Die cast crankcase vs. extruded...

Paul-e Fri Aug 26, 2011 1:36 pm

What is the difference between a Surestart with a die cast crankcase and the same engine (or similar) with the extruded aluminum case?

Are there any pros/cons to using one vs. the other?

andrew Fri Aug 26, 2011 1:57 pm

The die cast case (zinc alloy) was developed in an attempt to reduce cost. However, final machining of the case was problematic and the wear characterics of the casting were not as good as the extruded cases; consequently, it was dropped from production.

Generally, folks tend to shy away from the cast cases. As far as I know, there are no real advantages to the casting; it's heavier than the extruded case and it may exhibit accelerated wear. Given a choice, I would not buy the cast version.

However, with the knowledge of folks on this forum, some may have other, and better, opinions.

andrew

SuperDave Fri Aug 26, 2011 2:25 pm

Die-cast crankcases preceeded extrusion crankcases which were introduced to decrease production conts. The nature of an extrusion is that is produced in lengths rather than individual castings. The extrustion may be sliced off and is then ready for machine processing.

SuperDave

di

EXModelEngines Fri Aug 26, 2011 2:59 pm

Both will work well, but the extruded, bar stock case will give you more flexibility like the use of a throttle sleeve and not having to worry about the special gaskets and reed retainers that are required.

As others have mentioned the cast one was developed due to cost concerns, but the secondary drilling operations proved to be difficult resulting in a high defect rate. Please note that when I say that I DO NOT mean the ones that are assembled engines rather the cases would often break during the drilling/tapping operations and had to be scrapped.

The cast one does have slightly better cooling than the extruded, bar stock one and some claim it will result in slightly higher performance.

Overall, both will get the job done just fine for sport flying.

Matt

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Die cast crankcase vs. extruded...

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