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.
Ummm...something is wrong with your car if it runs better on premium. Have you checked the timing?
Exactly - a car will not run better on premium unless it was designed to run on premium.
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.
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.
There is no local dragstrip here. Just a dirt roundy-round track. :p
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.
Yeah, that was the extent of the other conversation I mentioned.
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).
His 87 would be cfi.
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.
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.
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.
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