Why you run 91? Super high compression.
CK5
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Only 9.76
Every time I have done a mileage test on one of my vehicles, I have put it on a spreadsheet and figured cost per mile for each fuel used, and carefully notated driving conditions
Each time I have found the increase in mileage offset the increase in cost or more
A big advantage of 91 is no ethanol, at least that's how it is here. I'm having some fuel mileage issues with my 2017 GMC, and even though winter is the time for bad fuel mileage I'm gonna try a couple of tanks of 91. See if the no ethanol thing helps some.
We don't do E85 here. E10 is max. 87 is 10%, 89 is 5% and most places the 91 is real gasoline with no ethanol.
You suck
Been tracking my fuel mileage on fuelly. Makes it easy to track on the phone. Don't have to keep receipts or write it down. Can pull reports out.
http://www.fuelly.com/car/pontiac/g8/2009/joshhefnerx/18218
http://www.fuelly.com/car/pontiac/g8/2009/joshhefnerx/18218
Care to elaborate? I didn't post that to rub your nose in something, just saying what our deal is with the ethanol. I don't pretend to know how the fuel thing is in CO. The only big difference I do know of is in regards to the E85.
Even for us, reaching for Premium isn't a guarantee of no ethanol. Shell for sure is ethanol free for their "Gold" (91 Premium) but other stations either don't say, or won't say. So, we still have to shop around some. Like I said I'm just looking to see if this makes any noticeable difference in my mileage. I'm hovering in the 14 mpg range with a direct injected 5.3 that is driven nicely, and 75% freeway. It's not super good.
We get 85,87,91 all 10% ethanol
We had E85, still see it in some stations
The 87 no ethanol is fairly recent change here. Discussion of others non-ethanol, but not yet
I’d really like to get back 91 no ethanol
We had E85, still see it in some stations
The 87 no ethanol is fairly recent change here. Discussion of others non-ethanol, but not yet
I’d really like to get back 91 no ethanol
I just bought these for my TH400 for -6 AN lines. I am doing the same thing. Havent researched the cooler ends yet.
https://www.summitracing.com/parts/fra-481670-bl
Here are the 4 fittings I used for AN stainless lines from the TBI sender to the hard lines on the frame.
I thought I was the only one who would do that.
Added value pays off more often than it doesn’t.
On another note my dad bought an engine from Ray Barton one time and we went up there and watched them dyno it. It made more power on lower octane at a given timing setting. Logic being that the lower octane burns slower and hotter. The only reason the higher octane makes more power is that it burns faster and subsequently allows higher timing.
Haven’t tried lower octane on this engine. On the old engine it would diesel so bad at 14* lead you had to drop it back to 8. Nothing here likes 8 degrees. Altitude sucks
Actually lower octane has more energy that is why it gets more mileage.
You should use the lowest octane that will work on your engine without detonating.
The lower the octane the closer to diesel which is the higher in energy.
The high octane is refined more and has less oil in it basically which can detonate under high pressure.
Now octane aside, any fuel with ethanol will have a lower mileage than the worst straight gasoline.
Unfortunately in California there are only a handful of stations that still carry the no ethanol fuel and the closest place is 3 hours from me.
Noticed E15 around here recently. I think that's all you can get in Iowa.
I run the 87 no ethanol in the 66 because I saw a video about how the alcohol in the old carbs can cause fits because it causes the fuel to agitate too much with the vibrations of the engine.
You’re right so it’s actually compression (not necessarily timing) that causes the higher octane requirement.
And when I tried using 85 octane on the old engine, I had to back the lead down about 10 degrees. The mileage certainly was not better
That's why I said you use the octane rating that works without detonation.
If at the timing you need it doesn't work it means you raise the octane instead of compensating with the timing.
But if 89 octane works for you and you use the 91 you are leaving something on the table is all I am saying
There’s no 89 here. The 4 octane I’d be giving up to 87 is a lot, and I’m not sure that benefits would ever be seen based on all the times I’ve already ran fuel mileage tests
But I am planning on doing the 87 no ethanol test. So we’ll see. Butt dyno is pretty calibrated
For giggles I put 91 octane in the 73 just to see if it would make any difference. It HATES it.
