I noticed today that my 997s requires 93 octane. Being that I am in California and 91 being max do any of you use octane boosters to compensate?

 

Nope. ...

 

No, seems to run fine with 91.

 

I do. But cost and effort are not really issues in my day. Because it amuses me, I boost octane but NOT with "over the counter" stuff... I combine 1 gallon of 110 octane unleaded racing gas, sold at the local dirt bike shop for $5.75/ gal., with 7 gallons of 91 octane pump gas ( or 2 gallons 110 racing gas to 14.9 gallons of 91 pump gas) to create 16.9 gallons of 93.25 octane. Though the car will use no better than 93 octane, the extra .25 is just necessary waste from "rounding-off" to even gallons of 110 octane racing gas.

We had a thread going many months ago on the topic that a search might reveal the details of but in a nut shell simple algebra shows that a quart of "over the counter" additive, and most come in volumes of less than 1 quart, but a quart would have to have an octane rating (R+M)/2 of approx. 226 octane or HIGHER to boost the remainder of a 16.9 gallon Carrera gas tank to 93 octane. Consider that pure Toluene is 114 octane (R+M)/2 and clearly "over the counter" boosters are all "can" but no "do".

I don't have access to a station that sells 110 from the pump, though some of you do in the LA basin. (They're on the net.) So, I have purchased one of those 5 gallon plastic bottles from the dirt bike shop, the bottles specifically meant to carry fuel, and once a week I take the bottle in to the parts counter and buy a fill of 5 gallons of 110 octane. Then, in the garage, at half a tank I add a gallon of 110, at empty tank I add two gallons of 110, and then drive to a pump station and fill the rest with 91 octane. IMHO, there is a Very noticible difference with 93 octane as the knock sensors don't de-tune the motor to prevent "bad things" at high RPMs. Basically, octane make the fuel-air mix LESS volatile so it can be compressed completely.

Hammer it on 91 octane, then put 93 octane in it and hammer it... you'll be shocked at the added pop.

Christ, can I type fast or what?

 

Johnny, Nice job, but you are not adding a booster, simply mixing higher octane with lower (of course there is nothing wrong with this...it is perhaps the best way to raise the octane). There are several problems...first the actual octane (when the pump says 91) is unknown due to measurement system variation and of course all of the processing variatios. There is the added...how long has the gas beeen stored and under what conditions. You have about 2 months under ideal conditions before the gas starts loosing its octane properties. Boosters work, but you need to choose wisely (most OTC stuff is crap).

Johnny is correct that with higher octane you will get more power out of the engine. Just such a PIA to get higher octane.

 

What about the lead? Isn't the 110 leaded and won't it hurt the cats?

 

My bad... ah, it might be a wash because of the ratio but it certainly won't help the cats live a long and healthy life. Bottomline is that yes, you are correct, and I have been wrong about the 110 I've been pretending to use.

Why in the name of all that is holy I would believe a teenage kid working the parts counter at a dirt bike shop is beyond me. Thank God I haven't bred. Can you imagine the offspring? These genes stop here.

I just did what I should have done from the beginning and checked VP racing fuels website. The VP-110 is leaded. And though one might be safe because of the ratio of 14.9 parts unleaded to 2 parts leaded I certainly have no data on that wild *** guess. Be safe, don't do it.

In fact, I made it all up... ah, yeah, that's the ticket... sure, I made it up and I have NEVER put leaded fuel in my Porsche. NEVER. Just kidding. That would do "bad things" to the warranty. Clearly I was bull****ing just to get attention. I hear voices... ah, never mind.

What? Who said that?

 

Johnny...dude...lay off the drugs for a while.

 

I have never heard of 110 octane UNLEADED fuel. Are you sure it is not leaded?

 

OK, good advice, you're right... I'll give it three hours but I can't run the grill without a beer... it just impossible.

Yes... wait, no... it is LEADED 110. And I've never used it, I haven't seen it, and I don't know where to get it.

 

We, the Rennlist jury, find you GUILTY!

 

It's possible to find high-octane unleaded fuels. I know of a station here in Florida which offers 105 octane unleaded at approx $6/gal. And that would be a much wiser fuel to run in your car as opposed to a leaded fuel. Even if your dealer's service dept is sympathetic to modified cars, it's just wasteful to use 110 leaded and destroy stock cats, only to have them replaced under warranty.

 

They sell 100 and 110 unleaded fuel at Laguna Seca for $6.00 a gallon.

 

Is this really the conclusion the prior thread came to? Octane boosters do not work on a volume basis. They work chemically to reduce knock. A little can go a long way, although a lot of the OTC stuff is overrated.

Michael

 

Out of boredom and wanting to go for a spirited drive on the angeles crest highway, I put in octane boost on 1/2 tank. There is a noticeable difference in engine smoothness and power. Not significant but noticeable. I guess the AK sensors work overtime on the west coast. Wonder if there'll be an issue with longevity due to constant knocking?