Did you degree the motor?
degree the motor as in degree the bisi cam? no. i emailed bisi about it and he said not having the cam degree'd wouldnt give me the high rpm problems i was having... (no mention of melted pistons how ever, lol). but i have a degree wheel and dial for next time around. just need a piston stop to find true TDC.
what are you getting at JD? I really would like to know what happened.
cam and crank were timed to each other perfectly.
If the deck or the block were ever machined, I'm afraid they very much weren't timed to each other perfectly. For whatever reason, I see 2-3 degrees off as being very common. I've little use for degreeing a motor with a wheel and dial unless it's design dictates their use. Hondas do not. Center the distributor (on non-D16Y cams) like it comes from the factory, lock your timing to whatever your pulley is indexed at, and shine the timing light around. Instead of moving the distributor to get the engine into mechanical time, move the cam gear. This procedure is also applicable to an Evo with a 4G64 block and AEM, among others.
If your cam is too advanced then you hit full boost and mostly full power at 5000-ish rpms, and the power output barely climbs from there becuase the engine is fighting itself. With the cam correctly timed you hit full boost at the same place and the power curve keeps sailing smooth and fluidly and the engine isn't fighting itself. Do I think this caused your valve droppage? No, unless they got super hot and bound up in your guides, but I really doubt that happened. What I have seen is some cars fight themselves on the dyno, and on the street if they are hooking really well in 3rd gear or higher. It's kinda wierd to go through the datalogs and watch the engine decelerate for a quarter second before climbing right back up, something's happening in the combustion chamber and that might be your piston problem.
You want to get pictures up of the pistons, etc? You might have had two mechanical issues going on, the valve dropping and then the pistons. Or a mechanical/tune correlation on the pistons and a mechanical failure on the valve. Or, who knows? A thorough teardown and high res picture thread would help you pinpoint it though.
Uhm, I'm not a huge fan of the two Bisi regrinds I tuned recently, and there's a forum member here not happy with his. Neither made the difference you expect a cam to make, the all motor F23 one I believe to be the vehicle owner's fault as he called up for a performance cam and said the words daily driver and reliability ten times each for every tme he said increase of power, and saddled himself with a stage 1 baby regrind, about as worthwhile as paying $$$ to replace early LS cams with B20 cams. The other was a Y7 turbo cam, Vitara motor, made 280 whp @ 18-19 psi with a T04E compressor and we called it a day as he was out of MAP sensor (2.5 bar). It wanted 14 degrees @ ~12 psi, and 16 degrees at 18 psi (eCtune numbers), kinda wacky if you ask me as I usually find D16 wanting a lot less timing in the upper teens. The only reason I'm even bitching is Bisi told the kid, when asked what sort of power the grind was making, "I don't know, I've sold a couple others but haven't gotten any feedback."
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Topic: why did this happen? snapped retainer (Read 7344 times)