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16 PSI test run, now my T3 has an issue.....

D

DET17

Reformed SAABaholic
Joined
Nov 1, 2009
Location
NW Georgia
OK, subject vehicle is my 940, the DD. I won't belabor the details of the car; you can check the build thread below. Almost all "wear parts" are new, including all sensors. Your typical B230FT squirter, IPD Turbo cam, fresh 530 head, Garrett T3 from Tryingbe, Browntops, cam advanced 4* via Dales, TME cat back exhaust, and TLAO chips in LH2.4 boxes.

Been slowly twisting the MBC, then making simulated 1/4 runs at my local "proving grounds" ;-)

Well the car has been rich at WOT and full boost, showing low 10's on the AEM wideband. Mike (and others) suggested raising the boost which should help lean out my engine just a bit more. On the last round I twisted it up to what I thought would be 15 PSI, and took my son along for a test ride. Well at launch it hit 17 PSI for just a second, then stabilized at 15~16 PSI, smooth power until I was winding out 3rd gear. THEN I heard a different noise....and suddenly the turbo whine was VERY audible, where it was always muzzled previously.

Well, riding home the car was showing LEAN, so I suspected I'd blown a hose...limped her home a couple miles. However my son said he heard something at the end of the run that sounded like "a turkey gobble".......WTF I'm thinking? :wtf: We popped the hood and no hoses were obviously blown or off. The AFR's were leaner but still OK. I decided to make a couple light throttle stabs, and the T3 still boosts with what feels like the same power (butt dyno, I know), but the turbo whine is MUCH more noticeable, and when I lift, the "gobble" is there for a second.

Parked it, and decided to do a leak check across the IC & both hoses attached. Custom made hose plugs from my machinist buddy, and put approx. 15 PSI in the IC, no leakage. I did find a small tear on my cold side IC hose, so I replaced with a spare. Fired up tonight and the AFR's are sitting rock steady on 14.8 when idling, but then don't twitch around like before....I'm afraid when the issue occurred, the AEM saw lean conditions for a couple seconds and something might have happened to my BOSCH sensor. Tonight, putting around the hood, I warmed it up thoroughly & then punched it going up my hill, and again the WHINE is still quite loud, and the "gobble" is still there. :grrr:

Well, not an IC problem, so I am suspicious that the wastegate diaphragm is blown, which is allowing the turbo sound to project from it, and then "fluttering" as some describe it, on decel. when back into vacuum.

Certainly somebody out there has BTDT. I can't believe I've got a gasket flapping somewhere on the intake, but I've yet to pressurize the intake from TB to the head, hoping to find the issue on the exhaust side.

Will pull a vacuum check on my old school T3 WG tomorrow; this WG was clearly not replaced when Tryingbe rebuilt the T3. Is the blown WG the most likely suspect?
 
The turkey gobble sound seems like compressor stall to me. should probably check for tears between the AMM and turbo. How's your intake setup?
 
You may have just snapped a couple studs that hold the downpipe to the turbine housing.
Explains the turkey, and leanout.
 
I've only done a hand inspection (feel) of the AMM --> turbine hose, but all clamps are tight and no obvious tears. Since this hose is suction, I'm not grasping how I would hear the turbine loud & clear if this hose were torn, and then the gobble on decel? Will remove the hose & inspect. Perhaps this air tract goes positive pressure on decel? Car has an AW71 so there is no shifting BOV needed to protect overpressure.

All studs are AOK on the DP; top inspection shows 2 intact, bottom stud not checked but the conical flange is tight. All 4 studs are tight at mounting flange to the 90+ mani.

Presently no BOV, which is why I stopped twisting the MBC at 15ish PSI. Shopping for a GReddy, Blitz, and will add soon (planning for a NON-recirc.).

Performance still there; boost looks the same, although I've not really stood on it, just a few boost blips to confirm the sounds are still present. Don't want to risk LEAN issues with my AEM acting flakey.

As I understand it, the MITSU have a true CBV, where the T3 Garrett has a wastegate actuator. I will be hooking that dude up to my MI-T-Vac tonight and see if it is infact blown. For all the $ I've invested in this build, that is one old piece I ignored; reused the old unit which came with my T3 when I bought it. Hope that is the weak link in this chain.....will advise the discovery. :roll:
 
I would agree with the others about the compressor surge. It produces a similar sound. Most of the factory T3 turbochargers had a CBV bolted to them. Yours may just be worn out at this point.
 
ovlov760 said:
I would agree with the others about the compressor surge. It produces a similar sound. Most of the factory T3 turbochargers had a CBV bolted to them. Yours may just be worn out at this point.
Click to expand...

Roger that, I'm confused on terminology here. My old T3 has the classic WG diaphragm bolted to the underside....and it's OLD, probably an original. I don't recall Garrett referring to it as a CBV, as I thought those recirc'd and functioned as a BOV when overpressure occurs. But then I'm a relative newbie to these beasts, so I'm likely just confused. If I can just find the pic, this will show exactly what I'm rambling about.....here is the old dog, hanging under the T3:

IMG_0379.jpg
[/IMG]

Will vacuum test tonight and see if she's blown. Hoping that's all...I never saw any lean AFR's until the limping drive home, and I suspect the fuel ECU was dumping, trying to cover that leak.
 
It doesn't look as though you have a CBV on there? I see the wastegate actuator, but no cbv. If you don't have one, or some other kind of blow off valve then you are definitely hearing compressor surge.
 
grnmachine02 said:
It doesn't look as though you have a CBV on there? I see the wastegate actuator, but no cbv. If you don't have one, or some other kind of blow off valve then you are definitely hearing compressor surge.
Click to expand...

^This. If you're going to bring the boost up like that, you'll need a BOV. All turbos have a wastegate (internal has the actuator you see, like all stock Volvo turbos), some external on the header. But some turbos (like my Mitsu 19T) also came with a CBV, which is part of the compressor housing itself. Has a little spring in it to control a diaphragm preventing compressor surge, unless you crank the boost too much and you need to change springs, or block it off altogether and install a BOV)

It's the triangular shaped doohicky on the compressor housing as seen on this 13c file photo:
TurboMitsuTD04B.gif
 
Dakar09 said:
^This. If you're going to bring the boost up like that, you'll need a BOV. All turbos have a wastegate (internal has the actuator you see, like all stock Volvo turbos), some external on the header. But some turbos (like my Mitsu 19T) also came with a CBV, which is part of the compressor housing itself. Has a little spring in it to control a diaphragm preventing compressor surge, unless you crank the boost too much and you need to change springs, or block it off altogether and install a BOV)

It's the triangular shaped doohicky on the compressor housing as seen on this 13c file photo:
TurboMitsuTD04B.gif
Click to expand...

Thanks, that Mitsu CBV is what I was thinking of, that my system doesn't have. I made my first test pass at 15 PSI, no issues, no sounds whatsover, just still rich AFR's (low 10's). The second test pass however burst the bubble. I need to get an education on compressor surge, and will study it. As I'm running the AW71, no shifts to deadhead the turbo, and I'm lifting "lightly" so the boost tapers back toward vacuum, I thought I could get by without at these levels of boost. I'll definitely adjust my MBC backwards to around 13 PSI until I get the BOV installed. First thing however, isolate the leak, and perhaps source a new WG actuator. ATPturbo, fleaBay, etc. They have 18 PSI units, but with the MBC I'm thinking I won't need more than a 6 PSI as the actuator should not be seeing those levels of boost. Am I correct?
 
IPD sells a 7 PSI garrett actuator (I think...saw it a while ago) for ~$80 or so.

ATP Turbo has good stuff, but isn't cheap, nor is it Volvo specific...so you'd have to make sure you get the right length, rod bend, etc...but I'd go either of those routes before fleabay :p
 
Doesn't sound like you need a wastegate actuator.

You do need a compressor bypass valve, though. The 740 Turbo used an external CBV plumbed between the compressor inlet and compressor outlet. That's what I'd run on a LH car, what we run on our LH2.4 lemons car as opposed to a BOV that vents to atmosphere.

The 1g DSM CBV works well for us. I had to make a flange for one side, cut a piece of steel plate, drilled a big hole and two small holes to bolt it up, and welded on a stub of pipe. Then cut a gasket, and since it sees pressure I globbed on a bit of a bead to hold the hose on.

133532125.jpg
 
towerymt said:
Doesn't sound like you need a wastegate actuator.

You do need a compressor bypass valve, though. The 740 Turbo used an external CBV plumbed between the compressor inlet and compressor outlet. That's what I'd run on a LH car, what we run on our LH2.4 lemons car as opposed to a BOV that vents to atmosphere.
Click to expand...

Well it certainly needs something...as in "something sh*& the bed" at the end of that 16 PSI run. I'll inspect the suction hose and the actuator, but something is broken, as it never made the compressor surging sound (if that is what it is) until THE something let loose. As you can see in this pic, my intake system is stock 9 series parts, still running the 016 AMM and the factory inlet hose bolted right up to the T3 (even tho both my 9's came with Mitsu's). Here are the factory pipes installed to the T3:

DSCN1246.jpg
[/IMG]

All the Turbo SAAB 16V (and maybe the 8V also) came factory with a BOSCH bypass valve, aka the "hooter valve" as the SAAB boys call them.....same function. In order to integrate a CBV between compressor exit and inlet, I could modify the factory hot side pipe, but would be tossing my inlet hose. Perhaps the time to do this job is when I upgrade to the 012 3" AMM, as the hose is toast anyway at that point.

Can I safely run 13 PSI with the current system, minus the CBV (or cold side BOV)? I don't want to hack up these intake pipes after just getting this car running on July 9th. Thanks Michael, I'll see if I can find some pics of the 740T Garrett factory setup with CBV.

Thanks.
 
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If you don't have some way to vent pressure on throttle lift you will get compressor surge. Period. You may not have been hearing it, but I can almost promise you its was "gobbling" the whole time. Its quiet at low boost and gets louder the more pressure you have in the charge pipes.
 
Ok noobs...

-Garrett T3's don't come with internal CBV's. Only the rare Garrett T25.

-IPD Aftermarket wastegate IPD isn't 7 psi either. Stocker is about that with normal preload.

That is all I have to add to this "performance" thread.
 
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