Well, I've got the flutter. Anything above 31psi and the gauge becomes a blur, varying about 2-3psi back and forth real fast. I'm thinking my turbo master boost controller just can't hang on, but I'm looking for any suggestions. Gaskets are all good, as well as clamps. What's weird is it started happening when I cranked the TM down a good bit, while everything seemed smooth when the spring tension was less. I'm gonna back it down again and go for a test drive.

 

I wonder if it's just the intake pulses you're seeing. Does your gauge include a snubber. It's a tiny orifice in the input to the gauge. My Autometer has this and it is steady.

Edwin

 

Not sure on the snubber. It's an older isspro combo gauge. But, it's always been smooth right up to pegged at 40+ for the year and a half I've had it.

 

Can you describe the movement a little better. Is the needle a blur when it does this? Is it eratic and relatively slow up down action? If it's not the pulses from the intake stroke of each cylinder then I'm unqualified to answer.

Edwin

 

It's just a blur, and only over 31psi, or so. It's rock solid up to and including 31, which leads me to suspect the turbo master controller, though I have yet to test dirve at different settings of the WG...maybe after dinner.

 

If you mean the Turbo Master is a Boost controller and it's causing the turbo to flutter I doubt it. The rpms of the turbo can't change fast enough to make your gauge needle a blur.

Have you changed the length of your hoses in the boost controller/gauge circuit? Maybe it's some sort of accoustic resonance.

Also try grabbing the gauge to see if it's a resonance in the dash vibrations causing the needle to vibrate. Just touching the gauge may make it change.

Edwin

 

The ''Turbo Master'' is a spring only controller. You just turn a locknut to add spring tension and raise the waste point. I don't think it was meant for..ahem, severe duty.

 

WHOA! Way to many parts in that thing and it looks to be way harder to put on than a bleed valve type that goes in the WG actuator hose.

Edwin

 

That's the one for a Chevy, but it's the same idea. It completely replaces the stock actuator and allows you to adjust the opening point of the gate with a 1/2'' wrench. Works pretty slick, but I don't think the spring is capable of dealing with an agressive setup like I have. My guess is that when the spring is tightened down for a higher waste opening, the gate is opening a small amount since the spring is so tight, then boost drops and it closes...etc etc. When the spring is loose, the gate opens at about 15psi and swings wide open, again, due to the light pre-load on the spring. Basically, I'm in the market for a stock-type wastegate actuator now

 

Greg, you have MWE slots, don't you? I didn't think it was possible to get the turbo to surge.

What you are decribing seems to be turbo surge -- do you hear a sort of "rattling" noise coming from the turbo, too?

I am surprised Dave hasn't replied about this -- when he had his TM, he was getting surge, and talked to the guy at TM. The word was that the way the actuator was designed, it would not go into oscillation. You could test to see if it is the TM or the turbo map by locking the gate closed, and running the turbo at the same boost/rpm. If you get the surge, then it is the turbo map, if not, its the TM.

By the way, the turbo WILL fluctate that quickly, which is why surge is so damaging.

I'm curious to see what the test results are . . .

 

Greg, when I was testing that theory I put a deep socket in place of the spring. Still surged.

 

I didn't have a chance to do any ''testing'' today. Too much real work to do [rolleyes] It seemed to happen when I cranked the gate up, so I backed it all the way off this morning, but didn't have a chance to wind 'er up all day. To be continued...

 

Just to clarify, is this surge caused by too much restriction at the turbine housing? I'm going to try and get a video of the gauge today while I'm out and about.

 

A turbine compressor requires a certain minimum mass of air flow to support a specific pressure ratio.

So, to support 32 psi of manifold pressure, at a given altitude, with a given intake restriction (these two determine the inlet pressure seen at the turbo -- outlet pressure/inlet pressure = pressure ratio) you have to be moving a minimum amount of air molecules (most easily measured in pounds or some other unit of weight). The mass of air that you can move, is determined by the manifold pressure, engine displacement and engine rpm's.

So, before I had MWE, I could make the turbo surge like crazy at 10psi and 1500 rpm, but at 2500 rpm, I could support 24psi all day long with no surge.

I hope that was inteligible and helpful . . .

 

Thanks Alec So here's what's happening: I get the gauge flutter anywhere over 30-ish psi, regardless of wastegate setting. Everything sounds the same, just the gauge goes nuts. I can hold 10, 20, 25, 29 psi all day long, steady as a rock, but once I push over 30, things get wacky. I tried a couple times to get a video, but just couldn't hold my camera steady enough...anyway, I don't think it's RPM dependant either because I've been loading it in 5th starting at about 60mph and boost doesn't hit 30+ untill maybe 1900-2000 rpms. So, I'm still searching, and of course, I just got rid of my 18.5cm housing, so I can't even give that a try...