Is there a way to test gasoline?

<div class='quotetop'>QUOTE(TonyPSchaefer @ Aug 10 2007, 09:43 PM) [snapback]493843[/snapback]</div>

My testing results:


These initial tests in April-May 2007 showed there is about a 10% energy difference between Shell 87 and Sept 2006 Costco over the other brands tested. Shell 87 had more energy than Shell 93 and Texaco 93 that can only be detected by a slight increase in energy at higher rpm.

In late June, I began looking at gasoline density and energy of two brands previously not tested, Exxon and Chevron:


I was surprised to find Shell, Exxon and Chevron all came in with nearly identical energy densities. Looking at the specific densities, the Chevron and Shell came in about the same and only Exxon had a unusual specific density. However, lack of a low energy gas in the sample, I can not see with this data a correlation.

The Dept. of Energy reports that in the USA we have a "summer" and "winter" blend. The "summer" blend typically has more energy and the "winter" improved combustion, lower emissions. The first set of data would be consistent with the Shell dealer starting a "summer" blend before the other tested brands. The second set of data would be consistent with all three tested brands using the higher energy "summer" blend. Unfortunately, only Shell 87 was common between the two sets and it takes about a week to do an energy test of a brand.

To test gasoline energy, I plot the fuel consumption versus the ICE shaft power across different rpm ranges. I use a Graham scanner and record the data on a laptop. I run the car out of gas and use a 1 gallon spare can of the test gas to get the car rolling again. I then drive to the test brand station and put in four gallons. I then drive to a 525 ft., 6% grade hill called Brindley Mountain and climb it at 55 mph in a throughly warmed NHW11 03 Prius. I have set mark points at the bottom and top of the hill and use this data for the energy analysis. When the fuel indicator starts flashing, I refill the 1 gallon can with the next test brand. The whole process takes about a week per brand.

Bob Wilson

 

<div class='quotetop'>QUOTE(TonyPSchaefer @ Aug 10 2007, 08:43 PM) [snapback]493843[/snapback]</div>

Just don't use a lighter and a Magnifying Glass

 

Tony I believe all e10 gas in the Chicago area comes from the BP refinery near Gary, so the only differences are the additives or maintenance/delivery. Perhaps where you bought it from has some water or other impurity in the storage tank.

I would guess that bp would have the best of the lot, although some people are boycotting bp gas due to the extra dumping in lake michigan proposal that you have probably already heard about.

One thing I've been wondering about is my tanks with 100% petrol seem to do lower than e10 (90% of my fills are e10), so I wonder if the computer is used to the e10 and e0 confuses it?

 

Another thing to consider is that you might just be pulsing at 100-200 higher rpm than normal combined with a couple of extra wasted pulses per trip due to heavier traffic or bad light karma.

 

I'm driving on 'flash' and have a gallon of BP's finest in the trunk. Once I run out, I'll re-run the BP test only this time with density. Besides, I've got a new data collection program to test.

I'll probably have some results by the weekend.

Bob Wilson

 

There is a simple test for octane level (my brother uses it to test the fuel customers have put in their Audis to show them he knows they haven't used Premium, but Regular, and that's where the knocking comes from). But that won't show you if there's water or some other contaminant in the gas.

 

By any chance did you add a fuel system cleaner to your tank after your bad tank? One of the ways that a fuel injector cleaner works is it causes the fuel to burn slightly hotter, which will lower the MPG by a small percentage on the first tank, but once it clears out the impurities it will significantly raise it on the following tanks.

 

<div class='quotetop'>QUOTE(morpheusx @ Aug 17 2007, 12:56 AM) [snapback]497664[/snapback]</div>

No extras are put in the tank during the testing. I use an injector cleaner once per year when I also clean and scrub the throttle plate assembly. The throttle plate and injector cleaners come in a Toyota kit so I just use both bottles when doing my 'spring' cleaning. For testing, I run the tank dry and then use a 1 gallon tank of the next test gas to get back to the source station to add 4 gallons. This method appears to do a pretty good job of diluting any inaccessible gas from the previous tank to insignificance.

I'll post the numbers later this weekend but it looks like BP 87 came in slightly lower energy, ~2%, than Chevron-Exxon-Shell. This supports the summer-winter blend hypothesis versus brand specific differences. However, I made two runs with the BP 87 and need to double check everything before posting numbers.

I've got to run my wife to Nashville and I'll be using Shell 93. The spring testing showed Shell 93 and Texaco 93 had an incremental improvement at higher power settings but base energy densities closer to Texaco 87. The run to Nashville will be high-speeds through some Tennessee hills and I'll be able to compare this data with Shell 87 from my recent North Carolina trip.

OWCH!!! I forgot, AC!!!! It is already 90F at 8:00 AM and I know my wife is heat intolerant!!! This data won't be any good. I'll have to settle on doing a Shell 93 hill climb test . . . rats!! ("I'm sorry baby, the AC just broke. Here, just wear this wet T-shirt . . . and we have a cooler of ice.")

Bob Wilson

 

Wow! Really, really impressive test data, but the engineer still has a few questions. I don't mean to pick on you, but I just gotta know;

1. Since the efficiency of the engine is dependent on the temperature of the ambient air. Do you ensure your tests are all done at the same ambient air temps? Normally that would not be a big deal, but you are measuring very small differences in energy content for the various fuels, so the ambient air temp could matter.

2. Are you actually going to use some high octane gas in your Prius? Wouldnt the cost difference negate any positive effects it might have on your fuel economy? Plus, you say you are going through some higher altitudes on your trip. The high altitude combined with high octane would have an especially negative effect on engine performance.

3. Tell me more about the throttle plate, and fuel injector cleaning kit from Toyota. Do the parts counters have it? How much does it cost.

 

<div class='quotetop'>QUOTE(Winston @ Aug 17 2007, 10:45 AM) [snapback]497840[/snapback]</div>

I was concerned about this too so in the spring tests, I was able to test the same tank at ~65F and 88F and found no difference in the results. There are two sources: (1) injector timing and ICE rpm, and (2) air mass sensor. So far, I'm getting identical results regardless of source and my differential temperature tests gave the same results.

I suspect the fuel lines and injectors are pretty much at engine block temperature, ~80C, and the flow is slow enough that the fuel is at block temperatures when it is injected. This means we don't really have to worry about gasoline density changes when using the injector timing. As for the air mass-flow, I believe it is already temperature compensated.

Without putting a thermistor at the intake valve, I suspect the manifold and "in-out" Atkinson cycle also significantly pre-warms the fuel-air mix. Let me think about it and I may come up with something to do that someday. There is also the unknown heat of vaporization from the fuel but again, it is orders of magnitude off from the heat of combustion. But it might be an interesting metric.
<div class='quotetop'>QUOTE(Winston @ Aug 17 2007, 10:45 AM) [snapback]497840[/snapback]</div>

I'm doing these experiments to expand our understanding about how the Prius systems work. In particular, there may be infrequent operational scenarios where ultimate performance is needed.
<div class='quotetop'>QUOTE(Winston @ Aug 17 2007, 10:45 AM) [snapback]497840[/snapback]</div>

I think it is around $12-15 and the parts counter has them. My last one came in a cardboard box with pretty green print. The first one was in shrink wrap. I'll have to search Google to find the part number, again.

GOOD LUCK!
Bob Wilson

 

Hi Tony... you don't mind if I pop in here to mention that I have NEVER - in seven years of EV driving - gotten a bad tank of electrons...

Funny thing is, this points out just ONE of the reasons that oil companies aren't too thrilled about electric vehicles. NO way to brand the fuel. Why buy from one place over another? No way to convince you to buy "high test" electrons. And certainly no way to water down the gas!

OK... sorry... had to do it.

 

Thanks a lot for that info on the throttle plate cleaning kit. I do all of my own maintenance, including cleaning the throttle plate on my cars, and there is always some concern on what type of cleaning solution to use and its compatibility with any plastice parts or gaskets in the throttle plate area. I know that I cannot go wrong with the Toyota kit, and $12-$15 for the cleaner and fuel tank additive seems reasonable to me.

Thanks, again.

 

I've updated my earlier charts to show BP 87. It still has a reduction in specific energy but the API, density readings are similar to Shell and Chevron. Curious.

Bob Wilson