Erfan

Mean Gene,

Will my 96 ES300's anti knock sensors pull back my timing in a pinch?

mooretorque

Erfan, not addressed to me, but the answer is "yes". This is a process occurs constantly and so rapidly that you'll never hear knock, much less damage your engine with it.

kreativ

Mean Gene -
Thanks for the write-up. It's people in the oil industry, like you, from which I've garnered all the advice.

I haven't had any personal experience with Arco, since I've always heard it was the major gasoline brand to avoid. Thinking this was hearsay, I checked in the online newsgroups and read some posts concerning why it was bad..something about high alcohol content? Don't recall the exact reasons anymore. Around here, Arco is consistently the cheapest, so I would be using it otherwise.

Out of convenience and price reasons, I use Shell. I've heard good and bad things about it, but I figure as long as it's a major brand and there isn't a strong quality concensus either way, it's okay. But Shell doesn't mention any sort of detergent additive in their gasoline.

I read that Chevron Supreme has 3 times the level of Techron as the lower 2 grades, and that the reason they reduced the levels of Techron in the lower 2 grades was because it was cleaning too well and loosening too many deposits in old engines, causing some issues with the deposits building up somewhere else.

willard west

This last may I picked up my 2001 AWD 911 at the factory.

Since I was to be driving in Europe I was advised about the fueling needs in reasonable detail. Basically I was told not to worry about the Octane rating, that if I could get the premium then I should do so, but if I could not then the engine ECU would detect the deficiency and correct for it automatically.

What I was warned to avoid was leaded fuel.

D.K.

Mean Gene, oh man you had the hemi!!! The elephant motor. That beast could pound holes in the pavement. I had the 340 small block(non six pac). God I would have loved to see that 426 hemi cuda in action launched off the line with that Dana rear end w/ say 411 or 513 gearing....... LOL

Mean Gene

E - Yep, MT's right - pretty much every car built with an ECU has a knock sensor which will pull back the timing to allow for lower octane gasoline - even my 1987 Corvette had one back then. The ECU is calibrated to adjust the spark curve to allow the maximium amount of advance ( octane's not a problem with initial timing as there's very little load on the motor ) but it's still limited to the pre-programmed parameters as burned into it by the factory. That's one of the reasons that aftermarket chips show larger power increases on non-performance cars. The factory ECU's in the Corvette, Mustang, etc, are already pretty much at their programmed limits ( allowing more spark, richer fuel curves, etc ) while the ECU in, say, a base Camaro ( non-IROC ) has much more conservative factory data in it so it has more room for improvement ( up to the limits of the ECU ). BTW - I'm just an engineer with Amerada Hess ( major independent ) but I've got a drag racing past as well as in audio competitions ( where I'm a Moderator here ).
K - The Techron adjustment was based more on revenue than concern over engine deposits. When people found out that the mid & lower grades of Chevron cleaned almost as well as the premium ( which I was told ( by a Chevron refinery engineer-friend ) does have at least twice the Techron as the other grades, they simply quit purchasing the top grade & stepped down to the others to save a few pennies/gallon. The almighty dollar rules!!:eek:
As Willard pointed out, avoid any leaded gasoline as it leaves deposits on your O2 sensors & will render them useless after a short period.
D - I started with the factory installed 4.11's & then got stupid! My 426 had the dual Carter AFB's ( mechanical secondaries, I recall ) so when I floored it off the line ( even after reving to 3-4k & slipping the clutch, there was still a slight bog. I got a set of 5.13's from Richmond Gears for the Dana 60 & the bog went away, along with traction & any mpg!!:eek: Finally settled on some Richmond made 4.56's ( the old Chevy gearing ) & this was the best compromise I could find. No street tires would handle the power ( remember the old non-metric tires like G60-15? ) & street legal slicks were yet to come. Still, with a set of M&H slicks & at State Capital Dragway in Baton Rouge, I managed to lay down several low 12 second runs. Remember that this was back in the late 70's so those were excellent times for a street-legal 4000#+ all steel sled!! Nitrous hadn't come down the pipeline yet either but the Hemi ( & it's drivetrain ) could have easily handled a 150 hp squeeze, IMO. Lord, it's turning into "Old Farts Day" on the Board - where's Ron430 when I need him??!! :eek:

Erfan

MG, thanks for sharing that info with us. It is so nice to hear stories of old hot rods of an era gone by. MG, why did they discontinue the "White Pump" gas?

Mean Gene

E - I'd say that both the Texaco "white pump" & Amoco "white" gasolines ( as well as other brands of high octane ) were discontinued because, while they were in the high 90 octane range, manufacturers began to turn away from high compression engines & the high octane gasolines were no longer needed. Also, CARB & EPA began to get stricter on emissions & it became more costly for the petroleum companies to economically produce a gasoline which was falling from demand. So "Big Oil" cut their losses & discontinued the super high octane blends, leaving those of us with high compression big blocks to either run an additive like 104+ or blend 110 octane aviation fuel with our "high octane 93" stuff!! I know that factory engine compression ratios have risen in the past few years but I'd attribute that to the onboard ECU's making the engine's so efficient & much more forgiving. Nowadays if ya get a load of bad gas ( or the wrong octane ), U MIGHT just hear a brief bit of detonation before the ECU pulls the timing back. Back in the muscle car days, detonation sounded just like they described it - marbles rattling in a tin can!! The only way to stop it was to lift your foot from the throttle & where's the fun in that?? Of course, detonate the motor enough times & U'll be replacing pistons & THAT's not fun either!! Oops - time to wake up & go back to the year 2002!!!

Erfan

Thank MG Would the additive 104+ make any performance diffrence in my stock 96 ES300?

Mean Gene

E - I'd kinda doubt that it would help ya, at least as long as U're stock. It's only about $3-4 a can so U could always try it but I wouldn't rely on the "seat of pants" dyno to verify it. Get your hands on a G-tech Pro or wait until there's a dyno day in your neck of the woods. In truth though, I wouldn't expect to see any appreciable gain - maybe 2-4 horsepower at best. I don't think the ES3's tuned for maximium performance from the ECU so I wouldn't think that the computer would allow much more additional timing to capitalize on the extra octane.

Erfan

Thanks for all of your help. what do you think of the Exxon supreme 93 octane, I have been using that lately.

Mean Gene

E - I run either the Exxon Super or Chevron Super in the GS4 & even in my Corvette years before the Lexus. Never had any injector problems in 20 years of using these gasolines so I endorse them 100% ( even if they R competitors! )

Erfan

Great, I kind of knew that the gas would be good, but i wanted to ask a expert such as yourself

kreativ

I did a little more reading into gasoline brands, and here's what I found:

You can't go just by the name brand since there are so many cross-agreements between retailers and refineries. This is because oil companies will have refineries at different places.
E.g. in N. California the Shell refinery supplies Shell and Arco. In S. California Arco supplies Shell.
Of course just because the same refinery supplies two differently named stations it doesn't mean that the gasoline is necessarily the same. One refinery was adding more Ethanol to gas it sold to other than its own stations. It was a legal amount, but the MPG is
lower on gasoline with more Ethanol so the 15 cents per gallon discount at the discount stations was being lost with lower MPG.

I'm not sure how it works then with all the different type additive packages, or if the additives are the same and Chevron just has a trademark on the Techron name.

It gets pretty confusing. I'm just going to get gas at Costco and not think about it.

Erfan

I didnt know that, thanks for telling me. What is the best way to find out what gas and brand does my particular station carries?