What fuel do you use?
Hotshot
Joined: Jun 2003
Posts: 12,340
Likes: 4,363
From: SW VA
The higher the octane, the lower your power will be (unless modded to perform on higher octane), and the worst gas mileage you'll get
I run 89 (mid) in mine to keep it from pinging...Still does it sometimes too...
I run 89 (mid) in mine to keep it from pinging...Still does it sometimes too...
Fleet Mechanic
Joined: May 2005
Posts: 1,739
Likes: 14
From: Vale, NC
While I do not know all the chemistry as many before have addressed, I do consistently get 18.2 to 18.8 mpg on the highway with the higher octane and my Diablo tune (the Diablo specifically calls for the higher octane gas). I haven't tested lower octane simply because that is not what the Diablo user's guide recommends AND because of the math I stated earlier that makes the higher cost seem a wash. I also didn't want to go through lots of trial and error tanks to eliminate any "pinging" - which would require altering the timing specs for the tune until it went away. I'm not sure how much damage "pinging" can do and I preferred to be safe than sorry. My only other piece of evidence is that I don't see many others getting that kind of mileage on this site - most posts suggest less. My dad had an '01 just like mine and he never got above 17mpg.
Sounds convincing that the lower octanes wouldn't hurt, but why would my tune require the 91+ and state it so directly?
Sounds convincing that the lower octanes wouldn't hurt, but why would my tune require the 91+ and state it so directly?
Posting Guru
Joined: Feb 2007
Posts: 2,351
Likes: 8
I will not pretend to know about "all triton motors" or even all Triton motors in the '97-'03 range.
However FORD published "9.0:1" compression ratios for 4.6 & 5.4 Triton motors in '98. That model year represents my F150 & that year literature happened to be on my desk.
When unleaded gas came in virtually all manufacturers began to produce relatively low compression motors.
However FORD published "9.0:1" compression ratios for 4.6 & 5.4 Triton motors in '98. That model year represents my F150 & that year literature happened to be on my desk.
When unleaded gas came in virtually all manufacturers began to produce relatively low compression motors.
Posting Guru
Joined: May 2006
Posts: 2,486
Likes: 0
From: Iowa
While I do not know all the chemistry as many before have addressed, I do consistently get 18.2 to 18.8 mpg on the highway with the higher octane and my Diablo tune (the Diablo specifically calls for the higher octane gas). I haven't tested lower octane simply because that is not what the Diablo user's guide recommends AND because of the math I stated earlier that makes the higher cost seem a wash. I also didn't want to go through lots of trial and error tanks to eliminate any "pinging" - which would require altering the timing specs for the tune until it went away. I'm not sure how much damage "pinging" can do and I preferred to be safe than sorry. My only other piece of evidence is that I don't see many others getting that kind of mileage on this site - most posts suggest less. My dad had an '01 just like mine and he never got above 17mpg.
Sounds convincing that the lower octanes wouldn't hurt, but why would my tune require the 91+ and state it so directly?
Sounds convincing that the lower octanes wouldn't hurt, but why would my tune require the 91+ and state it so directly?
Yes you will get better miliage with your tune, thats because it has upped teh timing... but somebody with a stock tuner wont have that option...You need to run the higher octane when on your perfomance level tune, same as i do with my edge...
I actually normally run the 87 octane tune, and put my 89 octane E10 in, and bump the timing a degree or two... makes it purr like a kitten....
Posting Guru
Joined: Jul 2005
Posts: 1,940
Likes: 0
I will not pretend to know about "all triton motors" or even all Triton motors in the '97-'03 range.
However FORD published "9.0:1" compression ratios for 4.6 & 5.4 Triton motors in '98. That model year represents my F150 & that year literature happened to be on my desk.
When unleaded gas came in virtually all manufacturers began to produce relatively low compression motors.
However FORD published "9.0:1" compression ratios for 4.6 & 5.4 Triton motors in '98. That model year represents my F150 & that year literature happened to be on my desk.
When unleaded gas came in virtually all manufacturers began to produce relatively low compression motors.
You have non-PI heads on your Triton V8.....Ford upgrades the heads (PI) around 99-00 on 5.4l and 4.6l engines which resulted in an increase in compression.
Senior User
Joined: Sep 2006
Posts: 151
Likes: 0
My truck gets 87 octane. My other cars get 91 b/c they are designed to take advantage of the timing advance and getter efficiency of the higher octane fuel. I actually ran 87 octane for a month in my mitsu and found that the reduction of fuel efficency was greater than the extra cost of the 91 octane fuel.
Bottom line F150 with premium - waste of money. Car designed for premium and running 87 - waste of money.
Best fuel? Any name brand has the good additive packages like techron to keep everything in order. OR you can run COSTCO/Starvin marvin fuel and buy techron additive every so often to get the same benefit.
Bottom line F150 with premium - waste of money. Car designed for premium and running 87 - waste of money.
Best fuel? Any name brand has the good additive packages like techron to keep everything in order. OR you can run COSTCO/Starvin marvin fuel and buy techron additive every so often to get the same benefit.
Senior User
Joined: Sep 2006
Posts: 151
Likes: 0
While I do not know all the chemistry as many before have addressed, I do consistently get 18.2 to 18.8 mpg on the highway with the higher octane and my Diablo tune (the Diablo specifically calls for the higher octane gas). I haven't tested lower octane simply because that is not what the Diablo user's guide recommends AND because of the math I stated earlier that makes the higher cost seem a wash. I also didn't want to go through lots of trial and error tanks to eliminate any "pinging" - which would require altering the timing specs for the tune until it went away. I'm not sure how much damage "pinging" can do and I preferred to be safe than sorry. My only other piece of evidence is that I don't see many others getting that kind of mileage on this site - most posts suggest less. My dad had an '01 just like mine and he never got above 17mpg.
Sounds convincing that the lower octanes wouldn't hurt, but why would my tune require the 91+ and state it so directly?
Sounds convincing that the lower octanes wouldn't hurt, but why would my tune require the 91+ and state it so directly?
With that said, im suprised that its as simple as advancing timing to get better fuel efficiency. Usually greater timing advance is due to higher compression ratio motors. Maybe your block is a later model which has higher compression.
If you are getting 18 mpg running the diablo with premium, you are doing better than 90% of the guys on this board and stick with what works!
Posting Guru
Joined: May 2006
Posts: 2,486
Likes: 0
From: Iowa
Tuners make a big difference, i was getting that kind of miliage with my 4.6l all day... now with my 5.4l swaped and running a 4.6l tune from my edge, and its not to bad... i got 17.2 runing 75 down to ST.L with a tail wind, and runing 75+ coming back up with a head wind i still got 14.3 or somthing... but i can pull 16 pretty easy at 70 mph normally... cant wait to get my truck tuned for the bigger engine... hopefully will see some MPG gains
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Fleet Mechanic
Joined: May 2005
Posts: 1,739
Likes: 14
From: Vale, NC
I suppose I will try a tank of the 89 and see if it starts pinging or if I loose mileage. With my Diablo I can go in and retard the timing gradually, it just takes time and makes me nervous because I'm messing with something on the computer I really don't know a bunch about. However, since premium just went over $4 a gallon at my favorite Hess station (usually 5-20 cents cheaper than anywhere else in town), the downgrade to 89 would get me back under $4.
Just to make sure, though, how damaging is "pinging" while I experiment with this?
Just to make sure, though, how damaging is "pinging" while I experiment with this?
Posting Guru
Joined: May 2006
Posts: 2,486
Likes: 0
From: Iowa
i dont think you should be messing with the timing, i would continue to run what your tuner specifies as safe for that tune, dont you have more than one level on your diablo? I have 3 on my edge. Level 1 is towing, trans adjusment only, level two is for 87 octane and does the transmession and messes with the timing and fuel curve, and level three is for 91 octane and it messes with the timing and fuel curve even more... But run the fuel your tuner specifies... unless you want to do some tuning yourself...
Pining can be harmefull if let go and done alot. But back in the day, guys used to tuned there engines so close to max power that they would get some pining under heavy load...
I would just stay away from tuning if you dont really know what your doing..
Sorry if this is confusing bud.. GL
Burns
Pining can be harmefull if let go and done alot. But back in the day, guys used to tuned there engines so close to max power that they would get some pining under heavy load...
I would just stay away from tuning if you dont really know what your doing..
Sorry if this is confusing bud.. GL
Burns
Fleet Mechanic
Joined: May 2005
Posts: 1,739
Likes: 14
From: Vale, NC
Seems like it might be easier to go tar and feather a couple of oil speculators than get this mix right!
As for "what is pinging" - it's a distinct noise you hear when accelerating (generally) that sounds very much like a "ping". I believe it is pre-detonation of the fuel in the cylinder and so you hear this sound - others can be far more accurate with the definition. But you generally can hear it if you have it until you get into the grey areas between having and not having it. That made no sense.
Posting Guru
Joined: May 2006
Posts: 2,486
Likes: 0
From: Iowa
My edge has all that to...
The pining i heard sounded like a loose bolt rattling around inside the engine... it was loud and very distinct... but yes its pre ignition, the fuel ignites due to pressure instead of from the spark plug
The pining i heard sounded like a loose bolt rattling around inside the engine... it was loud and very distinct... but yes its pre ignition, the fuel ignites due to pressure instead of from the spark plug
Posting Guru
Joined: Apr 2005
Posts: 1,290
Likes: 1
From: Edgerton, WI
Basically, what is happening is that the air/fuel charge is ignition before the piston reaches TDC and puts a lot more stress on the piston and conneting rod.
If your tuner says to run 89, thats what I would use.
