Do different Gas Brands burn more efficiently? Higher MPG's?

[rmay635703]

I started testing a mix of 87 e10 e85 and 91 ethanol free

Thus far my lie o-meter reads 60mpg on flat ground when before it topped at about 53mpg on the same stretch but only if my motor is warm, my startup/warmup FE is MUCH lower.

Very odd effect.

My test mix is
50% e10
30% e85
20% 91 e0

The car hops less accelerating during warmup.

[rmay635703]

Well Lie-O-Meter is behaving the same average per it is 47.8mpg ave on this mix and I am in my in town cold weather mode so I expect it to drop further, trouble is my father also drove the car (-3mpg on a 150 mile tank) and its getting cold which takes off 5 to 10mpg on this car easily.

This is actually doing "well" considering the amount of higher speed driving and town driving was done in colder weather. I will know when I eventually fill up if this mix paid off, was a wash (I lean to that choice) or cost more $$$

I chose the mix based on the fact that it cost the same price as plain e10 but had much higher octane, it appears the octane on a 2.2ltr 10.5:1 compression ratio car wins out over the additional ethanol in the tank.

The ethanol MASSIVELY affects my acceleration FE during warmup, bleh 9mpg instead of 18mpg sucks.

Ah well

[serialk11r]

Originally Posted by rmay635703

I started testing a mix of 87 e10 e85 and 91 ethanol free

Thus far my lie o-meter reads 60mpg on flat ground when before it topped at about 53mpg on the same stretch but only if my motor is warm, my startup/warmup FE is MUCH lower.

Very odd effect.

My test mix is
50% e10
30% e85
20% 91 e0

The car hops less accelerating during warmup.

That's a lot of E85! Just for kicks I decided to add 1.3 gallons of E85 to the 9.2 gallons of 87 (we only have E10 in California) and maybe 1 gallon left in the tank, for a 20% ethanol blend. The E85 was rather expensive at 3.89/gallon, but this was just to see what would happen. I had a tiny bit of knocking at low speed even after "steam cleaning" my engine, so I was thinking maybe running some more alcohol would help wash it out a bit more. I figured just 1 tank of E20 can't be any worse than pouring some fuel injector cleaner stuff in, and though I lost about 1 dollar because of the E85's price, my octane rating is probably bumped up a little so it's just like buying 89 instead of 87 or something I figure.

Observations so far: engine seems a little smoother, but I did switch from Chevron to NTG so maybe there is a gas blend difference. Cold idle seems to be a little rougher, but not sure. MPGs don't appear to be affected, but it's obviously going to be hard to tell. Engine doesn't idle consistently and seems to have slightly out of calibration O2 sensors as the exhaust always smells a little like unburned HC, so that's another unknown. I should log the timing sometime, I think it was a little lower than normal last time, hopefully the ethanol is allowing full advance.

[rmay635703]

Originally Posted by serialk11r

That's a lot of E85! Just for kicks I decided to add 1.3 gallons of E85 to the 9.2 gallons of 87 (we only have E10 in California)

Not really, I have run up to 60% e85 in the past and that was on a 98 buick. The cobalt seems to have no issue with any ethanol blend but it does kick the MPGs down a lot if I am more than 30% ish.

Normally I don't mess with E85 anyway because its not $0.99 a gallon anymore like it was 7 years ago. Thus not worthwhile but with gas prices higher than normal I thought about testing the $3.499 e85 with non-e10 87 octane gas (most of the stations aren't selling it again, blast!)

Anyway this was mainly to test the fuel economy and performance aspects, I don't get the hop I normally get during cold starts but other than that performance seems similar (to the butt o meter) and FE per the lie o meter is within the margin of error but I definitely notice poor fuel economy during start up and better than expected once warm. So for cold weather in town = bad, highway = good

[serialk11r]

Originally Posted by rmay635703

Normally I don't mess with E85 anyway because its not $0.99 a gallon anymore like it was 7 years ago. Thus not worthwhile but with gas prices higher than normal I thought about testing the $3.499 e85 with non-e10 87 octane gas (most of the stations aren't selling it again, blast!)

Anyway this was mainly to test the fuel economy and performance aspects, I don't get the hop I normally get during cold starts but other than that performance seems similar (to the butt o meter) and FE per the lie o meter is within the margin of error but I definitely notice poor fuel economy during start up and better than expected once warm. So for cold weather in town = bad, highway = good

I see. Yea at 3.89 a gallon I knew I was getting ripped off, but I am treating it as a cut price octane boost of sorts, and hoping that it will have some cleaning effect.

At 20% ethanol I didn't notice any different behavior other than an idle that dipped lower than usual for a few seconds making some unhealthy noises, and a more inconsistent idle while driving as the engine was adjusting the fuel trims or something. Engine was warmed up though, and no fuel economy loss apparent. This morning I started it at ambient (18C I think?) temperature and drove, felt exactly like using normal gas according to the butt-o-meter. Did not use the mpg gauge though, since I didn't feel like pulling out my phone. Supposedly 20-30% ethanol is the best for thermodynamic efficiency in some tests, I'm guessing it's a port injected engine thing where going too high in ethanol + port injection doesn't cool the charge enough to offset the unvaporized ethanol wasting some of the heat of combustion, whereas a direct injected engine makes better use of the cooling effect of ethanol and will see greater improvement from running a higher amount of ethanol.

[TheIVJackal]

I can't believe you guys are running anything higher than E-10 in your vehicles that are not equipped to handle such high levels of Ethanol. Are you not worried about wearing out seals and what not? EPA just mandated that all cars must fill with at least 4 gallons of gas if the station has E-15 or higher on the same pump. Be careful!

[serialk11r]

Originally Posted by TheIVJackal

I can't believe you guys are running anything higher than E-10 in your vehicles that are not equipped to handle such high levels of Ethanol. Are you not worried about wearing out seals and what not? EPA just mandated that all cars must fill with at least 4 gallons of gas if the station has E-15 or higher on the same pump. Be careful!

A lot of people in the E85 community say there's no problem with the fuel system, that they've been running E85 with only upgraded fuel pumps and injectors for years without issue. The EPA seems to think that E15 is safe though car manufacturers don't.

The fact that the car manufacturers think it's bad makes me too afraid to run it all the time, besides the price isn't very good out here in California, but putting ethanol into this tank is more because I want to clean my engine and supposedly ethanol is good for that. I also want to see if boosted octane rating makes it smoother at all. I figure it can't be any worse than dumping a bottle of some unproven snake oil that goes for 10 dollars into the tank.

[ksa8907]

The reason e15 could be bad is some engines use exhaust valves that can't handle the heat. If you want to know you'd have to figure out what type exhaust valves you have.

[rmay635703]

Originally Posted by ksa8907

The reason e15 could be bad is some engines use exhaust valves that can't handle the heat. If you want to know you'd have to figure out what type exhaust valves you have.

I say MYTH ??? That only happens if your car runs lean during WOT, any modern car with an O2 sensor can handle E15 (or e30 for that matter) Just don't press the gas pedal to the floor, closed loop only please.

AKA running at stoich ethanol burns MUCH cooler than gas so no burnt valves.

[roosterk0031]

Filled up the Impala with 3.02 E85 over the weekend, 1/6 less is what it takes to be worthwile for it, 3.65 v 3.02 was close enough. Driving it 9 miles home after filling factory gauge displayed 32 mpg (50 mph). I'm sure my wife will pull that down.

Haven't blended any yet in the Cobalt but last 3 tank comparision E0 to E10 was only 1.6% loss of mpg and about 2.8% cheaper. (44.4 vs 43.66mpg) probably not a statistical difference.