frmula1

i know "unleaded fuel only"

but why?

i've heard something about that you shouldn't use leaded gas with a car that has cats... because it will clog them

is there any other reason?

i've noticed a consistant gain at the track by letting my tank get really low and mixxing a few gallons of race gas with the gallon or two of the 93 thats left.

i have gutted cats

is there any other reason i shouldn't put leaded race gas in my car? its only a few gallons once a week...

thanks

Jared

Z28barnett

Unleaded race gas is fine.

If you have already mixed leaded gas with your fuel, you have ruined your O2 sensors.

The lead destroys the O2 sensors and will cause your fuel injection system to fail to work properly.

My guess is that on an 2002 you have 4 O2 sensors at about $40.00 each. A few gallons of leaded fuel may have cost you $160.00.

This is not a wise thing to do.

Stop doing this or you will cost yourself some repairs for sure.

Z28

Kataklysm

If he gets AC Delco O2s they are $70 each, OUCH! Your injectors would probably clog up, new injectors run over $300 a set too. Use unleaded, don't be crazy! If you do decide to go leaded put deisel in too, I'm curious to see how bad it would run with the higher flash point.

Greed4Speed

IF you had cats it would kill them too. Leaded fuel also leaves deposits. Thats why cars started running hardened valve seats when unleaded became manditory.

Chances are, with the few mods you have, the gains are seen because you have a lean condition and you're picking up some detonation and therefore some knock retard. The ONLY thing higher octane does for you is not detonate as easily as lower octane fuel. Higher octane gasoline DOES NOT burn hotter, cleaner or create more power. It just takes more heat/energy to ignite.

frmula1

i know what higher octane does...

and it does help

but my car is not running lean

i am using unleaded 101

i was just hoping i could start using leaded 110 so i could use less of it (its pricy)

so just one use can mess up your o2's huh?

383Z4ME

I spoke with an engineer at Bosch in California this past spring and he said their O2's will last at least 100 driving hours using leaded fuel. I would think mixed like that it would be much longer.

CrabhartZ28

Lead makes the gas thicker, and reduced knock considerably. This allowed huge engine cars to run crap gas. When they took lead out, those engines would knock like a biatch.

Greed4Speed

Lets see. If you know higher octane olny reduces the tendency to detonate and that the only reason you'd see more power from running higher octane is if you were detonating. And detonation is caused from lean conditions, too high of compression, timing advanced too far, or something in the cylinder getting too hot. And the LS1 is designed to run 93 octane, but can still run on 87 octane. So we can factor out compression and timing if you're running the factory specs. There is something up.


And yes, the O2's may LAST a certain amount of hours running leaded fuel, but will they perform as well as they should after running 1 tank of leaded fuel?

frmula1

you don't have to have a screwed up engine to benefit from higher octane fuel if you have an even somewhat high compression engine... stock.

markinkc69z

Leaded fuel use over time will contaminate the O2 sensor and slow its resonse time. You did not damage the sensor with your track use.

Race fuel comes in many flavors. Different fuels have varying specific gravity numbers. Depending on the race fuel and pump gas you run the afr mixture can vary because of the density of the fuel. This can affect how the car runs at the track.

Track fuel isn't going to hurt your injectors or any other kind of voodoo assuming its good clean fuel like it should be.

Race fuel also can be more stable than pump gasoline and the car may idle smoother and run a bit better at high rpm.

Running fuel with an excessive octane number, such as 110 on a stock motor will likely result in a power loss as you just don't have the compression to make use of it. The fuel can burn slower in that case and cause your pressure peak to occur at the wrong time and be lower over all.

frmula1

yes,

i haven't used leaded fuel, like i said i have been using unleaded 101


i wasn't planning on running straight 110
i thinking i could dillute 1 gallon of 110 with 2-3 gallons of 93 in a mix.

but i won't now anyway..

i'll just let my tank get down really low... (to like a gallon or so) and add a couple gallons of 101

i keep my tank low for track events anyway for weight

Greed4Speed

Yes, but the LS1 was designed to run on 93 octane not 101.


Problem #2. The intake pump is designed to use fuel to cool it. Running the level down really low lets teh pump overheat. Let any electrical device overheat and it tends to crap out on you.

Even with all this, what are you picking up? MAYBE .1 sec tops? More likely half that.

frmula1

.15

which could be the difference between a 13 et and a 12

LT1WanaBe

Like Greed4Speed said... running REALLY low on your electric pump will cause it to overheat as lubrication of the pump is dependant 100% upon the fuel. If you "already know" your car makes a difference of almost 2 tenths on your track time, why risk the possibility of a pump just because you want bragging rights? Put gas in your tank, keep your pump cool, subtract 2 tenths, and there you go. When your fuel pump goes and you have to waste the time and money upon replacing it instead of going to the track that day, maybe you'll think twice.

ChicagoTransAm

Also, keep in mind that if you are running 2 gallons of 93 and 2 gallons of 101, you only have 97 octane.

First of all, your car won't benefit much (if at all) from it. If you're running an engine with forced induction, this can allow you to run more boost without detonation.

FWIW, I wrote up a article awhile ago on Toulene vs Xylene vs MTBE (MethylTertiaryButylEther) vs Methanol vs Tertiary Butyl Alcohol if you'd like to read up on octane boosters. They all pretty much have a R+M/2 of around 112-117 (with the exception of alcohol and methanol which are around 100-102)