cscrogham

What fuel are you guys using in the new RS?

I put Shell pump gas in the thing just because I remembered that was one of the few companies in the US that still uses old school detergent fuel, but I am guessing the unleaded 100 GT Sunoco that we use in the racing series would be a good choice too. Sunoco also has a 94 octane street fuel but none near me.

I noticed the fuel that came in the car from Germany had a very strong chemical smell to it, unlike our pump gas and closer to the 100GT racing fuel. I am hesitant to put it in there due to the warnings about eating the fuel cell lining, but the plastic tank might be ok. I do like that the 100GT lasts up to 2 years when pump gas lasts about 2 months before breaking down, since I dont drive it a lot and even track cars sit a long time in the off season.

The reason I am bringing this up is I just helped a guy resurrect a 1992 America Roadster that has 180 miles on it, the tank was ok but the rest of the fuel system was a mess and I'd like to keep that from happening to the RS. Any fuel experts out there?
Cole

Macster

Quite a difference between a car that was driven just 180 miles in 18 years (10 miles per year or 0.83 miles per month?) and one used more frequently than that.

In the car that is used more frequently, not only is the gas in the tank renewed every once in a while but the engine is run so the gas in the rest of the fuel system gets flushed out with fresh(er) gas.

Unleaded racing gas ok but I suspect it would go stale quicker than premium gas so I'd arrange to when the car left the track to add some premium gas to the tank. This gas stays fresher longer though it too will lose something over time.

Buy from a busy station to ensure the gas is as fresh as it can be. Sometimes when I encounter a tanker filling up a station's storage tanks I ask the driver how often he delivers fuel. Quite common for a busy station to get gas delivered every day. At one Shell station just off I-35 in Olathe KS I was told the station requires up to 4 deliveries per day.

I've never used it but you might consider a gasoline additive intended to stabilize gasoline in cars that see little use.

Sincerely,

Macster.

911SLOW

standard unleaded is 95RON in Europe and super unleaded is usually 97-98 RON and 100 in some countries.
In USA its lower thats why the cars that go to US market have different motronic software than the RoW cars.
So adding 100 gas in a USA RS i dont beleive it will benefit but it wont hurt it either. And here if you fill the GT3 with 95RON engine output is reduced. It has a sticker in the fuel door saying super unleaded only +98.

John

edit: Also BP and Shell apart from some performance and lubrication additives they also aromatize the super unleaded fuel for easier distinction from the simple fuel preventing monkey business from the pump shops.

The Baron

Cole,

A few Sunoco dealers in Baltimore have 100 octane at the pumps. It is a specific pump not a multigrade pump.

As a rule, I have been putting Sunoco 100 octane in all of my cars including the three RS. My decision to use 100 octane in all my cars is as much the quality of the fuel as the octane. Two key aspects are at the forefront.

All standard grades (86, 87, 89, 91, 92, 93 even 94) have the mandated 10% ethanal which is slowly destroying many of the rubber, latex, silicone, etc, parts in the fuel system. I'm told this from some reputable engine builders. Sunoco 100 octane has NO ethanal in it.

The second concern is the fuel stabilizers that every fuel company uses. Fuel stabilizers were developed because WW II and the logistics problems in the Asian theatre. In the past, fuel stabilizers were able to give road fuel a shelf life of 24-28 weeks (5-6 months). Prior to the interstate System, service stations in the remote parts of the country might sit on a truck load of fuel for half a year before being used and the fuel would turn bad.

Today, with the average gas station pumping 10,000 gallons per week, there isn't the shelf life issue and fuel companies have cut costs by reducing the stabilizers and now the fuel typically lasts 2-3 weeks before starting to turn (just check your gas cans)

Sunoco 100 at the pump has long term stabilizers because at $8 per gallon, a station can sit on a load (5000 gallons) for 6 months.

This is very good if your Porsche sits for the winter !

Hope this helps.

ADias

Gas in Europe and the US are the same. They just use diff scales (RON for Europe, AKI for US). The European 98 gas is the same as the US 93 gas. The CA 91 is another issue.

There is no tune diff between Porsches sold in the European or the US market.

tcsracing1

i try to run North American grade 91 minimum.

this is another reason why i do not yet run a CUP car. In my area high octane fuel is hard to come by and pain in the ***.

malmasri

93 Octane from Costco which BTW is a high volume seller....the car loves it, and Porsche recommends it..I do not see a reason to use a more exotic difficult to find PIA 100 Octane in it...Been there done that with supercharged engine, and I do not miss it.

911SLOW

Dias I know about the different measuring scales. And if you read the link you posted it says same thing regular fuel in US is lower graded than regular fuel in Europe.
Row Porsche have different ecu settings than the US cars and different than Japan. Reason is that in some states you have lower octane gas. And different laws about pollution. If you run a Row Porsche there it will pull back timing etc to accomodate. US version maps of motronic have this taken into consideration.
Btw motronic ecu are programmable you have to connect PIWIS and
Input Vehicle identification number then
Input DME programming code
and then select data record US, EURO4-5, EURO 3, Japan.
and that proccess changes programming to sellected region.
Also US cars dont have the sticker saying use super unleaded only min 98ron which is 93–94 AKI do they?

John

Cupcar#12

Cole,
Suunoco is about it for decent fuel in the USA outside of the 100 unleaded race suppliers you are already familure with.

Storage is a problem as after 6 months or so the fuel loses a good bit to breakdown.

I do not like fue stabilizers in either of the cars (92 Cup USA or the 356) as it seems to gum up the systems (esp carbs) more than just running it in place one a week. and getting things moving.

btw.... scotty's 356 is headed back east next month and me with it.

Nugget

Yes they do. US cars have the sticker saying the minimum octane is 93 "RON+MON." 93 octane (AKI) fuel is readily available in the US. The owner's manual clarifies that the engine is designed for 98 RON fuel, just like the one you pasted (here's mine from my C2S).

ADias

Yes they do. All Porsches do have a sticker saying premium unleaded 93AKI only (91 OK).

These are the facts:

1 - US 93 AKI = EU 98 RON - Fact!

Pumps in the US sell 3 types of gas Regular/MidGrade/Premium - all unleaded. Most states in the US sell 93 AKI (98 RON) or 91 AKI (California ans some western states). Many years ago PAG sold cars in Europe with one tune (because pollution laws were non-existent or mild) and another tune for most of the US, and a 3rd tune for California. That is all gone. Starting with the 996 all cars in Europe and all US have the same tune. And yes, the ECU adjusts to octane level (more below).

2 - PCNA recommends in the US 93AKI (98 RON). See page from my manual below. Fact!



Of course, the ECU will adapt to lower octane - in the US and anywhere else (even in Europe) if the gas is lower octane. In CA the available gas is 91 AKI and yes the ECU will adjust (the same ECU cars in Germany have. Even within the same region from pump to pump gas quality varies and the ECU must adjust.

Carrera GT

For the '07 and later GT cars, even "California water" (93) is fine.
For older Turbo's, I have a habit of keeping a 5 gal jug of 100 and blending up for sustained wide open on the track. Just mix in Stabil for long term barn owls and make sure you run it long enough to get the mix all the way through the filters and injector rails. If you're really trying hard, the Chevron Techron injector cleaner is something that I started using by advice form Porsche Master Technicians in the 90's. The idea is to mix it into a half tank, burn it through to pick up fuel deposits, lacquers, crystals, oxidized whatever and carry it through the downstream of the filters. Then it gets burned and redeposited elsewhere (out the exhaust, away from the valves and injectors ... and in the oil ... so the next step is an oil and all filters swap.) The theory is, the engine will be shiny inside. So far, so good. But don't bother if you keep the car less than five years and have no real intention of keeping it forever.

Cupcar#12

btw...
Pumps in the US sell 2 grades of Gasoline, Low (87) and Premium (92-94), Mid grade what ever is blended from these.

gas stations only have 2 tanks for Gas storage, normally 27K gallons of Regular and 10K of the good stuff. ---- ask em'

Carrera GT

True enough. I'm no authority, but I have noticed the "older" stations in California have only high and low filling valves. The mid-range is presumably a blend at the bowser. Newer stations have three fill points. I don't know if the tankers deliver three fuels or two.

The issue is the "cool" stations (some Unocal 76 or Conoco or whatever they are -- the much appreciated and long standing source of 100 on Woodside Rd on the corner of Kentfield in Redwood City or the one off 87 near the Automall Parkway in San Jose) have 100 "Race Fuel" and, for maybe $2-3 over the price of premium 91 (still $1-5 less than paying at the track pump) they're great.

And the blend math is simple if you want 95 as a mix of 91 and 100, just call it 90 and 100 or 1:1 and bingo, the engine DME is happy and it opens up the advance, the boost stays on and the heads stay cool. Again, I should make it clear, this is talking about older turbo's. For the '07 and later GT cars, I've never run anything more than 91 pump gas.

911SLOW

Thanks for the information guys.
It’s interesting to know that the 98RON sticker is in US cars as well, but the ecu still has different settings for US cars. Anybody that has performed an update in his ecu in the dealer can verify it by looking at the screen in PIWIS tester. I have seen it 100 times so it’s a fact!

Probably the threshold of ecu's adaptation parameters is changed to be able to cope with the 91aki and other low octane fuels available there that don’t exist in Europe at all or something that has to do with emissions but this is a guess.

John