After giving it much consideration, I have decided to go in a completely different direction.

 

Huh?......

 

OK Teaser McTeaser ****... (your phrase, not mine, but it is funny)

This is Valentine's Day, not April Fool's Day...

We support you in whatever decision you feel is right in your heart and we will help you in anyway we can.

Also, harharhar...

 

If the waste gate is before the vanes and the vanes close causing a spike in pressure. The WG would open and the gases would be diverted around the vanes completely, lowering the pressure in the turbine housing. Just a theory though.

 

But the problem is the lack of pressure causing the turbine to stall, not excess pressure.

 

I’m sure this isn’t serious, but admit my first thought was ‘I’ll take that turbonator stuff off your hands!’

 

Meanwhile, maybe we just need a stronger/larger turbine shaft??

Also wanted to add that the 6.7 PSD I picked up for a friend a couple weeks ago has an S364.5sxe conversion and allegedly makes 625hp. It EASILY bangs out 40psi of boost and lights fast.

 

oh yeah, duhh

 

I may be off base but I don't really think the turbonator is the culprit here. I'm definitely not an expert on this stuff but I don't really see how the vgt could be stalling the turbine because the turbine isn't trying to pull out exhaust gas its being pushed by it. In my mind the turbine is still able to spin fairly free under a chopped throttle situation but the compressor is still trying really hard to push compressed air through an engine that has suddenly greatly reduced the amount of air that can be flowed through it (not quite as bad as a gas engine with a throttle plate but the sudden lack of combustion moving the pistons would cause pretty much the same thing). So you have a turbo that is spinning very very fast with similar amounts of load on either side but all of a sudden the load is increased on the compressor as it is still trying to draw in more air and force it into the motor but on the other side the load is diminished. Basically what I'm trying to say is that the forces being applied to the compressor are trying to slow it down and the momentum of the turbine is trying to keep things moving causing the broken shaft. Now that I've typed all this out I just had another thought, if the mapping controlling the vgt is clamping things down too fast when you dump the throttle then its acting as an exhaust brake and slowing down the engine even more abruptly causing an even worse spike in the resistance working against the compressor. So I guess I'll eat my words from the top of the post and say that the turbonator could be exacerbating the inherent issue of chopping throttle under boost but only if the mapping for it is clamping it down to fast. Thats my drawn out way of saying that I think all you need is a rebuild and a blow off valve. Like I said I'm definitely not an expert but this is what makes sense to me. Let me just say how sad I was to read about your turbo breakage because I thought it was a sweet setup. Been keeping up with this thread because of how cool your setup is.

 

You should have that chinesey turbo on by now. You gonna make it to GA????

 

Geez dude. Way to spoil the prank before it even got off the ground.

Hah! You're quite the vulture, aren't you?

Yeah, I definitely have to do something to take the stress off that turbo's shaft. See my comments to BA86f250 below.

Be careful what you call chinesium. That's a KC.

Actually I am in agreement with you. My prime suspect is compressor surge causing that wheel to come to an abrupt stop while the turbine keeps trying to spin. This is borne out by the fact that there are no compressor wheel shavings but the turbine is bent to heck. Funny you should mention a blow off valve too because that's shipped as of Sat night.

 

Mike from Borg Warner Customer Service just texted me at 0645CST. I am impressed.

 

Often wondered about the Blow Off Valves. Do they dump just a portion of the boost pressure or all of it? Since there is no intake butterfly like a gasoline motor to stop up the air what determines when it opens on a diesel? Will it only open when you let off the throttle or will it try to open between shifts as well? When it does open does the turbo have to spool back up, causing lag because the system was depressurized?

 

It depends on how you tune the BOV. The one I ordered has a controller to tweak things. I will report once I have had some experience with it. Theoretically, when tuned right the BOV allows the turbo to get back on it faster because the rotating mass is still spinning at close to full rpm.

 

This is interesting.

Here’s a video of a stock turbo being flogged and clearly not happy in the situation we are discussing.



Here’s the same setup surging on acceleration. (PSA - don’t let your turbo do this. If you do, please post pics of the carnage.)