So, I picked up a little 2 seater in early November that hadnt been really run since early 2010. It initially (before I got it) had a STI 2.5 with 75# low-z flow matching injectors that had a static flow of 164 and a cc/min @43.5 psi of 492. The ECU was managed by on older Megasquirt II setup. The previous owner had done his own DIY and tuned it to run E85, but on the dyno they spun the bearings in the STI motor. He picked up a JDM 2.5 and swapped out the injectors and "supposedly" was running fine. During the purchase he offered up the STI shortblock that had a new crank, new bearings, arp studs, pistons and rings. As part of the sale, he had cleaned the fuel system and it was running good.
When I got it, I resealed the valve covers and changed the oils. The oil had some small aluminum pieces in the oil and maybe some VERY SLIGHT silver glow to the oil, but other than that it looked fine. On its maiden voyage with me in early November, we put about 25-30 gallons of fuel through it and it seemed like everything was good. Put it in the trailer and nothing much to do before next trip.
Fast forward to New Years. I got Covid and my son wanted to take the rail so I let him. He let it warm up, took it on a quick ride and it was not running well. Took it back to camp, we chatted. He cleaned the air filter. Said it looked like the oil was overfilled, but we both had checked earlier and it was fine. He ended up sending me a video of it idling.
Needless to say he was done. I had some wishful thinking that possibly it was bad gas. I was worried that the timing belt had jumped a tooth. When he got home, we tested the fuel. It was at 85. My boy pulled the oil. It was a full of silver glow. Pulled the pan and looked like someone had pealed potatoes in there. Full of shavings and chunks. And of course, playing with the rods, the bearings were shot. Ya me.
So, I am looking for some thoughts. FIrst of all, I am worried that the tune that is in it needs some love. I believe it would be foolish to do any fixes on the engine and not address the ECU. With it being a megasquirt II, I know it is somewhat dated and thinking of having someone do an online tune to see what I had as well as tune it correctly for the e85 once I have the new engine sorted.
With regards to the engine, initially I had thought of just picking up another JDM 2.5 for $1,300 and sticking it in BUT I do have this STI motor that needs a little work. At the minimum I know I need a new oil pump. I was/am thinking of doing a 12MM to up the oiling. What about using the heads from the spun bearing block? I was thinking of basically taking the top end from the JDM motor and mating it to the short block. Anything I have to look out for? What say ye?