Steve Weiner-Rennsport Systems

Hi:

Recently, the State of California has chosen to eliminate MTBE from motor fuels and instead, use Ethanol as the oxygenate to reduce emissions.

There are some concerns about this change that everyone who drives a performance car should be aware of, especially turbocharged ones.

1) Octane Rating: The highest octane fuels you might see now are 91, instead of 92. This may be an issue for cars with certain performance chips, high compression ratios, and forced induction. 91 octane is, IMHO rather marginal unless this is taken into account when undertaking any program of performance enhancements.

I've posted a matrix chart on our website for blending 91 octane pump gas with 100 octane unleaded race gas. I hope this helps. Look at the URL below

2) Elastomer Compatibility: This is largely an unknown as the long-term database is incomplete. For certain, Ethanol is well known to attack and slowly dissolve certain rubber parts used in all fuel systems. You may not get the long life expected from such items and this deserves some scrutiny. Ethanol is also an excellent solvent and scours out all dirt, rust, and contaminates in the fuel system sending them into the filter. This causes rapid filter clogging and immediate fuel filter changes are recommended along with more frequent changes than the Factory recommends. This will stop your car dead! Change that filter at least twice a year.

Last, octane boosters are not recommended except in emergencies. The additives in any effective octane booster leave a big brown mess inside your engine and they do not improve octane proportional to costs. Further, these additives WILL attack the rubber gaskets, O-rings and seals with the attendant troubles that this will create in the long term.


Lets Talk about Porsches

Greg Fishman

Steve,
Thanks for the info. I guess this is one reason to be glad I live in the Midwest/South.

One question related to this. For my 993 race car with stock engine, ecu, etc. What is highest octane I should/need to run. I normally use Sunoco 94. Should I add some 100 octane fuel to bump that to 96 or so? I don't want to throw money down the drain. (Ironic, isn't that the definition of racing anyway?) but want to have max performance and reliability. This would also apply to those guys that do serious DE's with their 993's.
As always thanks for your help.
Greg

Steve Weiner-Rennsport Systems

Hi Greg:

Indeed, in that respect, you are lucky to live there and have the availability of good fuels that are simply not on the West Coast.

As long your engine is stock, the 94 octane Sunoco is great stuff and will suffice just fine for what you are doing. If its very hot outside and you are running some long tracks with straights that you can hold it open for a bit, then blending some 100 octane race gas cannot hurt a thing.

Enjoy!

H. Miller

Ethanol is not new to us in Colorado, neither is 91 octane fuel since that is all you can get around here and it all has ethanol.
However, I believe you said in a previous post that at altitude (5500 ft) the lower octane is ok. But it still has ethanol so I am assuming I need to get the fuel filter changed frequently:
Is once a year often enough? is this a difficult or expensive change if done at the dealership?
I've been looking for 100 octane racing fuel in the yellow pages but can't seem to locate any. Do you have any suggestions how to find this type of fuel?
Thanks for the information, octane ratings continue to interest and frustrate me.

David T.

Try

http://www.76.com

and click on Station Locator, when searching limit on Racing Fuel

H. Miller

David T.,
Thanks for the suggestion. The 76 locator only lists 8 states and unfortunately Colorado is not one of them. The closest is Arizona - a little too far to drive.
I'll keep trying and thanks again for the advice.

Anir

Greg,

Where do you get Sunoco 94?

Thanks!

Steve Weiner-Rennsport Systems

Hi:

Personally, I do not like being stranded and I've seen many cars with clogged fuel filters that have left their owners calling for help. This was all caused by the detergent action of Ethanol-blended fuels.

I would recommend changing the fuel filter twice a year if you are driving 10K per year or more. Its pretty cheap insurance.

Regarding the availability of unleaded race gas, Look to see who distributes either Union 76-Sunoco-VP Fuels-ERC in your area. All of these folks make an unleaded race gas. You might also check with NHRA as active drag racers would also know.

Greg Fishman

In Ohio or Indiana, usually along the way to the track. There are a couple stations in Ky but nothing near us. For street use just use whatever I can find, usually 93.
Greg
Greg

DoubleNutz

Steve,,,WOW" !!! That was extemely informative.

I have been meaning to stop by your shop to learn more about these things. This was REALLY informative and my incentive to get over and talk more with you (squeeze in some business too).

Thanks

E. J. - 993 Alumni

Miller go here:
VP Fuel info and email or call the guy in Kansas. He will know of a local speed shop that sells the vp fuel. I have a friend out in Denver who drag races and he buys fuel from somewhere out there. Also, maybe easier to call Bandimere Dragstrip and ask them where you can get the fuel. I guarantee they know.

laurence '97 C4S

Steve, very informative post. I do have one question: I was under the impression unleaded gas would destroy catalytic converters? Is the blend ratio you recommend not of sufficient levels to cause damage? ...Or am I mistaken?

Steve Weiner-Rennsport Systems

Hi:

Unleaded gas will not harm converters, LEADED race gas certainly will, in short order.

Unleaded race gas is available in 100 octane and 104 octane formulations.

os993

I don't know why, but this latest step here in California really boiled my blood!

MTBE was bad enough, and now this. Ethanol and 91 octane gas!! I'm just waiting for the price to go up, just to add insult to injury Also, how far will this go, before it becomes ridiculous to even own a performance car! Hey, a marathon athlete won't be much of an athlete if he continually eats KFC and Burger King... Am I missing something here??

Steve, what does this mean to us normally aspirated, non-chipped 993's (great article BTY, thanks)? Will my car detonate more often? Will I notice any power decreases?

I'm sure I'll notice less fuel economy (heard that ethanol is worse than MTBE for gas mileage - great ). Actually I've always wondered about this logic. By adding these additives, we need to burn more fuel to travel the same distance. So, doesn't that defeat the original purpose of trying to improve the air quality??

As far as gas filters go, how difficult is it to replace these?

Thanks in advanced for any inputs and for listening. I've lived in California all my life, and love the State very much, but all these gas laws, power shortages, high-cost of living, etc.. has really gotten ridiculous. Don't know why, but this latest 91 octane move really hit a nerve....

Steve Weiner-Rennsport Systems

Hi Oleg:

First, I think you are not alone in your sentiments. I have a feeling that many people will soon discover that CARB's priorities do not include making sure that everyone's car runs correctly, performance car or SUV, inclusive. Politics and Federal tax incentives play a major role here.

Second, Its my opinion that under certain circumstances of outside air temperature and load, will make the 91 octane fuels somewhat marginal and further measures will need to be taken to maintain performance. The Motronic's knock-sensing system should prevent any damage unless you run DE events during hot weather. Under such conditions, it would be prudent to add some 100 octane unleaded race gas to the tank.

As a chip tuner, our "West Coast" timing maps will be modified to suit.

Third, there is no question that the reformulated gasolines sold in California containing Ethanol does not get the same mileage as their earlier MTBE-laced formulas and do not contain the amount of BTU's per gallon. All things being equal, this results in a net power and mileage decrease. If the knock sensors are activated more frequently, then the power loss will be more severe as the engine protects itself.

Lastly, fuel filters are easy to change and should be part of your routine maintenance.