This is an age old debate...93 or 87. Our trucks are made to run on 87 and anything higher will muck things up. Ive been conducting a little experiment. Ive been switching between 87, 89, and 93. I get the worst acceleration and mpg with 87, better mpg and acceleration with 89, and the best mpg and acceleration with 93. No, I dont have the super chip. Ive also been testing this on my 91 explorer and my girlfriends 93 Sable...all the same. So, if our engines are not able to handle the higher octane, why are these three different engines doing better?

------------------
The Truck: 1997 Black F-150 Flareside. Regular Cab ORP and Towing Package
The Mods: K&N Filter, Eurolid Hard Tonneau and Ford Bug Deflector.
The Site:
Triton's 4.6 Liter Web Page
www.mindspring.com/~acbradley/index.html



[This message has been edited by Triton46 (edited 09-25-1999).]

 

That is a very good question. The higher the octane, the slower the burn rate, so for some reason, putting a slower burning fuel in your gas tank(s) has given you more pep. Go figure.
Take care,
-Chris

------------------
Are you A.S.E. Certified ? If so, ask me about
iATN...the best tool you'll ever have ! ! And it's
free

 

Care to share your testing procedure, i.e. Dyno runs or quarter mile times?

------------------
1998 STX 4.2L V6 Auto

 

they all seem to run about the same to me
but i do get a mile or two better mpg
but it's 20 cents more for the 93
so i'm runnig 87 for now

------------------
99 XLT SC 4x4 STYLESIDE ORP 5.4,AUTO & 3.73 POSI
MED. TOREADOR RED
EXTANG TONEAU,BED MAT,
K&N FILTER & WOOD DASH KIT

 

I run 87 and feel like I have plenty of power.
I haven't even bothered with engine mods.

------------------
99 XLT 5.4L reg cab
4x2 120" Wheelbase
4 wheel disc brakes/ABS
5 star larait style wheels
Toreador Red/Silver
3.55 gears 255/70/16 OWL
Delta toolbox
Eclipse 5340 cd player
Memphis ARCS50 component speakers w/tweeters mounted flush in the door panels (excellent sound)
Sherwood 35x2 RMS amp for components.
Jensen 50x2 RMS for subs.
2 6.5" Bazooka tubes
Lowering shackles?
54regcab@duesouth.net in Columbia SC

 

The way I understand, it would seem that the computer pushes for the best spark advance, and until it senses ping it will not retard the timing.

More timing advance equals more performance. Pull the battery cables then go try your truck. It will seem faster because it is. It has a relearn time before it can make a change to the timing unless it senses ping.

I do not know the time cycle but the computer if forever pushing for increase spark timing. When it senses ping it retards the timing. It learns the max timing and will leave it there so as to avoin ping. Every once and a while it will push for more advance and If it doesn't sense it the timing will be set higher. This is why higher octain can be used. To speed up the process unplug the battery after filling up. Every thing will be set back to square one and the computer will test all of the spark curve for ping and realize the higher octain faster. The Superchips changes the spark curve so it would require higher octain because it can not reduce advance to the lower OEM levels.

Regards

JMC

------------------
On Order: 00 F-150 XLT SC Flairside 4x4 4.6 w/5spd
using: Wife'S 99 Explorer till arrival

 

JMC - Huh? Where did you hear this? This is only true if your truck had a knock sensor. It doesn't.

------------------
1998 STX 4.2L V6 Auto

 

I believe all 97 and up F-150's use a knock sensor. Not sure of the other vehicles. I read that the octane rating was a measure of a fuels resistance to knock (car and driver chip test). So if an engine's knock sensor retards timing or spark advance to reduce knocking, it should run better on higher octane due to more timing advance available with higher octane. As JMC stated more spark advance = better performance. I am not an auto mechanic just what I read.
Jeff

------------------
1999 F150 Lariat
Reg cab Short box Styleside
5.4L 3.55ls
Deep Wedgwood Blue/Silver
Lund Interceptor hood shield, VentVisors, Class III hitch, Ford molded mud guards, soft tonneau, factory CD with changer (thanks Dusty), tinted windows

Menasha, WI

http://www.fortunecity.com/silversto...ton54home.html

 

Thats pretty much what I found too, I read alot of articles on it today to become more familiar with octane. My main question was is harder to burn and robs performance, then why are products like 104 Octane boost out there? From what I found the only thing you can take for fact are:

All octanes burn at the same temperature.
93 is more resistant to knock than 87.
Minute performance gain in using 93.
Better MPG for 93.

In conclusion, whatever keeps it from knocking and gives you the best MPG...use it. Here are the articles I read.

[html]http://www.ma.iup.edu/~lmmd/octane.html[/html]
[html]http://users.aol.com/rtclapp/fuel.htm[/html]
[html]http://www.aaa.com/news12/Automotive/autonews/rightfuel.htm[/html]
[html]http://www.world-wide-glide.com/gas.html[/html]
[html]http://www.yft.org/tex_vfr/tech/octane.htm[/html]


------------------
The Truck: 1997 Black F-150 Flareside. Regular Cab ORP and Towing Package
The Mods: K&N Filter, Eurolid Hard Tonneau and Ford Bug Deflector.
The Site:
Triton's 4.6 Liter Web Page
www.mindspring.com/~acbradley/index.html

 

Ford Tweaks Engines for Premium Power Payoff

USA Today

Consumer groups insist there is no benefit in using premium fuel if the owner's manual specifies regular. But many Ford, Mercury and Lincoln trucks, and the 1998 Lincoln Town Car that goes on sale in December, have a feature that makes their engines more powerful and improves mileage slightly if you use premium. That's so even though the engines are designed for regular, and advertised poweris obtained using regular. Ford engineers David Amos, Gary Barringer and Gary Brewer came up with the clever gimmick brainstorming. The magic gadget is a knock sensor similar to those on many engines, but set to work differently. Other knock sensors work in the negative. That is, they tone down some engine computer settings when the engine starts knocking, quelling the commotion at the expense of engine power. But Ford's has headroom built in. It will work like the others, but if you use premium, it'll also step up settings to exploit premium's properties. Amos says it adds five to seven horsepower to the nominal 205 hp in the overhead-camshaft Explorer/Mountaineer V-6. And he says premium improves fuel economy in that engine 0.8 to 1 mile per gallon. Ford can't advertise the higher horsepower and fuel economy numbers unless it's willing to specify premium fuel, which marketers fear could scare off buyers. The sensor also is on all trucks using Ford's 4.6-liter and 5.4-liter V-8s and 6.8-liter V-10. That's most F-series V-8 pickups, all Expedition and Lincoln Navigator sports utilities, and some Econoline vans. And it will be on the 4.6-liter '98 Town Car.



------------------
1998 F-150 Super Cab XLT, 4x4, SWB, StyleSide, 5.4L, E40D Automatic, Dark Toreador Red, Med Graphite Cloth Captain's Chairs, P255/70R-16 OWL AT Tires, 3.55 Limited Slip Axle, Cab Steps, Trailer Tow, Power Color-Keyed Mirrors, Fog Lights, Cast Aluminum Wheels, 6-Disc CD Changer. Aftermarket: Penda Bedliner, Keyless Entry, Delta Deep Aluminum Toolbox, Hellwig Rear Anti-Sway Bar, Gibson Swept Side Stainless Steel, K&N, Custom CB and Amateur Radio Installation. See me and my truck at http://bluecrab.richmond.edu/crab-1.htm

 

I knew it Steve! Thanks!

------------------
The Truck: 1997 Black F-150 Flareside. Regular Cab ORP and Towing Package
The Mods: K&N Filter, Eurolid Hard Tonneau and Ford Bug Deflector.
The Site:
Triton's 4.6 Liter Web Page
www.mindspring.com/~acbradley/index.html

 

Steve- Great info ! Thanks !
Triton- To answer your question, different octanes may burn at the same temp, but the burn rate is slower with higher octane. Let me try to explain: The air/fuel mixture in your combustion chambers isn't flammable enough to run an engine on, as they are, but by compressing the mixture, it becomes more flammable. The problem is that if you compress it too much, the air/fuel mixture becomes unstable and will detonate on it's own with out the help of a spark plug (ie: detonation, pinging). In order to help make the air/fuel mixture more stable, octane is increased. The octane actually slows down the burn rate, so that you can run higher compression with out detonation. This is why engines with higher compression pistons need to have higher octane fuel than those with lower compression pistons. Additives like 104 octane boost are designed for vehicles whose compression is too high to run only 93 octane pump gas. In other words, if your compression was so high (say, 11:1 or higher) that even with 93 octane gas, the mixture was still too unstable and caused pinging, you could add an octane booster (104) to help further slow down the burn rate and make the fuel stable enough to support the higher compression. This is why "high performance" vehicles (with either high compression pistons, a blower or turbo, or ignition timing advanced beyond recommended limits) use higher octane fuel. Unfortunately, there is a misconception that the fuel alone will make any vehicle faster, which is why so many people waste their money on higher octane fuels. With the exception of the newer Ford vehicles that Steve mentioned, the best octane for any vehicle is the lowest you can use without causing detonation or pinging. Higher octane actually slows these vehicles down and promotes worse gas mileage. I hope this helps shed a little light on it for you.
Take care,
-Chris

------------------
Are you A.S.E. Certified ? If so, ask me about
iATN...the best tool you'll ever have ! ! And it's
free

 

This is great news!!!!!!!!!I am going for 89 octain next tank!!!!!

Hot v6 .............the 4.6 and the 5.4 do have a knock sensor.

------------------
97 F-150 4.6 auto, 4x2, 3.55 LS, trailer tow pkg, Air box modification with K&N, Dynomax Super Turbo exhaust.
Oh yeah, it's Oxford White with crome wheels, Legacy shell & custom grill, mlaugh-Meridian, Idaho.

 

PKRWUD-
Very informative!! You sure answered a lot of the questions I always had about octane.
Steve-
That information is from USA today?!? It sounds to me like Ford built a Superchip right in to their computer! Why go buy one? Would you please post that information over in the 'Computer Chips' discussion? There are alot of people who would really like to see that. Thanks!!!

 

Does anyone know if the 4.2L uses a knock sensor? If the V6 does use a knock sensor, will the engine benefit from higher octane like the 4.6L/5.4L?