Once you really start cranking up the boost pressures, dumping more fuel, your cars state of tune is very important.
Its also very critical that you monitor your car with an air/fuel mixture ratio gauge to make sure its not running too lean.
Why?
Take for example this forged JE piston that saw extremely lean cylinder mixtures. This car was smoking under boost BIG TIME, but yet still made over 400 wheel hp.
This piston had the upper part of the piston melt on both intake and exhaust valve side, the compression ring seized and failed, and the second was holding the compression, but not very well.
Also, the ringland between 2/3 rings had cracked and is only secure on 1/2 of the piston, the other half can be moved with your finger.
We have no idea what the air/fuel ratio was for this customers car, but we’re using this to stress again that its critical to 1) get a good tune with your big turbo 2) use an air/fuel mixture ratio gauge!!!
