A

ao.frog

Well Known Member
Hi.

I've a Superior IO-360 with 8,5 compression and according to the manual I can begin using mogas at 50 hrs.

During breakin I noticed that the engine was behaving better if I leaned during taxing.
I guess this prevents plug fouling and lead buildup.

My question is: schould I lean during taxing while using mogas too? Since there's no lead, is it necessary to lean? Or maybe leaning while taxing prevents the engine to run too rich?

What do you people out there do?

(So far, here's in Norway mogas doesn't contain ethanol)
 
When using 100 LL avgas, leaning during taxi is a good idea because the engine may not be getting hot enough to scavenge the lead, and that is why plugs foul sometimes. Since there is no lead in mogas, you will only need to lean if the mixture is causing roughness, usually happening at a high altitude airport. It does not hurt the engine to lean during taxi with any gas you use because the power setting is so low that detonation will not be a problem. Of course you save a tiny bit of gas too by leaning. I think it is just a good habit to get into.
 
I have the same engine setup & lean during taxi when using non-ethanol mogas. Florida has mandated up to 10% ethanol. Right now, I have one local station that is ethanol free until the end of this year.
Superior does not approve use of ethanol.
 
Yes yes and yes

Lean during taxi as you normally would whether running mogas with or without ethanol

Works just fine

Frank
 
Ok

Thanks guys. I'll do that then.

17 more hours to go.... (until 50)
Guess I'll start with a 50/50 mix in one tank, take off on the other and see how it works at altitude first.
 
If you're going to lean I'd suggest a good before takeoff checklist.

I know a retired American Airlines pilot that crashed because he forgot to push his mixture back in at a high-altitude airport. He got enough power to take off, but not to climb.....
 
Huck said:
If you're going to lean I'd suggest a good before takeoff checklist.

I know a retired American Airlines pilot that crashed because he forgot to push his mixture back in at a high-altitude airport. He got enough power to take off, but not to climb.....
Click to expand...

Normally, at our high altitude airports; we lean right after startup, lean before takeoff, and never go back to full rich on the landing either. Unless we've traveled to a lower altitude airport of course.

If we don't, we foul the plugs on warmup/taxi; and loose available power for both the takeoff and climb. The difference is very noticeable.
My airport is 4603' msl before factoring in density altitude.

L.Adamson --- RV6A
 
Huck said:
If you're going to lean I'd suggest a good before takeoff checklist.

I know a retired American Airlines pilot that crashed because he forgot to push his mixture back in at a high-altitude airport. He got enough power to take off, but not to climb.....
Click to expand...

Read an article that recommends aggressive leaning during taxi. So much so that the engine stumbles if the throttle is advanced much above idle. No chance of taking off with lean mixture that way. The engine needs rich mixture at take off and climb because it uses the excess fuel to help in cooling the cylinders.
 
exactly..

This is exactly what I've found too: to lean to the point where the engine stumbles alittle when pwr is advanced beyond 1100-1200 RPM

Before I started to lean while taxing, I'd had to to the plugfouling burnout procedure on almost every runup.

For the record: both my runup checklist and my before takeoff checklist has "Mixture rich below 3000'" on them.
This, in addition to the engine stumbling, schould prevent me from inadvertainly taking off with a lean mix. (I hope)

By the way; Before shutting down, I'm running the engine for 1 min with a lean mix (+50 RPM teqnique).

Since I started to do these two things, (approx 25 hrs ago) I've never had plugfouling at runup.
 
Last edited:
If you're going to lean I'd suggest a good before takeoff checklist.

I know a retired American Airlines pilot that crashed because he forgot to push his mixture back in at a high-altitude airport. He got enough power to take off, but not to climb.....
Click to expand...

JDRhodes said:
Read an article that recommends aggressive leaning during taxi. So much so that the engine stumbles if the throttle is advanced much above idle. No chance of taking off with lean mixture that way. The engine needs rich mixture at take off and climb because it uses the excess fuel to help in cooling the cylinders.
Click to expand...

But do keep in mind the reference to airports of3000' and above, as stated in one of these replies. When operating out of high altitude airports, it can become a compromise between leaning and a more rich mixture when breaking in a new engine and trying to control CHT's. You'll be doing both, as well as less aggressive climb rates.

While excess fuel does cool the cylinders, a disproportionate fuel/air mix can cause a loss of much need takeoff & climbing power. Do some additional reading, and you'll see POH's and engine guides suggesting full rich for takeoff. Do even more reading, and you'll see numerous references of leaning at 5000' msl and above airports, as well as 3000' and above...........sometimes. The 3000' mark is usually in backcountry flying guides.

The point is, at my airport altitude of 4600+' msl. ; all of our pre-flight checklists will include leaning after engine start, and re-adjust again before takeoff. It's just a way of life, that many of those who live closer to sea-level altitudes, are quite surprised about.

As to the American Airlines quote, there has to be more to the story, than what's in the paragraph.

L.Adamson
 
You must log in or register to reply here.