The Independent American Magazine for all Mini Owners
Issue link: http://mc2.epubxp.com/i/33536
Power In A Small Package Since the early days of the street rod, there have been many forced induc- tion systems. The most common, the GM Roots-style with its two or three internal rotors (lobes) and the turbocharger both were used as far back as WWII for aircraft engines, as naturally-aspirated engines don’t operate well at high altitudes due to the thin air density. The greatest problem is they’re both reasonably inefficient in the handling of air- known as adiabatic efficiency- and create a lot of heat from their operation. The belt-driven or screw-type supercharger can be 60-70 percent efficient as the lobes scuff the case as they age, reducing the operating ef- ficiency. Hence, the Teflon lining these units often have. Turbochargers are often better, but they produce massive heat the more power they produce, and almost every R56 S and JCW owner knows about under-hood heat and warped hood scoops. Just look at how many MINI USA has had to replace under warranty! The last decade several companies have accomplished some wonderful supercharger designs, none of which are as compact and efficient as the Rotrex has proven itself to be in small-displacement en- gine applications. Look- ing at the illustrations, you’ll see it resembles the turbo snail housing, but it has pulley ribs on one side, as it’s also a crank-driven supercharger. Also, it has no gears as with the factory Eaton M45 MINI unit, so noise is lower and will not wear like the Eaton. We suggest you visit www.rotrex.com and also www.Kraftwerksusa.com as one is the factory site, the other, the celebrated Oscar Jackson’s engineering company that has lead the charge with Rotrex. A highly respected name in Honda and Miata racing, Jackson sold his former Jackson Racing company to Moss Enterprises several years ago, but is soon to be back on the scene. We hope for some interesting engineering for MINI. Cool It! If you’re going to run high compression, put your engine under duress with high temperatures, and make horsepower, then you have to cool the engine combustion chambers, and very likely have to use a water/methanol injection system to increase its life. There are several suppliers, but few have the background of small engine racing water or water/methanol injection that the British-based Aquamist company does, and with the engineering background of Howerton Engineer- ing in central California, the kit is interfaced with RMW’s ECU, based upon boost, fuel injector duty cycle, or a combination of both. The system can use a under-hood water supply tank (many have used the windshield washer tank) or a 1-gallon trunk-mounted tank. The retail is $699. Essentially, a water/methanol combination is used to cool the charge of air/ fuel during ignition thereby preventing detonation, or “engine knock” as it’s usually called. This charge actually increases octane by several points, produc- ing greater power. In addition, it allows greater timing ad- vance, lowers cyl- inder pressure and EGT (Exhaust Gas Temperature), in- creases the com- bustible charge den- sity and is actually a good thing with lower quality gas. Methanol is ethanol with an ingredient that makes it foul and not drinkable. Also, distilled water is best, not some fancy brand name with a high mineral content, as minerals plug injectors. A variety of alcohol is injectable from denatured alcohol to Isopropyl if the best metha- nol is not immediately available from a racing fuel supplier. Straight methanol forces most engines to run rich, so it’s not a good idea. Also, all alcohol has less BTU than gasoline, and alcohol produces less horsepower than gasoline p/ gallon. These are the general points; Jeff Howerton and RMW can tailor your needs for R53 or R56 engines. Issue 32 MC2 Magazine 29