Something is going on with the fuel these days!

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Jun 02, 2006 11:23 am

Okay, the last two times I have filled up the Pinzgauer it has taken 5 gallons less to do so! The gas gauge doesn't work so I just look at the odometer and know when I need fuel, usually I hit it right on 2 gallons left in the tank, but not the last two tanks! Each time I have filled it up the tank has still held 5 gallons...

I didn't think much of it till Beth mentioned to me last night that she was getting 25+ more miles to a tank of fuel in her Trail Blazer (Radiator laden junker) and was averaging 25 MPG when she used to get 18-19!

This morning I come in to dyno an engine and I'll be damned if the dyno tank was still 1/2 full after Brent and I dynoed TWO engines! Typically two engines with 8 hours on them each will drain the tank to either completely empty or less than a gallon left!

hell even my lawnmower is using less fuel! Typically it takes 5 gallons of fuel to cut all the grass on the property but today when I checked it a I only needed to add 3 gallons to fill it up after cutting EVERYTHING on the hill!

So, something is definately up and it has happened in the last two weeks or so! i don't know if they are trying some new type of fuel blend or what... Anyone have a clue?? Anyone else seeing this??

Post by **Tom Notch** » Fri Jun 02, 2006 11:28 am

I see typically around a 10% mileage difference between non-oxygenated and oxygenated fuels out here on the left coast with my truck. When the alky is added my mileage drops.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Jun 02, 2006 11:33 am

I noted similar results in my cross country drive... BUT the best mileage we got was in Nevada, i the middle of no where... does Nevada use Oxygenated fuel?

500LbGorilla · Post by **500LbGorilla** » Fri Jun 02, 2006 11:54 am

That's really wierd - unless the physical properties of the fuel is also different, I'd expect it to use the same.. fuel being metered the way it is.. Maybe it's mo' pot'nent, and thicker too. lol

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Jun 02, 2006 11:58 am

yesterday I spilled some 93 pump on my hands and noted that it felt colder than usual and when it evaporated it left my hands way more dry than normal...

The more Brent and I think about it the more trends we are noting, especially that the last 4 engines we dynoed made peak power at 13.5:1 AFR when normally they are at 12.8 or so to make peak power!

eric wagner · Post by **eric wagner** » Fri Jun 02, 2006 12:11 pm

Jake,

Nevada does use oxygenated fuel, but if i remember right it is only from October thru Feburary.

Eric

dstar5000 · Post by **dstar5000** » Fri Jun 02, 2006 12:24 pm

The gas companies should have already switched to the summer grade fuels.

IF they are just switching NOW, it is because they didn't sell as much gas
as they thought they were going to, and ended up with extra fuel that
had to be sold prior to switching to the *summer load*.

That means that they had an excess, INSTEAD of a SHORTAGE.....
and have just been RAPING us for the $$$.

Don

Post by **Tom Notch** » Fri Jun 02, 2006 12:41 pm

with less energy being released from oxied fuels, to maintain the same speed the pedal is closer to the metal.

Arco here is year 'round oxied, while the major gougers switch. The pump is *supposed* to be labeled if it is dispensing oxied fuels.

vw_chuck · Post by **vw_chuck** » Fri Jun 02, 2006 1:11 pm

With 10 percent ethanol in the fuel, the mileage is worse. They probably took out the alcohol and the mileage went up. I noticed the same thing a few months ago.

dstar5000 · Post by **dstar5000** » Fri Jun 02, 2006 1:28 pm

AHA! So they were *diluting* the gasoline during the winter
months and STRETCHING their PROFITS into MORE profits?!

Why do I think that they would do just that?

Don

melville · Post by **melville** » Fri Jun 02, 2006 3:18 pm

Hey!

Oxygenated fuel comes in two varieties--the kind with alcohol and the kind with MTBE. When I lived in Seattle we had an oxyfuel requirement from, as I recall, October to March, in the years we didn't meet some atmospheric CO level. My 1600 Bay bus would gain and lose power from tank to tank in the winter and I finally traced it to some suppliers using ethanol and some using MTBE. For a while, I filled up only at MTBE stations but found that a PITA and went up a size on my main jet. The jet change was fantastic! All my power (45 or so!) was back! Fuel mileage went from ~20-21 to ~16! Thankfully it was winter only and the last couple years I was there (late 90s) Seattle beat the CO standard and did not have the oxyfuel.

Here in CA it's oxyfuel all year and ethanol only. I have a different 1600 Bay bus and it gets 18 mpg in general use.

Later

Mel

raygreenwood · Post by **raygreenwood** » Fri Jun 02, 2006 3:48 pm

Last weekend was the deadline for all fuel stations in North Texas to be on the summer blend. Also....MTBE...is no longer used in this region due to toxicity in groundwater. They are using a different additive to do the same thing. It was also the last weekend for all stations in certain metro areas in and around Dallas to be on E-10 at least (10% ethanol along with the oxygenation additives).

Here is one of the main benefits....and is part of what you are seeing in the milage spike. The oxygenation ingredients are there....to make the fuel burn more like the normal blends of fuel you get throughout the year. This is because.....with ethanol and other hot weather additives......the flash point on the fuel has risen. It evaporates slower....and is harder to vaporize with air. It needs more oxygen

What this is for......is two things. (1) the higher flash point keeps transient VOC emmisions down (evaporation loss into the atmosphere....one of the worst components of smog and the first to join with ozone in teh formation of smog)
(2) It keeps the flame temperature down. This keeps NOX levels down. This is the next worst component in summer smog. The lower flame temperature is helpful to many cars that normally run "warm".

The benefits for summer are......it evaporates slower. You lose less through evaporation. So if you are already on summer blend...but not "really' seeing super hot summer temps yet....you are getting less tank evaporation into your charcoal cannister. The sad thing about the charcoal cannister...is that it causes the 02 sensor on modern cars to sense a constantly rising and falling A/F ratio. As you drive......when vapors are being siphoned off and sucked into the intake.....the 02 sensor fights a constant battle to counteract ....the unscheduled minor "enrichments " that the gas vapors coming from the cannister represent. Its a submarining affect.

It is most noticable in stop and go and right after start up....because many cannisters only vent at certain rpm ranges, or right after start up. It is the stop and go drivers and the low rpm drivers that produce the most smog. Some of this due to tank sloshing and venting, some due to heavy right foot,some to long idles etc.

Also, since its not raging hot yet....the extra oxygenation of the fuel...coupled with the higher flashpoint (from the alcohol)....is giving more efficient running, less pinging on the knock sensor etc. These benefits during not so hot times.....far outshine the lower energy coefficient that the alcohol imparts to the fuel .

Anytime you can run the engine with out the constant rise and fall of the ignition advance rate (via the knock sensor).....and without the constant spike and fall of the CHT (partly due to advance rate and the action of the 02 sensor)......and without the constant submarining of the fuel mixture due to the 02 sensor.......you will get more efficient output......with less need for "right foot".....and gas milage increases.

When the outside temperatures finally get really hot....I would bet that the milage returns to normal. Ray

regis101 · Post by **regis101** » Fri Jun 02, 2006 5:14 pm

My last two tanks were at least 2 mpg more than the previous 6 months.

Steve Arndt · Post by **Steve Arndt** » Fri Jun 02, 2006 7:02 pm

raygreenwood wrote:
Anytime you can run the engine with out the constant rise and fall of the ignition advance rate (via the knock sensor).....and without the constant spike and fall of the CHT (partly due to advance rate and the action of the 02 sensor)......and without the constant submarining of the fuel mixture due to the 02 sensor.......you will get more efficient output......with less need for "right foot".....and gas milage increases.

When the outside temperatures finally get really hot....I would bet that the milage returns to normal. Ray

Jake's Pinz doesn't have these features.
I agree w/ your post, I'm just pointing this out in relation to the original post.
This is as far as I know though! All the Pinzs in our shop are very primitive old carb'ed inline 4 aircooled engines (no O2 sensor, charcoal system, knock sensor, etc.)

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Fri Jun 02, 2006 7:05 pm

The Pinz is as simple as they come... Thats why when I noted the changes with it, I knew someting was up....

My Pinz is only gonna be carbbed for another month or so before it gets EFI and direct fire ignition...