lisamcgu

I try to live my life with no regrets, so I thought I would just try it ONCE to see what it was like, just so I would know ...

So, I just spent $93.00 for a tank of gas at one of those 100 octane pumps at the 76 station at the end of San Miguel (in Newport Bch, CA).

Sh*t. My car f**kn loved it. SOOOOO SMOOOOTH. That's what I first noticed. Now I can tell the pick up is not only soooo much smoother but alot quicker. Sh*t.

The car takes such good care of me. How will I be able to deny it ... Sh*t ...

E55AMG99

The optimum octane for your car is much lower than 100. Probably somewhere between 91-93. Anything above that is simply being wasted.

Thericker

Totally TRUE if your normally aspirated anything past 93 is just being burped out your tail pipes, now if you had a blower then indeed your car will LOVE 100 octane and use it for more power. I've researched it's effects and talked to tuners about it and they said using 100 octane w/SC engine easily dynos 10 extra rwhp...But w/out blower your gains are nill if anything

E55AMG99

Blowers and turbos respond well to higher octane but at some point you would reach a maximum on a pressurized engine as well. I wonder how much higher it is on the 55K or V12 BiTurbo?

Thericker

From the tuners I spoke w/they tried it on the new 55k's and told me your pretty much wasting your money after about 105 octane, I don't know what the Turbos are capable of though....

lisamcgu

I'll try and remember what you're sayin, but have you tried it on your cars. I swear it is soooo much smoother, and quick, you can't help but notice. Just try. I would love to know what you think from actually experiencing it. I would love to be wrong on this one.

fredfromny

Very true- Unless the timing is advanced gains will be minimal.

E55AMG99

LOL! Yes, I have tried it on my cars and many other engines that I've built or tuned.

You are feeling the placebo effect.

lisamcgu

Have you tried it with the newly redesigned SLK55 engine?

E55AMG99

What "newly redesigned SLK55 engine"? The motor in your new SLK is very close to what is in my 99 E55.

AMGDAN

I agree. I ran out of gas on the racetrack and I have used 100 octane racing gas (6$/gal); not bad when you compare with the premium gas in Seattle these days at3.15$/gal.
I did not feel any major difference. I am sure if you remap your ECU, it might be a little different.

E55AMG99

I have the PowerChip 93 octane ECU program and there is a big difference between 91 and 93 but no gains over 94 as measured by the Gtech.

Mr Wolf

Lisa, how much did you pay per gallon? Jim

fredfromny

Then again I hear that 93 octane is almost impossible to get in Cali
so after a steady diet of lower octane, the difference you feel could be attributed to that higher octane!

Cheers.

E55AMG99

93 is impossible but not 100! There is a 76 station about 5 miles from my house that has the good stuff. I put about a quarter tank in before toping off with 91.

lisamcgu

Hey! I thought you said it wouldn't make a difference. My wallet hurts ...

Wolf - $5.49 a gallon

E55AMG99

I didn't say it wouldn't make a difference. I said that "The optimum octane for your car is much lower than 100. Probably somewhere between 91-93. Anything above that is simply being wasted." I also said that in my "E55 I have the PowerChip 93 octane ECU program and there is a big difference between 91 and 93 but no gains over 94 as measured by the Gtech."

What part of my posts aren't clear to you?

Chappy

What matters is that you enjoyed it

FWIW, I've run 100 unleaded in my CLK55 (same basic engine as your, except the compression ratio) and measured no difference in performance. I filled the tank several days before the track day and allowed the car to "learn" any differences.

Nil. Nada. Zip....no difference in performance whatsoever. Keep in mind that "standard" premium here is 93.

Bigdot

i agree with you lisa. i can feel the biggest diffrence in the SL than in teh 996. i think it is becsaue it is older and because i got a diffrent ECU. but i love the 100 octane

mark

lisamcgu

Huh? :totallyconfused:

Okay, how about this, I just do what you said you do before. A little 100 and a lot of the cheaper 91?

E55AMG99

Yeah, something like that....3/4 tank of 91 octane plus 1/4 tank of 100 octane will likely give you the same readings on your butt dyno as a full tank of 100 octane. :p

Falco

Yes! increasing above 93 will likley have no increase in performance. Although the compression ratio of 75%*91(68)+25%*100(25)=93 approx octane. Since the light comes on with around 15 gallons gone, 11.25 of 91 and 3.75 of 100 will get you there and cost around $60(LA prices). This is only $10 more than a full 15gal of 91 octane so i say even if it only satisfies the butt dyno, go for it!

I wouldnt be surprised though if getting to 93 vs 91 adds 10-15 hp at the crank...

On the other hand, the smell of 100+ octane gas is a wonderful thing!!! :v

Edit: forgot to mention that you will see a much greater increase in full throttle performance from a slight octane boost in hot weather. So while the car may run with little spark retard on 91 octane in <80 degree weather, as the temps increase you will definiatly be running increased spark retard.

lisamcgu

You guys hurt my brain

I just want to go fast and do it as quickly as possible

Falco

11 gal 91 + 4 gal 100=Go Fast :v