Is it possible to use MoGas in a 182 pponk? Hypothetically of course. Would there be any extra risks besides probably engine warranty?

ington6 wrote:Is it possible to use MoGas in a 182 pponk? Hypothetically of course. Would there be any extra risks besides probably engine warranty?

Hypothetically if you have a standard pponk and have not gone the route of getting the higher compression pistons (many of the shops offer to do a DER approval for 8.5 compression) - it would probably be fine if we are talking MoGas without the ethanol additive.

However we don't Hypothetically fly - it would not be a question of "probably" void your warranty. It would absolutely void your engine warranty, it would be illegal, and if you had an engine out and had damage to your aircraft - I doubt you would see a dime from your insurance company. If you hurt a passenger or anyone on the ground - you would be liable for a lawsuit

Sounds not worth the risk if someone were to do that.

The current holder of the -50 STC is listed, along with an email and phone number, on Knopp’s website. Betcha they’d have your answer.

It's not allowed in the STC, and using mogas makes the carb leak like a sieve.

SloRoam wrote:It's not allowed in the STC, and using mogas makes the carb leak like a sieve.

Is the carb leaking with mogas specific to the pponk/XP470 - or is that also true for a non modified carb on a O-470?

I posed this question directly to Pponk via email, here is the response.

The initial engine endurance run for the O-470-50 Engine was accomplished using auto fuel almost exclusively as we intended it to be one of the approved fuels. However, prior to completion of the STC process, the auto fuel manufacturers began changing the additives in auto fuel and we no longer had a consistent product to test. In the interest of time, we completed the engine STC with only Avgas as the approved fuel. Other projects and our busy shop schedule prevented us from following up with additional testing.

We know of -50 engine owners who have gone to TBO using auto fuel or a mix of avgas and auto fuel, but we cannot recommend this as it is not approved under the STC. You would also want to consider your aircraft insurance, and if use of auto fuel might void your coverage.

On the insurance topic: I’d suggest reading your policy and calling your agent to ask questions.

A few years ago I wanted to do some things to my plane but couldn’t get approval. I read my policy and couldn’t find a single word about the plane having to be airworthy. I called the agent, told them exactly want I wanted to do and asked if I would be covered in the case of an accident. A few days later they called back and said, yep I’d have coverage. There was not even a requirement the plane have a current annual.

corefile wrote:

SloRoam wrote:It's not allowed in the STC, and using mogas makes the carb leak like a sieve.

Is the carb leaking with mogas specific to the pponk/XP470 - or is that also true for a non modified carb on a O-470?

A few years back when it was really cold my carb leaked a bit of gas running mogas. As long as I blend or it’s warm not a prob. I have a regular O-470R

corefile wrote:

SloRoam wrote:It's not allowed in the STC, and using mogas makes the carb leak like a sieve.

Is the carb leaking with mogas specific to the pponk/XP470 - or is that also true for a non modified carb on a O-470?

Never had my carb leak and I burn almost entirely mogas through my 0-470

I have no hypothetical answers to offer.

So I will offer my experience, which may not align with the experience of others. My Pponk burns auto fuel just fine. It burns it regardless of brand, or octane, as most octanes available at the pump fall within the engines practical parameters. It burns fuel from native villages in Alaska, and it burns fuel from native villages in Canada... In fact as long as the fuel is clean and reasonably fresh, it doesn't seem to care a bit what that gasoline is labeled. Since this is a 1930's design, assembled with modern day rubber and attention, this really comes as no surprise...

The only carburetor leak I've ever had was in an O-320 that ran avgas, but had a float bowl come loose. Lesson there was MX trumps all.
No surprise...

The effects and requirements of various fuels are well documented. Assemble your tractor motor according to the fuel you want to burn and it will burn anything from straight alcohol to kerosene. Assemble it incorrectly and you will get to test your insurance.

I have never had to file an insurance claim on a Pponk powered ship, but claimed a cub out to total twice. Insurance adjuster only came out to one. Fuel was never a question, the root of the cause was. If you put bad gas in and flamed out, you might suffer consequences, If your wreck or damage was from other causes, they're not going to look for other reasons to void your coverage. If you have insurance with a company that looks for ways out of paying a claim, you have bigger problems than what fuel to use. Select quality insurance first, then select quality fuel.

Several Pponk owners I know like running mogas because it doesn't lead up the plugs. I prefer pulling plugs to clean and having another avenue to investigate my engines health over running them longer. So that's not reason enough for me to burn mogas.

My Pponk was assembled by Steve Knopp. While I can not speak for Steve, much less the current STC holder, I got to know Steve well enough during the build that it was my distinct impression that he was far more concerned with how you treated your engine than what flavor fuel you operated on (barring any terribly poor choices of course). He is an extremely reasonable man, and IMHO would honor any warrantee work that would have to be done as a result of something that went askew during the build up of that engine (what warrantees are for). He built engines that achieved legendary status, and he did that by treating people right, not by looking for ways out of correcting honest mistakes.

The internet if full of bad information. Most stems from folks meaning well but offering opinion myself included. Gas is exceptionally cheap in aviation terms. If the risk doesn't match the reward, by all means burn the legal, time tested, aviation friendly choice.

If there may be reasons to investigate the use of mogas (and there are for many) realize that you are not on some new uncharted territory. Research, as your attempting here, but ask pointed, honest questions. tip toeing around with hypotheticals just leads to hypothetical drama.

In closing I would offer that mogas is my last choice as a fuel for my 180. I hate the smell, I find it very inconsistent, and the one problem I have had with it (a split seam in an AKBW bag) left a bad taste in my mouth. Never the less, when I find myself wayyy way out in the boonies, and Wx, wind or some other unforeseen problem has me running tighter than I'd like on gas, I don't think twice about burning it. YMMV


Take care, Rob

Awesome and to the point reply Rob!

I don't have PPonk but wiil mention my experience.

I am no expert by any means, but have worked on many engines over my years and have had the same results as Rob. Burn auto fuel if I needed to, but usually run 100ll if I get it at an airport. I ran auto fuel in several different planes almost exclusively and never had any issues that I could contribute to the guel itself. Did have a leaky primer once, but with the age of it, I sure didn't blame it on the fuel. Cheap fix anyways.

I've been running 100ll exclusively in my O-300 for the last few years and I have found it is a good idea to remove the plugs and clean them at every oil change. Otherwise it will start to run a little rough. Never had the plug issue when I ran mostly auto fuel. Full disclosure on why I ran auto fuel, I was based at small strips wiyhout fuel and it was easier to get non-ethanol tham it was to travel to get 100ll. Plane has the Peterson STC, so no issue there.

Fraser Farmer wrote: Never had my carb leak and I burn almost entirely mogas through my 0-470

me too

Two things to be aware of with the use of auto fuel in our aircraft engines are the possibility of detonation, and the lack of lead which lubricates the valves. Detonation shows up pretty easily with a cheap borescope. It can be caused by other things besides inconsistent fuel, but either way its destructive. I use auto fuel in my working 182, but always use it in conjunction with an upper cylinder lubricant such as Marvel Mystery Oil, or Lucas Fuel Treatment. I've not had any leaking gasket issues, and still have a bladder in my RH wing from 1973. My present engine has 900 hrs SMOH and about half of those hours using auto fuel.

My R model engine is approved for auto fuel, however I know of one instance where a friend had an incident while using auto fuel without an STC. Although there was a violation, the FAA didn't make a ruling in regards to the fuel, and it did not effect the payout by the insurance company. Has anyone here ever heard of an instance where the FAA cited a violation because of the illegal use of auto fuel?

On The Fly wrote:the lack of lead which lubricates the valves.

Well there's an OWT that just won't die.

Bonanza Man wrote:

On The Fly wrote:the lack of lead which lubricates the valves.

Well there's an OWT that just won't die.

It's actually not an "old wives tale". Although there may be more lead than needed in 100LL, some is beneficial as an upper cylinder lubricant. Take it away completely, and some other form of lubricant becomes beneficial.

Marvel Mystery Oil, and more recently, Lucas Fuel Treatment, have proven themselves NECESSARY as an upper cylinder lubricant in my Teledyne Wisconsin (a subsidiary of Continental) air cooled, gas industrial engines used in my commercial tree sprayers.

On The Fly wrote:It's actually not an "old wives tale". Although there may be more lead than needed in 100LL, some is beneficial as an upper cylinder lubricant. Take it away completely, and some other form of lubricant becomes beneficial.

.

Umm, no. Taken from APS.



Let's not forget that lead exists during the combustion event as a salt of bromide--lead-oxy-bromide. Salts are abrasive. Abrasives make poor lubricants or "cushions." Lead-oxy-bromide has a melting temperature of 1305dF, so it is a gas and passes out the exhaust (temp of combustion is about 3500-3800dF).

That lead cushions valves or lubricates valve stems is simply an erroneous conclusion to an accurate observation of a problem after a change in fuel.

When the AG pilots started burning auto fuel in their R-985s and R-1340's, they had valve problems. Simply retarding the timing a few degrees stopped the valve problems with the unleaded fuels. If the lead had been doing anything, the valve problems would have continued. By keeping the ICPs under control through the timing change, the lack of lead was not a problem at all.

But the OWT will continue.......

I've been burning mogas in my airplanes for 23 years--
sometimes straight, sometimes mixed with 100LL.
Currently using the straight stuff,
but it is worth noting that both EAA & Petersen Aviation (the mogas STC holders)
mention using 100LL to some extent--
esp in engines which have recently been overhauled or had valve work done.

On The Fly wrote:My R model engine is approved for auto fuel, however I know of one instance where a friend had an incident while using auto fuel without an STC. Although there was a violation, the FAA didn't make a ruling in regards to the fuel, and it did not effect the payout by the insurance company. Has anyone here ever heard of an instance where the FAA cited a violation because of the illegal use of auto fuel?

I’m reminded of a crash from a few years back and makes me wonder about the outcome. I can’t remember the details and don’t want to recall incorrectly so when I have some time I’ll look up the info. It was a twin that crashes with mogas in the tank.

I talked to Steve Knapp when he was doing my Pponk about this, and he said the engine runs perfect with MoGas.