O-470-U and mogas/100UL/94UL

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4 months 5 days ago #3310 by STEVE ELLS
Replied by STEVE ELLS on topic O-470-U and mogas/100UL/94UL
Hi Alan,

I just wanted to give you an update on when your 182 may be approved for using GAMI's G100UL.

Today I spoke with someone in the know who said the FAA is in the final stages of expanding the approved model list of airplanes that have been added to the STC for G100UL.

That does not mean that an unleaded 100 octane avgas will be available immediately. It will take time for fuel blenders to gear up to produce the fuel.

Best,
Steve

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4 months 2 weeks ago #3302 by STEVE ELLS
Replied by STEVE ELLS on topic O-470-U and mogas/100UL/94UL
Hi Alan;

Alan, are you saying that you need to replace all your cylinders and are looking for a change/upgrade prior to spending $$$?

Technically, the U engine is more efficient than the R engine due to the higher compression ratio. This is the reason your take off rpm is 2400 instead of the 2600 of the R engine.

As far a cylinders going south prematurely, I would make sure that your mechanic knows the Continental cylinder airworthiness determination procedure inside and out. If cylinders are being pulled due to "low" compression numbers alone, than there's a good chance they are still airworthy.

The ONLY way to check the overall health of a Continental Cylinder is by using compression readings (using a compression gauge that has been calibrated) and a borescope to inspect the cylinder walls and valves.

The following article provides another engine upgrade option: www.cessnaflyer.org/cessna-singles/cessn...ngs-for-the-182.html .

The parts manual for your vintage 182 cites the R engine until serial number 63475; the S engine on until s/n 65175 and the U engine after s/n 65176.

The weight difference between the R (401 lbs) and the U (412 lbs) is very small so that really isn't an issue.

The U uses a different prop governor, and a different propeller. I'm not sure but it's possible that a good prop shop can make the changes to you R style propeller.

Since your 1979 182 has integral fuel tanks, keeping the tanks full to preserve fuel bladders in not operative. So technically, except for the possibility of condensation inside the tanks when your 182 is parked, there's scant chance of operational problems is the tanks are not filled all the way to the top.

In my mind, you're still very operational even though you can't top your tanks off at your airport.
So my advice is to do what it takes to keep 100LL in your airplane, and be patient.

Best,
Steve

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4 months 2 weeks ago #3301 by Alan S
Replied by Alan S on topic O-470-U and mogas/100UL/94UL
Steve:
Thank you for your very thorough reply. This is encouraging.
I will fill up elsewhere and then fly to my airport.

I was wondering if a downgrade to the O-470-R in the future would be a straightforward direct engine swap and whether I would need an STC for it?

From what I have read the O-470-R is a bulletproof engine and does not have the cylinder wear issues of the high compression O-470-U. It also has a mogas STC which is an advantage.

Thank you.

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4 months 2 weeks ago #3300 by STEVE ELLS
Replied by STEVE ELLS on topic O-470-U and mogas/100UL/94UL
Hi Alan;
You can fuel up at any of the nearby airports that still pump 100LL such as San Martin (L16), Livermore (KLVK), Watsonville (KWVI), Hollister (KCVH) or Salinas (KSVS) as a temporary solutions to this headache.

Your O-470U has a 8.6:1 compression ratio. I know that GAMI did a lot of the certification and acceptance testing protocol on engines that should have detonated under full power conditions and all of the engines passed the protocol.

Therefore, although GAMI has not yet added the O-470U engine to that STC approved model list (AML) there's no technical reason it won't be added at a future date.

It appears to me that the engine/airframes on the current AML are all lower compression engines that can safely used 80 octane fuel--shoo in winners.

You can modify your engine to a XP470 from Northpoint Aviation ( northpointaviation.net/northpoint-xp470/ ) and specify the 7.5:1 pistons.

And I suppose you could install the O-470R engine, which has a 7.0:1 compression ratio. Same horsepower output at your -U engine, just lower compression ratio and higher take off rpm

Personally, since your airplane has 88 gallon fuel tanks, I would refuel elsewhere with 100LL before flying home. Even with a takeoff you still won't burn more than 5-8 gallons. If you top off the tanks that will still leave you plenty of fuel for most trips and more than enough to get to another airport that sells 100LL.

I wouldn't get overly excited yet.

Let me know what you decide.

Steve
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4 months 2 weeks ago #3299 by Alan S
O-470-U and mogas/100UL/94UL was created by Alan S
Hi folks:
I am considering a C182R with a O-470-U. Unfortunately the county I live in (Santa Clara Co, CA) has banned 100LL at county airports.
Are there any replacement engines for the O-470-U that would use mogas or 94UL?
100UL isn’t available yet and I am not sure the high compression O-470-U will ever be approved to burn 100UL.
Thank you.

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