Logging observations could save your turbo...
Jun 5, 2008, 08:10 AM
#1
Logging observations could save your turbo...
Recent logs, both at the track and on my closed circuit road course, showed both FAST, MAXIMUM spoolup in 4th gear pulls on the 'road course' and slow, nearly non-existent spoolup at the dragstrip. It's now been proven that the turbo was very close to meltdown. Had the problem not been discovered, the compressor wheel would have continued to come in contact with the housing. Spoolup would have become worst and before very long, I would have owned a nice conversation piece. Fortunately, I log nearly every time we start the car.
Now, I would like to share what specifically I observed and how it created the 'Handwriting on the wall'. Initially, we just had a general performance loss. What made it difficult to assess was the fact that we also had a boost leak, prior to the decrease in performance. Even after correcting the boost leak, performance was down and I couldn't put my finger on any ONE thing. Early logs just showed that boost was down a little, so I turned it up, thinking that my tune may be off a little. Another thing to blame was barometric pressure, etc. As I turned the boost up, I was making a 'small area of friction' (the thrust bearing/shaft) become worst by increasing the boost pressure again. It became a continued 'fix' until we finally noticed that boost response between shifts was no longer recovering as quickly. On the logs, the time required to get back to maximum boost (not always the same boost as it was previously) was getting longer. When I finally decided to no longer run the car until it was checked out, the increased time required to build boost was approximately 1000-1200 rpms and the boost continued to become less.
The important thing is the fact that all of this occured over a time of no more than 8 - 10 trips down the 1/4. 4th gear, full on logs from 3000 to 5000 rpms still would hit max loads (379.xx) and hold it. The problem reveals itself during the lower loads and gear shifts.
With more and more Evos pushing the turbos to their limits, I'm afraid that this may become more and more prevelant. Be sure to log your car, not just when you're tuning. Read the logs and react on what you see. In my case, it saved destruction of a perfectly good turbo. A few parts and it will be as good as new. Had I continued to use it, in a VERY SHORT WHILE, it would have ruined the compressor wheel, scored or ruined the housing and even possibly sent parts into the FMIC, not to mention what could have made it into the oil.
Now, I would like to share what specifically I observed and how it created the 'Handwriting on the wall'. Initially, we just had a general performance loss. What made it difficult to assess was the fact that we also had a boost leak, prior to the decrease in performance. Even after correcting the boost leak, performance was down and I couldn't put my finger on any ONE thing. Early logs just showed that boost was down a little, so I turned it up, thinking that my tune may be off a little. Another thing to blame was barometric pressure, etc. As I turned the boost up, I was making a 'small area of friction' (the thrust bearing/shaft) become worst by increasing the boost pressure again. It became a continued 'fix' until we finally noticed that boost response between shifts was no longer recovering as quickly. On the logs, the time required to get back to maximum boost (not always the same boost as it was previously) was getting longer. When I finally decided to no longer run the car until it was checked out, the increased time required to build boost was approximately 1000-1200 rpms and the boost continued to become less.
The important thing is the fact that all of this occured over a time of no more than 8 - 10 trips down the 1/4. 4th gear, full on logs from 3000 to 5000 rpms still would hit max loads (379.xx) and hold it. The problem reveals itself during the lower loads and gear shifts.
With more and more Evos pushing the turbos to their limits, I'm afraid that this may become more and more prevelant. Be sure to log your car, not just when you're tuning. Read the logs and react on what you see. In my case, it saved destruction of a perfectly good turbo. A few parts and it will be as good as new. Had I continued to use it, in a VERY SHORT WHILE, it would have ruined the compressor wheel, scored or ruined the housing and even possibly sent parts into the FMIC, not to mention what could have made it into the oil.
Jun 7, 2008, 09:15 PM
#4
Tom is dead on. But, even if you don't have the capability to log as completely as he does, the general advice is still applicable -- if you start to notice any substantial degradation in performance, stop and investigate. You may save your parts and your pocketbook.
Thanks, Tom!
Thanks, Tom!
Great info for everyone with mods and running hard.
Jun 9, 2008, 08:41 AM
#6
Good post!
Same thing happened to my green. Thrust bearing went. Except I found out when the car started making an ever so slight whining noise when coming from vacuum into 0 or small boost. At the same time there was no loss in power.
FP guys told me the bearing went bad because of too much RPMs on the turbo, which usually happens with running high boost combined with a boost leak. I check for leaks pretty often and I don't think i had one, but nevertheless a piece of advice from me would be - if you run high boost on small turbos - boost leak can be pretty destructive - so log and check for leaks often.
And obviously check and change oil frequently.
Same thing happened to my green. Thrust bearing went. Except I found out when the car started making an ever so slight whining noise when coming from vacuum into 0 or small boost. At the same time there was no loss in power.
FP guys told me the bearing went bad because of too much RPMs on the turbo, which usually happens with running high boost combined with a boost leak. I check for leaks pretty often and I don't think i had one, but nevertheless a piece of advice from me would be - if you run high boost on small turbos - boost leak can be pretty destructive - so log and check for leaks often.
And obviously check and change oil frequently.
Last edited by mplspilot; Jun 9, 2008 at 08:46 AM.
Jun 9, 2008, 08:59 AM
#7
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Jun 9, 2008, 11:52 AM
#8
I prefer to just run my car into the ground when it starts driving differently 
I never would have thought over-spinning a turbo could cause a problem. Don't some nutcases on race fuel just run a vacuum line to the top of a Tial gate to keep the gate closed?
I never would have thought over-spinning a turbo could cause a problem. Don't some nutcases on race fuel just run a vacuum line to the top of a Tial gate to keep the gate closed?
Jun 9, 2008, 12:24 PM
#9
Good post!
Same thing happened to my green. Thrust bearing went. Except I found out when the car started making an ever so slight whining noise when coming from vacuum into 0 or small boost. At the same time there was no loss in power.
FP guys told me the bearing went bad because of too much RPMs on the turbo, which usually happens with running high boost combined with a boost leak. I check for leaks pretty often and I don't think i had one, but nevertheless a piece of advice from me would be - if you run high boost on small turbos - boost leak can be pretty destructive - so log and check for leaks often.
And obviously check and change oil frequently.
Same thing happened to my green. Thrust bearing went. Except I found out when the car started making an ever so slight whining noise when coming from vacuum into 0 or small boost. At the same time there was no loss in power.
FP guys told me the bearing went bad because of too much RPMs on the turbo, which usually happens with running high boost combined with a boost leak. I check for leaks pretty often and I don't think i had one, but nevertheless a piece of advice from me would be - if you run high boost on small turbos - boost leak can be pretty destructive - so log and check for leaks often.
And obviously check and change oil frequently.
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