O-470K and O-470R

I have O-470R in my Cessna 180H everything stock, 600+ hours on it at overhaul would the O-470K crank be of any use to get my 230hp motor converted to 285hp. What would be the best way to go about this? For price/aircraft down time. I have a timed out O-470K plus the motor I’m running in my 180 now. Our mechanic acquired the O-470K off some 182 years back.

A K crank will work. R and S cranks won’t. If you have the funds you could build the K into an 0-470-50 and sell your mid time R motor after you swap. With 7.5-1 and venturi valve cylinders you get 275hp. Sneak in 8.5-1 and you’ll be close to 285. Some may argue that higher compression needs a VAR crank. If you do the upgrade you’ll never look back. It’s the best 180 mod.

stewartb said:

A K crank will work. R and S cranks won’t. If you have the funds you could build the K into an 0-470-50 and sell your mid time R motor after you swap. With 7.5-1 and venturi valve cylinders you get 275hp. Sneak in 8.5-1 and you’ll be close to 285. Some may argue that higher compression needs a VAR crank. If you do the upgrade you’ll never look back. It’s the best 180 mod.

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Awesome! I just found the engine in the back of the shop. It sounds like it’s most def worth researching and turning into a O-470-50. The motor I have now has worked great with no problems, but I don’t just want a little extra hp I need it lol. Maybe this O-470k will be part of the path to get 275hp at least. Thanks

stewartb said:

Some may argue that higher compression needs a VAR crank.

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Never heard this but always wondered what the O-470-50 and VAR crank relationship might be. I have a non-VAR crank from a 520 that is perfectly legal to put in an IO-470 in an early 185 or 310. I wondered if it was okay for a O470-50. What's the thinking behind folks arguments?

If I remember right, back when that AD came out, lots of folks were shipping those cranks to NZ and Australia because they didn't seem to care about the FAA AD.

Non-VAR 4-blade crank (two sets of counterweights) is legal for a Nort Point (Pponk) O 470-50 with low compression pistons. It does take a lot more to complete the conversion however. You must have an approved shop do the work ,case mod ,crank mod ,carb mod ,ect and an approved prop. Good luck, they do really work well when done right.

YJLopes said:

Never heard this but always wondered what the O-470-50 and VAR crank relationship might be. I have a non-VAR crank from a 520 that is perfectly legal to put in an IO-470 in an early 185 or 310. I wondered if it was okay for a O470-50. What's the thinking behind folks arguments?

If I remember right, back when that AD came out, lots of folks were shipping those cranks to NZ and Australia because they didn't seem to care about the FAA AD.

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No VAR requirement for Pponk but the STC was specific about TSIO 7.5-1 pistons. Meanwhile, Texas Skyways does a very similar conversion using 8.5-1 pistons but uses 520 engines, so VAR cranks. I think some guys believe there’s a reason. Me? I have no idea. I do think it’s interesting. My Pponk was an 0-470S and got converted using a VAR 520 crank and TSIO cylinders.

stewartb said:

No VAR requirement for Pponk but the STC was specific about TSIO 7.5-1 pistons. Meanwhile, Texas Skyways does a very similar conversion using 8.5-1 pistons but uses 520 engines, so VAR cranks. I think some guys believe there’s a reason. Me? I have no idea. I do think it’s interesting. My Pponk was an 0-470S and got converted using a VAR 520 crank and TSIO cylinders.

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Northpoint claims their XP470 (formerly the ponk 470-50) produces 265hp with std 7.5 pistons, & 275hp with 8.5's.

Northpoint XP470 | NorthPoint Aviation | Brainerd Minnesota

Doesn't say on this webpage but as i recall they charge about $1000 extra for the 8.5 approval.
Might wanna think about the future of 100LL fuel if you're considering the 8.5's.

8.5s will still run with a small margin on 91 mogas, correct?

stewartb said:

.... If you have the funds you could build the K into an 0-470-50 and sell your mid time R motor after you swap. .

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This is an ideal situation, be able to have an engine built up without any down time.
Esp since in between employee/covid and supply chain issues,
most OH shops have a long turnaround time these days.

As far as use of 91 mogas goes, I have a local source of 87 e-zero but not 91.
Your situation might be different.
But use of mogas of any flavor with a 470XP might be an academic point,
paperwork wise anyways, as I don't believe their STC approves any sort of mogas use.
It'd be nice if they added it, or Petersen or EAA was to add it to their STC's, but I doubt that'll happen.