Turbo RPM?

[beav]

What max turbo speed should I be seeing (ballpark)? I logged my last run with a small tune and it read an average of 500 krpm and a max of almost 2 million!!!!

How is that even possible to read that high? From what I understand, turbos should be in the "few hundred thousand" range max, but not too sure.

[2007 5.9]

Sounds like that pid isint scaled right. I'll mention it in beta.


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[beav]

Sounds like that pid isint scaled right. I'll mention it in beta.


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I can upload the log file if it helps. What should I see at roughly 46 PSI boost?

[2007 5.9]

I have no idea...I haven't looked at a HE351ve map in a while...I'll see what I can come up with.


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[beav]

I have no idea...I haven't looked at a HE351ve map in a while...I'll see what I can come up with.


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Looked back on some older logs and it was still showing over 1.5Mrpm.

[cumminsDK]

I'm no expert on the he351ve for sure but 46psi seems excessive maybe someone can provide more insight.

[beav]

I'm no expert on the he351ve for sure but 46psi seems excessive maybe someone can provide more insight.

I was questioning that as well considering the tune that I have in it. However, this PSI is what scares me considering the rpm numbers that I am seeing - which really can't be that high. But, I have two different gauges that are saying ~46 PSI. It is making that boost somehow.

[DoghouseDiesel]

Any more than 36 psi is getting outside it's truly usable range. It'll make more than that, but you're way outside it's efficiency range on the compressor map. You really need to look at the compressor map and figure out your pressure ratio. That will give you 2 things....it'll let you know approx how many RPM's the turbo is really turning (which is likely 100k - 130k RPM's) and it'll let you know where you need to be running the turbo to stay in the safe area of the map.

Here's a good link on Garrett's site when it comes to reading and understanding compressor maps and doing the math....

http://www.turbobygarrett.com/turbob...bo_tech_expert

ANY time you run a journal bearing turbo north of 30 psi, it really should have AT LEAST a 6 pad thrust bearing it, which is usually a 270* degree bearing. Ideally, you want a 360 thrust bearing when the pressures get that high. All that boost pressure is pushing the entire rotating assembly backwards against that bearing and the greater the surface area and coverage of the bearing, the longer the turbo will live.

At 46 psi, your turbo is on borrowed time.

[beav]

Thanks for the info!

Strange thing is that it built 32 PSI on a stock tune and what should be a 60-80 HP tune puts it at 46 PSI. Then there's the inaccurate RPM reading...

Something is really wrong here. The engine is bored .020" so that will push a bit more airflow to the turbo, but the manifold, turbo and injectors are stock. And I see good movement of the turbo from ~76% to 3% as RPMs rise to about 2600. 2600-2800 is about all she does for now.

[beav]

I think I know why the boost and EBP are so high now. For some reason the turbo commanded and actual position readings are fluctuating during movement. When at idle the turbo position is at the expected 74% and as RPMs increase it starts to fluctuate until it goes to max RPM (close to 3,000) then immediately drops down to 0-5%. At higher RPMs it is no wonder that Boost hits 46 PSI and EBP hits 62 PSI...not good.

Any idea what would cause fluctuation in the turbo? My tables have been smoothed out pretty well so I do not think the tune is doing it, but I could be wrong. And it is too consistent when it fluctuates to be a short, but again I could be wrong there too. I would think that it would fluctuate at other times if it was a short.