Mogas in Radial Engines

[LittleMo]

I've been considering using mogas in my P&W 1340 radial due to cost factors. I've read the STC paperwork about vapor locks and mixing with avgas for lead cushioning on the valves, but would like to know how running an avgas/mogas mix affects TBO and power output, if any?

Regards

Mo

[barit1]

Since the 1340 was originally cert on 80/87, and operated several decades on that fuel, power output (limited by preignition/detonation) with mogas should not be affected.

And if you're not operating an aerial mapping ship at FL200, vapor lock should not be an issue either. If tankage is below the carb and a fuel pump is used, that shouldn't be an issue anyway.

But check with operators with more experience - they'll have the right gen.

[Moretimeoff]

I use to use lots of it in my crop dusters. I would mix 1/2 gallon of marvel mystery oil to every 100 gallons. I never had any problems.

[Old Fella]

As I recall the R1830-92 (1200 BHP) used 100/130 Octane Leaded fuel. Certainly would be seeking advice from an authority on using Mogas and only leaded or an approved lead replacement if using Unleaded fuel. Don't know where you will be operating but there is bound to be some advice available.

[Wageslave]

Be aware that the vintage motorcycle fraternity in UK is sufering dreadful problems using unleaded due to the addition of significant amounts of ethanol (a biofuel) by most suppliers which they were never designed to withstand which rotts seals and tank linings etc .

Does this problem affect aircraft too? Why wouldn't it?

[Intruder]

Some fuel deicers are essentially alcohol, and some of those are ethanol. In mixtures up to 10% ethanol (e.g., US mogas), engines designed to use such additives show no ill effects. OTOH, ethanol is a real problem in the recreational boating industry, where some plastic/GRP fuel tanks were NOT designed to resist alcohol attack.

There appears to be another step abuilding to increase the allowable methanol to 20% in US mogas. That may cause more problems for more engines/installations.

Airplane installations have much wider temperature and pressure extremes to deal with, as well as reliability requirements, so a minor problem in a car could become a disaster in an airplane...