Best Mogas

[WesRagle]

HI Guys,

Setup:
I've been working with a Sonerai with a GPAS 2180 w/8:1 compression and a RevFlow carb. I'm getting the engine ready to serve as a test bed for fuel injection experiments. All fuel lines have been replaced with ethanol tolerant rubber. The experiments I intend to run require an O2 sensor. As most probably know, these sensors don't like lead. I'm getting ready to add fuel.

Questions:
What is the best high octane car gas to use in an 8:1 compression VW engine?
Is there any reason not to use a fuel preservative while running a VW?
Are there any special precautions when burning/storing car gas?

Any advice appreciated.

Thanks,

Wes

[kmacht]

Around here there are a few gas stations that sell 110 octane mogas with no ethanol in it. It’s designated as racing/off road use only. I would start by looking to see if there are similar places close to you. There are a few websites out there. One is:

https://www.sunocoracefuels.com/fuel-finder

If using regular mogas be on the lookout for engine “pinging” or pre-ignition. I ran regular 91 octane mogas during flight testing as my airport didn’t have fuel available and had the engine start pinging on takeoff one hot summer day. I had to retard the throttle and level off to get it to stop. Also keep in mind that if you have a Princeton fuel probe any gas that has ethanol in it will destroy the probe. I went through two probes until figuring that one out.

Keith
#554

[WesRagle]

Thanks Keith. I'll check it out.

I can't help wondering if any of the "Octane Boosters" are more than just snake oil.

Ref. https://www.autoguide.com/top-10-best-octane-boosters-you-can-buy

Another somewhat interesting finding. I have always wondered if the octane of mixed fuels could be calculated as the average of the octanes. According to these folks it's that simple.

Ref. https://www.sunocoracefuels.com/tech-article/mixing-fuels-calculating-octane

Wes

[tx_swordguy]

Hi Wes,
I run 91 non ethanol in my jabiru 3300 and it does fine. I put marvel’s mystery oil in for the feel good factor. I have noticed it runs richer at the same settings with car gas vs av gas with decaline. I store it in a 55 gal drum originally used for motor oil and have a water separator filter on the pump. I probably use it over the course of six weeks. I keep a tarp over it and off the floor on 2x4 s to try and keep as much moisture out and away from it as possible because my hangar gets wet. I get ethanol free up in Gainesville. I think buccees’s also sells it not sure if it is reg or prem. I would stick with e free if poss ESPECIALLY if you are storing large amount. Hope you are doing well and maybe ill see you again at ranger this yr.
Mark

[daleandee]

I mix a little 100LL with my 90 E-Free Mogas to bring up the octane level. Here's a handy calculator:

http://wallaceracing.com/octane-mix-calc.php

Dunno if this helps ...

[WesRagle]

Hey Mark,

Thanks for the reply. I'm doing fine.

It starting to look like my best bet might be Shell 93 Octane. It's available locally. I'll keep the runs short since I'll be in the shop without cowl. And, I'll keep it fresh. If I do the testing successfully with 93 it will give me peace of mind when I "go live" with 100 LL.

I've been thinking about the Ranger fly in. I've also been thinking about the Light Sport fly in down in Dublin which is usually scheduled for the same weekend. I emailed the airport manager and got this reply:

Hello!

Yes! We’re planning on early October again, date to be determined. I’m planning on posting details starting in July.

——————————————
Brad Stanford
Airport Manager
Dublin Municipal Airport (9F0)
Dublin, TX
(254) 445-4404

Haven't seen anything yet. I hope to make one (or both). We'll see.

Hope all is well with you.

//-------------------------------------------------------

Hi Dale,

That may be handy in the future, but absolutely no 100 LL for the time being.

Wes