what forged pistons brand

[oldeskewltoy]

WARNING:

All the piston manufacturers have the WRONG information when it comes to the volume of a 4AGE head....

A uncut stock 4AGE head has 36.25-36.50 cc combustion chambers. There IS NOT an untouched production 16V 4AGE head ANYWHERE that has a combustion chamber anywhere near 39CC!!!


Below is a head I recently ported. The upper view is the haed with stock chambers- 36.25cc. The lower head is the same head AFTER I opened up the combustion chambers too 39cc. If you have a tough time seeing the difference, look at the space between the chambers




My point here.... 39cc chambers are no where near stock. That means the Probe Industries claim of 9.21 CR is dead wrong!


Now on a completely different note, the Probe Industries pistons DO look like they will run nicely in a stock, or mildly modified engine. GUESSing here, but the actual CR is likely going to be in the low to middle 10 to 1 range with those pistons under a stock 36.25cc chamber head.



30cc chambers are tiny.... have they been "opened" up yet? See above photo. What porting have you done to improve the flow. A quality porting job can ad power, AND lower temps @ the same time.

Concerning the piston lands...I'm not sure which pistons you are using, but TRD had offered DIFFERENT pistons for rally, as opposed to N2 or other track type events.

For rally you want a full skirted piston, have the piston skirts coated with a low friction coating. Also have the piston domes ceramic coated to dispel the heat.