is higher octane really any better for the 4 cylinder?

my last fill up was with 87 again and i'm going to keep track of the mileage so we'll see how it goes

 

In my 02 2.4L auto the truck does best on 89 octane. Runs smooth and consitant. When filled up wih 87 I can notice more acceleration lag less mpg. on 91 it felt the same as 89.


I always fill my truck wth 89.

 

i run medium grade, what ever it is, 89 or 91.

i run premium in all my power equiptment

 

My 05 RC 2.7 I use 87 and get 400 miles to a tank.

 

Well, I have never seen an owners manual that clearly directs you to use 87 Octane.
They all say "Minimum of 87" This means never use anything lower.

So, If you are using 87 and your knock sensor detects ping, the computer retards timing to lessen the spark knock. Retarded timing equals a slight loss of power.

I actually tow with my 4cyl, I use mid grade (89) to avoid the issue of spark knock, and retarded timing resulting in loss of power.

Rememgber that octane is the measurement of a fuels ability to resist knock.

 

how do u know if ur truck pings?

 

You will hear it. It will be a high pitched knocking noise coming from your engine. It usually happens under load and is more common when it's hot outside. I had a 1994 Ford Ranger that could run 87 octane in the winter, but during the summer, I had to run 89 to stop it from pinging. My current Tacoma has never pinged on 87 octane, even in +100 degree weather.

 

There's more energy is regular gasoline, which has more volatile molecules (more explosive power) than high test. The additives in high test promote a more uniform burn, in order to reduce engine knock.

 

in my opinion, if you say its a waste of money to use higher octane thats a little silly. It cost like 20 cents more so after 15 gallons thats like 2.50. i can definitely tell a difference in my truck going up hills, with 87 it seems like I'm driving through mashed potatoes and i have to down shift. as for mpg im unsure because i have been buying 93 octane since i got my truck and only put in 87 on accident. thats just my opinion though, i love my truck so i give it the best drinks when its thirsty!

 

Doing the test now, My FJ Cruiser burns supreme and if I run regular it cuts my MPG about 3 miles per gallon. I'll post up after this tank.

 

Isn't your FJ a 4.0l V6. We are talking four cylinders here. The V6 can take advantage of higher octane fuel but the I4 was designed to use 87 octane.

If you think that you get more power or better MPG out of a I4 with high octane fuel then something is wrong with your calculations or your engine.

It would be almost impossible to prove one way or the other without a controlled test environment.

87 octane has more energy than higher octane fuel because higher octane fuel has additives that reduce the burn rate to prevent preignition (knock) in higher compression engines.

 

well i tested 3 tanks of each and i got just under 20 mpg running around town in the same spots (i drive a lot) and with the 87 i was getting about 17 so it does make some difference with the mileage, idk about performance tho

 

So for the V6 4.0. what about mid grade gasoline? I have a 2010, do you hear ticking in your engine? I use 87 per the service dudes, they say don't waste your money.

 

If I were you, I would judge for yourself if it's worth it. Try a few tanks of each grade and see if you notice enough improvement to warrant the extra cost of higher grade gas. Your truck will run fine on 87, but you may like the performance increase of premium.

 

i have a second gen 4 cylinder 5 speed, and I only run high octane in the summer when I know im going to be using the AC, the small increase in power seems to bring my shift points back to where they were without the AC on. Although you have to pay pretty close attention to the truck in the first place to pick out the difference between the high octane vs regular

 

Is it bad to switch back and forth octanes? Will "spark knock" occur? If I go long driving, should I put premium? When is the best time to put premium and regular? Sorry if this question has been asked already...

 

Not bad to switch back and forth.
Spark knock (pre ignition) should not occur on normally aspirated four cylinder Tacos unless something is wrong with your engine or the gas isn't really 87 octane. In any case, don't lug your engine.
Best time to buy is when you need fuel.

 

In middle Georgia all we have is 87, 89, 93, I tried 93 for about 3 weeks and seemed to use MORE fuel using 93. So I went back to 87.

 

In theory that is what should happen since some energy is lost in higher octane fuel because of the anti knock additives.

 

http://green.yahoo.com/blog/daily_green_driving/62/six-gas-mileage-myths.html

From Yahoo...