leaking or something else. The car has an ocassional surge problem, sometimes up top of 4th gear ..I do notice the needle will fluctuate on the gauge sometimes. I was thinking this was due to location on the intake manifold, near a runner. Hmm I wish I could figure out what is causing this. I was thinking about reversing the vacum line on the b.o.v to keep it shut and floor the car to see if it still surges, atleast that would eliminate the b.o.v having a problem. On the dyno it seemed as if the car would jerk a little while surging. Any input ?? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 8, 2005 Share Posted November 8, 2005 This being said, I have had a surge problem while I was on the dyno.. I thought it was my blow off valve leaking or something else. The car has an ocassional surge problem, sometimes up top of 4th gear ..I do notice the needle will fluctuate on the gauge sometimes. I was thinking this was due to location on the intake manifold, near a runner. Hmm I wish I could figure out what is causing this. I was thinking about reversing the vacum line on the b.o.v to keep it shut and floor the car to see if it still surges, atleast that would eliminate the b.o.v having a problem. On the dyno it seemed as if the car would jerk a little while surging. Any input ?? What kind of BOV? Greddy can flatter if you are using both ports and bottom port is getting more pressure than top port. You can control the bottom port pressure with EBC or just a regulator. Quote Link to comment Share on other sites More sharing options...
AnTmanS130T Posted November 8, 2005 Share Posted November 8, 2005 It's a greddy type-s. The bottom port is not being used.. I was never exactly sure what it was used for? Is there something that can be done or why would the b.o.v be doing this? Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 8, 2005 Share Posted November 8, 2005 It's set too lose probably. Tighten down and use the bottom port, it'll help opening up the BOV even when you set the BOV tighter. I run Greddy type-R with 30psi spring with bottom port hooked up. Only time it doesn't open is below 3-5 psi. Quote Link to comment Share on other sites More sharing options...
AnTmanS130T Posted November 8, 2005 Share Posted November 8, 2005 Should I use a T off the same source or use a seperate source of vaccum for the other port? Thanks, - Ant Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 8, 2005 Share Posted November 8, 2005 I would T it off with the boost signal for the WG. The bottom port doesn't need to see the vacuum from the intake Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 8, 2005 Share Posted November 8, 2005 yeah I did post this at the SRT forums but they really... hmmm how to put it nicely.... they're not the most knowledgeable bunch of guys. And even from their 'gurus' I have gotten several different answers. The BOV thing was my idea since my BOV on my Z sounds like that. One 'guru' said it was the wastegate door flapping and wouldn't harm anything, another said it was compressor surge. It happens the worst at between 1/3 - 2/3, at low rpm like around 3000rpm, boost will get up to anywhere from 7-12psi, then I get a high pitched, fluttering hiss sound. No one has compressor maps for the SRT turbo, I guess it is just a variant of a mitsubishi TD04? It's small, VERY small. It is to our T3 what a T3 is to a T4. I didn't think it would be off past the surge line (far left line on a compressor map) at high boost/low rpm which is why the surge idea didn't make sense to me. If anythign wouldn't it be way off to the right of the map, basically just way out of it's efficiency range? But how do you factor in a part throttle opening on a compressor map? Again, this HAS happened at WOT as well when boost got up to 19psi at a low RPM. If I floored the gas at less than 3000rpm, boost shot up to 19psi and I heard that flutter until after 3000 then it went away. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 8, 2005 Share Posted November 8, 2005 SRT-4 got some crazy 16G I think. and there is about noway you can surge the turbo on 2.4L but you could go other way to the right size of the map pretty easy. SRT4 seems really finicky about things. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 8, 2005 Share Posted November 8, 2005 Well on the compressor housing I found today that it does actually say TD04 on it. And yeah, on a 2.4L with a very small turbo, it only makes sense the line on the compressor map would be way over to the right, out of the efficiency range probably and way far away from the surge limit. So this should NOT be surge, but it's been confirmed from a few guys it's not the BOV fluttering either, as they've blocked off the stocker and upgraded to aftermarket BOV's and still get the same noise regardless how tight or loose they set them. So what else could make a fluttering noise like this??? Now I have two shop owners saying it's the waste gate flap fluttering, and that all it could damage is the wastegate actuator. Quote Link to comment Share on other sites More sharing options...
Clifton Posted November 9, 2005 Share Posted November 9, 2005 Here's some Mitsu maps. http://www.rbracing-rsr.com/turbotech.html#mitsu Quote Link to comment Share on other sites More sharing options...
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