Today's Gasoline

Scott Calabro · 15th November 2009, 04:39 PM

Anyone have bad luck with fuel by letting your GT40 sit idle for a few weeks?

I seem to have, the fuel acts as if it is going stale.

My plugs never really clean up, even though the engine runs fantastic, pulls like a raped ape. I have had the exhaust anylized while rolling down the road with an O2 sensor, so I'm sure the the carbs mixtures are set up well.

They don't cough or spit either.

So today I pumped out the tanks and put 6 gallons of 100LL AvGas in each tank. Look at the picture of the two plugs, the one on the right is after 50 miles on the 100LL, the one on the left is 93 Sunoco.

The engine actually seems to pull harder on this stuff.

Any oil company petroleum chemists here?

What gives?

Cheers,
S

Randy V · 15th November 2009, 05:31 PM

I don't know about the fuel in your area but around here it's mixed with Alcohol and is good for maybe 60 days before it's NFG.

You can stretch it with a stabilizer like Sea Foam or Sta-Bil but maybe only 6 months total with that stuff mixed in the recommended amount.

We have a lot of humidity here in Minnesota too so I think that plays a part in it with a fuel system that's vented to the atmosphere.

Just got done draining 1.5 gallons out of my Ninja as the bike would barely pop let alone run. It was about 4 months old..

David Morton · 15th November 2009, 05:32 PM

Your 100LL is doctored with Tetra ethyl lead which is where the octane rating comes from (It used to be AVGAS 100/130). Flame rate and vapour pressures are radically different from Forecourt pump gas. It really is a radically different product. Racing fuel is virtually 100LL with a couple of other ingredients instead of the lead.

Scott Calabro · 15th November 2009, 05:35 PM

Yes Randy, we have a maximum of 10% ethanol here in New England.

Your Ninja sounds exactly like how my GT40 sounds after a while, real hard to start and soots up the plugs.

Well David, it runs radically different! It looks like I'll be filling up with Av Gas more often.

Its cheaper than race gas too @ $4.25 a gallon.

Cheers,
S

David Morton · 15th November 2009, 05:59 PM

Yes indeed - I used to run my Duke on Shell Racing Fuel simply because I got it from the back of a lorry and 98 pump gas was about $7 dollars per gallon. It performed so much better. I think.

Cliff Beer · 15th November 2009, 08:04 PM

Scott, that's interesting. You're sure there's nothing inside the tanks which is possibly deteriorating over time and affecting gas which sits in there for a stretch?

Scott Calabro · 16th November 2009, 06:34 AM

Screens and filters are clean.

Julian · 16th November 2009, 03:24 PM

There is a lack of awareness and education on Ethanol blended fuels, here's some facts;

1. All low chain alcohols have solubility in water, ethanol and methanol are fully soluble.
2. Not only is it soluble, but ethanol is highly hygroscopic (readily absorbs water/moisture)
3. Because gasoline does not tolerate water a phase separation occurs at 0.5% water content in a 10% ethanol (E10) fuel
4. Most blending of ethanol is not done at the refinery, but at the supply chain point often by the truck driver, so it can be hit and miss.
5. Lower end gas stations often have poor tank management and drainage systems so water ends up in the fuel storage tanks. With gasoline it's not much of an issue unless the tanks are pumped down very low. With an ethanol blend the water is immediately absorbed by the ethanol.
6. Ethanol based fuels are considered to have a 90 day shelf life from time of addition of the ethanol. Many gas stations don't realize this either.
7. Fuel stabilizers do not prevent ethanol absorbing water, they can help with other unwanted solvent effects of ethanol e.g. seal and rubber parts life

Fuel longevity can often be improved by changing gas station to one that has higher turnover/throughput.

Scott Calabro · 16th November 2009, 04:24 PM

Good stuff Julian.

What really amazed me is the power increase on AvGas.

I know its not an octane requirement issue because I have never heard it ping/detonate on 93 Sunoco. No evidence on the plugs of that either.

But I know it has more BTU per pound than pump gas simply because it is not diluted with ethanol, and I new about the affinity for water. I'm just amazed at the difference in how the engine runs now.

Cheers,
S

I also know the Av Gas will not go stale either!