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Engine configuration

I am going thru the process of New engine vs overhauled options starting from a core….. i have searched and searched for information but still don’t fully understand.
I am in need of a IO-540 D4A5 for the RV10…… but i keep getting responses from core owners that they have a C4A5 or a J4A5?
If i am completely overhauling does this make a difference?

Any help would be appreciated.
 
Engines

C4A5 is a Piper Commanche 260 engine. Parallel valve Similar to 250 hp version except for slightly higher rated r/m.
J4A5 is Piper Aztec engine. The Aztec engines are probably the most plentiful of the Parallel valve 540's. Fuel injection started with the 1964 Aztec C model. Rated at 250 hp
Both of these engines should be a good candidate for RV10. Can be modified to around 300 hp with common "hot rod" mods such as high compression pistons, balancing and port work.
I think they are both conventional dual mag engines. (two Mags)
 
Here is the TCDS for all of those engines. Using it, you should be able to compare any version against the D4A5.

http://wiki.velocityoba.com/images/d/d0/IO-540_Type_certificate1E4.pdf

Beware the 300 hp engines. They are dimensionally different and substantially heavier. The C series engines are placarded at reduced RPM, but that's a marketing thing, not a physical limitation. The camshaft is the same as on the D series.
 
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Be aware that some of the C series engines are set up for the old, larger hartzel hubs, where the D4A5 is set up for the newer hartzel compact hub. I converted an old C1B5 (set up for older hub) and purchased the counterweights, bushings and pins that are spec'ed for the D4A5 (pretty much all of the other parts, including the crank were identical, excluding the difference with wide/narrow deck). The weights are matched for numerous characteristics, including the prop hub and you don't want to put a compact hub on a crank set up for the older, heavier hubs.

You will see the text outlining this near the end of the doc linked above.

Larry
 
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To be doubly certain this is understood, if you do a part by part comparison of the C4 vs D4 series, you'll find that their entire rotating assemblies (everything that's spinning with the crankshaft in the engine) are the same part numbers.

The main difference between the two is that Piper set the redline at 2500 rpm for the C4B5 (250 hp) vice the 2700 redline (260 hp) of the D4A5. These RPM limits are certification limits based on airframe limitations, not the rotating assembly of the engine.

For RV-10 purposes, both engines provide identical service and both can be governed to 2700 RPM in the Experimental category.
 
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To be doubly certain this is understood, if you do a part by part comparison of the C vs D series, you'll find that their entire rotating assemblies (everything that's spinning with the crankshaft in the engine) are the same part numbers.

This blanket statement is NOT correct. Several of the C series variants use different crank counterweights and pins. Many, like the C4B5, do have the same weights as the D series, but some do not, like the C1B5. I have done the analysis and can confirm that. The C1B5, as stock, should NOT be used with the comact hub. The D4A5 is designed for the compact hub and it does this by using heavier counter weights to offset the lighter hub.

Ron, You are welcome to look at the parts list and confirm for yourself. To the OP, best to avoid the internet opinion parade and do your own research. You DO NOT want to run the lighter weights with the compact hub, though it is fine to run the old hub with the heavier weights, I believe.

This issue is even addressed in the written descriptions of the variants in the doc linked above. C4B5 says same as C1B5, except has heavier conterweights to support the compact hub.
 
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Ron, You are welcome to look at the parts list and confirm for yourself.

Sure... check out the link in my post. Also beware of the wide vs narrow issue as well. OP's question was in regard to the C4B5, so...see my previous post corrected to C4's vs D4's.

To the OP, best to avoid the internet opinion parade and do your own research.

So true, Larry. Nothing like a reference and data vs a forum posting.
 

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