IAME pre-08 leopard failed conrod bearing

I have 2 pre-08 leopards that the conrod bearing failed on me. One engine had 3 hours on complete rebuild and the second I have no record on the bottom end but the top end only had 1 hour…

My first engine lasted all day during our Saturday event til about 3 laps to go and the bearing gave out around 11k rpm. The second made it through a 8 lap practice session and gave out on lap 2 of qualifying on sunday.

Engine number 1 I usually rev around 16500 but this track I never revved past 15500…water temp never passed 150 and I run on the rich side on the carb.

I use vp c12 and 8oz of maxima 927 oil.

Another guy in my class has a pre08 also and he had the exact same problem with 2 laps to go in the final on Sunday. I know he uses c12 and red line synthetic, and his engine only had about 1 hour run time since fresh.

Both conrods definitely show they got hot at the bearing area.

I am rebuilding these as the cranks are still okay as i have all the parts needed and capabilities to press and align the crank…

Just crazy it happened to both my engines and another one.

Also, what main bearings would anyone recommend? One engine has SKF and the other has Koyo.

8oz (236ml) oil to how much fuel?

8 ounces per gallon. Sorry for not clarifying that

Seems like enough oil.
SKF are my favourite but I’m not married to them
A thing to consider, is that the intake is directly in front of the crank. A correctly oiled filter is necessary to keep dirt out of the bearing. I have heard of big end bearing failing due to incorrect oiling of filters.

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I would think the 8oz to a gallon is enough, and I was leaning toward the SKF bearing myself.

As far as the air filter goes, I run the foam insert, and the screens on the intake tubes of the airbox as well. I’ve picked up an X30 in the meantime and I’m excited for that.