I've been thinking about the what if's of a low compression 550 and wondering if the extra 30 cubes would make much more power than my O520 XP470. This is all theory and won't happen but anyone got an idea? There is a TSIO550 to start with.

180Marty wrote:I've been thinking about the what if's of a low compression 550 and wondering if the extra 30 cubes would make much more power than my O520 XP470. This is all theory and won't happen but anyone got an idea? There is a TSIO550 to start with.

So, are you contemplating converting the TSIO 550 to an O-550? Or installing it as is? If as is, in what airplane? A 180?

One issue will be converting the airframe to fuel injection.

Biggest issue, of course, will be approvals. And, yes, that’s plural.

MTV

A friend of mine used to own a 180 with a carbureted 550,
I was told that Steve Knopp built it up and installed it on a field approval.

I believe Texas Skyways or Air Plains or someone offers a carbureted 550 conversion.
Same compression & rpm as the XP470 but with 30 more cubic inches would be more steam,
but it's a matter of opinion whether it'd be worth the cost of admission (which would be pretty high).

FWIW NorthPoint told me that they offer an option of 8.5 pistons on their XP470 builds,
allegedly adds 10hp (from 265 to 275) and also $1000 to the price tag.
From their recent email to me:

"Thank you for your inquiry about our NorthPoint XP470 engine upgrade for your Cessna 180. We can get your Cessna 180 upgraded with a 0 SMOH NorthPoint XP470 engine for $42,500 with factory overhauled cylinders or $47,500 with new Continental cylinders. The overhauled NorthPoint XP470 engine comes with overhauled Bendix magnetos, new harness, new plugs, overhauled carburetor, overhauled starter adaptor, overhauled energizer starter and overhauled big oil cooler. Engine core charge would be $8000 until we receive the core back and can inspect it to determine if it contains the correct serviceable crankshaft, serviceable rods, case halves, etc. Our current lead time is 14 to 16 weeks. I have attached a distributor list to this email for your reference. Feel free to contact any on the list as they may have better pricing and lead times that we offer. They are reputable distributors and we can recommend any from the attached list. Custom Aircraft out of Palmer has done several of the conversions and would be the closest distributor to your location.

If your O-470 crankshaft does not have 4 counterweights, there will be a chargeback of $6250 to the core charge to obtain the correct 4 counterweighted crankshaft. The procedure to inspect your crankshaft to see if it has the provisions for 4 counter weights is as follows;

1 Rotate cylinder #3 to the (BDC) Bottom Dead Center position of the compression stroke.

2 Remove the oil filler neck.

3 Use a borescope aimed towards the #3 cylinder to see if the crankshaft has the 2nd set of flats with two holes drilled into them for the extra set of counter weights.

4 Re-install oil filler neck gasket and oil filler neck.

If you are interested in a new 3 blade -401 McCauley propeller, they are currently available for $13,100. McCauley propellers usually take 3 to 4 weeks to ship out. We can order a Hartzell PHC-C3YF-1RF8068 propeller for the same pricing as the McCauley -401 propeller for you at this time. Three blade MT Propellers are also available for $19,950 delivered in the lower 48. A 2 blade MT Propeller is available for $15,950 delivered in the lower 48 states. I have attached a propeller comparison sheet for your reference.

TBO for the engine is increased to 2000 hours as long as you install the spin on oil filter. The standard NorthPoint XP470 engine comes with 7.5 to 1 compression pistons which equal 265 HP. For $1000 we can get 8.5 to 1 compression pistons installed which equal 275 HP.

Please let me know if you need any additional information.

Joe Birkemeyer"

My thoughts were carb'd O550 with 7.5 compression ratio on the 180 and using 91 or 87 octane car gas. That'd be in a perfect world and maybe get another 20hp or so would be my guess. I delivered my 470U to Central Cylinder for hopeful conversion to low compression XP470 today. 150 miles at mostly 70mph and no pallets and shipping to deal with.The back two counter weights on the crank are the ones that got changed on my other 470K but not exactly sure what order they are. I guess the diameter of the pins through the counter weight decide which order they are.