Lord Khan
20+ Year Contributor
- 174
- 0
- Aug 23, 2002
-
Baltimore,
Maryland
Follow-up of repaired installation is further down in this thread
It seems that I ruined the turbo from extreme exhaust gas temps cooking the oil and seizing up. Here is the original thread
http://www.dsmtuners.com/forums/showthread.php?t=131509
Here's the diagnosis:
"The failure mode was a coaked turbine side journal bearing. The bearing became coaked in place and could no longer float in the bearing housing. With the bearing not spinning, all the rotation was between the shaft and the ID of the bearing instead of 50% bearing OD/Bearing housing and 50% bearing ID/shaft. Whenever a bearing coaks in place failure inevitably follows, as all the rotational velocity is intended to be shared by both surfaces, not just one of them. With time the ID of the coaked bearing eventually no longer receives any oil at all, without oil supply to the bearing ID/shaft OD surface material begins to wear off the softer bearing and transfer onto the shaft, increasing the freeplay of the shaft to the point where the blades begin rubbing the housings. At this stage of the failure repair is still possible, at the first sign of noise.
Proceeding beyond this point results in massive blade damage and fragmentation as seen in your turbo. Repair is no longer possible, the entire CHRA must be replaced.
The coaking occurs due to excessive EGT. I have reviewed the mods listed to your car and the manner of operation of the car. You indicate that you are running 17psi on stock injectors and fuel pump with a host of airflow improvements in place on the car, the most significant of which is your increase in turbo flow rate from 370cfm with your T25 to 550cfm with your FPBig28.
My assessment of this situation is that you are leaner that Olsen twin that just went into rehab. Your excessive EGTs resulted in coaked and choked off bearings within the turbo. Sustained 120mph driving was the straw that broke your camels back, and I am surprised that you have no engine damage as a result of operating your car in this manner, and you may actually have engine damage that you are not aware of. The only thing that probably saved you from blowing a head gasket or melting a piston was the fact that your knock sensor was pulling all your timing in a vain attempt to keep you from destroying your engine. Ill also point out that a 2G in full knock retard can elevated its EGTs by several hundred degree F just as a result of the retarded timing."
Good news is that although I had to pay a couple of dollars for a rebuild, the turbo is being fixed and shipped out this week. So I should be back on the road by next week. I had bought an Autometer A/F guage with this turbo, but didn't learn til the day the turbo died that without a wide-band 02 sensor, the A/F guage is highly innacurate. Which is why I didn't know I was running lean on 17lbs of boost. Even when at wot the A/F guage still showed running rich.
All I can say to you guys that don't know like I didn't is to take it easy on your cars til you get your fuel mods done, or you will cause damage. If you upgrade your turbo first, keep the boost down at least to 14 until you do the fuel, or you will cook stuff and cause yourself uneeded stress.
It seems that I ruined the turbo from extreme exhaust gas temps cooking the oil and seizing up. Here is the original thread
http://www.dsmtuners.com/forums/showthread.php?t=131509
Here's the diagnosis:
"The failure mode was a coaked turbine side journal bearing. The bearing became coaked in place and could no longer float in the bearing housing. With the bearing not spinning, all the rotation was between the shaft and the ID of the bearing instead of 50% bearing OD/Bearing housing and 50% bearing ID/shaft. Whenever a bearing coaks in place failure inevitably follows, as all the rotational velocity is intended to be shared by both surfaces, not just one of them. With time the ID of the coaked bearing eventually no longer receives any oil at all, without oil supply to the bearing ID/shaft OD surface material begins to wear off the softer bearing and transfer onto the shaft, increasing the freeplay of the shaft to the point where the blades begin rubbing the housings. At this stage of the failure repair is still possible, at the first sign of noise.
Proceeding beyond this point results in massive blade damage and fragmentation as seen in your turbo. Repair is no longer possible, the entire CHRA must be replaced.
The coaking occurs due to excessive EGT. I have reviewed the mods listed to your car and the manner of operation of the car. You indicate that you are running 17psi on stock injectors and fuel pump with a host of airflow improvements in place on the car, the most significant of which is your increase in turbo flow rate from 370cfm with your T25 to 550cfm with your FPBig28.
My assessment of this situation is that you are leaner that Olsen twin that just went into rehab. Your excessive EGTs resulted in coaked and choked off bearings within the turbo. Sustained 120mph driving was the straw that broke your camels back, and I am surprised that you have no engine damage as a result of operating your car in this manner, and you may actually have engine damage that you are not aware of. The only thing that probably saved you from blowing a head gasket or melting a piston was the fact that your knock sensor was pulling all your timing in a vain attempt to keep you from destroying your engine. Ill also point out that a 2G in full knock retard can elevated its EGTs by several hundred degree F just as a result of the retarded timing."
Good news is that although I had to pay a couple of dollars for a rebuild, the turbo is being fixed and shipped out this week. So I should be back on the road by next week. I had bought an Autometer A/F guage with this turbo, but didn't learn til the day the turbo died that without a wide-band 02 sensor, the A/F guage is highly innacurate. Which is why I didn't know I was running lean on 17lbs of boost. Even when at wot the A/F guage still showed running rich.
All I can say to you guys that don't know like I didn't is to take it easy on your cars til you get your fuel mods done, or you will cause damage. If you upgrade your turbo first, keep the boost down at least to 14 until you do the fuel, or you will cook stuff and cause yourself uneeded stress.
