OS Speed .21 V-Spec First Look


Quote from R/C Car Exclusive :

You’ve probably heard all about it, seen some photos and noticed that this engine is the current IFMAR World Champion in 1/8 Buggy (thanks to Mark Pavidis), but we now have exclusive internals photos of this amazing mill.

OS’s latest flagship model is a work of art, with many features reserved for only the finest high-end engines in the world.

The visual similarities to the original V-Spec are all there, but it’s what’s inside that makes this engine special. First, the V-Spec’s port timing has been modified by OS Japan to produce more mid-range and top-end power. The sleeve itself, however, looks very “standard” V-Spec, with transfer port “fangs” that help direct fuel/air flow. Although we haven’t had the chance to time-out the sleeve, the Speed’s exhaust port looks wider and higher-duration than the stock V-Spec as well. This extra exhaust timing should help the Speed version make more top-end power.





The Speed’s crankcase is slightly updated as well. It features lower case reinforcement channels that extend from the backplate screw areas to the front of the case. The backplate is now also hard anodized for extra durability.


One of the Speed’s most notable upgrades over the stock V-Spec is its ceramic main rear bearing. OS includes this bearing for two reasons: the ceramic bearing prevents and nearly eliminates premature bearing failure that the steel bearing has experienced, and the lighter weight, lower drag ceramic balls reduce rotational mass and friction allowing for higher RPM production.

The Speed’s carb is also updated from the standard V-Spec, with a black anodized aluminum carb body and cast fins to dissipate heat. Also unique to the Speed version are its red-anodized aluminum carb venturi inserts. The Speed includes red aluminum 7mm, 8mm and 9mm inserts for extra tuning options.


We absolutely love the Speed’s hard anodized, milled and machined and epoxy ramped crankshaft. The thing is simply a work of art. A black hard anodize coating minimizes wear and slop, while the induction port has been drilled, lightened and epoxy ramped for quicker throttle response and spool up.

By far the Speed’s most notable and important modification is its tungsten slugged crankshaft counterweight. The process involved with installing counterweight slugs is more than we care to explain here, but let it suffice to say that it’s not cheap. The result, however, is a smoother running engine with fewer power spikes. Because the counterweight is now balanced in relation to the piston/con-rod weight, the engine should spool quickly, smoothly and to higher RPM’s than a non-balanced crank possibly could. Con-rod wear and tear should also be reduced as well thanks to the balanced counterweight.


Finally, topping the entire Speed engine off is its ultra lightweight, trick looking magnesium head. The head weighs a full ounce (28 grams!) less than the blue-anodized aluminum V-Spec head. We’re anxious to test the head, since it does weigh significantly less than the stocker, but we are questioning its heat transfer abilities—magnesium typically doesn’t transfer heat as well as aluminum. Like the stock V-Spec, the Speed version also includes a 2-piece head design with separate head button.


Source : R/C Car

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