There are two upgrades I am aware of (John Jewell and Norland) for C182 NA engines, both of which move the redline to 2625 rpm (from the stock 2500). The engine volume stays the same. While higher revs help with the take-off and initial climb, how can that help a cruise climb at 15,000 ft, as some people are reporting? If it does help with the cruise climb at high altitudes, wouldn't you have to set the prop to 2625, which is not really good for the engine (for an extended period)? Would like to hear some more wisdom here.
The Norland does more than bump the redline. The O-470 only produces 230HP at 2600RPM. In cruise that means you are making less. The Norland bumps it to 260hp at 2600RPM and you will see more HP at 23 squared. We priced out the Norland when our club plane needed an overhaul. Reach out to them, they can do the engine in <12 weeks turn around for the same price as most shops but... 1. You have to have an IO-470 handy 2. You have to make sure your propeller is on the list. We had the wrong type of propeller.
I suspect they increase the compression ratio, increase the Governor RPM, increase the number of oil galleries for cooling and maybe a cam change.
It looks like both STCs go about it differently, but are switching to a higher compression engine. The O-470-R and S are 7.0:1. The O-470-U and IO-470 engines the STCs are using are 8.6:1. And then, of course, there’s the higher RPM that helps with climb. But the cruise improvements come from the extra HP from the higher compression.
Larger carb jets too, I believe. More fuel=more go. FWIW, none of the engine mods to 182s, except maybe the 550, produce a whole lot more more cruise speed. A few knots at most, at the cost of a lot of fuel. They improve climb performance noticeably, and significantly better high density altitude performance.
Carb jets? Higher compression doesn’t increase HP much. The combo of compression and RPM works. For a 470 using the Pponk method is the popular path. There’s no replacement for displacement. Higher compression comes after that. What 0-470s are rated at 2500? My S model used 2600. U models use 2400 (I think). I’ve never heard of a 2500 rpm 470.
The JJ just allows the engine to be run continuously at 2600RPM at higher compression. I can't comment on fuel use but I suspect it is higher at those RPM as normal fuel use at take off is ...egregious? The Norland uses the higher compression IO-470 that is rated at 260hp. Given that I fly a IO-470 right now, I would assume .5-1gph increase at 23 squared with a carb.
To give you a sense of the increased fuel flow with some of these mods, a PPonk (520 cyls, modified carb, increased RPM to 2700 for 5 min max) is 23 gph at sea level takeoff on our ship. This is nominally about 270 hp with the Millenium cylinders we have. I flew it the other day with only 20 gal and 2 people on board. On a practice go-around I very briefly didn't realize how fast I was starting to go because it was climbing so fast.
Pponk has a 5 minute limit? I don’t recall that in my installation. Not that I’d ever fly it like that, but I did during break in. 184mph at 1200’ MSL. These days? At 24”-2450 I Iean for 16 gph at 1500-2000’ MSL. As with most engine upgrades, the most noticeable change is rate of climb. With respect to engine upgrades? The best feature for the 0-520 is applicability of better props and the power to make them work. In any engine upgrade, consider the prop choices.
5 minute limit above 2550, if I recall correctly. It's loud af above that anyway, you wouldn't want to stay there long. This is with the 2-blade McCauley. There is a three blade option too, but it's so nose heavy already, I can't see that being something I'd want to live with.
I’ve had an 86” 3-blade on mine since the conversion. I wouldn’t want to go back. One summer my prop governor was mis-adjusted and it was spinning 2900. Dang, it sure performed well at that. I believe most pponk owners are spinning 2800 or 2850 judging by their prop noise at takeoff. It works great.
Depending on the shape of the torque curve, higher rpm generally means more HP, unless the torque is falling off faster than rpm is increasing. HP = torque x rpm / 5252
I don't recall who, but one Pponk owner, I think in the northwest, got field approval to put the FAT supercharger on a Pponk. It was a rocket, of course, but I recall long threads on the old Cessna Pilots Association forum about his struggles for adequate cooling.
CHT. This was a field approval, not STC. It was combining two STC'd products, which can result in unknowns.
Well... here's a Norland ready to go: https://www.barnstormers.com/classified-1803061-O-470-“Norland-Conversion”.html?catid=17352
