Ok, forgive me if this is a stupid novice question, but can the engine of a 997.1 Cup car be "tuned" to run on 93 or 94 Octane pump gas? Knowing, this decreases the HP, but for just tracking the car and not looking for "personal record lap times", is this even an option? Sometime 98 fuel is just hard to find or get at certain tracks. Just a thought.

Thanks! Ben

 

So another question. My car is rated for: 98 RON Super plus lead free gas. Which I "think" converts to US Octane 94... 🤷‍♂️ Maybe...

According to "google" RON converts to 94 octane (US). So can we actually run 94 "octane" in a 997.1 Cup car?

https://www.google.com/search?q=ron+...client=gws-wiz

 

More info:

Europe vs the States

In Europe, gas stations describe different types of gasoline based on their RON rating. It is typical to have 100, 99, 98, 97 or 95 RON with prices varying accordingly. In the States the descriptions look a lot like RON, but they are not.

Pump gas

In the United States gas stations describe the types of gasoline based on the Pump Octane Number (PON). That number is the average between RON and MON. This causes many problems.

If a fuel is 98 RON then it will be 93 PON -> 93 PUMP
If a fuel is 95 RON and 87 MON then it will be 91 PON -> 91 PUMP



So, never-mind it appears that we can run "93 or 94" octane fuel in a 997.1 car that is rated for; "98 RON Super Plus lead free" gas. RON 98 + MON 90/2 = 94 octane (US)

Thanks, Ben

 

check on cup car subforum. 93 94 highest retail octane. can get 118 trackside

 

Search in your area for Sunoco stations, some have 94 octane at the pump-none in FL last time I checked. The higher octane Sunoco for racing is pretty expensive. Here's a no ethanol, no lead one-I'd like two run a pail in my car:
https://www.sunocoracefuels.com/fuels/fuel/260-gtx
JB

 

Thanks guys! Much appreciated! My overall concern was, that I HAD to run 98 "octane" at a minimum, which I now know is not true. 93 or 94 equals the Porsche recommended 98 RON fuel requirements. I do run 98 octane some, but don't want to HAVE to run it all of the time. Good to know.

Thanks again, Ben

 

I have a buddy (I work for every so often) that sells all the Sunoco Race Fuels, as well as VP & Stinger. I've run several combos in my 2010 GT3, including straight up Sunoco 95 Optima (non-ethanol, unleaded), as well as mixtures of 260 GTX or 260 GT (100 octane) with a lower 90 octane non-ethanol giving me a blended approx 94 .... but I do it primarily for winter storage when the car will sit for a few months (Jan / Feb & sometimes into March). It just gives me peace of mind knowing when I fire it up, it'll run great. Been doing it for 5 yrs now. I also get it at cost.

But to answer your question, I do not "feel" the difference in performance. My seat of the pants cannot tell the difference between the good juice, and 93 pump fuel.

 

I've heard this same comment from others too. And although I am a racer, I am not a Porsche racer with a lot of GT3 Cup experience, so I am 100% sure that I wouldn't feel the difference either. My main question or concern originally, was could my car be safely run on pump 93 or 94 octane and clearly the answer now is, YES! Getting pump gas fuel versus buy and storing "race gas" makes things much similar!

Thanks, Ben

 

agreed. and per your original 3 posts, I did learn a few new things. so thank you for that.

 

You're welcome! I'm just glad to learn and share it too. I'm probably the "rookie-est" guy on this Rennlist forum so appreciate the education myself..!!

Cheers!

 

I purposely have not been over thinking it. I only do it for winter storage (& to burn some good fuel at the beginning of every Spring season). But it is good to have a baseline understanding of the fuel ratings.

maybe there's a lyrical rhyme to be made for RON MON PON

 

I've been reading about unleaded avgas for a while and it looks like it's becoming available. Nowhere did I see discussion of using it on car engines but I imagine it will be a good choice especially for turbos. For our cars I imagine there would be longer storage life-I've used 100LL leaded avgas on my bikes-my friend is a pilot and gave me 5 gallon freebies once in a while. Still not sure of any benefits and couldn't use it on the GT3 or S3. But the new G100 UL unleaded avgas might be excellent. I checked 100LL prices recently and an airport nearby had it at $5.73 for self service. the unleaded G100UL is said to cost about $1 more.

https://www.g100ul.com/

JB
I know a guy here that has a bunch of 930s and runs 100LL since there's no catalytic issues and the gas is good for storage, no ethanol for the older injection system.