Race Gas Question

[widebody911]

Is it advisable to run leaded gas with an oxygen sensor?

[masraum]

Nope

[jeff1hughes]

NO, but you can get unleaded super high octane, I've seen as high as 110 at a regular pump! Didn't buy any, I like the leaded stuff myself

[ZAMIRZ]

I haven't said much about race gas, but it's pretty much the only fuel I run through my SC. I pump TRICK 101 octane for 3.99 a gallon at the Alliance Gas Station on the corner of De Soto and Vanowen in Woodland Hills (right down the street from my house). The car f'ing screams on this ****, it's unreal how much more responsive it is and I can throw ass coming out of most corners that on 91 octane I'd choke. Furthermore, I've found that on warmer nights I can keep the revs up above 4500 rpm for extended periods without the temp needle even creeping up to the first skinny mark on the guage. With gas prices so high already and the fact that the 911 only sees action on the weekends, I find it a bargain.

later,

amir

[SilverPoly]

Ok. I'm heading down to Alliance Gas Station on the corner of De Soto and Vanowen in Woodland Hills and I'm gonna put some of this stuff into my 3.0

I usually go with 91 at Chevron but I'm curious after reading your post.

[ZAMIRZ]

steven, even running a mix will make a difference. My favorite thing to do is wait for the gas light to come on and then drive it hard until i get to the race gas station (blow as much 91 that's left in the tank) and then pump like 20 bucks worth of race and BONE OUT for the rest of the night. The car gets gradually faster because it burns the rest of the 91 off and then it's sippin on pure race.

Remember in High School when you'd drink Vodka and then you tried gin for the first time and it got you all whacked outta your mind, that's how race gas hits. Enjoy it.

[SilverPoly]

Cool Amir, I'll try it your way.
I'm familiar with Trick and VP racing gasoline.

When I was young, I used to race expert class in a local circuit with a modified stand up Jet Ski 650, though it was always mixed with oil as the case with that 2 stroke engine. I had that thing modded to do 60mph on the water! As for the P-car, I noticed a huge difference in 87 to 91... so I'll try the Trick 101. Besides it'll be fun, and like you said regular gas is already ridiculous anyways. Not only that, I don't drive the P-car everyday so I'll spend a little extra for a little more thrill ! I'll try it and report.

Nice anology but as for the Vodka, I didn't touch the hard stuff until I got into college. In high school I started out drinking that 'sissy' drink Bartles and James (remember those two product spokesmen).. until I went to some cool backyard parties and got bagged on for not hitting the keg. After a summer of hangin' out with the guys I was a beer man.
Still am.

[pkfrdh]

I don't think you can buy leaded gas anywhere...it's been outlawed around here for over 20 years now.

I've seen lead additives for marine use only...tetra-ethyl lead added to a kerosene base. It is very poisonous and will absorb directly into your skin and then your blood. If leaded gas gets on your hands, within minutes, you will feel a strange tingling/buzzing sensation in the nerves of your hands. It soaks in with the fuel almost immediately.

Catalytic converters that have leaded gas run through them get a lead layer that "poisons" the platinum catalyst that coats the converter rendering the converter useless .

JGL

[beepbeep]

Do you have turbocharger? Are you running exorbitant C/R? Is your car equipped with knock-sensor?

[ChrisBennet]

Originally posted by beepbeep
Do you have turbocharger? Are you running exorbitant C/R? Is your car equipped with knock-sensor?

Ah come on Gooran, don't burst their bubble. The Placebo Effect is real!
-Chris

[JackT]

I did not know that higher octane gas would give your car more power or better throttle response. I run premium in my two cars, one because the computer in the car requires it so the valves do not go crazy and the other, my 911SC, because the motor is so loud I cannot hear if the motor is pinging.
I thought the idea of higher octane gas was to be able to advance the timing and the car would not ping.
I know this is a very simple way of putting this. Am I missing something?

[Tim Walsh]

I think you can still get leaded gas in a VERY few places. Mostly around race tracks and it's labeled for "off road use only" I know I've seen it at least in Wisconsin (In a small town about 45 minutes north of milwaukee)

[jmohn]

Originally posted by DrewT
I did not know that higher octane gas would give your car more power or better throttle response. I run premium in my two cars, one because the computer in the car requires it so the valves do not go crazy and the other, my 911SC, because the motor is so loud I cannot hear if the motor is pinging.
I thought the idea of higher octane gas was to be able to advance the timing and the car would not ping.
I know this is a very simple way of putting this. Am I missing something?

No, you're not missing a thing. But, they're happy and having fun, let's not spoil it.

Jerry M
'78 SC

[LeRoux Strydom]

I always thought that unless your engine is specifically designed to derive advantage from higher octane gas, such as high compression ratio, valve & ignition timing issues etc, you're basically wasting your money going for the avgas stuff. Octane rating is a measure of combustibilty, therefore you need a minimum RON value to avoid detonation (or pinging) at a certain ignition advance. Going beyond that RON value brings no more benefit if everything else on your engine remains the same (CR, timing etc.). If you run a racecar with engine modifications that do take advantage of the higher octance gas, its a different story of course.

Educate me if I'm wrong, but none of these street rumours and heresay being propagated here, please.

BTW, the lead additions in leaded fuel has a natural tendency to raise octane (RON) ratings, but to answer the original question by widebody, it is probably OK to run it if your car has only has an O2 sensor for mixture control but no exhaust catalyst. Our experience here in SA where most older vehicles still run on leaded, is that the O2 sensor tends to lose efficiency over a long period of time from the Pb deposits, so most people just disconnect them to run the DME in open loop. If your car is equipped with an exhaust catalyst however, (which btw absolutely requires the O2 sensor to keep the mixture stoichiometric where the catalytic effect of the platinum coating work most efficiently converting those nasty NOx and SOx and unburnt HC's), you're signing its death warrant by running leaded. The lead compounds "poisons" the platinum coating to the point where is no longer works and then you have an expensive ceramic filter that will just let through all the nasties and give you a nasty surprise come emissions inspection time.


Edit: Check out this link for a nice technical description of the combustion process and the effect of variables such as ignition timing, compression, RON on it.

Regards

LeRoux

[cstreit]

Guys,

Unless your car has a knock sensor for detecting detonation and adjusts the timing up or down based on this, higher octane fuel will actually make a car slower.

Higher octance prevents detonation at high loads and high advance levels because it is actually harder to detonate. Gallon for gallon 87 octane would actually give you more power given the same timing and compression rations because it burns more easily.

Now it's still conceivable that higher octane would make your car faster if your ignition was advanced too far and you were getting sub-audible detonation... But your motor wouldn't last long with this....

[Zeke]

I have two things to say here (only two?). Yes, they sell leaded gas at the race track. It's 110 octane at Willow Springs.

Secondly, Chris is right about octane. In karts, we were limited to 7.5:1 compression by the rules. High octane was useless, especially at 14,000 rpm. Who needs gas that is hard to ignite at 14 grand? But, pure racing gas, or should I say, gas that is more pure than street gas with all it's additives, does burn well. Just buy low octane race gas. BTW, you can accelerate the burn rate with chemicals, but that's another subject and has been discussed at length.

[ttweed]

Race gas is readily available here in San Diego in 100 octane unleaded and 110 octane leaded (for off-road use only, you can't pump it directly into your car).

I blend 2 gallons of the 110 with 4 gallons of 91 unleaded pump gas to make approx. 97-98 octane blend for my 10.3:1 compression motor. It will eventually gum up your O2 sensor from the lead additives, but mine just runs an A/F meter, so it's not a problem. Others I know with later race engines that use the O2 sensor for the DME just replace them more often or use the 100 unleaded.

TT

[beepbeep]

Octane is measure of gasolines resistance to self-combustion. High octane gas has less energy per weight unit than ordinary one. Diesel has most energy/weight. If your car isn't knocking, you don't have knock-sensor and are not force-feeding air high-octane gas is expensive way of destroying your catalyst or gumming up lambda-sensor.

There are no good ways of detecting pre-ignition in inherently noisy aircooled 911-engines except measuring ionisation current trough spark-plugs which is still covered by SAAB's patent, i believe...

[cstreit]

I'm pretty sure that later 911's had knock sensors, though I've heard as much beep-beep. It would be nice to get a definitive answer on whether or not a knowck sensor on an earlier motor can work,...

[ChrisBennet]

I looked into using the 964 knock sensors on my 3.4 project. It wasn't practical to weld 964 style bosses onto my cylinders so I didn't pursue it further. I think the Imagine Auto guy (Stephan?) mentioned using the MSD knock sensor on 930's. The stud that stuck up for the base of the throttle crank to mount to was used if I recall.
-Chris