03-05-2006 Ask Mike! Archive
Considerations of upgrading from an E-series engine to a more modern engine

My A35, E225-8 died, want to get away from the Hartzel 500hr/5yr.AD.,and the oil leaks.
The 520 conv. seems too exp. as I'm on a budget looking at a 470 conversion, what's the difference between IO470J vs. IO470N ? What prop selections would I have? And would this be a good pick for this aircraft and my wallet?

Gary

 
Gary;

Any (modern) engine conversion to your bird will not be inexpensive. To start with, there are major structural changes to be made. The mount (engine attachment to the airframe) is completely different between the old (E-series) and the new. D'Shannon has a mod to upgrade the rear engine mount area, but the front still needs to have an upgrade, also; parts from Beech. That said, yes, it can be done.

The IO-470-J is a parallel valve version of the 470 series, rated at 225 HP, the IO-470-C is 250, the IO-470-N is 260 HP; both the C and the N are angle-valve.

Used engines do occasionally appear on the market; be cautious and ask plenty of questions about history. Any engine involved in a ground-strike must be carefully inspected for serviceability.

If you are looking at a factory reman, the last time I looked the IO-520-B's were actually less expensive than the IO-470-Ns, although it was not a major amount.

As for a prop, there are many things to consider. Generally, a 2-bladed prop will result in faster cruise speeds, where the 3-bladed props give shorter take-off roll and better rate-of-climb. We have had good luck with the Hartzell Super-Scimitar; it is 3-bladed and does appear to improve cruise speeds also. But, there are many 2 or 3 blade props that can fill the need. If you do get a used engine, I would strongly recommend staying with the same number of blades the engine is used to. Quite often, when going to a 3-bladed prop on a mid-time engine, there are undesirable vibrations as the counterweight bushings and pins (deep inside the engine) can be worn and will not accept the different configuration.

Only you can answer the wallet portion of your question. Expect to spend $30K to $40K, minimum; if your aircraft is otherwise configured how you want it, then a transplant like this can yield big results.

Gear Green,
Mike