Honda D16y7 spun bearing

Hi guys,

I'm helping to rebuild a friend's d16, one week ago he was testing the car (with a "safe" tune that a friend let us) he ended up with two spun rod bearings and two scored cylinders.

I wasn't on the car in that test but checking the log (i can't find it rigth now) the engine was at 5300 rpm and 5 pounds of boost, afr 11.5 and spark at 24 degrees.

I'm asking for your help because i want to know what cause that (if it was the tune or was and clearance issue) to avoid the same mistake on this new build.

I can upload pictures of the damage if you can check it.

Pd: the engine is a stock d16y7 with a t3/t4 turbo, 300cc injectors and hondata s300.

Thanks in advance.

In general it's hard for a tune to cause a bearing issue in the engine. It definitely is possible, however this is normally attributed to knock hammering the rod bearings. In my own experience you'll almost always see damage to the piston, or even complete piston failure, well before you experience rod bearing failure. My initial guess would be oil starvation, oil contamination or bearing clearances. All of that being said, 24 deg is quite a lot of timing for the boost and rpm (not withstanding the fact you haven't disclosed compression ratio or fuel).

Thank you for your reply Andre, Pistons (crown and ring lands) are in good shape, no signs of detonation also spark plugs are in good shape.

The compression is 9.4:1 and fuel octane ratio is 91 (best pump gas in my country :| )

On that basis I'd say the tuning is probably not the culprit and I'd be leaning towards oil supply and/or oil quality.