MUMBAI: Blackstone, the world’s biggest private equity fund, has emerged the front runner to buy Kirloskar Oil Engines Ltd, the listed flagship company of the $3.5-billion Kirloskar Group that is in the middle of an escalating family feud, multiple people familiar with the development said.Promoters own 59.33% of Kirloskar Oil Engines (KOEL) that has a market cap of Rs 4,947 crore at present.