'03 2.3 will I get better mileage with 89? 93 a waste of cash?

 

Run 87. Your motor was designed for it. Anything higher is a waste of money.

 

+1

 

will the mileage be the same if you use 93

 

might have adverse affects actually. Every engine responds differently. I could almost guarantee you won't get better mileage that overcomes the extra 20-25cents a gallon you are paying for the 93...

 

the computer is not tuned for it i would not bother

 

I treated myself to 89 octane this week and my mileage stayed the same, but truck cranks longer before it starts now.

 

Just use regular chevron/texaco gas and you'll see better mileage. Compared to the watered down murphy (walmart) crap, racetrack/raceway or any other cheap gas, you'll see/feel better results with Chevron.

 

QT is on every corner around here so that's what I use - Top Tier rated.

http://www.toptiergas.com/retailers.html

 

If you wanna run higher octanes you need a tune.

 

Unless your engine is tuned for something else, you should be running 87. Putting in anything higher is not of any benefit or gain. You aren't treating yourself. At best it is a waste of money. At worst, you engine will run like crap.

 

in my truck i ran 87 and got 20.5
i ran 94 and got 17

in my bike i ran 94 and got 40
i ran 89 and got 51.2

 

Hence ... "but truck cranks longer before it starts now" so I went back to 87 and truck seems happier now. Saved enough to pay for a stripped down QT hotdog.

 

Ill go ahad and stick with 87, truck runs fine on it, i just wondered about better mileage.

 

I never noticed anything, stayed the same for me

 

Since your truck is N/A, Your compression ratio isnt high enough to see an advantage (performance/mileage) to be worth using that gas.

Believe what you want, but I get paid to tune.

Your best chance would be setting the target closeloop AFR to 1.03 lambda, instead of a stock 1.00 - any leaner than this will cause a motor that old to run hot, and it will start pulling more fuel to counteract this (hence killing any gains you made)

You will need better fuel control to do this than the stock OEMECU. AEM w/ Wideband support FTW.

I doubt you will spend the 2500$ or so on this equipment so best bet is run 87 and keep your foot out of it.

 

This is something I've experimented with quite a bit. In summary.. if your tune is stock you won't gain anything from the octane alone. The fuel might have more energy in it causing the load to go down. And from that you'll gain a little. But if it's just cheap gas at a higher octane you won't gain a lick.

Now if your tune/timing is adjusted for the appropriate rpms vs load. Then yes you will increase MPG. Since I can tune my own, this is what I've done.

Even though I run shell 93 or sunoco 93/94 costing $0.20 more per gallon. It's cheaper overall because of the increase. Another thing I greatly benfiet from is low end power. I've got lots more timing down low too..

 

I noticed a few extra miles per gallon but wasn't worth the extra money it cost for it. So I am back to 87 again.