97 civic HX K24a
That is some great information , I love reading his posts.average piston speed at 7800 is 25.74 m/s. That is F1-level on a cast piston.
For a rally application on cast pistons and rods, I'd stick to something like 7200 to 7300 . That corresponds to the piston speed of a K20 spinning about 8300 or 23.8 m/s.
That is near stock, but it will last. Make it 7500, but not higher on a stock bottom end.
Joe McCarthy once posted here 2013 about the K20a that is essentially using the same rod and piston technology.
"I'm basing that bit of advice on many years of experience of endurance racing stock bottom end K20's in the 25 hour at Thunderhill. If the rev limiter is set at 8,200-8,300 the engine will finish the race without exception. If its set at 8,600 one of the pistons will disintegrate by the 11-12 hour mark. At 9,200 I've seen stock pistons last under 10 laps. I can't even begin to count how many times I've seen people destroy perfectly good engines by doing this. I've also seen engines limited to 8,300 last through 2 complete seasons of endurance racing, which is about 100 hours total.
Its metal fatigue, which has 2 components, load and time. That's what determines the lifespan of any metallic part.
On the street the time span is SO short that a lot of people get away with over revving the engine for a long time, but its just a clock ticking off the seconds at that load level and eventually the piston WILL be destroyed."