I'm just curious why I didn't have a catastrophic failure with my GT42R-76 when the intercooler pipe came loose, I notice a huge loss of power at full throttle. I started trying to figure out what went wrong. First I checked for smoke in the rearview ... none Then, I looked at the AFR at WOT and it was normal (a little rich - need to work on the tune). Then, I checked the boost pressure, and noticed that it only made 2.2 psi, but the turbo sounded like it was spooling. I got out and checked the lines to the EBC and to the W/G because I've had a problem with them in the past, and nothing was wrong. I took them loose and reconnected them and found no change at WOT, still 2.2 psi.

Then, I checked all of the induction pieces and found that the intercooler outlet pipe had come loose. Obviously it wasn't completely disconnected, but I was surprised that it was making any boost.

So, my question is that considering how fast the turbo must've had to spin, why didn't it come apart? I'd guess that this situation would be similar to running a closed waste gate since the EBC would never command the gate to open. Was I just lucky, or was something else keeping the turbo from overspinning?

Thanks,

Chris

 

I had my wastgate hooked up backwards on time and it spiked to 22+ pounds and blew off my inlet as well. put it back on and it worked fine. to guess on how fast your turbo spun during that is hard, but had to been well over 100,000 rpm. if it is not locked up and there is no play in it you should be ok.

 

Kinda hard to believe the car ran good once the pipe blew off, especially if it was a maf car. Even if it was a MAP tuned car it shouldnt have ran good at WOT. Plus its hard to over spin a turbo, they are balanced for extremely high rpms. there should be no problems with your turbo. I have never heard of over spinning a turbo and it coming apart.

 

so maybe this is a little off question but....

i'm guessing the boost pressure the wastegates monitor or work off of is from in the intake manifold right and thats why if the pipe from the intercooler outlet blew off, there would be no pressure for the wastegates to read off of????

 

Chris,


The turbo probably wasn't spinning as fast as you think it was, because as soon as the pressure pipe came off, the exhaust energy output of the motor dropped like a rock.

David

 

good point, it might of spiked, but fell on it's ass right after, and all of this happening in a matter of second. makes me feel better about my accident.

 

I have seen many boost pipes blow off but I have only seen 1 turbo come apart and it was just that it was way to small for a application.

 

The max rpm u see on most conpressor maps is due to the fact the the inducer tips are nearing the speed of sound and at that point airflow characteristics change drastically. I don't think it has anything to do with the structural integrity of the turbo itself.

 

The main reason was due to the Garrett DBB design. Under testing shaft speed has been almost doubled over factory rating....still in one piece.