so what do all you guys say about octane ratings and such..? Do you use hi octane fuel at the pump or do you use an octane booster in a bottle. what do you feel are advantages of either..best brands ets..? best octane numbers..94..98..104..? some helpful insight on this is appreciated as the guy at auto zone answered..'you can pay the gas company or you can pay me'..big help.

 

Buy hi octane from the pump. The additives don't raise the fuel octane rating much if any. I mix 100 octane race gas with 91 octane to get the level I need. I have heard of people mixing gallons of toulean with gas to get real octane increases. You are better off spending your money on gals of race gas rather than octane boosters.

 

You'll be fine with 93 (or 91 if you don't have 93 in your area.)

oh and don't pay the Autozone guy lol.

 

Let me say this. There is great misconception about octane. Higher octane fuels do not provide any more explosive power. What they do contain are additives that help prevent pre ignition. Thus, timing can be more advanced (mechanically or by the ECU) and that adds power. Most engines today have knock (pre ignition) sensors that can retard timing and therefore engine output. So that 93 you find at the local pump allows your engine to work its best without timing retard coming ruining the fun. Other guys may want to chime in as I don't know the maximum octane our engines can use where higher numbers don't add additional knock protection.

 

Don't forget compression. For the most part, higher compression engines require higher octane gas. There are some exceptions to this.

This has been discussed a million times, and the general consensus is just use whatever the manufacturer recommends. They designed and built the car, they'd know what they're talking about.

 

Ah yes, you are correct, with higher compression and the resulting higher temperatures the knock sensor needs to be kept out of the picture with higher octane fuel.

 

well, you guys are always a big help.. Ill stick with buying the higher octane at the pump and I wont pay the autozone guy..! Thanks again.. Merry Christmas

 

Waiting for IHC to chime in because I know this has been gone over and over and he knows it more than anyone (And I'm too lazy to search)

 

Aman..love your avater..kinda freaky..!

 

I agree with your posts.

I did some knock monitoring in the middle of a hot summer and the TL knocks badly in stock form in high temps. I tried different mixtures of 91 and 109 and it took around 96 octane to completely get rid of the knock.

So the answer is to use the highest available octane for the TL. Octane boosters usually have toluene as their octane booster but you can but this stuff at the paint store in a gallon container for about the same price as the 8 ounce container in the autoparts store. The little bottle they sell won't boost it more than a few points at best. 91 to 91.3
octane.

You will see gains of mpg and hp until you get past the point of knock. How much of a gain depends on the severity. You might see a few lbs of torque on the dyno and mpg change would be there.

In a hot summer mine pulls so much smoother and without the initial hesitation from the ECU pulling timing and trying to put it back in constantly. My mpg went way up in city driving but mine was pretty bad without the extra octane.

To the OP, I just wrote nearly this exact thing in another octane thread last night and I have several much more detailed threads on octane out there that you can find with a search.

 

what ratio do you mix the toluene..and do you add it to hi octane gas from the pump..?

 

No more than 30% for fuel system safety or whatever mixture it takes to get rid of the detonation.

 

more like how much tolulene would you add to a full 15 to 17 gal fill up. .? And do you add it to regular 87 octane or do you add it to the highest available at the pump..? Im not very good with the 30% thing..math was never my forte..

 

High Octane gas isn't made completely by additives. It is refined and blended differently. It does contain a different and/or more additive also depending on the supplier. Most majors use more of a better additive in their premium fuels.

 

your gas light comes on when you have a 3 gallon reserve out of your 17 gallon tank

17-3=14 gallons

30 percent of 14 gallons is 4.2 gallons of toulene

percentages are calculated in this manner

14 (# of total gallons) * (times) .30 (decimal in front of percentage) = 4.2 (the amount of the percentage out of the total)

if you have a smaller percentage, say, 3% you would add a zero after the decimal like this - 14 X .03 = .42 gallons (half a gallon)

 

math..grrrrr.. so what your saying is then a half gallon of toluene to a full tank of gas..right..? Thanks for the help

 

If you want a 3% mix do half a gallon.

You have to count the reserve capacity also.

Just make it easy. Run it down to the light, put 7 gallons fuel then add 3 gallons of toluene. The second time, do 10 gallons of fuel and 3 gallons of toluene.

30% will give approx 96.7 octane.

It's more cost effective to run 100 or 109 unleaded fuel in a mix.

 

Is it bad for the engine to run octane booster regularly? I've been using Lucas octane booster (red bottle) over the summer to tame knock. It does a great job using MMT as the main sauce which is supposed to be safe and widely used in high octance fuels.

 

I doubt it would hurt the engine. Though I'm not sure why you're experiencing knock if you're using premium to start with. You'll probably want to look into that issue rather than using an octane booster which is more of a band aid than a true fix.

 

IHC,

What about just having a full tank of race gas? Would that damage the engine at all? Or is just for cost savings to mix the fuel?

 

^cost effective.
at $6-8 dollars a gallon, it would be pricey to fill up the full 17 gallons. or if not counting reserve, 13 gals.

 

unless your engine is specifically tuned to use race gas (i.e. heavily modded), you don't need a full tank. if anything you are hurting the engine a bit because it is not making the most power from the race gas.

this is because the higher octane of race gas (I personally use 4-5 gallons of 100 super unleaded during the summer months) makes it a more stable fuel that is technically not as easy to ignite under stock engine operating parameters. the whole point of raising the octane of fuel is to prevent pre-detonation, especially in the compression stroke, and allow more ignition advance.

if your engine has not been tuned to run on increased octane, you are just likely wasting fuel using a tankful of race gas. generally speaking, you want to use the highest possible octane that would prevent knock under heavy loads on the engine. anything more, and you encounter the point of diminishing returns. for me, 4-5 gallons of 100 octane mixed with the readily available 91 octane make a typical concentration that approaches 92-93 octane which is more than enough to prevent knock for my use and maintain engine power without retarding timing.

most octane boosters increast octane up to ten points, which if you're using 91 octane, just goes up close to 92 if anything. just dont overuse them, because most use MMT to boost octane. MMT, in high enough concentrations, isnt good for your engine. below are some pics of spark plugs that fouled out by using an octane booster called Torco, which uses a lot of MMT. he used Torco for a full year. It did increase his octane as advertised, but found his plugs in this condition after pulling them. You do the math if its worth it:

 

It's just not needed. Once you're past the detonation threshold, adding more octane won't hurt anything but it won't help either. It will just cost you more. A 50-50 mix is way more than any TL could ever need.

 

That looks familiar. When I got the GN at 17yrs old and me and my father started running the "104+" octane booster, the first time he changed his plugs they looked like that. We were suspecting a blown head-gasket as this was the pre-internet days but finally figured out it was just the octane booster.

Just one point to clarify, high octane is not harder to ignite and it doesn't burn slower. It resists uncontrolled explosions (detonation) better. Some racing fuel like the C10 (114 octane) I used to use in my car for the 30psi+ runs actually had a quicker burn rate than 91.

 

thats what I meant to say

it allows for the engine pretty much to advance timing and/or put on more boost without the fuel pre-igniting before the actual ignition from the spark plug.

I found that pic when I was researching about the Torco unleaded fuel additive. almost every information (credible or otherwise) yielded very positive and promising results. something like an 8 oz bottle would make 91 octane behave like it was just over 100 octane or race gas. but noone has torn down their engines (those plugs were from either a WRX or STi) to see what their combustion chambers look like but if the plugs are any indication, I almost dont want to look.

Im thinking the Torco, in very small amounts (like the small octane-booster bottle amounts), would effectively raise your octane just enough. too much can likely damage or gradually harm the engine. the MMT would be my suspect, as there is a likely reason that has been removed as an additive in pump gas.

 

That's exactly what it is. In the old days (mid '90s) we developed a misfire on both cars and coupled with the orange rust colored plugs, you can see why the headgaskets came into question. I was a kid, didn't know that the plugs are usually cleaner with a blown headgasket.

It's nothing you can't get rid of in the combustion chamber. Usually over time it will go away. If you're worried, do a top cylinder decarbonization with either water or Seafoam (first time I've ever recommended Seafoam lol).


Back in the old days, we were just getting into octane and it's enhancements on boost levels and all of that. No real internet to get info from so it was coming up with theories and testing them. It eventually progressed into racegas and meth injection but during the days of just octane boosters, they did work. The cars were always tuned to the threshold of detonation where it would actually detonate a little when it shifted gears. These boosters did work but they were good for running an extra psi of boost or getting rid of the knock on the shifts but they didn't allow anything such as going from 14psi to 20psi of boost. Just a tiny little bump in performance if you knew how to take advantage.

I've seriously screwed my GN up experimenting with fuels and additives. The worst was Av gas and using it 100% of the time when commuting 210 miles round trip for work every day. I won't go into details but it was a failed experiment that cost me an engine.

Off topic but toluene or xylene is a much more effective booster and cheaper in the dollar per octane point if you must run one. Unleaded race gas is the safest and one of the most cost effective when mixed with pump gas.

Anyway, good discussion. If you feel the need to continue with a booster, I would definitely hit your paint store up.

 

I like the discussions on here. Some really knowledgeable facts and opinions are being talked about. I agree that running 92-93 octane is a good idea by itself, and I'm not sure if running an octane booster is a good idea bc you need to be precise and it's hard to judge what you're making by combining fuels together. It's kinda like putting a small amount of nitrous in the tank. The only thing I would add is a little information about what octane really means. Octane, or C8H18, is eight (the oct in octane) carbon atoms with 18 hydrogen atoms chained around it. you can form different isomers of octane with chains branching off of the original by adding different polymers and isomers.
for example, One of these isomers 2,2,4-trimethylpentane (isooctane) is used as one of the standard values in the octane rating scale. True octane is 100 percent hydrocarbons and 0 percent heptane, which is the lowest amount of isomers in the chains to sustain cohesion. So when you read 91 octane, this means that the gasoline is 91% octane and 9% heptane. Make sense? no? good me neither. It all sounds like science garble to many but just keep this in mind when you fill up on gasoline. Higher octane fuel is relative percentage from 0-100 on how many hydrocarbon chains are in the gasoline. Low octane burns hotter and quicker, higher burns cooler and slower, producing more "bang for the buck". The difference in competitors gas is the additives and detergents they add, but crude refined 91 octane would be the same anywhere before the additives are put in. Personally I run 92 octane from the same station for 3 years. No knock and I get about 30-40 mpg on the highway.

 

Here's an octane mixing chart between 91 & 100. If think blending gasoline is for you, keep a copy of this chart in your glove box:

 

You guys make all this fancy talk about high octane. For me it's as simple as:

The highest octane gas at all the gas stations I go to contain zero ethanol. I don't want ethanol in my car, so I buy the stuff that doesn't have it in it.

I don't think ethanol is bad for my engine, I just hate corn, and think that Monsanto shouldn't profit from me buying gasoline. (Weird reason, I know).

 

I'd rather see people use ethanol, it's cleaner for the environment and cuts our dependency on foreign Arab oil, which in some circumstances funds terrorism. The problem with corn oil is it's very expensive to manufacture and produces more waste than usable product. But some genius will figure it out in the future.

 

Corn Oil <=> Ethanol

Ethanol combustion energy < gasoline combustion energy

3G TL sub-forum <=> Religion & Politics sub-forum.

 

Nice find!

Rule of thumb for 91:100 mixing if you forget or lose the chart. Pick your desired octane and remember the ratio:

93= 3:1
94=2:1
95=1:1 (actually 5:4)
96=4:5
97=1:2

 

Incorrect on a few items.

 

Here in the southeast, the grades of fuel one finds is 87, 89, and 93. IN my '04 manual TL, I have burned only Amoco 93 its entire life with the exception of one tank of Shell 93 V-Power. I just had my timing belt replaced last month, along with some other items, and also had the plugs changed. The factory plugs which were removed from my engine had 92,400 miles on them and they were beautiful. A nice light tan color (and dry), and all the same. The electrodes were near perfect. My car has never pinged, nor has it ever miss fired. Every 10,000 miles, I run a quality fuel system cleaner (either Sea Foam or Chevron) through my tank.

So folks you don't need to burn octane booster in your engine, unless conditions exist for this, because your engine will do just fine with the grade of fuel it was designed to burn.

 

Same here, but all on 91 Octane with the occasional 93 octane fill up (maybe once or twice/year). Plugs pulled at 106K, looked like they could go another 106K, gap was still at factory specs. Never pinged nor miss fired nor had loss of power in the summer, and this includes two years in the TX/LA heat. Now at 125K and running as strong and ping free as ever.

 

I think the knocking issue is with the Type-S. I've never had any probelms with my 05 6MT running Chevron 91.

BTW: Here is how clean the ports & intake valves stay with Chevron gas only (106k mile Honda Pilot).

 

damn nice and clean

 

found a station in Pensacola selling 93 octane ethanol free (never seen that, only 90 or 91 usually). filled up, reset ECU, drove like I stole it. Didn't tell my roommate who was riding with me what I was up to, but he still said, 'whoa, your car feels faster than usual'. butt dyno agrees. 3rd gear pull from 60-80 got my pulse up a bit! maybe just placebo but interesting anyways.

 

I buy Sunoco becasue they are one of the few that sell 91 which is the recommended octane for our engine. 93 octane is overkill and why pay for it? Another big misconception is that one gasoline brand is better than the next. Most stations receive their gaqsoline from the same distribution system and just add additives at the station in the bulk tanks. If they didnt do distribution this way, you would have a gazillion underground gas lines running all over the country instead of just a few. However, if you are racing, then throw away everything I just said and buy racing fuel.

 

Another thing. Ethanol is a big hoax. There are less btu's per gallon for ethanol than for gasoline so your mileage goes down and you pay more on a $/MMBtus. Ethanol is used as a blending agent to raise octane levels, so in this regards it is good and also buy ethanol keeps farmers employed.