Would putting in higher octane say 89 or 92/3 yeild any better performance/mpg? Or is it just a waste of $?

I spend probably 90%+ in ICE on, 45-65MPH for the daily work commute of 6mi each way.

 

From whats been posted here, NO. Higher octane fuels aren't "better" fuels, they are designed for engines that are high performance so that the gasoline doesn't ignite too early. Our engine is not high performance, the fuel should not ignite early. If you get some knocking mid-grade might help that, however I've never had knocking. Other than that you are just spending more money.

Some people who have tried higher octane have posted that their mileage even went down slightly.

 

It would be worse esp in the adkinson cycle engine. These engines take advantage of a greater delta change in compressed to expanded volume. This means it can take advantage of lower octane fuel and not waste a larger percentage into the cooling and exhaust systems.

 

Thanks. I pretty much assumed octane increase would be a waste of money, I haven't seen many, if any, threads on it. Now I do understand ( I think) if I can find 100% gas vs ethenol blend it will get better, but how do you find a station selling that these days?

Overall I'm still completly impressed. 4400 miles, still averaging 32Mpg, when my mini van was getting 16!

 

a handy trick I've learned to find pure gas--go to a station near a marina. Most boats won't run well on ethanol blend, so the stations near marinas have premium non-oxygenated gas for the boats.

 

The question I always have for that is... Sure you have better gas mileage, but if you are actually trying to pollute less are you doing the environment a favor by doing that? They oxygenate the fuel with ethanol or whatever for a reason. Presumably to reduce emmisions that cause smog in the summer (hence summer blends). Are we environmentalists, or just people trying to brag to each other about out peak gas mileage?

 

Ethanol is used primarily to reduce CO emissions. Smog is mostly due to oxides of nitrogen (NOx). CO is needed by your catalytic converter to reduce the oxides of nitrogen into N2 and CO2. That is why your mixture oscillates around 14.7 A/F instead of sticking there. Rich produces CO to reduce the NOx, lean produces O2 to oxidize the CO and HC into H2O and CO2. The net effect of reducing the CO before the catalytic converter in modern engines is minimal on post catalyst emissions. Your exhaust is about 15% CO2 and .01% CO. CO2 has not been considered bad in the history of emission control, in fact it has been considered desirable. The only way to reduce CO2 is by improving the fuel economy of your vehicle.
In a low DCR engine like the FEH, your fuel economy suffers from the ethanol, hence more CO2, the primary greenhouse gas. Which do you want?

 

Oxygenated fuels were designed to help NON computer controlled cars or cars that have BROKEN computer systems. They are actually harmful to fuel economy, ergo the enviroment. The extra oxygen in the fuel is of no use to a properly operating OBDII (begining in '94) car. The purpose of the oxygen sensor(s) and computer systems is to closely control the oxygen content in the exhaust to maintain a 14.7 air/fuel ratio. This allows maximum efficientcy (fe) and the cleanest emissions. Some of these modern engines almost don't need a catalytic converter they are so clean. Claimming oxygenated fuels are needed for the enviroment is like saying we need big SUVs for saftey. The time has passed for oxygenated fuels.

 

Mary! You are breaking the law in your state of MN!

Plus, only the "premium" or most expensive gas is not blended with ethanol. You are loosing money if you go this route, and the higher octane will lower your MPG to boot.

A lose - lose situation for your FEH, and you are breaking the law in MN.
The "non-oxygenated fuel" says "for non-highway use only" in the state of MN. I was just there last week and that is what it said on the premium pumps.

37.4 MPG for me with 10% ethanol.

 

I didn't say I buy the gas. I don't. It's about 40 cents more per gallon, and I wouldn't do it. However, since Wisconsin has a different blend requirement, I can go over there and fill up and drive here and be fine since the gas meets the Wisconsin standard. What a weird system. I just dislike ethanol and the ridiculous amount of subsidies we've pumped into it, when that money could have been used elsewhere.