Type: Single cylinder, 2-stroke cycle, Schnuerle scavenged, ABC, air cooled, glow ignition
Bore: 21mm (.827")
Stroke: 19mm (.748")
Displacement: 6.58cc (.4016 cu. In.)
Compression ratio: 8.63:1
Horsepower: 2.2 @ 16,500
Weight: Bare – 12.1 ozs. With muffler – 15.6 ozs.
Length: (back of case to face of prop driver) 3.530"
Height: (mounting lug to top of head) 2.660"
Width: (mounting lug to mounting lug) 1.960"
Crankcase width: 1.370"
Mount bolt pattern: 18mmx42mm(.708"x1.654")
Manufacturer: MVVS Ltd., Brno, Czechoslovakia
U.S. Distributor: MVVS Corporation of America, 7 Switchbud Pl., Suite 192-211, The Woodlands, TX 77380, (281) 364-8011

It might be said that the development of the Schnuerle scavenged front intake, side exhaust, .40 displacement size 2-stroke engine could be divided into two eras – before and after the Rossi 40. Prior to the introduction of the Rossi 40, and front intake, side exhaust .40 that could top 14,000 rpm with a 10 x 6 prop could be considered an exceptional engine with the majority of the better sport type engines turning in the 12,000 to 14,000 rpm range; however, this all changed with the introduction of the Rossi 40 in 1986. The Rossi 40 would turn a 10 x 6 prop in excess of 15,000 rpm and the engine we reviewed in the June ’88 issue would turn a 10 x 6 Rev-Up 15,700 rpm. This was an astounding figure in that it was almost 2000 rpm faster than any engine in this class we had previously tested. Although the Rossi was intended as a Sport engine, it soon became the engine of choice for the Quickie 500 Pylon event. Both Fox and Webra introduced Quickie 500 engines shortly after the Rossi which were in the same power class but for a variety of reasons that we will not go into here, the Rossi remained king until the release of the Nelson 40. The Nelson 40 which we reviewed in the May ’92 issue would turn a 10 x 6 Rev-Up 17,500 rpm – 1800 rpm faster than the Rossi making the Nelson 40 the new "King Of The Hill." However, due to the High power developed by the Nelson (and cost), many clubs have either banned the Nelson directly or placed a price limit on the engines that can be used for Quickie 500 type racing events which indirectly eliminated the Nelson.

In 1993, Dub Jett, who heads Jett Engineering, entered the model engine business with his "Sport-Jett" and "Quickie-Jett" engines that have been giving the Nelsons some serious competition at considerably less cost.

The latest engine to join this "Super" class of .40 displacement size engines is our review engine for this month – the MVVS Quickie 500 40. The MVVS Quickie 500 engine was not designed to be competitive with the Nelson or Jett engines but designed to race in the sanctioned "Sport Class" Quickie 500 events where out of the box the manufacturer claims the engine to out perform all other unmodified front intake, side exhaust .40 displacement size engines. Our testing verified this, as excluding the Nelson and Jett engines, the MVVS Quickie 500 engine is the strongest running .40 displacement size engine we have tested to date; and, a "Nelson and Jett beater" is under development for release at a later date. Let’s take a look at the design and construction features of the MVVS Quickie 500 40.

With a bore of .827 and stroke of .748 the engine is of "overbore" design which probably by more than coincidence is the same bore and stroke used by the Rossi 40. As a comparison, the Nelson and Jett 40’s utilize a .846" bore and .709" stroke making them have a slightly higher bore to stroke ratio. In theory then, the Nelson and Jett engines should develop their horsepower peak at slightly higher rpm’s and favor the smaller prop sizes, whereas the MVVS and Rossi engines should favor slightly larger prop sizes at lower rpm. This proved out in actual application as the spread in rpm with the 10 x 6 prop was much smaller between the MVVS and Nelson/Jett engines than with a 9 x 6. For this reason the manufacturer recommends that a little more prop be used on the engine and all engines are tested with a 9 ½ x 6 ½ APC prop before they are shipped with all engines turning in the 17,400 to 17,700 rpm range with 15% nitro fuel. Our review engine, incidentally, turned exactly 17,700 rpm with this prop and fuel. Naturally, other factors besides the bore and stroke enter the picture when it comes to an engine’s power curve such as rod length and angularity, porting and timing, etc.

Crankcase:

The engine utilizes a rugged two-piece crankcase casting composed of a lower crankcase and upper cylinder. Although the use of a crankcase and separate cylinder have been used by other engine manufacturers over the years, unusual is the method of joining the two parts together. This is accomplished by four long capscrews that thread from the top of the cylinder rather than attachment by a flange and screws at the base. When the two parts are assembled it is difficult to tell that the casting is not one piece until the head is removed. K&B uses a similar two-piece crankcase arrangement with their Sportster counterbalance will also give a small rpm increase. Evidently, the shape of the counterbalance is affecting the fuel distribution and transfer to the combustion chamber.

The counterbalance would balance out the full weight of the connecting rod and about 90% of the wrist pin’s weight. This could be considered slightly on the light side but did not seem to affect the engine’s vibration level, which was as smooth as the majority of the engines in this displacement size we have tested. The relatively light 9.5-gram combined weight of the piston and wrist pin would be a contributing factor here.

The crankshaft is supported y a 28mm (1.102") o.d. x 15mm (.590") i.d. steel caged ball bearing at the rear and a 19mm (.748") o.d. x 7mm (.275") i.d. steel caged ball bearing at the front. The rear bearing is somewhat smaller than the 30mm o.d. x 17mm i.d. rear bearing used in the Rossi, Nelson, and Jett engines which we were rather surprised to find. The 15mm i.d. of the rear bearing and crankshaft journal allowed for a .415" gas passage through the crankshaft which, again, is somewhat smaller than the .437" gas passage used by the Rossi, Nelson, and Jett engines. The crankshaft intake port was timed to open 33-degrees after BDC and close 56-degrees after TDC for a total duration of 203-degrees. The 56-degree closing time actually being on the conservative side. Another 5-degrees here should make this already strong running engine even stronger in the rpm range that it is intended to operate in. As pointed out at the beginning of this review, the MVVS was not intended to be competitive with the Nelson and Jett engines, so I imagine that the Later closing timing and larger rear bearing size that, in turn, allows a larger gas passage through the crankshaft will be incorporated in the engine intended to be competitive with the Nelson and Jett engines.

True ABC piston/sleeve metallurgy is used, i.e., a high silicon content aluminum piston running in a hard chrome plated, brass sleeve. As we have pointed out in previous engine reviews, we have always found chrome to hold up better under some of those "metal melting" lean tuns fellows expose their engines to on occasion, than does nickel that some of the engine manufacturers are using.

Conventional Schnuerle plus boost port scavenging is utilized with a single transfer port on either side of the exhaust port and a single boost port directly opposite the exhaust. The exhaust is timed for an open duration of 164-degrees, the transfer ports 126-degrees, and the boost port 122-degrees. The 164-degree exhaust timing would be considered mini-pipe tuning which when used with the special "tuned muffler" which is basically a mini-pipe within an outer shell accounts for a good portion of the engine’s power output.

The connecting rod has been machined from aluminum plate and bronze bushed at only the crank pin end. If we were to fault the engine, this would be the only area. An engine intended for racing purposes is bound to see some lean running, low oil content fuel, etc., and unless the rod is machined from a high silicon content aluminum, which the MVVS rod does not appear to be, you can expect the wrist pin end of the rod to be subject to wear.

Cylinder Head:

A two-piece head assembly is used consisting of the upper finned or clamp portion and a separate combustion chamber "button." Both parts have been machined from bar stock aluminum. The combustion chamber shape consists of a .115" deep, flat bottomed bowl surrounded by a .165" Series engines, but in the case of the K&B’s, the head screws also retain the cylinder whereas the MVVS head screws are separate. Unlike the MVVS 61 that we reviewed in the May ’94 issue that could have the cylinder positioned with the exhaust facing either side or to the rear, the 40 cylinder can only be positioned with the exhaust on the right side for proper transfer and boost port alignment.

Crankshaft and Bearings:

The crankshaft has been machined in one piece from bar stock steel, hardened and finish ground on all bearing surfaces including the crank pin. The finish grinding operation has been performed "on centers" rather than by centerless grinding which assures dead true concentricity between the main journal and bearing seats. Something that is not always that accurate with the more commonly used centerless grinding method which is faster and less costly.

A constant thickness counterbalance is utilized, cut away on either side of the crank pin for counterbalance action but leaving a .040" wide, full disc section at the face. For some not clearly understood reason, this counterbalance shape has proven to give a small increase in engine rpm in a front intake engine. With a rear intake engine the full disc section at the rear of the wide squish band with an approximate 2-degree angle. The measured combustion chamber volume was .5cc which computes to a compression ratio of 8.63:1 figured with the closing of the .315" high exhaust port. Although this is right in the ballpark for a sport type engine, it is somewhat lower than the compression ratios used by the Rossi, Nelson, and Jett engines, all of which were above 10.3:1. Evidently MVVS wanted to make the engine a little more "use friendly" for the sport class type of Quickie 500 racing.

Carburetor:

The carburetor is the tried and proven two-needle, rotating barrel type that most of you are probably familiar with by now as most of the model engine manufacturers are using it in one variation or another on their engines. Unusual here is the .365" throat diameter of the carburetor. This is big for an engine of this displacement size and another significant factor contributing to the engine’s high power level. As a comparison, the Rossi 40 we reviewed had a rather small .302" throat and the Nelson and Jett engines both have a .343" throat. The only other .40 displacement size engine we have tested with an intake in this range was the Fox Quickie 500 which had a .360" throat.

Performance:

Prior to beginning the testing, the engine was given a 30-minute break-in period consisting of six 5-minute runs alternating the mixture from a rich 2-cycle to peaked out and then richening back up again with a cool down period between runs. Following the break-in period the engine would hold a leaned in setting without slowing and we proceeded with the testing. The test fuel consisted of 10% nitromethane, 18% Klotz KL-200, 2% castor oil, and the balance methanol. All percentages are by volume, not weight. The temperature was 71-degrees Fahrenheit – the Relative Humidity 30% -- and the Barometric Pressure 30.00 inches of Mercury. The engine comes equipped with a MVVS glow plug, which lasted for the whole test period and was still in good shape upon completion. This would indicate that a slightly higher compression ratio could probably be used. All propellers were Rev-Ups.

9 x 6 ………………….. 17,800

9 x 7 ………………….. 17,500

10 x 6 ………………… 16,400

10 x 7 ………………… 13,100

11 x 6 ………………… 12,300

As mentioned previously in the review, the Quickie 500 engines are test run prior to shipment with 15% nitro fuel which in this case was Jim Morgan’s Omega and a 9 ½ x 6 ½ APC prop. A certificate of performance accompanies every engine, which must turn between 17,400 to 17,700 rpm. We also tested our review engine with the 9 ½ x 6 ½ APC prop and Omega 15% and got a tachometer reading of 17,700 rpm. The performance figures pretty well speak for themselves, as anyone with experience running .40 displacement size engines will know. The MVVS Quickie 500 40 is a real barn burner equaling many of the .50 displacement size engines in power. Even with its high power level, the engine had no bad handling characteristics or temperamental qualities and was very easy to start, adjust, and run. Although not intended to idle, we had the engine idling at 2500 rpm with the 9 and 10 inch prop sizes and 2250 rpm with the 11 x 6. Although the engine could be idled slower, there was some hesitation on acceleration due to the larger than normal carburetor intake size. With the idle speed set at 2500 the acceleration was within acceptable limits.

The engine has an introductory selling price of $199.95 and comes complete with the tuned muffler, a radial backplate mount, Tru-Turn spinner nut, and spare head shims. A real bargain price for an engine of this power and quality. Check one out. You will be seeing a lot of the MVVS Quickie 500 engines at the Quickie 500 racing events as the racers begin to realize the engine’s power potential.