2000 green hornet

as i worked in an oil refinery for 26 years i watched how carefully gasoline was blended from many different products in order to reach the required octane. after lead was wisely banned i saw toluene, mmt, mtbe, etc being used to increase octane ratings. the premium gasoline in my area is 93 octane. the question in my mind is what is the maximum octane rating that our corvette engine is designed for to reach the highest horsepower? since our cars have an electronic knock sensor and are designed to increase timing to the point where knock begins i know the higher the octane the faster it becomes. if i use a commercial octane booster it only raises the rating maybe 2points which is to say from 93 to 93.2. even then i can tell from the seat of my pants that my engine becomes more powerful. are commercial octane boost harmful to my engine. dont wont to hurt my baby but it jumps like a scared frog now. before it just jumped like a frog. :hurray: :D andy

boblackhardtop

93 is all you'll ever need in a N/A car w/ stock CR
I'm boosted & can't even find 93 oct. here. 92 is all we got & even that is hard to find.
I mix mine w/ 10 % Toluene.

RHILL

I wish we could get 93:sad: I live in the land of the tree huggers and you can only get 91 :banghead: :skep:

kewlbrz

Hornet, as im sure you know, octane rating does not produce more power because of a higher number, and is simply a rating of a fuel not to combust under heat and pressure before the spark ignites it.

Too much octane rating when not needed, can actually act as timing retard, because of the burn rate of the fuel slows as you go up in octane rating.

I've seen hundreds of readouts where there is no knock retard through the WOT, RPM range, when using 92 and even 91 octane. I have seen many with KR, even when adding 100+ octane. This is usually due to some other issue, such as carbon building in the chamber, a rattle in the drivetrain, faulty or too sensistive knock sensors, etc.

With that said. 91-93 Octane is sufficient enough on a otherwise stock compression ratio with respect compression ratio and heat requirements. But as said, there can be other contributing factors that creat KR that increasing octane rating isnt going to help, and can actually be detrimental if taken too far.


[Modified by kewlbrz, 10:29 AM 1/12/2003]

topgun

Additionally, if I remember correctly, octane boosters with MMT will void your warranty. Many if not most boosters contain MMT. Any gains felt are probably the opposite end of SOPT, "BTEP" (Between The Ears Performance) JMHO

If you really want to increase Octane, add 10% (10:1 ratio) Racing Fuel (110 Octane) to your tank, now you'll have 94.5.

Richin Chicago

After watching lots and lots of C5 dyno runs I can say I have never seen a car with decent gasoline go into knock detected retard. That's not to say it doesn't happen but I don't believe it is going to happen if you get a decent fill up of 93 octane. As far as octane boosters you add from a can. IMO they are a total waste of money. If your car doesn't knock extra octane will do nothing but add deposits.


[Modified by Richin Chicago, 11:42 AM 1/12/2003]

The Batman

Search on the www.76.com station locator for racing gas.

RWhite

boblacktop, how much do you pay for your toluene per gallon? And where do yo get it? Is it readily available?

sick_vette

i run only sunoco 94 octane. I notice a big difference if all I can find is 91.
My friend runs a mixture of 94 with race fuel when he is spraying(that's pretty much all the time) and no problems!

RangerMan

n/m


[Modified by RangerMan, 1:49 AM 1/13/2003]

rwj383

or they contain MTBE, either of which leaves a nice brownish-red residue from your combustion chambers on down to the O2 sensors. I wouldnt put an off-the-shelf octane booster in my car if god himself put a finger of wrath on me.

Kwlbrz hit the nail on the head in his post here. Octane is only its ability to resist knock. nothing to do with more power. too much octane vs the engine's real need WILL hurt performance due to flame burn rate and propagation.

If you do discover you can benefit from increased octane, use Toluene or Xylene, both of which have an octane rating of 116-117. just do the math to figure out your ratio to achieve the final octane you require. Again, i caution about increasing your octane a whole bunch without knowing your needs. If you've modified your car (blower, increased static CR, heavy nitrous use) and you know you need more octane to combat knock, experiment with ratio's of pump gas and Toluene until your knock goes away, then maybe go one more point above that. I can purchase a 55 gal drum of Toluene here in Oregon for ~$2 a gal. A 5 gallon drum from a paint store goes for $35 ($7/gal).




[Modified by rwj383, 10:53 PM 1/12/2003]

Mitch Alsup

A gasoline engine delivers the most HP at the point just below detonation and pinging.

J-Rod

http://www.mr2.com/TEXT/gasoline_faq.txt
http://www.gnttype.org/techarea/misc/octanebooster.html
http://www.gnttype.org/techarea/misc/Octanemix.html
http://www.gnttype.org/techarea/misc...explained.html


[Modified by J-Rod, 2:17 PM 1/13/2003]

fdxpilot

I think you're putting the cart before the horse. I may be wrong, but the car is set up to run with the stock program on premium (91-93 Octane) and won't increase the timing. It can only retard the timing if the sensors detect knock (or something similar sound-wise) in the block, hence the term, "knock-retard). Therefore, unless you up your cylinder pressures (NOS, SC, or higher CR) Higher octane won't do much good, and as previously pointed out, may harm the engine. Hopefully, some one with the real story will chime in.
IMHO :yesnod:

J-Rod

The engine will only retard timing when it detects knock. Also refered to as KR. You can look at this with ATAP or EASE. Toluene can boost your octane from 93 to 96 pretty easily. ! gallon of Toluene or Xylene to 5 gallons of 93. Or you can get 104 race gas for $4.75/gallon...

Your factory timing is set already. Even if you have 104 octane, it won't go pasts its maximum without a programming change (diablo or ls1edit). Your factory program is optimized for regular gas...

As for octane boost. Make it yourself and save a lot of money. Most octane boost is simply a small bottle of Toluene marked up 500-1000% or a small portion of MMT.

bierbelly

Well, I had been running 93 octane since I first got my '01 vert in July '02, but when I mashed the gas it would ping. Switched to Sunoco 94 octane recently, now no ping.

Toluene or mixed xylenes are probably the cheapest way to boost octane. Toluene is frequently used as paint remover--so don't get it on your paint, needless to say.

kewlbrz

I highly doubt that 1 increase in octane would fix a consistant pinging problem when going to WOT. The more likely reason is that the quality of the fuel is better then the the quality you were using before (not the difference in octane). Just my guess. :cheers:

bierbelly

Well, it wasn't a constant problem...just when I really got on it. Quality of the fuel is problematic. You never really know what you're getting. It all comes from a pool, so no matter if you buy from Exxon or Wa Wa, it's probably the same base fuel. The only real diff is the additive packages. and who knows, maybe the "93" I was getting was only 92 or less?