Hey guys I need help deciding what went wrong with my build. I figured this would be a good place to start.

My motor blew just 2 days after it was tuned, i didnt even drive 50 miles with the head done. My block was sleeved with forged pistons, H-beams, with micropolished crank. The bottom end was balanced and blue printed and tuned with hondata s200 and has been running for almost 2 years with no problems at all NONE. Then when i had the funds I started building the head. I took my head to portflow where they ported and installed the whole valvetain. I was running all Skunk2 flat valves, retainers, springs, and stage 2 cams. I clayed the motor for clearances and I had plenty of clearance from valve to valve and piston to valve. I didnt want to risk anything with the motor so after i started it up and checked for leaks and problems it stayed parked until the day of the appointment where i left early and drove steets under 3k the whole time. Only after it was tuned did i punch it. Then one day when i was coming back from pink's the engine shut off (no cel light, no leaks whatsoever). tried cranking to no avail.

My friend took out the valve cover and I didnt drop a valve, the whole valvetrain looks fine. Took out the spark plugs and #2 spark plug is all chewed up. None of the other plugs where chewed up.

Now onto the tuning. AFR stayed from 2k all the way to 8500k stayed around 13.0 and 13.5. I didnt look at the AFR ratio when i left, but now that i'm looking at it, i thought it was suppose to go rich at WOT and under heavy loads. My friends and i are thinking that it was tune that made my block go lean and eventually blow. I need to get other peoples opinion whether or not i should go back and show them my afr and get my money back for a bad tune; maybe even more for the 1100 dollars spent in building the head. I'll post pics of the AFR and the spark plug if anyone needs to see it.



Modified by Mr. Samurai at 7:39 PM 8/14/2006


Modified by Mr. Samurai at 7:49 PM 8/14/2006

 

That's way too lean....you need to be in the mid to high 11's on the AFR to be safe......

Anything in the high 12's is pushing it...and you were in the 13's....that's why your motor gave.

 

Mid to high 11's on an N/A motor? I'm not so sure about that, you'd just be wasting fuel.. Assuming the wideband was properly calibrated, I would have run it around 12.5:1 for the thermal management benefit.. Although, the one plug you've shown doesn't show evidence of a lean condition, it shows evidence of mechanical collision..

I assume you've checked to make sure that a rod didn't let go?

 

i havent had a chance to tear the motor part yet i'll probably start tomorrow; see what the damage is

 

You need to tear it down to see what went on in that cylinder. Can you see into the sparkplug hole? Something broke or got into the cylinder. That's not damage due to a lean fuel mixture. It would be melted. It's possible it was detonating and blew a chunk of porcelin off the inner part of the plug and started a chain reaction.