In preparation for an upcoming race, I took off the head to inspect the piston in my IAME X30 engine (around 7hrs since the last top end rebuild). The carbon build up on the piston looks a bit strange to me, and it’s different than what I usually see. Based on the plug, the mixture is close to ideal (I usually jet my engine while driving to hit 600-630°C EGTs).
Could this be due to the mixture leaning out and starting to ‘burn’ through the middle of the piston?
Has anyone had pistons look like this, or maybe someone can shed some light on it?
X30’s never really show how good your carburation is based on piston reading due to the cylinder wash geometry and the squish band / cylinder head used.
As James stated, the plug helps quite a lot more for these engines (in complete opposition of a KZ, which benefits from piston reading and disregards plug reading).
Best is to just have a baseline EGT for what your engine likes best, and stick to that when tuning it track side.
I highly suggest running your data through telemetry to see how the temp fluctuates, as ultimate EGT values are a good starting point to know where you’re at but can heavily fluctuate based on sensor and data logger when hitting the limiter, for instance.
