gaijin_rokurunner wrote:Bad news unfortunetly the engine blew on the dyno today but made 252hp and 164 ftlbs torque at 9000 before it went boom...Sandy at the shop said the lowest torque figure was 140 ftlb which is outstanding...he also said with a dry sump, longer runner intake and a little more c/r this thing would of made 280hp range bo problem he was very impressed...anyhow we suspect incorrect valve to piston clearence in the number 2 cylinder as one of the valve hit a piston over and over till it snapped which in turn tore up the piston and other valves...heading to the shop tomorrow to see the damage...they are investigating if its a part problem which would mean coat to rebuild is out of my pocket or builder error which they would cover everything free of charge...called Zeke down at Ferrea and he told me the valves i have are top of the line before titanium and are not made to break but bend and that fact that one broke means it hit the piston continuously till it snapped again meaning inproper valve clearence...anyhow keep u posted will probably take a while to rebuild since everything is custom more then likely need a new head which will require a whole new port and valve job as well as flow benching then if the cylinder wall is trashed a whole new block...no fixing 83mm bores... On a good note made more hp then the f20 and f22 as well as a FA so my money is well spent in my book....pictures to come
Good luck on the future.... 164#/ft is pretty good.
Besides the piston to valve clearance, I'd also check the valve springs... one reason the Atlantics go over 10,000 is because the valve springs are more than capable (dual), and it seems odd that one piston was machined incorrectly... or one valve was mis-seated. It seems more likely that a spring was not up to the task... floated... and BOOM.....