Comparison: Aprilia RSV4 Factory vs. Honda VFR 750 R (RC 30)

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Comparison: Aprilia RSV4 Factory vs. Honda VFR 750 R (RC 30)

V4 generations in comparison

Finally. While V4 pioneer Honda only has to offer a shrug of the shoulders to sports fans looking for a V4 in their sportswear, Aprilia runs open doors to them with the RSV4.

V4 or rather inline four-cylinder? If you look at the matter soberly, there is little that can be criticized for a properly made inline four-cylinder. Today’s specimens have achieved an enormous degree of perfection, are stable, run smoothly and deliver performance like hell. But when it comes to the tingling in the stomach, increased pulse, then the hour of the V4 strikes. The exotic sound alone, which stands out from the monotony of screeching row fours, electrifies this sound that tastes like pit lane, start lights, race track.

Comparison: Aprilia RSV4 Factory vs. Honda VFR 750 R (RC 30)

V4 generations in comparison

Aprilia is now back on the red V4 thread.

As was the case with the development of the Honda, in the case of the RSV4 it was not the controllers but the technicians who were in charge. They went to work just as consistently as their Honda colleagues at the time and opted for a V4 for good reason. Although it is more complex and therefore more expensive than an in-line engine and weighs a little more due to the double camshaft drive and two separate cylinder blocks, its advantages are undisputed. Why do you think there are only V engines in MotoGP with the exception of Kawasaki? The Aprilia technicians say that their V4 is a good 40 percent narrower than a comparable in-line engine. This enables a silhouette so narrow that aerodynamicists have tears of joy in their eyes and ordinary superbikes suddenly look rather chubby next to them. And thanks to its compact design, the V4 offers a lot of leeway in the installation position and thus the choice of the center of gravity.

Running culture

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Generation high 4: Aprilia RSV4 Factory and Honda VFR 750 R compete against each other as representatives of the V4 generations.

If the Aprilia spreads its cylinders by 65 degrees, the Honda wears hers at a 90-degree angle. Which basically creates the best conditions for a good mass balance. This is why – unlike the Aprilia – it does not have a balancer shaft. In terms of running culture, however, the Honda is not completely perfect either. Because unlike the civilian sister VFR 750 F, the crank pin offset is 360 degrees on its crankshaft. That of the F on the other hand 180 degrees. Better power delivery and traction due to the narrower ignition intervals, so the reasoning by HRC at the time, should have been decisive for the 360-degree wave. If the RC 30 purrs like a kitten up to 6000 rpm, the unbalanced second-order inertia forces become noticeable as vibrations in the notches. However, this takes on just as little disruptive form as the impatient drumming and pulsing of the RSV4 unit, whose balancer shaft does a great job.

Although the two V4s may have clear differences in layout, they reveal their close relationship in the way they develop their power. This creamy start from low speeds, followed by the rubber band-like march of the tachometer needle through the wide usable speed range. Because the V configuration does not bring any performance advantages. With 179 hp, the RSV4 is probably good at music in the superbikes, but nothing more. On the other hand, the power output of the RC 30, throttled to Teutonically correct 100 hp for the market at that time, seems modest. But be careful. From the factory it was 112 hp. Which at least corresponds to a liter output of 149 hp. The Aprilia uses the whole arsenal of modern electronics and aids for its yield in order to achieve this performance. Ride-by-wire, adjustable intake funnels, two injection nozzles per cylinder – one of them centrally above the funnels, ultra-fast injection computer, servomotor with exhaust flap.

Of course, the RC 30 doesn’t have everything. And if you wanted more power, you had to come to terms with a kit ignition box, camshafts and an arsenal of carburetor nozzles, needles and springs. Nevertheless, it is worth taking a look inside. Not only because of the high-precision gear towers that drive the RC 30 camshafts. The Aprilia, on the other hand, leaves it with one chain per cylinder bank. It only drives the inlet camshaft, which is geared directly to the outlet shaft. Which saves a lot of installation space. The compression of the Aprilia engine from 13 to one is typically high for today’s athletes who are trimmed for performance and efficiency. It requires a compact combustion chamber, which is made possible by the valves, which are very narrow at 22 degrees.

Drive technology

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The Aprilia uses the compact design of its engine to offer racers different engine positions to change the vehicle’s center of gravity.

The 38 degree valve angle of the RC 30 V4 engine, on the other hand, was almost moderate (the valves of the RC 45 were already significantly narrower at 26 degrees) and its compression of only 11.0 to one. After all, the model athlete was designed for regular gasoline. His finesse is waiting elsewhere. Trimmed for low friction, the Teflon-molybdenum-coated pistons only have two rings and the hollow-bored camshafts run in needle bearings. The valves with their 4.5 millimeter thin shafts are made of steel, but the connecting rods are made of titanium. With the RSV4 it is the other way around. Amazing things also in the combustion chambers. Honda technicians installed 28 mm inlet valves in a 70 millimeter bore. The Aprilia has 32 inlet valves with a 78 millimeter bore. Valve and piston areas are thus in a ratio of about one to three in both. The difference is only made by the free valve cross-section, which is determined by the valve lift. And here the RSV4 clearly has the better cards in terms of power output due to its proud 10.2 millimeter inlet hub. With an inlet cross-section of around 1450 square millimeters, it sucks its fresh gas from an 8.2-liter airbox through a size 48 intake throat, into which two injection nozzles pump the exact amount of fuel required to the millisecond. In extreme cases, 14,000 times per minute. With their stroke of 52.3 millimeters, the pistons are already traveling at an average speed of 24.41 m / s. With a stroke of 48.6 millimeters, the pistons of the 12500 rpm Honda have to cope with a maximum of 20.25 m / s. Here, too, is progress.

In addition, the Honda’s intake valve lift of nine millimeters and its 1120 square millimeters of free intake cross-section appear just as modest as the 3.4 liter airbox and the 35.5 millimeter carburettor. They have another delicacy: The lids of the mixture factories have service openings for a quick change of nozzles and needles without the delicate removal of the membranes. In terms of smoothness, throttle response and load change behavior, however, the Honda is more than one row ahead of the Aprilia. It reacts very smoothly to gas commands, its load change reactions are limited to a minimum. In comparison, the Aprilia’s manners seem a bit rough and rustic. In terms of chassis technology, the Honda does not show any nakedness: impeccable handling, almost Ducati-like stability in fast corners and suspension elements that offer a lot of comfort. The RSV4 appears like the logical further development: intoxicating precision, striking handiness and, thanks to the very tight coordination, bombproof. To achieve an impressive balance, the technicians have not only found the optimal location for the engine, but also for the tank, which extends under the seat. While the RC 30 was a dainty motorcycle crouched flat on the asphalt at the time, the RSV4 goes one better. Although it was 1000, it was almost as filigree as a 600, which is why tall people on the spartan, high – the Aprilia pilot sits six (!) Centimeters higher than his VFR colleague – look almost gigantic. Only the V4 Honda was an almost unaffordable dream at the time of 25,000 marks, the Aprilia brings it within reach today. But both are a great achievement.

Technical data – Aprilia RSV4 Factory / Honda VFR 750 R (RC 30)

Artist

The structure of the Honda is straightforward, even under the pretty dress.

engine
Type V4 / V4
Cylinder angle, degrees 65/90
Camshaft drive chain / gears
Bore / stroke 78 / 52.3 mm / 70 / 48.6 mm
Compression 13.0: 1 / 11.0: 1
Displacement 1000cm / 3748cm3
Output 180 PS / 100 PS at 12500 / min / at 11000 / min
Torque 115 Nm at 10000 rpm / 67 Nm at 10500 rpm
Clutch slipper, oil bath / slipper, oil bath
Mixture preparation injection Ø 48 mm / carburetor Ø 35.5 mm

landing gear
Frame bridge frame made of aluminum / bridge frame made of aluminum

Front tires
120/70 ZR 17
/ 120/70 VR 17

Rear tires
190/55 ZR 17
/ 180/60 VR 18

mass and weight
Wheelbase 1420 mm / 1410 mm
Steering head angle 65.5 degrees / 65.5 degrees
Trail 105 mm / 95 mm
Seat height 845 mm / 785 mm
Weight with a full tank 204 kg / 208 kg

Performance
Vmax 295 km / h / 234 km / h
acceleration
0-100 3.2 sec / 4.9 sec
0 ?? 200 7.8 sec / 9.3 sec

Draft
60-140 7.3 sec / 12.8 sec

price
19,790 euros / 25,000 marks (1988)

Engine technology – the essentials are invisible to the eye

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With the Aprilia, playful details meet functional delicacies such as the adjustable steering angle.

In search of even power delivery and optimum traction, Honda relocated the crank pins of the cylinder pairs to one level with the 360-degree crankshaft. Two cylinders fire within 90 degrees of crankshaft rotation, followed by 270 degrees of "idle". The 65-degree V-engine of the Aprilia with a 180-degree shaft is different. Good to see: chain-driven camshafts from Aprilia, gear tower from Honda.

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