There is arguably no more extreme of an internal combustion operating environment than an 11,000 horsepower, nitromethane-sipping Hemi engine aboard a Top Fuel dragster or Funny Car, and as you can imagine, that creates a host of engineering challenges for the manufacturers creating parts and lubricants for them — even if they only must survive for a little more than 3.5-seconds. In the case of engine bearings and bearing coatings, the answer to extending the life of a part may lie in doing everything one wouldn’t do with a more contemporary engine designed to last for tens of thousands of miles.
King Engine Bearings, one of the leaders in auto racing engine bearings, has developed a fresh, new approach to coatings on the bearings for nitro engines, and it bucks conventional wisdom.
“All coatings are designed to reduce friction, to take the place of oil. When oil starvation occurs, the coating is there to help the part live longer. Just like coatings are applied to pistons to prevent scuffing, they’re added to bearings for much the same purpose — to add a little insurance for your engine. So we have different coatings to achieve different things and for varying applications,” explains Kings’ Roberto Trinidad.
“The coatings for a general engine, say a small-block Chevrolet or LS, we have a coating that we like to have stay on,” Trinidad goes on to share. “When you start reducing bearing thickness, if some of that layer comes off, you’re expanding that clearance. Now you’re effecting the way the oil is going to flow, along with the pressure. The bigger the hole, the less pressure.
“When we get to a nitro motor, we’re only trying to survive for 4-seconds; an engine that makes about 11,000 horsepower, spinning 10,500 RPM, is really squeezing the oil film out between the crank and the bearing — it’s just simply pushing it out, because there’s so much pressure there. Well this coating, which we haven’t officially named yet (King displayed them as “King Top Fuel,” or ‘TFC’ at SEMA), is designed to scuff off. I know I’m going to have contact, so I have a material that is going to ‘give’…that’s not going to resist. As the crank turns, some of the coating scuffs off as the RPM keeps climbing. What we’re trying to prevent is failure, from the bearing locking onto the journal and spinning the bearing. In order for this to happen, we’ve designed the coating to come off; right now we’re at one, maybe one and a half, but we’re hoping to get two passes out of a set of bearings, effectively doubling the life of the part,” Trinidad shares.