'No I will not sell this engine to you because you will write critical things in your magazine, I will build you a special good one and give it to you so you will be happy.'

Those were the words of the CS engine boss when I went into his office to buy a new CS 60 F2B. I was in China to fly stunt for Australia at the World Championships and the CS engine factory, which is in the Shanghai competition site, was open for business. My reaction to such an incredible statement was to turn around, walk out, give the money to a member of the UK stunt team who bought the standard production motor for me. (This curious incident was witnessed by a member of the US team.)

Before we start, let's get one thing very clear: this is not the same engine used by the all-conquering Chinese team in the world stunt championships late last year. They used genuine but locally converted built Italian ST60s. This motor on test is a Chinese made version of the ST60 that has recently been put onto the market at a very attractive price.

While die first ST60 replica to hit the market the Double Star 60 from the former Russian empire of Moldova, has emerged as a excellent stunt motor, this latest offering has taken a different approach and incorporated a few interesting modifications.

The CS company in Shanghai has spent much energy in the past few years making replica engines, What started as just a cheaper version of the legendary Oliver Tiger 2.5 quickly expanded to include other classic diesels and even a popular OS FP glows. With such a broad range of replicas aimed at so marry mark it was inevitable that the Super Tiger ST60 would be included.

(And before anyone says it is not based on a copy of the legendary big Tiger let's get the following clearly stated: its has the same overall layout and capacity from the same bore stroke, the same mounting dimensions, the same width/length/height and the same NVA/venturi design. The only major changes are to the cylinder and head location/finning and the backplate.)

And so, under the name CS60 F2B, the Chinese factory has released its latest offering which is a new large stunt engine that has more than a coincidental relationship to the legendary Italian The important differences which can be described as improving the design include running the exhaust stack on the other side which is more suitable for an inverted engine, an ABC piston/liner and more head fins that include a screw-down liner clamping arrangement. Unaltered is the unmistakable ST-style venturi/NVA layout.

Taking it all apart reveals 125-degree exhaust timing, 110 degree transfers and a shaft timed at 32-46. Those number are good but the fact that the liner has no taper is not good and the small gap under the piston skirt at top dead center (otherwise known as sub-piston induction for engines that do not run a muffler) means the intake breathing is compromised.

While the port timing is milder than those used on the Italian product, the compression at 12.9: 1 is very much in the ST60 league. Unfortunately, dismantling the test engine showed the Chinese piston was hitting the Chinese head and so a 10 thou shim was added which reduced to compression to 1 1.6: 1. (Remember, both the ST46 and the ST60 gain their famous torque by using compression ratios around 12.7: 1.)

Instead of 6 screws retaining the cylinder head, CS has used a system more popular with high performance 15s where the liner is held down by machining a large time thread to the head which is screwed into position. This offers the benefit of even clamping pressure over the inevitable minor local distortions of separate screws. Such a gain is very small and it is debatable whether the change is an improvement for a relatively low temperature stunt engine.

While the piston/liner is an ABC, the fact that the liner has no taper is bad. This is unfortunate because the engine loses one of the main gains with an ABC design - optimum sealing should only be achieved towards the top of the stroke (where it's most needed) and the remainder of the piston travel is done with substantially reduced friction. Less friction means less wear, less heat, better fuel economy and more power. In the case of this new CS60, the piston drags on the liner for the full 360 degrees, which is bad. But a 60 is a 60, which develops fistfuls of torque to help overcome such a minor design shortcoming.

Other aspects of its design, which are interesting, include:

- The head needs a special pin wrench for its removal, but two small rods and a screwdriver lever can do the job. - The fins are machined into the one case casting, which extend to the full height of the motor. 'Ibis results in a very unusual looking motor.

- The conrod is bushed at both ends, which is very good.

- Dismantling the motor is a bitch as the piston pin can only be removed after finding a way to pull out the wire circlip through the small hole in the rear of the upper case. (I used a little patience and a lot of swearing.)

- While the main casting incorporated lugs on either side of the exhaust stack for ST60 dimensioned holes, these are partially machined off with closer holes for a very ordinary radio 60 muffler. This huge thing weighs 3 ounces and incorporates a removable internal baffle.

- Without the muffler, the weight is an acceptable 12 ounces.

Running in was very quickly completed on the stock fuel I use in all Stunt News engine tests: 25% castor and 5% nitro.

In typical ST60 style, the engine was fitted with a 12x6 two-blade Bolly prop after being bolted into the test ship. This was a SIG Magnum, which had been built exactly to the plan except that fuse-mounted undercarriage had been fitted and the rudder/spine was enlarged to increase the side area.

The motor bolts straight into the ST60 mounts and as the NVA is the same height off the bearers as the Italian motor no work was needed to make the plane quickly ready to fly. The use of a different side for the muffler meant no more than leaving off the cowl for the test flights.

In the air, the bargain-priced Chinese motor performed well in that it quickly adjusted to a four stroke set on the ground which subsequently translated to 8 reliable 4-2-4 switch through the maneuvers. The only really noticeable changes from the Italian motor were the lower power and the improved fuel economy - whereas the ST60 needs tip to 180cc of fuel, this milder version is happy on 140cc. But my Magnum came in at only 65 ounces, if it had been over 70 then this new CS limited power would have been borderline.

The combination of mild porting and constant drag of a parallel bore resulted in the engine running slightly low on power and up on heal With the stock muffler in place the noise is exceptionally quiet due to the internal restriction, but withdrawing the removable internal baffle resulted in only a small (but acceptable) increase in noise with a very small gain in performance.

But the main benefit of the slightly lower porting is the mildness of this Chinese motor' performance. It's very happy to work within its optimum torque output in reliably swinging a big stunt prop at about 8,400 rpm as a four stroke setting on the ground which subsequently switches to nearly 9,000 through the pattern.

The combination of lower porting, less compression, no liner taper and the gap under the piston results in this Chinese replica not having the same power output as the legendary Italian, but the performance is adequate for a good 60 ship. Its overall performance reminded me of a stock 2 ring Merco 61.

(Super Tiger used a variety of porting for its various ST60 engines which generally ranged from the 140 exhausYI20 transfer for the earlier models to 130 exhaust/120 transfer for the later production. The compression ranged from just over 11 to nearly 13: 1.)

The best future for this engine is for an entrepreneurial engine modifier (such as Randy Smith or Tom Dixon) to buy them in bulk from the factory (specifying at least I thou liner taper, no muffler and ST60 muffler mount holes) and prepare them to be sold for stunt with a tongue or tube muffler. Presumably with their buying discount and the cost of such work/parts, a stunt suitable CS60 could be made available for about S 165 which adds up to a good deal for the average competition enthusiast

Well set 60s fly on the stability of a flat and smooth torque output and not the demands of a peaky/high revving/high power 40.

With the '94 world championships resulting in the Italian-made 60s returning to the winner's rostrum so convincingly, it is now inevitable that the few genuine ST60s left in circulation will be hoarded and not put onto the market. This means the replicas will be in even greater demand and as this Chinese CS can be bought for half the price of the Moldavian-made Double Star it will create considerable interest.

And if anyone tells you that traditional ST60s are a dead dinosaur compared to piped 40s... just point to those last world championships where the big Italian was the dominant motor. The states to prove it are 58% of the total entry, 6 out of the first 11 individual, the top two teams and the all-important 1-2-3 on the winner rostrum. That's game set and matches in anyone's scoring.

That championship judging reflected the flying and the flying reflected who'd done the most practice. The old rule on stunt is still true (with a modem amendment) that practice with or without a pipe makes perfect. If the ST60 can dominate at world championship level it can sure win at a club meeting.

Conclusion: This new big CS60 is a budget version of the ST60 layout. It is recommended for those who don't have a 60 and can perform OK after suitable preparation.