Jason Judd

Solo,
We've got a manual boost controller


944 fanatic,
Yes, I am using the Autronic SM4

Chris,
We're using Lindsey's Super 75 turbo with a Tial wastgate

Sorry I forgot to mention that stuff before.

Jason

RolexNJ

Jason, I believe Chris is looking for more specifics of the turbo. Is it a KKK hotside, ir so a #8 or #10? Or did you use a T3/T4 hotside? What size wheel did they use? Stuff like that. I am sure if you called Lindsey, or looked at your receipts it would be on there? And maybe I missed it, but are you using a stock cam or a modified one too?

Jason Judd

Rolex,

I do know that we went to Webcam when the engine was built.

As for the specs on the Lindsey turbo, I don't know, I thought they were all the same ...Sorry!

When I'm back up there next week I'll find out.

Jason

SoloRacer

Do you think the fluctuation in your boost curve is due to the manual boost controller? Or is there a pressure leak somewhere in the system? Did your shop give you an explanation for it? The reason I ask is that I was experiencing boost spikes on my 968 Turbo and haven't diagnosed the problem yet. I'm guessing that either there was a problem with the turbo itself - it appears to be blown at the moment - or that something in the control system was at fault. However, the car also has a high idle that Jon Milledge said wasn't there when he finished with it. This spring I will be going over every square inch of the car to make sure everything is in good shape.

Jason Judd

Solo,

I think it was just part of the learning curve; the chart that Rolex posted for me was one of the earlier runs...They are still fine tuning it and I expect that when final tuning is completed all will be well.

By the way, the Lindsey Breather Tank is wonderful...you should see the steam vented out during the dyno runs. I can't believe that used to be routed back. Rolex was right to reccommend it!

Jason

RolexNJ

Oh I see. I didn't know they have a lot more of tuning to do. I assumed the chart you provided me was the final tuning, or close to it. You didn't clarify that for me Jason, but hey, that's ok. Hopefully they will get it better for you in time. And if you can, find out the exact Specs on "your" Lindsey Super 75. At one time I had the same exact turbo, but I don't know if my specs are the same as yours. See if you can find out, for I'm curious as we all are too. So when are they planning on tuning it more? And then are they going to do a few more runs too?

Porschefile

Do you happen to know what brand MBC Jason? There are some decent ones out there, though generally MBC's tend to be less consistant than EBC's and especially so when there are drastic changes in temperature among other things.

Soloracer, the turbo itself can't cause boost spikes. That's entirely a function of the boost control (wastegate, MBC/EBC, etc) system. What kind of boost controller do you have? How exactly does it spike, and how large are the spikes?

SoloRacer

Porschefile: At first I thought the boost problem was due to a loose hose or a hole in the intercooler piping. My turbo is currently making no boost and makes a sound similar to blowing down the neck of a pop bottle when you cross the threshold of where boost used to come on. I was told that the turbo is full of oil. My thoughts are that it's either a) wastegate or b) turbo center section is blown and since the turbo has oil in it I'm leaning towards b). Thoughts?

P.S. Perhaps boost spike is not the correct term. At peak boost my boost gauge would go up and then down and the car was noticeably surging. Probably a 3-5 psi swing if I was to guess. Looking at the chart that Jason posted I thought that we might have similar problems.

Porschefile

So is the sound the turbo makes more of a whining sound? Have you checked both of the wheels for any physical damage? It sounds like there is definitely something physically wrong with the turbo. If the boost is dropping back down, then it's definitely a spike and not creep. What type/brand of boost controller do you have? I'd take a look at it as boost controllers are probably the number one cause of spikes.

SoloRacer

I haven't removed the turbo yet but will do so before spring arrives. I suspect there is physical damage. As for boost controller all I know is that there is no manual controller and there is no aftermarket electronic boost controller either. However, there is a **** connected to the MoTec that changes boost settings & fuel maps so I assume that the MoTec could be controlling boost.

Is it possible that the center section of the turbo was binding at high rpm and causing my boost fluctuations? It is possible that I have an early model ball bearing turbo.

SoloRacer

The other concern would be if there was damage to the impeller that pieces got sucked into the engine. However, would they make it through the intercooler core?

special tool

The pop bottle sound is not damage.
I have experience with this with TWO turbos on 951's only.
NOTHING, nothing at all would cure it on my k27. I tried everything (you know me )
Yes, I know EXACTLY the noise you are talking about also.
It is my opinion that it is a characteristic of certain turbine wheel/housing relationships AND the long x-over 951.

Keep in mind that I have extracted MAXIMUM compressor flow/horsepower with these turbos - damage was not an issue.

SoloRacer

ST: The thing is that when the car made boost it wasn't making the sound. It was only when it stopped making boost (I mean ZERO boost..nada..nothing....not even 1 psi) that it made the noise. I instantly thought that an intercooler hose had popped off or one of my intercooler pipes had ruptured. On my 968 the turbo hangs off the headers so there is no long x-over pipe. I don't have an explanation for the sound other than maybe a stuck wastegate or seized turbo. It's just a guess at this point.

Porschefile

That makes sense that it's using the Motec boost control. I don't know as much about Motec, however with what you are describing it's possible it might be an issue with the load sites for boost control possibly needing to be retuned. Is there anything you've changed significantly from when the car worked fine before?

As far as turbo damage, that "whine" noise I mentioned sounds much more like a mechanical whine similar to a worn wheel bearing mixed with a supercharger or something. It's hard to describe but, very mechanical sounding in nature. I've heard damaged turbos sound that way before, and it's definitely a serious issue if you get to that point. Though, Soloracer, what you described doesn't appear to be the whine I'm speaking of.

As far as the shaft binding at high rpm, I doubt that's an issue. Come to think of it, I've never heard of that actually happening before so I'm not too sure if it's possible without causing serious damage. Turbos spin at such high rpm that the slightest imperfections and/or damage can cause a catastrophic failure.

SoloRacer

I've changed nothing on the car. It was doing this right from when I bought it. However, the previous owner may have had some work done on it. I have spoken with Jon Milledge and he has requested that I send him the maps to take a look. I will do that as soon as I find out what version of software I need for the MoTec in my car.

As for the noise, it's not mechanical in nature at all. The closest that I can approximate is when you blow into an empty pop bottle. That is almost exactly what it sounds like.

When I get the turbo off I will also remove the wastegate and take a look at it. The car has a huge 935 wastegate on it. The nice thing about the turbo install is that the turbo sits in a really easy position to remove. It shouldn't take more than an hour to get it out and that is for me. A pro could probably do it in minutes.