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RV-4 Engine; O320E2A 150 to 160hp upgrade

For my Vans RV-4 project, I have a O320E2A engine available. Newer type (2012 reman, ser nr ending with 27E) with rolling tappets.

So I have some questions I hope you guys could help me with.

1. This engine has been in a accident (inc proper strike). State of the Crank in unknown so it must be sent out for inspection. I could measure the prop crank myself but don’t have access to a proper micrometer set up. Could anybody recommend someone in the Bodensee(Lake of Constance) area/Southern Germany, that could make an inspection. Estimated price for a schock loading?

2. Considering upgrading this engine to a 160hp. According to some, this is more or less only about changing the pistons to 8,3 : 1 versions.
The question is then fuel. Can the 150hp be run on Super 95 (sold at the airport)? I assume that the 160hp have to be run on 100LL.

3. Would you need a new fixed pitch prop when changing from 150 to 160hp?

Espen

spirit49
LOIH

Autofuel STCs are available for aircraft with both 150 HP and 160 HP O-320s (STC info), which indicates that both versions are tolerant of auto fuel provided the aircraft fuel system functions with it (some don’t). However the higher power/compression STC requires 91 AKI, which is roughly equivalent to 95-97 RON (as used in Europe for car fuel) so Super 95 might be marginal, or not. I’d guess you’d be OK, particularly if you keep the CHT at a reasonable level.

The 150 HP STC requires 87 AKI which is roughly 91-93 RON so that would be OK for the engine, again assuming the rest of fuel system functions OK with auto fuel.

I doubt you’d need to change the prop as long as the static rpm remains within recommended limits. The main effect would be slightly higher rpm during full throttle climb (but still under red line rpm), and therefore higher climb rate. In cruise if you run the same rpm with the same prop you’ll get the same speed but the throttle will be closed a little more, which will reduce fuel consumption.

Last Edited by Silvaire at 04 Nov 17:19

I have a 74 Warrior with a O-320-E3D engine with 150 hp and a MoGas STC.

All i know is that i was told the 160 hp version only has different pistons, and there’s a MoGas STC too.

My RV-4 has an O320-B2B originally from a Tri-Pacer. It has 8.5:1 compression and is approved for 100LL or 91/96.

You would turn a few more RPM with the extra HP, so you could keep the old prop and get the extra take-off and climb performance or re-pitch and get better cruise.

Sensenich recommend 79" pitch for 150HP or 81" for 160. A prop shop could re-pitch a metal prop. Wooden props can also be re-pitched by reprofiling the leading edge, raisng or lowering the stagnation point the odd millimeter is usually sufficient.

KHWD- Hayward California; EGTN Enstone Oxfordshire, United States

spirit49 wrote:

I could measure the prop crank myself but don’t have access to a proper micrometer set up. Could anybody recommend someone in the Bodensee(Lake of Constance) area/Southern Germany, that could make an inspection. Estimated price for a schock loading?

I would recommend Ghönert in Bad Wörishofen. Very good workmanship. Cost really depends on what you want. If it’s just a shock load with no problems found, it’ll be at least 8000 €. If all you want to do is have them measure a part like a crank, it’s going to be much less obviously. However, measuring the dimensions is only a small part of it, what you’re really interested in is internal cracks and that requires a lot more involved inspections (dye, ultrasound).

spirit49 wrote:

2. Considering upgrading this engine to a 160hp. According to some, this is more or less only about changing the pistons to 8,3 : 1 versions.
The question is then fuel. Can the 150hp be run on Super 95 (sold at the airport)? I assume that the 160hp have to be run on 100LL.

Indeed. However I assume there would be no problem with Mogas and being an experimental I’d have less of a problem pouring that in…

That was a lot of answers, very quickly. Thanks a lot.

Reason Im asking, is that I would have to make up mind kind of early in my restoration project, so to avoid doing things twice.

I guess I should have asked first if it makes sense to do the 10hp upgrade, but since it seems that the conversion isn’t that big of a deal, and that I can use fuel that is 0.75€ cheaper than 100LL per litre, makes it a “No-Brainer”.
Deciding early also gives me more time to find the correct propeller (if I decide that I want more cruise speed than climb that is)

achimha wrote:

If it’s just a shock load with no problems found, it’ll be at least 8000 €.

That doesn’t make any sense. I could buy a new Crank and have it installed with my A&P for less than that…..
What if I have the Crank removed from the case, and sent out for inspection?
Or just bite it and buy a new/reman crank.

Last Edited by spirit49 at 04 Nov 19:07
spirit49
LOIH

A “shock load inspection” is a lot more than measuring your crank. It means overhauling the magnetos and several other accessories, many parts inside the crankcase (can’t just split and reassemble it), testing on the dyno etc. You also want to completely test the crankcase for cracks after an accident.

Just call Ghönert and discuss the best course of action.

spirit49 wrote:

I could buy a new Crank and have it installed with my A&P for less than that…..

Show me the A&P that installs a new crankshaft in a Lycoming and then signs off the aircraft…

Last Edited by achimha at 04 Nov 19:17

Assuming you hand the crankshaft to the shop and no engine disassembly is required by them, the crankshaft inspection should not be terribly expensive. If you want a ‘release to service’ as required for a certified engine crankshaft leaving a repair station, then the part will require an overall inspection as well as checking for cracks and run-out. That may be no bad thing notwithstanding the tendency of shops to destroy parts that were good when they received them. A friend gave a rare O-340 crankshaft to a well known repair station and they managed to throw it across the room before red tagging it (rejecting it) and denying the whole thing (really!)

With the above in mind note that your options for the inspection procedure/shop and for determination of airworthiness for the crankshaft of an Experimental engine are likely greater than they would be for a certified engine. You can likely have anybody you deem competent inspect it, and make your own determination of airworthiness. Another friend with a similar O-320 in his Oshkosh Lindy Award winning Tailwind built up the engine with parts which failed inspection, but for ‘letter of the law’ type reasons that do not affect performance. Just some things to consider. That guy BTW is also an FAA A&P and signs off his own engine overhauls for certified planes, with machine work done by a well known air boat shop to a high standard. The last one was for his Extra 300 (now sold) with new Lycoming ‘recall’ crank.

Another A&P friend just finished an E-185 for his Luscombe sedan. Lots of FAA A&Ps do their own engines, in particular for their own planes.

Last Edited by Silvaire at 04 Nov 19:40

I think I might have misunderstood the work involved in a “shock loading”. Your list of things that needs to be looked over makes that price more reasonable.

Since the engine will be on a experimental, I do have some possibilities.
What I have understood from asking around a bit, is that the O320’s are a bit less complicated than fex a TSIO520, and that an good A&P would be willing to assemble one after all the parts have been out for repair/OH/inspection. So I might go that way.

spirit49
LOIH

What is the reason for the shock load inspection? Sorry if I missed an earlier post.

A standard inspection includes e.g.

  • NDT (dye penetration / magnaflux) of all moving parts and crankcases (requires paint stripping)
  • dimensional checking
  • overhauling certain items (magnetos, prop governor)
  • discarding many items e.g. conrod bolts at $20 each

You may have a homebuilt which avoids the legal necessity (you could smash a homebuilt into a brick wall, repair the body, stick a new prop on the front and legally fly it) but there are good reasons for the shock load inspection. When I had my prop strike in 2002, an EASA engineer had the authority to countermand a shock load inspection of the engine didn’t stop rotating during the event (and the crank flange met the specs) but the mfgs have since found that was not good enough and there have been cases of hidden damage e.g. cracked crankshafts or cracked crankcases.

So it isn’t just the crankshaft. It can be the gears in the accessory gearbox which can get cracks.

An inspection in 2002 was GBP 6k plus VAT, and they found no damage.

I would also not use just any European A&P for an engine rebuild because there are various tricks involved e.g. the way the aluminium plugs are inserted into the pistons can cause them to come out and rub. This won’t stop the engine, however… In Europe there is too little experience in the field in engine rebuilds, IMHO.

As I said much would depend on what it hit. If say somebody raised the landing gear when on the ground and smashed the prop, then obviously you need to check only the crank and the crankcases (plus the firewall and the mounting frame of course). But “officially” on a certified engine even that would require a standard shock load inspection.

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Shoreham EGKA, United Kingdom
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