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Topic: Treid 93 octane (Read 2021 times) previous topic - next topic

Treid 93 octane

and now i hooked. My old 3.8l loved it. and when i tried puttin back in regular it acted so nasty(no worse than before) so now im hooked.
and possibly becoming a 5.0 soon.

Re: Treid 93 octane

Reply #1 –
Ummm...something is wrong with your car if it runs better on premium.  Have you checked the timing?

Re: Treid 93 octane

Reply #2 –
Exactly - a car will not run better on premium unless it was designed to run on premium.
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣

Re: Treid 93 octane

Reply #3 –
We just had a discussion on "octane creep" over on the Lincoln board.. older cars needing higher octane as they get older. (my '89 needs 89 octane now, or it knocks) Don't know that performance changes when I use higher octane, though.. aside from not knocking anymore.. so I don't know if that discussion is applicable here.

Re: Treid 93 octane

Reply #4 –
Quote from: Bird351
Don't know that performance changes when I use higher octane, though.. aside from not knocking anymore.. so I don't know if that discussion is applicable here.

None. 87 octane and 93 octane have the same energy density (MJ/kg). The only (notable) difference is that 93 has a higher auto-ignition temperature than 87. 93 doesn't burn any slower than 87, no matter if "Zeke" down at the local 1/4 mile track says so.

Re: Treid 93 octane

Reply #5 –
There is no local dragstrip here. Just a dirt roundy-round track. :p

Re: Treid 93 octane

Reply #6 –
One possibility behind the older cars needing higher octane would be excessive carbon build up in the combustion chamber, which would effectively raise the compression ratio slightly. Increased compression ratio would require higher octane.
[SIGPIC][/SIGPIC]http://www.fquick.com/slicksport88
88 Sport - 5.0HO, Mass Air, A9L, 73mm C&L meter, BBK CAI, 255 lph pump, 1.7 roller rockers,Professional Products damper, Chuck W motor mounts, BBK shorties & H-pipe, Flowmaster 40 series, 8.8 rear w/3.27's, 93 Cobra M/C, BAER 13in. drilled/slotted rotors front and back, cobra calipers, Russell braided brake lines front & back, C/C plates, 03cobra rims, 255/40/17 Nitto 555's all around

Re: Treid 93 octane

Reply #7 –
Yeah, that was the extent of the other conversation I mentioned.

Re: Treid 93 octane

Reply #8 –
Octane creep is all to real.  In addition to carbon in the compustion chambers, sometimes a bigger problem is a malfunctioning EGR system.

On "newer" (hotter compustion chambers to promote complete combustion) engines with multiport injection, the EGR system will often plug up with carbon (with age and miles).  Certain engine are very pr0ne to this (I don;t know why...just recoginsing a pattern here):  Chrysler 2.3, 2.5L FWD, Ford 2.3L HSO, anything by VW, etc....

I know personally my tempo's egr failed four years ago, and I dissabled the valve.  Now the car will always ping with regular 87 octane (it needs 89)  Keep in mind this engine has no form of knock sensor, and over 300 000km.  I felt the more expensive gasoline justified by foregoing the $400 egr valve and $250 module.

In the case of the first posters T-bird, something is advancing the timeing too much.  Often the rotating plate for the mechanical advance in the dist will stick perodically if not lubricated.  (This assumes your 3.8L is carbbed, my old one was).

Re: Treid 93 octane

Reply #9 –
His 87 would be cfi.
One 88

Re: Treid 93 octane

Reply #10 –
My vote is for slipped ignition timing or possibly the carbon thing.  Though, I think it would take a hell of a long time for carbon to cause that much trouble.

Re: Treid 93 octane

Reply #11 –
my wifes car runs for  on 87, we put in 89 and it is smooth as hell. been in the shop several times, even has new intake gasket. I don't know why but it is true.

Re: Treid 93 octane

Reply #12 –
Both of my CFI 3.8s run on 87 just fine. I'd runn some SeaFoam through your engine to clean any carbon deposits. If it still runs poorly on 87, I suggest taking the CFI off and cleaning the EGR passages. The EGR passages on my 3.8s were all but closed up after 15+ years of running.
 

Re: Treid 93 octane

Reply #13 –
My '83 T-Bird 3.8L (carburated) has showed no difference in back to back runs down the 1/4 mile, using higher octane fuel.  The C.R. just isn't high enough to utilize it.  My 3.8L Buick, (8.3 to 1 C.R.), I used to race did see a performance increase with the use of 101 race gas, but only because it allowed more spark advance before detonation.  IMO the weather makes more of a difference that high octane gas, all things being the same.  Fred