C180_guy wrote:

slow18 wrote:Thanks.

If anyone needs help with approval send me a PM.

It is a lot simpler than folks think. We posted all the technical data on the supercub forum a year or so ago in the 180/185 section.

Can you post the link in Supercub.org

alaskan9974 wrote: Just curious does anyone have field approvals on higher comp pistons on the 470s? Curious if I could get that past the fsdo. I heard of a few guys running them with approval up here but haven't seen the details

I got curious about the Bendix fuel injection & googled up this older thread.
Then got interested in high compression pistons...

The North Point XP470 (formerly known as the pponk 470-50) is 7.5:1 compression for 265 horsepower,
but Northpoint sez 8.5 pistons are optional for 275hp.

As long as you don't mind 100LL-only ops,
high compression pistons would seem to be a worthy change for a stock displacement 470.
There seems to be at least two ways to go:
1) the Norland conversion creates a carbureted 470 with 8.6:1 pistons, 260hp at 2625.
However, you must start with an IO-470 core.
2) Texas Skyways converts the 470U (230hp at 2400 rpm) into the O-470-U/TS, 250(+) hp at 2600.
However, you have to start with a 470U core.

Seems like IO470 pistons (8.6:1) in a regular 470 would be pretty easy,
but for whatever reason no one seems to have STC'd that change.

but for whatever reason no one seems to have STC'd that change.

More metal in the high compression cylinder heads thus the long reach vs short spark plugs. Here's another thing I have pondered. Taking the Texas O470UTS one step further. The 470U I am converting to Northland 470XP will turn 2700 rpm with the bigger connecting rod bolts. So, what if you take the Texas 470UTS, put bigger rod bolts in and turn it up another 100 rpm to 2700. Should make even more power and a MT propeller like I am using would be plenty good.

For those who've converted to the Bendix FI--
I understand that the injector nozzles go into the primer ports on the cylinders.
My 470K has 2-point priming, I'm looking to set it up for 6 point priming
and so I need the primer block (aka "distruibutor, fuel") p/n 0750125-10.
If anyone has one that's surplus to their needs I'd be interested in buying it.
I don't have the p/n's handy, but there's also a couple brackets for the primer lines that I'll need,
plus the fittings for the primer lines themselves.

Please pardon reviving an old thread...

I have an O-470-R as well and am interested in this. Did you all buy the STCs or just go the field approval route?

What was the all-in cost on this change?

Precision Airmotive will give you a copy of the STC (see Supercub thread), but you are going to have to do a field approval due to all the parts substitutions. As far as cost, for the latest maybe ask Russ at D&G Supply.

I talked to a DER about doing the Bendix conversion on my 0-520. Carb heat is still required, and carb ice is still possible, though the likelihood and severity are reduced. I decided to stick with my carburetor, and not add two fuel pumps, and associated plumbing. He also said it would NOT increase HP. My 0-520 runs lean of peak quite nicely at lower power settings and higher altitudes.

Probably little to no HP gain is correct.

Just curious, how is carb ice possible with less likely severity if there is not a carburetor? Why is carb heat required without a carburetor? Or do you mean alternate air source?

Did he explain any of that?

what he explained to me was that the way the bendix injection metered fuel was through a pressure differential from either side of a VENTURI. Like the venturi in a carburetor, less chance for ice because there was no atomizing fuel near the venturi.

He explicitly stated that carb heat was still required with the bendix injection setup.

I think he’s right in principle, that the same issue exists with injected engines, just that the conditions are much less frequent. The alternate air would work to heat the fuel servo and melt ice effecting the impact tubes.