As some of you may know, Align had great success bundling their popular T-rex 600 NSP package to include an Align-labeled OS50SXH hyper engine. In fact it seems that they sold so many of these packages that they ran short of the Align-branded engines and are now packaging the standard OS-branded models.
Hoping to continue that success, Align has again partnered with the Ogawa Seiki Co. Ltd. (OS) to produce an Align-branded engine for the newly released .90 size T-rex 700. The new Align 91H helicopter engine is an Align branded OS 91HZ and the differences between this and the older OS 91 heli engine, the 91SZ are significant. We’ve seen this new motor already here on RC Heli Resource, but here are some side-by-side comparison shots of the 91SZ and 91H / HZ and their internal components.
These photos will show that OS has taken the 91SZ and improved it in several ways. The most obvious is the new square, black-anodized head which adds a bit of style to the engine. The new head not only looks good, but it cools better than the older style, blue anodized round head on the SZ. It’s also reshaped on the inside to change the compression profile slightly to compensate for improvements OS has made in another are: airflow.
OS has redesigned the intake system of the 91HZ to open it up considerably, thus allowing more air to be drawn into the engine. More air in to an engine means that engine can produce more power. This also means more heat, and this is one of the reasons for the improved heat sink.
Since it was fairly important to keep the external dimensions unchanged while increasing internal volume (lest the engine not fit where a .90 size engine is supposed to), OS removed some material form the inside of the motor and crankshaft. This has the bonus side-effect of making the engine lighter. The size of the carburetor has also been increased to improve airflow.
All in all, this looks like an impressive new motor. We will of course, have to wait to pass final judgment until there are a bunch out in the field for long enough to prove their durability and power capacity, but for now, the Align 91H / OS 91HZ helicopter engine looks like a winner and will be a strong selling point when included with the T-rex 700 kit, or even in its own right.
(All images courtesy of Align Inc.)
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