Higher Octane Gas and MPG

[Louisiana_CRX 5,000+ posts]

My Saleen requires 91 octane with the mods...I usually run 89 octane gas in it...because the rating is min 89 ...I've noticed I get about 2-3mpg better gas mileage running the 89 over the 93 ...I was curious if anyone else has noticed less mpg running the higher octane gas as well //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif...I don't run the 87 because I've been told it could damage the motor...I'm not sure how...it might would get even better mpg...who knows...lol

Another trick I was told and it seems to help MPG is turning the traction control off....It auto. comes on everytime you crank the vehicle so it has to be manually turned off...I do leave it on when the roads are wet or curvey...I was also curious on any insight to this....as well

I can do all sorts of wiring but I only know basics about car performance and features...so any information on this would be appreciated...Thanks //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Click to read more...

 

[kasimo420 10+ year member]

High performance vehicles that have a high compression ratio and also turbo/superchargers require higher octane. If not, you get that little knock in the engine that is no good. Had to run 91 in my SRT-4 and it sucked.

 

[mlstrass 5,000+ posts]

higher the octane rating the slower the fuel burns. This is to help prevent pre-ignition/detonation in higher compression engines that build more cylinder pressure. Pre-ignition means the heat in the cylinder is causing the mixture to burn and not the spark from the spark plug. That's why you hear that horrible rattling sound when it happens as the mixture is igniting at the wrong part of the piston stroke.

You're probably getting a more complete burn when running 89 octane and if you're not beating on the car then it's probably fine...

 

[Grinder1989 5,000+ posts]

My Saleen requires 91 octane with the mods...I usually run 89 octane gas in it...because the rating is min 89 ...I've noticed I get about 2-3mpg better gas mileage running the 89 over the 93 ...I was curious if anyone else has noticed less mpg running the higher octane gas as well //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif...I don't run the 87 because I've been told it could damage the motor...I'm not sure how...it might would get even better mpg...who knows...lol
Another trick I was told and it seems to help MPG is turning the traction control off....It auto. comes on everytime you crank the vehicle so it has to be manually turned off...I do leave it on when the roads are wet or curvey...I was also curious on any insight to this....as well

I can do all sorts of wiring but I only know basics about car performance and features...so any information on this would be appreciated...Thanks //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

X2 on what they said about gas. 89 will burn more thoroughly can 91 in your engine but you risk pinging if you beat on it hard. 91 is the safer beat if you run it hard. Traction control only engages when provoked. It does not run all the time (at least on every car I've driven) so it should not affect MPG when it's on.

 

[kasimo420 10+ year member]

X2 on what they said about gas. 89 will burn more thoroughly can 91 in your engine but you risk pinging if you beat on it hard. 91 is the safer beat if you run it hard. Traction control only engages when provoked. It does not run all the time (at least on every car I've driven) so it should not affect MPG when it's on.

True on traction control. Will engage when you slide or if you are burning out.

 

[Louisiana_CRX 5,000+ posts]

It seems on the dash mpg gauge it goes up with the traction control off...I seldom run it too hard...I play in it every now and then...but nothing major....also I don't hear any knocking in the motor from 89 octane gas...I've noticed in the miata after it sits for a while it will make some clattering though its designed for lower 87 octane...usually a tank of 93 straightens it out....I figure the 87 gets weaker with age....

My 87 Caravan 3.0 mitsubishi V6 had 2 year old gas in it ...can't remember the grade but most likely higher ...it still cranked and the motor sounded fine

 

[FineLinePimpin 10+ year member]

Traction control has ZERO effect on MPG's..if you are seeing a change its purely coincidence. Im guessing you have the non supercharged Saleen, so the 89 octance will be fine unless in very hot weather you get spark knock. 05 and up mustang have the Spanish Oak ecu that can use either low..87-89 octane or higher 91-93 octane and adjust accordingly and actually make a little more power on the higher octane. If your car ISNT tuned for higher octane it will actually get WORSE mpg's on said higher octane because it will burn through it quicker.

I would run the 91 octane in the warmer months because of the way the car SHOULD be tuned from Saleen. You could always get a handheld tuner to change that though. Unless its blown the lower octane tune will work fine.

 

[dman4486 5,000+ posts]

I think you will find it has less to do with the octane rating, and more to do with the different loads of fuel the station gets. even sticking with the same station, you will get different percentages of ethanol.

I found that 0% ethanol premium gas in my motorcycle allows me over 200 miles on 2.5 gallons. as the % goes up my mileage drops. average for me is between 50 and 65 mpg, but on my trip last year to myrtle beach for bike week, we stopped at a station about half way down SC and filled up. I noticed a sign that said "we are ethanol free". I ran 180 miles before switching into reserve...that is 2 gallons!!!!!90mpg!!!!!

 

[dman4486 5,000+ posts]

Traction control has ZERO effect on MPG's..if you are seeing a change its purely coincidence. Im guessing you have the non supercharged Saleen, so the 89 octance will be fine unless in very hot weather you get spark knock. 05 and up mustang have the Spanish Oak ecu that can use either low..87-89 octane or higher 91-93 octane and adjust accordingly and actually make a little more power on the higher octane. If your car ISNT tuned for higher octane it will actually get WORSE mpg's on said higher octane because it will burn through it quicker.
I would run the 91 octane in the warmer months because of the way the car SHOULD be tuned from Saleen. You could always get a handheld tuner to change that though. Unless its blown the lower octane tune will work fine.

this new computer allows the timing to be retarded in order to run the lower octane gas. When you go to a higher octane you can advance the timing and get more performance.

I also tested this on my Maverick. higher octane gas allowed me to go as far as 14 degrees above TDC where regular unleaded could only run 8 degrees before getting a knock.

 

[blackdragonaudi 10+ year member]

My honda civic take regular but I have done a few drives with premium and saw 4-5 miles more per gallon.

 

[bones22 5,000+ posts]

higher octane =

more refined, burns hotter & faster, you will see better performance because of those things. mpg will drop slightly but engine will last longer and perform better.

some engines designed for it will do well though

lower octane or regular unleaded =

lowest quality or waste product from making higher grade fuel. mpg would be much higher if it didnt have the ethonal mix

 

[dvrmstrng 5,000+ posts]

hmmm maybe ill try this out cause i know i CAN run 89 with no problems and i could try the TC thing...but what if its manual?

 

[FineLinePimpin 10+ year member]

this new computer allows the timing to be retarded in order to run the lower octane gas. When you go to a higher octane you can advance the timing and get more performance.
Thats pretty much exactly what i said lol