just curious , my stock 05 ,except for exhaust , 50,000 miles runs great on 91 octane gas, in California, highest we have @ the pump.
not sure if octane boosters really work or if any higher than 91 is going to boost performance .
any info would be nice

 

Ls2 wants straight 93 octane to run its best, and the E10 in the 91 octane fuel is not helping the cause.
The LS3 compression was lowered, to allow it to run its best on 91 octane instead.

Quick way to feel the difference,is to run a few tanks of Lucas fuel additive in the 91 fuel and you will be able to feel the difference.

 

Dano 523 , the picture you posted is Lucas cleaner/ lube , not sure if it will boost octane any , but Lucas make octane booster , mix like .6oz. to a gallon of 91 octane gas will bring it up to 94 octane , on the vette 18 gallon tank , 10.8 oz./ 11 oz.

 

The only time an octane booster (I prefer Torco) will make a difference, is if you're getting KR at WOT. Assuming you don't log your WOT events to know if any KR exists, you won't know how much octane boost it even requires. For 99% of your everyday driving, 87 octane would work OK.
IMHO, if you're not racing and you're happy with the current performance, don't mess with anything.

 

but going by GM's / Corvette owners manual 2005 LS2 10.9 to 1 compression ratio, they recommend 91 or higher octane , it does state that it will run on 87 octane but might knock and or reduce performance automatically by the computer , guess it can sense between 87 & 91 ? I'm in SoCal. 91 octane is the highest you can get at the pump, and really wonder if it really is 91 ? so to make sure I have 91+ , thought i would try Lucas Octane booster , they say it will up 91 to 94 ./ or 87 to 91
GM did lower the compression ratio in the LS3 ???

 

everyday driving in a Vette is always at least 1 real hard pull off a standing start

 

No, your car doesn't detect or sense between the octane ratings, although that is how a flex fuel sensor works with ethanol percent to pull/add timing from different tables based on %s.

Octane is how well (controlled) a fuel burns. The dumb down version is when you're running higher compression you're putting unburnt fuel under increased heat and pressure. Too much of this heat/pressure will cause the pocket of unburnt fuel to detonate prematurely before the flame from the spark has had the chance to propagate in the combustion chamber and burn cleanly. That's premature detonation is knock and that's not good for your engine.

Now someone mentioned knock retard... So if you were to log those wide open throttle pulls you do and see that your ECM is showing any KR, that's where the higher octane would boost your performance. This means that your sensor has detected a level of detonation and the KR pulls timing to prevent that. This timing that is pulled results in power and performance loss. So if you were to log WOT pulls and see that your KR is 0, then all things being equal, boosting the octane wouldn't help performance. If you add timing you'd gain power but may get into KR, and that's where the higher octane comes in.

This is extremely high level explanation as there is a ton going on, but hope it makes sense.

 

good explanation , to keep it simple ? if GM recommends 91 octane or HIGHER , hoping that 91 will not knock at any hard pull , so your getting all available HP, then I guess having like 92-93 octane would be like a insurance policy ,
but did read some info on dyno pulls with too much octane, like from 91 to 100 produced less HP, so i guess you can overdo octane
why I'm only interested in a slight bump to 93-93
again in California only have 91 octane, other parts of the country have 92-93 at the pump ? do the Vettes run better in those areas ?

 

In your case and if you really want, 92 - 93 would be fine. More than likely not necessary, but fine. If it were me I wouldn't want to dump dollars down my fuel tank unless I knew it was necessary.

Yeah you can get too high of an octane. Really you should run the least octane possible without knock. The best way you can be for sure is to log your driving and WOT pulls with something like HP Tuners. There are guys on CF over at the Z06 forums that live in Cali and are running much higher compression with milled heads on 91 octane. But they've dialed in their timing and monitor KR.

No those cars in other areas don't necessarily run better because of access to 93 octane, but in some cases you can add more timing to get more power out of the same setup. There's a point of diminishing return. Just because you put 100 octane in something doesn't mean you'll be able to throw timing at it and infinitely increase power. Eventually you'll lose power, then have to back off timing. And again, if there was no KR then the higher octane didn't matter and doesn't benefit. The octane boost is really beneficial to added compression. As I mentioned above, let's say a guy in California has 12:1 and is tuned on 91, they will likely be limited on adding timing and run into KR at some point. Where I'm at I have access to 93 at the pump, so I'd be able to throw some more timing at the 12:1 CR and not have the KR and make more power with the same setup.

Just as an example: Let's say I'm tuning a car at WOT and the first pull leads me to a max HP of 500 with no KR. For my next pull I add 5 degrees of timing and the result is 505 HP but my KR is now 2 degrees. The ECM has taken out 2 degrees of timing for knock so of the 5 degrees of timing I added only 3 is being used. I bump up the octane but change nothing else and do another pull. The result is 508 HP with 0 KR. In this case the octane bump helped. I add another 2 degrees and do another pull and still see 508 HP with 0 KR. This timing increase didn't add performance and increasing the octane and/or adding more timing won't be beneficial so I take the 2 degrees out.

 

So if you try anything or lots of things, how will you know what works and what doesn't, because you have no method to measure the difference. If you think you can "feel" the difference in a 12.70 or 12.60 second (the average for a stock LS2) pass in a 1/4 mile, you have a big imagination. Unless you have a timing issue, which won't exist in a bone stock car, the chances of getting KR from 91 octane fuel is near zero. Maybe on a hot day at WOT shortly after a shift to 3rd it could happen, but you still couldn't "feel" it.

That's the 1% that I referred to in post #4 that requires something more than 87 octane. You could drive all day on 87, if you never pushed the skinny pedal more than halfway down.

The bottom line is you need to do something other than raise octane to produce more power.

 

Although I agree with your explanation, it doesn't fit real well at the drags where KR tends to happen at high loads and low rpm, such as after a gear shift. If I see KR in 3rd at 5400 rpm, I can either add a couple ounces of Torco to bump octane or dial back timing 1 degree at 5200 and increase it 1/2 degree at 5400 and again at 5600. There's more latent power in 87 octane, but increasing compression requires more to control the burn rate. You just can't add octane quickly at half track.

 

well, I'm just a street driver and mess with idiots in ricers , mustangs / dodges etc. , not doing pulls to check it,
might just try a tank full of the mix, see if I feel any difference , if I had 93 @ the pump that would be it, but I don't
can mix 18 gallons of gas with a 15 oz. bottle $7.94 to get 93-94, = .44 more a gallon for a tryout
just like i just removed the K&N $500 COLD AIR [ not really cold air ]
re-installed the 2 stock factory filters / modified , closed off the total top area of the area above the filters / intake , getting real cold air from the bottom 2 vents on each side up to the stock filters , runs great ,\
cold air ?? just hit 105* in SoCal 18% humidity,, to dam hot

 

You can get VP 101 octane fuel at the pump in so cal at multiple places.

 

I think I'll stay with shell 91 $3.49 gallon + .34 per gallon octane booster =$3.83 a gallon for the 94 octane, all i need for the mix