95sc300t

It is usually pretty evident in the labeling if it is leaded, or unleaded gas. With the drastic increase in import racing, most drag racing strips have high octain unleaded, and as far as that is concerned, any modern fuel-injected car has oxygen sensors, and would need unleaded also.

Fact is, a tank or two of leaded fuel is very unlikely to hurt anything that much. I had a 93 Eagle Talon a few years back, with a very oversized turbo, running as much as 27psi of boost, and I probably ran 5 or 6 tanks of aircraft fuel, which is leaded, and never had an o2 sensor problem.

The lead in the fuel, is there to lubricate the valves on high-compression race engines, and the lead itself has a bit to do with making the higher octain in the gas. Anyways, the lead goes through the engine, and slowly deposits on the o2 sensor, and inside the catalytic converter, so yes, eventually it would mess up both, but not in one or two tanks.

I'd say put a couple gallons of the race fuel in, reset your ECU, by disconnecting the battery for 1 minute, and see how it does for you.. If it pulls stronger, then your local premium gas isn't quite covering all your detination...

Thought I would mention.. Disconnecting your battery will loose all your radio presets, and any seat/steering wheel presets also...

Neal Rikal

correct me if i'm wrong but the higher the octane the faster the liquid gas turns into a gaseous state to mix with the oxygen in your cylinder.

If you run to low an octane such as 83 and the timming of your engine dosn't slow you will be burning partly liquid and partly gaseous gasoline. Liquid gas burns longer than it does in a gaseous state so it is this leftover liquid gas burning that hurts your piston rings and can burn up your caytalyic converters.

So basically running a high octane gas at the same engine timming provides no performance increase, the gas is just in a gaseous state sooner then it needs to be.

am i right? somebody help me out here

95sc300t

Um, this is not entirely accurate..

I'll give an overly simplified explanation of how Octain works. This won't hold up to scientific analysis, but the gist is correct..

Higher octain fuels can be crushed in the combustion chamber more before they self-explode. With compression of 8.0 to 1, low octain will not blow up before the spark initiates ignition. But, with 12.0 to 1, the fuel would explode before the spark plug ignits the mixture, meaning that the piston is still on its way up.. The exploding fuel trys to push the piston down, and the resulting extreme pressure breaks rings, puts holes in pistons, and makes a HUGE amount of heat, melting things...

Here are some snipits from a web page I found.. web page link below..

The higher the octane rating on fuel the less volatile (evaporative qualities) and the slower the fuel burns. Higher octane fuel contains more POTENTIAL energy but requires the higher heat generated by higher compression ratio engines to properly condition the fuel to RELEASE that higher potential energy.

If fuel octane is too low for a given compression ratio, the fuel prematurely and spontaneously ignites too early and the fuel charge EXPLODES rather than BURNS resulting in incomplete combustion. The net effect is a loss in power and possible engine damage. The operator hears an audible "knock" or "ping", referred to as detonation. Detonation may vary from a faint noise on light acceleration to a constant, deep hammering noise while driving at a constant speed. Improper timing adjustments, vacuum leaks, or excessively lean fuel mixtures may also cause detonation.

There is much more on this page:

http://www.leeric.lsu.edu/bgbb/7/ecep/trans/b/b.htm

U R 2 Ez

Well I can personally attest (unfortunately) that running 87 octane won't make our inline 6 ping or anything. I accidentally put in 87 octane on my last tank of gas (bad habit, been driving cars that would suffice with 87 octane my whole life). Of course, I realized this as I was driving off, so I never went over 3k RPM's. I also drove it down about 1/4 tank and then filled her back up with 101 octane (there is a gas station a couple miles down the street from my house owned by a highpower Supra owner, so he has 2 pumps running Trick Racing 101 at the pump). So after that I should be running just fine as far as my octane goes. But I experienced no pinging whatsoever.

Keith13b

iTrader: (3)

95sc300t gave a good reply. If the car is completely stock, only run the octane that is recommmended by the cars owner manual. Adding 93 octane gas to a car that only asks for 89 octane will give you no performance gains. And it will even give you lower fuel economy believe it or not. Putting in a lower octane gas than recommended is not good either, as it will hurt performance and it allows your ECU to learn the wrong maps.

It is a common belief that increasing octane will add horsepower. I see lil' hondas buying octane booster for their street races friday nights then dialing in more timing. This is an absolute waste of money. Then again these guys have the supra wings on the back too, with all their stickers and fart can mufflers. Got Rice?

Octane has a direct relationship to the vehicles compression- thats pretty much it. If you don't have high compression, adding higher octane will do absoutly nothing.

The higher compression you have (i.e. turbo, NOS, or SC; for example) the better efficiencty you can achieve by using CAM fuels. The higher octane allows for more timing WITH higher compression. The higher the compresion, the higher the octane NEEDS TO BE! You aren't gaining anything with the higher octane, its a mere necessity to alleviate detonation. Not having the higher octane hinders you. If that makes sense. Please don't addd octane and bump your timing up; its a little more techincal than that- let me re-phrase that - A LOT more technical than that.

And also, most CAM fuels are leaded. How many big blocks do you know that run blowers and still have factory fuel injection. Not many, if not any at all. I know we as import guys see Supras running high boost, along with other turbo 4's, but if you honestly go to the track, most cars are old school muscle cars. Most of the serious racers do build motors to a specific tolerance and trailer the car in. Then they juice up the fuel cell with just a few gallons of high octane fuel. We on the other hand have street driven cars with full size fuel tanks. We are the minority and thus we have to hunt down unleaded high octane fuel. Thats another reason why octane booster additives are so popular, as they allow the use of unleaded fuel. Unless it clearly states unleaded, it will be leaded, and it is the norm. Besides, not running leaded at high boost is asking for trouble anyway. Just look at aircraft engines.

Anyway-

Not trying to preach, just help-

Keith

Dimcorner

little off topic. but are you gonig to rotorfest? I'm going to try to swing by. I know cam is going up on sat night with his 3 rotor.

Keith13b

iTrader: (3)

Where is it at; Moroso?

I doubt I'll be able to make it.

Cameron hasn't blown that thing up yet?

carnal_c30

ahhh the guy with the black Supra?? wish we had people like that running gas stations in CA

U R 2 Ez

Yeah he has a black Supra, thing is a beast! He's got the King of the Southwest sticker on the rear windshield, nice guy. I'm just glad the gas station is just a couple miles away instead of the other side of town!

jimmit

Thanx for the info keith. I thought the SC4's were supposed to use 93 octane tho? Anyways so how you been? You're gonna make it to the spring break centrel FL meet right? check out the southeast forum. Nothing is set but hope to see you there.

carnal_c30

yup yup... and we only get 91 out here its hard to find stations that sell racing gas for 'cheap' usually about 5 bucks a gallon for 106 or 100

how much are you paying for the 101?

U R 2 Ez

The 101 here is $3.99 a gallon, pretty expensive but none the less its cheaper than 5 bucks a gallon! And its convenient to just go to a Mobil gas station and pump it right there from a regular pump. I'll only use maybe a gallon mixed with a 1/4 tank of premium 91 (we don't have 93 either) when I go to the racetrack, other than that i'm just going to use 91.