What grade of gas do you pump?

Gen2, not arguing with you, this is a honest question.

I think aviation gas for piston airplanes is even higher octane than what is sold for cars. If so, then they burn a, "...lower the energy in the fuel..." type of fuel? I thought that they needed all the performance that they could get without adding the weight of a bigger engine.

 

That will set you back a hundred spot.

What makes a car so good if it cost so much to go from point A to point B?
Couldn't they at least least make it so it would run on 87?...... we are such suckers... <_<

 

Is airplane gas the same gas that is pumped into autos? In our FAQ it is very clearly stated that airplane octane is not the same as automobile octane. Please read the link surrounded by the [4]. Maybe this will answer your question.

When lead was banned, gasoline got more expensive because refineries could not boost the octane ratings of cheaper grades any more. Airplanes are still allowed to use leaded gasoline (known as AvGas), and octane ratings of 100 or more are commonly used in super-high-performance piston airplane engines. In the case of AvGas, 100 is the gasoline's performance rating, not the percentage of actual octane in the gas. The addition of TEL boosts the compression level of the gasoline -- it doesn't add more octane.

 

Just to add to the geek factor, since the topic of avgas was introduced, I spent 20 yrs flying navy aircraft, usually with large radial engines. These engines burned 115/145 octane fuel. In an emergency, we could use 100/130 octane but our normal maximum power for takeoff of 56.5 inches of manifold pressure would have to be reduced to 49.5 inches if we used the lower grade fuel. Using the higher power settings with the lower octane fuel would cause engine damage and ultimate failure due to pre-ignition (pinging). During my later flying years in the military, refineries began to severely reduce the refining of 115/145 fuel as the military was rapidly converting over to jet aircraft. What was being produced was reserved for the last days of the piston engine.

Back on topic: I use first tier 87 octane in my prius and F150 truck. On occasional trips to Colorado, I use the 85 octane available there. See no upside to higher octane.

 

For what it's worth, my 8th grade physics teacher went through the whole octane rating and waste of money using premium when it is not required. If I knew that in the 8th grade, I gotta question this so called mechanic's knowledge of cars and engines

 

It does run on 87, I just put premium in occasionally for the hell of it. And Not $100 its only about $60 if the tank is really empty. :lol: :lol:

 

Wow... 2.00/gal for premium... we are really getting shafted I guess... :angry:

 

No matter how "geeky," reality just turns me on.

 

Both General Motors and Chrysler both experimented with turbine engines (I got to see a demo of the Chrysler). They basically ran on anything that was liquid and burned. Avgas, regular gas, cigarette lighter fluid, kerosene, tequila and even Chanel #5! Lot's of pluses, but there was problems with efficiency and the lag between throttle and movement. Interesting idea, though.

I put 87 in my Prius.

 

galaxee,

I have had my Barcelona Red (Beautiful) for 4 days now up to 47mpg average but after a snow today down to 45.2 with heating,etc.(109 miles so far). Temperatures have been between 24-48F degrees, mostly mid-30's. Drives very quiet and smooth and more room then my 2002 Camry leg/room (not as much width of course).

No, actually I'm along the Wisconsin/Illinois border. There are about 6 gas stations within 1.5 miles of where I live. All but 2 have 89 for regular and only Shell and Phillips 66 are "Top Tier" as recommended on www.toptiergas.com/retailers.html. Mobil has 87 octane but from what I read a few years ago their regular is not the quality of Shell, Phillips 66 and others. Their higher grades do have better detergents as I remember from about 5 years ago. The "Top Tier" article doesn't list Mobil or any other around my area such as Chevron, Texaco, 76, etc..

Once again I looked up in my 2006 Manual and it says the same thing "87 Octane or higher".

Thanks for your response. I would gladly use a Top Tier 87 Octane if it were readially availble. Thanks for the help!

joe
T

 

I've seen the numbers 13.5:1 for expansion ratio, and 9.5:1 for effective compression ratio mentioned in several online sources. In fact, I've seen them enough times that I'm inclined to believe that they are the correct figures, not the 13:1 and 8:1 that you listed.

My Acura MDX was designed for premium fuel, but the ECU can retard the timing to prevent pinging when you put regular in it. I get about 10% better fuel economy on premium (due to the timing advance), so as long as premium is less than 10% more expensive than regular (as it is now), I put premium in it. Most cars that were designed for premium, but which can run on regular behave similarly to this.

 

Hi Guys!

I use 87 only cos it's what the manual says. Also, I bought the car because it runs on 87 which is the cheapest. :lol:
This topic is crazy. We are mostly tight-wads, anyway. Why bother.
I will bet if there was 80 at a lower price, and the Prius manual says to use it,
y'all will use it!! Trust your Toyota maker!! :lol:

 

That's hog wash!!
Keep your motor oil changed every three months. That's what keeps the motor clean!! Don't be ripped off!! :lol:

Andy

 

"Humm.. I believe the prius has a high compression ratio... what is it?... 12:1 or so?
Yet I've heard it does not better.... of course the atkinson engine is a whole different animal. "

I want to say the Atkinson cycle has a high-expansion ratio, not high compression ratio. I'm actually not sure what that should mean but I'm sure someone here can comment...

 

strange. are you on the WI or IL side of the border?

i'm actually from WI, and i've never seen 89 as regular. maybe it's an IL thing? or they've changed things since i've been home? (argh, i've been gone too long)

i know kwik trip a few years back decided to price regular and midgrade the same, when i lived in la crosse. maybe that had something to do with it? ah, now i'm just blathering. :lol:

i wouldn't worry too much, no need to go to extremes here. it's not like you're dropping 93 in there right?

if you do get one of those "engine failed to start" codes after long term use (can be caused by high octane), then i'd consider going a little farther to get 87.

 

Just as you wrote, "performance" in an airplane means more power per engine mass. For a piston engine this requires the highest possible compression ratio, which requires fuel with (ta da!) a very high octane rating. The slightly lower energy density of that fuel is not very significant.

 

I'm now using 85 octane with no noticable penalty of any kind. I'm half way through my second tank. Woohoo, I can save an extra $1 at the pump.

Richard, that's interesting. I read somewhere that Snaab or Volvo was developing an engine to run on E85 that had very high compression ratios to compensate for the lower energy density of E85 vs Gasoline.

 

<div class='quotetop'>QUOTE(tripp @ Apr 24 2006, 08:15 PM) [snapback]244669[/snapback]</div>

Say tripp.. does that have even more ethanol than 87?... if so, are you getting worse mileage and so not really saving a buck?