Head to head: Serpent Impulse vs. Mugen MTX-2

Radio Control Car Action, Sep 2000

Serpent, wellknown for its on-road nitro racing prowess, caused a stir when it debuted its Impulse touring car late in 1999. It was the first competition car to derive its suspension and chassis design from proven onroad technology, and it represented the "next step" in the evolution of the nitro touring car. In fact, it was innovative enough to earn "Car of the year" status (see last month's issue). However. the Impulse was not the only racer bred from a winning on-road gene pool to hit the competition scene; soon after the Serpent hit the track, Mugen launched a nitro tourer (the MTX-2) based on lessons learned from its own successful lo on-road machine, the Avance. Racers took notice, and comparisons to the Serpent benchmark were unavoidable, and that is why we're pitting the cars against each other, head to head, to see which is the better machine. We'll save the results for the end, but we can tell you now that the Mugen MTX-2 and the Serpent Impulse are the best nitro tourers available. How do we know? See the latest edition of Radio Control Touring Cars, our annual all-touring special issue. We tested nine competition nitro tourers in all, with the Serpent and Mugen topping all comers; it's a must-read, if you're shopping for a new race rig.

The Impulse is the first of a new generation of nitro touring cars and borrows from technology originally developed for the rigors of 1/10 fuel on-road racing. The result is a stout car whose nearest ancestor is a purebred nitro racing machine rather than a retrofitted electric touring car.

The Impulse features a narrow, thick-aluminum lower plate with a molded upper plate. The Impulse is available with a very powerful Mega version of a NovaRossi engine and fitted with a standard two-shoe clutch and a single-speed transmission. A triple-belt drive system feeds six-gear planetary differentials at the front and rear, and dogbones transfer power to the wheels. Damping is handled by molded shocks with threaded preload collars and externally adjustable valuing.

ASSEMBLY

The Impulse is a car for serious racers. The four-corner, pivot-ball suspension states the use of more sophisticated setup equipment to get the maximum benefit from its design. Despite the extra challenges that result from the extra sophistication, the Impulse has adequate instructions for a car from a specialty manufacturer. They aren't detailed enough to walk a first-time nitro builder through the process but they're clear enough for those with experience.

PERFORMANCE

The very tall-5.75:1-final drive ratio of the single-speed setup leaves the Impulse struggling to get off the line, but it's not too long before the engine gets on the pipe and really starts diggin' asphalt. It will easily break 50mph with the standard single speed.

The racetrack is where the Impulse is most in its element. After abet half about half a day of tweaking, we settled on a setup that's essentially stock, but the front and rear suspension were widened to the 200mm maximum. The Impulse turned in the fastest lap times at a blistering 13.9 seconds.

FINAL ANALYSIS

The Impulse demonstrates best-in-class performance on the racetrack, which is its intended environment. It isn't the best drag racer or speed-run machine, but it's at the too of the list in the twisties.

There isn't a lot to complain about in the manufacturing department. The parts are made of a high-quality composite, and almost everything fits without hassle. Some of the upper chassis plates have been known to be slightly too long to be perfectly aligned with the components already attached to the lower deck. The front steering hubs are also very picky about which wheels will fit over them with enough clearance, but it's a minor concern once you've found the right wheel-mostly nit-picking complaints rather than real faults. Overall, the Impulse is an excellent choice for serious racers.

Mugen has done some impressive work. This car is based on existing 1/8 and 1/10 on-road technology that shows on the track as well as in the pits. Pivot-ball-style suspension is used in the front and the rear. The benefit of this design is that camber, rear toe and track can easily he adjusted. Threadedaluminum shock bodies damp the suspension. The chassis plate resembles one from a 1/8-scale on-road car. but it has fairly sharp edges. so be careful when you handle it; in fact, why not sand them and save everyone's fingers? The upper deck is a composite plastic, and the electronics are neatly arranged and reasonably accessible, though the receiver can be hard to reach. Smooth bevel-gear diffs are powered by a 3-belt drive system that's coupled to a potent Mogen rear-exhaust engine and a 2-speed transmission. Hardened dogbone drive shafts get the power from the diffs to the wheels.

ASSEMBLY

The MTX-2 went together without any real problems. Just make certain that the width of the car is the same from the center out to the wheels on both sides. Also spend extra time on the differentials. After long tests, our MTX-2's diffs started to leak; when you build them, seal the halves together with silicone adhesive and avoid a future mess.