Gas Grade...

[Wilson]

If your running 87 becose it's cheaper just use e-30 cheap and high in octane.

 

[Cleave]

I run 87 octane with my DiabloSport 87 tune.
Octane is the resistance to Detonation (ping), High octane fuel burns SLOWER this is why it resists ping and can accept more timing. I have always been told that you make the most power running the lowest octane fuel you can without detonation.
Has anyone ever tried to verify this 10HP gain with higher octane fuel?

this is true everything else being equal, but higher octanes allow you to take advantage of timing manipulation, which will increase performance, as an example, say two engines that are exactly the same in every way, one has 87, the other 91, let's say the perfect timing advance for the engine running 87 is 21 degrees at full throttle, if both engines are run at 21 degrees, the engine running 87 octane will make slightly more power than the engine running 91, but, lets say the engine running 91 had it's perfect timing at 24 degrees, if all else is exactly the same but you're running the "perfect" 21 degrees of advance on the 87 engine and "perfect" 24 degrees of advance on the 91 engine, you will get more power out of the 91 engine

 

[Wilson]

all car's truck's are set to run rich from factory. This is why leaning it out with e-30 or a higher grade gas works.

 

[Nick@Apollo-Optics]

all car's truck's are set to run rich from factory. This is why leaning it out with e-30 or a higher grade gas works.

I don't think that's necessarily true anymore. In this day and age, where every manufacturer is making an effort to maximize fuel efficiency, I doubt they're burning excess fuel and running rich.

 

[Blind1]

I have to concur with you. The O2 sensors along with the ECM keeps them from running richer now a days.

 

[Cleave]

all car's truck's are set to run rich from factory. This is why leaning it out with e-30 or a higher grade gas works.

this is the opposite of the truth for modern cars, during normal driving, say going down the freeway, a modern car with air fuel ratio sensors will run 15.0:1 to 16.0:1 air/fuel ratios, the technical "perfect" air/fuel ratio for normal driving is 14.7:1, and it's the same for full throttle driving, pre-ECM vehicles usually ran around 7.0:1 to 10.0:1 air/fuel ratios (this is a range of what one car could experience throughout one 1/4 mile run at full throttle) at full throttle, which reduced maximum horsepower and torque output, but was required to prevent full throttle detonation due to the inability to precisely control air/fuel ratios, modern cars will run 10.7:1 to 11.7:1 air/fuel ratios at full throttle, which while an improvement over pre-ECM vehicles, it still isn't perfect since we can't predict the exact conditions inside the cylinder before we have to inject fuel, we can only find out after the fact, so we still play a little on the safe side, under all conditions, modern cars run very much on the lean side

 

[Wilson]

yes but still a tad rich^

so what's the best fuel mileage in your opinion? slow burning lean ethanol that runs cool yet burns completely or better than most becose of high octane. or 91

the problem is I'm not burning crap 87 octane in my truck and everyone else is too chicken to try e-30 so we may never know.

 

[Cleave]

how much does E-30 cost compared to gas where you're at?

---------- Post added at 10:01 PM ---------- Previous post was at 09:59 PM ----------

by the way I don't see how that's rich, ethanol runs richer than gas, only diesel runs leaner than gas

 

[Wilson]

10 cents cheaper than 87 I get 13-16 mpg with e-30 could do better could do worse. but like I said I don't want to put 87 in the truck ever. I did run 91 octane on the way back from the hills sdbr and got I think it was around that 14 but on the way out using e-30 got 16.5 I think it's on the mpg thread. I'll try and find it.

 

[Cleave]

which way was more uphill, I'm guessing the way back

---------- Post added at 10:17 PM ---------- Previous post was at 10:13 PM ----------

I've gotten much better than 16.5 running 91, my best is 22.1, I have photo proof of 20.8