How Honda's S600 Sports Car Reached 9,500 Rpm With Nearly Zero Oil Pressure

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If you're fortunate capable to get down nan instrumentality of nan diminutive 1964-1966 Honda S600 sports car, arsenic Jason Cammisa did for his Hagerty Revelations show, you'll announcement there's nary lipid unit ray aliases gauge. This is because location fundamentally isn't immoderate unit to measure. And yet, nan tachometer shows a redline of 9,500 rpm, nan highest redline of immoderate accumulation car earlier aliases since. Just listen:

Well, nan cardinal to that dental-drill spinning velocity is mostly owed to Honda's usage of roller bearings for nan crankshaft. Normally, motor crankshafts rotation connected a bladed movie of lipid betwixt nan crank's journals and plain hydrodynamic (or fluid) bearings. In Chevrolet and GMC pickup trucks pinch nan 6.2-liter L87 V8, that movie of lipid was, until recently, thinner than nan crippled of a modern-day Marvel movie. But GM did commencement suggesting nan usage of heavier, thicker oils to help prevent further motor failures. 

Anyway, astir engines walk lipid done nan crank's main journals to mini holes betwixt nan diary and nan main bearings. Since these surfaces are ridiculously adjacent to each other, there's measurable unit arsenic nan lipid gets forced through. This unit is changeless arsenic agelong arsenic nan parts are wrong due tolerance, but will driblet arsenic parts get worn retired and tolerances decrease.

By tossing retired plain coagulated metallic bearings and swapping successful roller bearings, lipid unit becomes incidental. Now, lipid still gets splashed onto nan bearings to make judge nan rollers rotation freely and support teeny-weeny hydrodynamic films betwixt nan roller surfaces, but lipid doesn't request to provender done nan crank journals. There whitethorn beryllium immoderate nominal lipid unit because an lipid pump still helps move lipid to lubricate moving parts, but thing for illustration nan 25-30 psi successful normal engines.

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Given that nan Honda S600 revved truthful freely pinch truthful small friction, it mightiness look prudent to spell up and make each engines pinch roller base crankshafts, right? In 2009, base shaper Timken grabbed a 3.5-liter V6 from a Toyota Avalon and converted its crank and cam trains complete to roller bearings, and recovered that clash simplification was arsenic precocious arsenic 10%. 

Even nan thinnest modern oils can't support up. As per a 1999 SAE insubstantial from Honda, experiments showed 0W-20 lipid usage improved substance system by 1.5%. But successful Timken's paper, nan institution mentioned moving straight pinch nan EPA to find nan clash simplification effect pinch roller bearings and came up pinch a substance system betterment estimate of 5%. The point is, arsenic awesome arsenic roller bearings are astatine kicking clash to nan curb, they tin coming much problems than they solve, which is why car manufacturers person abandoned them. Some motorcycles, such arsenic Harley Davidsons, still usage them, but it's rare.

Crankshafts, whether cast, forged, aliases billet, are almost ever 1 coagulated chunk of zig-zagging metal. Roller bearings, dissimilar plain bearings, are coagulated circles that aren't meant to beryllium divided successful half and pieced together astir a crank aliases rod journal. Imagine trying to gaffe a roller base past counterweights and you'll understand nan problem. So, successful bid to make a roller base crank, it has to beryllium precision assembled portion by piece. Even worse, individual rollers tin get stuck erstwhile nan lipid is cold. Over time, this develops a level spot connected nan roller, which prevents it from rolling — its only job.

It someway gets worse. Roller bearings tin only beryllium pushed truthful difficult earlier they deed their fatigue limits. The Mercedes 300SLR's M196 S engine used roller bearings, but nan German shaper constricted its redline to trim this fatigue during 24-hour races. In Formula One, cars utilized roller cranks disconnected and connected up to nan V10 years before giving up nan chase. Not only was nan capacity summation negligible, but nan manufacturing was analyzable and nan bearings ate up excessively overmuch space. In 1996, nan FIA banned nan ceramic bearings astir commonly utilized for nan roller cranks, and everyone was happy to spell backmost to regular crankshafts, anyway. 

Bugatti (the first one, not nan Romano Artioli aliases Volkswagen one) utilized roller base cranks, making assembly an arduous task, peculiarly for nan company's straight-eights. Although Bugatti's engines became immoderate of the astir celebrated straight-eight engines ever made, nan configuration is uncommon today. Advanced arsenic they were, Bugatti's roller cranks were still highly temperamental and only lasted astir 5,000 miles earlier needing to beryllium swapped out. Porsche besides experimented pinch roller-bearing crankshafts. The 356 and 550 Spyder utilized nan Hirth roller crank, which became celebrated for being arsenic robust arsenic dried leaves.

The high-revving Honda S600 was a marvel, pinch its 57-hp oversquare 606 cc double overhead cam, aluminum block, hemi-headed, roller crank inline-four that propelled only 1,576 pounds of miniature convertible. Though Honda besides utilized roller cranks successful nan anterior S500 and consequent S800 sports cars, arsenic good arsenic the two-cylinder N360/N600 sedans and plentifulness of motorcycles, nan institution yet stopped trying to technologist astir nan design's shortcomings. While roller bearings featured successful Honda's 1968 RA301E Formula One V12, plain bearings arrived successful nan consequent RA302 V8. Honda besides switched to plain bearings for its 1969 CB750 motorcycle and ne'er looked back.