Saito FA-180

The battle for the biggest single-- cylinder 4-stroke engine started when, quite a few years ago, Saito increased the displacement of its 1.20 to 1.50 cubic inches (ci). More recently, Enya answered the call by increasing its R1.20 to 1.55ci and designating the engine as the 81.55 (see "Air Power," June 2000 issue of Model Airplane News). In both of these cases, the larger displacement version uses the earlier, smaller engine's crankcase and will fit the mounting-- bolt pattern of the smaller, original engine. Now, Saito has upped the ante again with the FA-180; it also fits the bolt pattern of the 1.20, and it has the same mounting-bolt-to-- thrust-washer dimension, so it can be bolted directly into any model that had a Saito 1.20 (or 1.50) in it, and it will also fit almost any model designed for a 1.20 4-stroke.

THE PROGENITOR

The bore and stroke of the Saito 1.20 and 1.80 are 32x24.8mm and 36x28.6mm, respectively. Considering that the 1.80 has 50 percent more displacement than its progenitor, and that its piston, which is 4mm larger in diameter and, therefore, heavier than the 1.20's piston, you might think the 1.80 would vibrate more than its two smaller brothers, but it really doesn't. Yes; the 1.80 does vibrate more than both the 1.20 and the 1.50, but vibration levels throughout testing can be characterized as moderate at worst.

CARBURETION

Except for a lmm increase in venturi size compared with the 1.50's, the carburetor is a time-proven, 2-needle design that has been used on both the 1.20 and the 1.50, with one obvious exception. The manual choke has been removed, and this, in my opinion, was a good thing to do. If you're not very careful, using a choke on these large, single-cylinder 4-strokes can easily cause dramatic flooding to the point of combustion chamber hydra-lock. I've been removing these manual units for years now because they are simply not needed. I start all my 4-strokes the same way: with the throttle closed down to the high-idle position, I spin the prop with a strong electric starter-- with the glowplug battery disconnected, of course-for a few seconds. Unless something is wrong, this always draws sufficient fuel for starting into the combustion chamber. Then I connect the glow power and start the engine at the high-idle position. You should never start any engine at high throttle, but this mistake can be especially dangerous with large 4-strokes because of the instantaneous high thrust produced by the large props they turn.

PORTING

Not only has Saito increased the displacement and carburetor venturi size, but as part of Saito's "High-Cam Series," the 1.80 also has a high-lift valve train with large, l5mmdiameter valves. The intake port's diameter is 11.6mm, and the exhaust's diameter is 11mm. This is quite large and no doubt is accomplished more easily because of the one-piece head/cylinder and resulting absence of head-bolt bosses, which leaves more room for larger porting. All of the features found on the 1.80 add up to one thing: a very powerful engine.

Of course, kickbacks and detonation can be experienced with any 4-stroke, depending on how it is handled by the user. Since the introduction of the Saito .80 back in the late 1980s, however, I can't remember having recurring problems with detonation and thrown props with any Saito, despite the engine's impressive power and extremely reliable idle. This, no doubt, is due to Saito's extensive development of the hemispherical combustion chamber used in the 4-stroke glow engine. It might also be appropriate to note that, for many years, I've run all my 4-stroke engines solely with the O.S. "F" glow plug. In my opinion, it works best.

PERFORMANCE

Saito's instructions simply state that a good-quality commercial fuel should be used for break-in; then they go on to name a few well-known brands. For all my breakin (45 minutes of running, divided into short runs), I use Wildcat's 5-percent-nitro break-in fuel with 20-percent-oil content (synthetic/castor 80/20 blend). After breakin, I switch to Wildcat Premium Xtra 15-- percent-nitro fuel with 18-percent oil-also an 80/20 blend of synthetic and castor. I always use a fuel with a bit of castor in my 4-strokes because I strongly believe it protects against low-end bearing corrosion. For the first 15 to 20 minutes of the breakin, I keep the engine at or slightly under 4,000rpm. The instructions also recommend using a Hangar 9/McCoy plug. It works OK, but I'm sorry; I've found nothing that works the way an O.S. "F" plug does on any 4-stroke I've ever run, regardless of manufacturer. I do wish someone would offer a comparable plug because the O.S. unit is a bit pricey.

As you can see from the rpm chart, this is one big, powerful engine. You will need a very powerful starter. I find the ones powered by Ni-Cds have more amp-- producing torque to get the job done, and there is no annoying cord that might get caught in the prop. Even with a strong starter, after priming, you will need to turn the engine backwards against compression (with the glow power disconnected) before you apply the starter to gain enough momentum to drive the engine past compression. Using this method, the 1.80 started easily every time.