HB280ZT Posted January 12, 2008 Share Posted January 12, 2008 OK I know that does not sound right but that is what my car is doing! Here is what I have: MS 1 V3 with 29v Extra code 82 ZX turbo motor with N42 head using turbo cam T3/TO4 turbo intercooler Tial BOV running 12 psi boost manual DIY boost controller 60mm TB Here is what the car is doing. When I am just getting into boost the car sometimes flutters, no better way to explain it. However when I get into it hard it does not flutter. So what could be causing it? If you look in the datalog around record 3185 (415.414s) you will see what I am talking about. So if anyone has any ideas please let me know as this is driving me nuts! HB280ZT datalog200801111738.zip Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 12, 2008 Share Posted January 12, 2008 Probably turbo surge causing the boost to bounce off your BOV. Mine does the same thing sometimes. It happens when I acclerate and then back off the throttle slightly. The problem is that there is no hysterisis built into the BOV's so they get into this confused state of open-close-open-close. Search for "surge". Quote Link to comment Share on other sites More sharing options...
nando280zxt Posted January 12, 2008 Share Posted January 12, 2008 I think cygnusx1 is right. My first reaction was your bov. Is yours adjustable? maybe its too soft. But i think he's right. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted January 12, 2008 Author Share Posted January 12, 2008 Well I have used several different BOV's and they all did it. 1 - was a 1st G BOV and it drove me crazy, up to 15 psi of boost, ti would leak at lower boost 2 - was a 1st G knock off BOV and it did the same, it was adjustable but it did not matter, it would also leak at lower boost 3 - latest I went with a new Tial 50mm BOV, it is non-adjustable but it is running a -18 and -21 in/Hg Un-painted spring, I no longer have the leaks and when I am really in boost it holds great. So I guess I will do some searching for surge and see what is up. If anyone has a solution that would be great as I really need to get rid of this if I every plan on having any fun on track days at Sebring!! HB280ZT Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted January 12, 2008 Share Posted January 12, 2008 I have used some that did and some that didn't. You'd just have to tweak it a bit. Perhaps placement isn't ideal. Always try to put it right up close to the TB. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted January 12, 2008 Author Share Posted January 12, 2008 Well I found this great thread: http://forums.hybridz.org/showthread.php?t=123560&highlight=surge now I just need to figure out what to do to solve the problem. I understand that it could be a driver problem but I also believe that I am missing something in the setup! I guess with all of the leakage that my old BOV's had it was masking the surge issue. Here is my turbo information that I got from James at Speed Shop Thagard! T3/TO4 Turbine wheel is a stage III. A/R .70 Compressor wheel is a T04B hi-fi A/R .63 and it flows 55lbs/min It is not a crazy turbo so I really do not see how it is causing turbo surge? I guess I need to do some more research on this problem and maybe I can find a solution that I can make work. HB280ZT Quote Link to comment Share on other sites More sharing options...
nando280zxt Posted January 12, 2008 Share Posted January 12, 2008 Hmmm... Well you're using some sort of manual boost conrolling right? Before i rebuilt my 82 turbo motor i was boosting manually. WORST spiking in the world....i recall my boost gauge going crazy like you mentioned in the thread. Anywho, it took its toll on the motor. Now i use an electronic boost controller. Don't have any problems with boost now or spiking. I haven't really encountered too much turbo related troubles....but i'm not too sure thats your problem. I wish i could help you more... Im gonna do some research. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted January 13, 2008 Author Share Posted January 13, 2008 Well I did a bunch of research and I think I may give something a try. You see the fluttering issue really drove me crazy last year while at VIR running the north course. When I was coming out of turn 7 ( a sever up hill right hand turn) it fluttered almost everytime I went through the turn. Now I did this turn in 3rd gear because I did not have the rpm to use 2nd (3.90 rear gear). So if I put in the 3.54 rear gear plus I now have more rpm's out of the motor, an intake restriction issue, gone now. I could have pulled more rpm's and powered through the corner using 2nd gear. So I think I will swap out my rearend and see how it works. HB280ZT Quote Link to comment Share on other sites More sharing options...
Clifton Posted January 16, 2008 Share Posted January 16, 2008 It sounds like compressor surge. If so it has nothing to do with your BOV. Does the boost needle fluctuate too? Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted January 17, 2008 Author Share Posted January 17, 2008 Yes I understand that it was compressor surge and in away the BOV did have something to do with it. My old units leaked so badly that they masked the problem and I did not realize I was getting compressor surge as much as I do now. You see I replaced the cheap BOV's with a good Tial 50mm BOV that seals and now I have compressor surge all the time. So to remedy that I swapped my rear gears from a 3.90 to a 3.54 and now it is hard for me to hit compressor surge without really trying to do it, you know 5th gear pulls form say 1800 rpms! I will have to wait and see how it affects the car at the track. Hopefully I will get a chance to run it at Sebring in April or so. Will keep you all posted. HB280ZT Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted January 27, 2008 Author Share Posted January 27, 2008 Well changing the gears and staying out of the throttle below 3000 rpms did not really help at all. Now I am really pulling out my hair because now I can get the car to flutter in all gears, that is also above 3000 rpms. I am even now getting it upwards of 4000 rpms when I am at part throttle. However, full throttle runs are fine, up to 17psi without any fuel issues. So what to do!! I checked all of the system and cannot find any problems, I/C plumbing has no restrictions in it. Here is my I/C specs: I/C tubing 2 1/4 I/C is bar and plate with a fin area measures 3" wide X 8" tall X 20" long. Came off of a Supra that was putting out 550 rwhp, so it should work on my car. Tial BOV is mounted 12" before the TB. Spark plugs NGK BKR7E gapped to .025 Not sure what else to try so any .02 is well worth it right now!! HB280ZT Quote Link to comment Share on other sites More sharing options...
lifegrddude Posted January 27, 2008 Share Posted January 27, 2008 Doesn't really matter where your bov is mounted as it does its job regardless. Clifton is right in that it's just compressor surge. You're probably at the surge limit where the turbo is moving more air than the engine can ingest at that moment. It happens to me on occasion during part throttle boost at lower rpms. You'll see it happen as the boost gauge will fluctuate rapidly. It used to be worse for me until I got myself a Trust Profec B boost controller and slowed the response on the wastegate. Quote Link to comment Share on other sites More sharing options...
Clifton Posted January 27, 2008 Share Posted January 27, 2008 A BOV just prevents surge when you close/ are closing the throttle. I don't even run one on my 71'. Part throttle surge is worse because the volume of air being used by the engine is less than at WOT. No one likes to hear that there turbo isn't matched good but if your hot side and cold side were a good match for the engine, you wouldn't have surge problems. If it's a stock turbine wheel the easiest way to get rid of surge would be clipping it. If you look at a compressor map for your turbo and look at the pressure ratio it is happening at and the volume of air you are using with you engine size at that boost, I'm sure you will see it is on the surge side of the island. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted January 28, 2008 Author Share Posted January 28, 2008 The part that is killing me is that before I rebuilt the motor and added the new BOV it only happened every once and awhile. Now it is pretty much all the time. So I guess I need to find James Thagard and see if I can get the maps from him. So James if you are around let me know. HB280ZT Quote Link to comment Share on other sites More sharing options...
Clifton Posted January 28, 2008 Share Posted January 28, 2008 If you know what the compressor wheel is just google compressor maps. There's a bunch online. You'll need to figure out the engine airflow though. Quote Link to comment Share on other sites More sharing options...
ktm Posted January 28, 2008 Share Posted January 28, 2008 I looked at your logs and the "fluttering" you are describing is showing up as a drop in RPM. What is the O2 reading, volts (0-5 volts)? If you notice at the time stamp you mentioned, your O2 voltage suddenly plummets. If this is a wideband sensor, that low voltage means VERY rich conditions. Also, look at the time stamp 415.026 and 415.155. At 415.026, your MAP is 138 (5.5 psi), but at 415.155 its 180 (11.6 psi). At that same time, your PW2 jumps from 10.9 to 16.2 and your O2 voltage PLUMMETS. Maybe a bad MAP sensor? You should not be jumping from 5.5 psi to 11.6 psi in 0.129 seconds. If your MAP sensor tells MS that you are at 180 but you are only really at, say, 150, it will set the PW accordingly and you will run SUPER rich. This could cause a miss. Quote Link to comment Share on other sites More sharing options...
Clifton Posted January 28, 2008 Share Posted January 28, 2008 Not to say it's not a map sensor but surge will make a boost gauge jump around quite. If the boost is set high enough it won't even make full boost. Quote Link to comment Share on other sites More sharing options...
ktm Posted January 28, 2008 Share Posted January 28, 2008 I understand what you are saying Clifton, but wouldn't t surging keep the AFRs correct? His O2 voltage drops from 1.157 to 0.157. Surging would show up as high MAP, but there is airflow there as well at that MAP and the O2 voltage should only fluctuate slightly. I am asking. Quote Link to comment Share on other sites More sharing options...
HB280ZT Posted January 28, 2008 Author Share Posted January 28, 2008 This is getting interesting how about some more datalogs to look at: log 1032 - 135, 139, 671, 1142, 1361, 1365 log 0745 - 890, 893 log 1655 - 801, 848, 955 Let me know if you have any more ideas of what could be causing this. HB280ZT datalog200801271032.zip datalog200801270745.zip datalog200801241655.zip Quote Link to comment Share on other sites More sharing options...
ktm Posted January 28, 2008 Share Posted January 28, 2008 In Log 1655 at 801, I see that you are idling. If you notice from record 782 to 801, your TP is 0 and your RPMs are fairly steady at 1125 to 1200. However, your MAP is fluctuating from 27 to 38 over this period. Your PWs are increasing and your O2s dropping. Later in the log at idle your MAP is fairly steady at 35 (955 to 991 for instance). At record 955, first take a look at records 791 and 792, specifically the MAP and O2 voltage. If you notice, record 955 shows a voltage of 0.49!! while 791 and 792 show an O2 voltage of 1.4.....both 791/792 and 955 are at the same MAP! A look at log 745, records 890 and 892 reveal odd O2 voltage drops again while at idle. You are clearly at idle before and after the records, yet your voltage drops from 1.6 to 1.2 and then back up. You are showing us records at idle, which would eliminate compressor surge from a possibility. Have you checked your spark plugs? It looks like you are experiencing transient rich periods and may be missing. By fluttering do you mean a very short, periodic hesitation when accelerating? Quote Link to comment Share on other sites More sharing options...
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