Why am I not revving out higher? Shooting for 13k+ rpm and looking for ideas.
Right now I'm hitting 11k, maybe 11.5 based off of gearing calculator. Setup is Athena ajh copy with split exhaust port ported wide, decked 3mm and with correct piston to correct squish and keep the ring out of the exhaust at BDC. Boyesen dual stage reeds and 24mm oko carb. The spark plug threads shot out of the airsal head pictured, right now I'm running a 70 low comp head with single base gasket. HPI mini rotor, initially set to 1.8mm btdc but I've played around with the stator a bunch and not sure what it currently sits at, launches well and stays cool tho. Kamikaze pipe. 18x56 gearing.
I know my port timings are fairly aggressive. To port map, I set the piston to bdc and taped in some graph paper, crayola crayons are terrible for this lol. Probably not super precise but a good idea of what it's at. Port durations are 196 exhaust, 132 transfers for a blowdown of 32. So the ports are definitely in the pretty aggressive range, enough according to some sources that my low end would suffer. It launches pretty hard tho, but that's mostly due to clutch I bet, not sure what rpm I'm engaging at but it's up there.
Pipe hits pretty hard but I'm hitting the rev wall, and I feel like there should be more. Pretty sure gearing isn't holding me back. Retarding timing didn't result in any more rpms, just made launch shittier. Pipe *should* wind out pretty far based on what I've read about it, but I have a simonini I might try. Can lowering compression result in increased rpms? I have a head gasket and a few different thickness base spacers to play with. Any other thoughts?
Piston clears all the ports it's supposed to at bdc. It's actually an Athena small reed piston, modified with gas ports, oiler holes for exhaust bridge and intake skirt cut for 360 intake timing. I tried using the Teflon reed kit piston from treats but the ring pin was too close to the ports, between the exhaust and main transfer. The ring pin on this piston rides between the intake booster port and the secondary transfers. (edited)