We recently have a gas station start selling 94 octane “gasoline”, which contains 10% ethanol. Would this be appropriate for running the GIAC 94 octane program? Anyone have any opinions on gasohol with Porsches and more importantly modded Turbos?

Would I be better off using 91 octane “real gas” or using the 94 gasohol with the 91 &/or 94 octane program?

Mike

 

All Colorado gas has 10% ethenol (I think it is state mandated). I run both 91 and 93 (when I can) with a modded 996TT. Seems to work just fine. I would love to get better than 93, but very hard to come by (except at the tracks).

 

Greetings Mike,

Sunoco 94 octane in Ontariariario has the ethanol as well. I run it almost exclusively on a Stage 3 system producing over 600 BHP and have had no issues whatsoever. EVO did my ECU.

 

What stage 3 program are you running? 94?

 

I don't think EVO describes their programming relative to an octane level. I am able to run a range of 91-94 with no issues. My preference is the higher octane even though it is part corn.

 

CamNeelyphile:

With the IBE switch or the new-fangled flash loader, you get different programs to maximize higher octane. Mabye this is not the case with stage 3(?). For example, I have a switchable program to run 91 & 100 octane. 94 octane will be in my selection list when the 700 kit is installed.

My question is, if I am running the more aggressive 94 octane program, will 94 octane gassohol do the job, or will I be into detonation and all sorts of K-OSS.

Mike

 

Use ethenol.

 

What do you mean? The stuff comes in the gas out of the pump.

 

I mean, gas with ethenol performs very well and has the added benefit of keeping the fuel drier.

 

I've been meaning to read some links my brother-in-law sent me regarding 94 octane gasohol. I believe they were suggesting that EGT's are considerably higher with ethanol and over all performance, under boost, suffered.

http://forums.nasioc.com/forums/show...hlight=ethanol

Forgive me if I'm incorrect, I only glanced at the first couple of posts.

Mike

 

Here's a post by a smart sounding guy on the above link:

Now things need to be clarified here and it can get quite confusing so bear with me here.

To calculate the AFR for 10% ethanol by 0.1 kg of ethanol needs 0.9 kgs of airplus 0.9 of petrol which needs 0.9 x 14.7 = 13.23 of air. Thus 1 kg of 10% ethanol blend requires 14.13 kgs of air. Now let's assume that the ECU applies no corrections or fuel trims. At idle the ECU will inject 1 kg of fuel for every 14.7 kgs of air measured by the MAF, however our 10% blend of ethanol only requires 14.13 kgs of air. This means that there will be an excess of 0.57 kgs of air.

This should mean that you will need to richen up your maps by a percentage that increases the open loop fuel AFR by about 0.57 of an AFR. Note that this enrichment should be applied across the map including the closed loop region.

To retune for a 10% ethanol blend, ideally we should tune using lambda as lambda = 1 is stoich for all fuels. Now remember the Tuner actually measures lambda but converts the number to an AFR based on the fuel that is used. However to make things easier (?) we will keep the petrol stoich ratio and tune assuming that 14.7 is stoich. (Technically this should be reset to 14.13 but this only adds more confusion we feel.)

At idle and under closed loop control the ECU will compensate. Thus assuming that the fuel trims are not maxed out, then the ECU will tune the car for lambda = 1. This will read 14.7 on the Tuner. You should find that the fuels trims are making the ECU add more fuel and so some fuel should be added by the UTEC in the closed loop region to help bring the fuel trims to zero.

At an open loop fuelling point the AFR should read 0.57 higher. For example at 10.0 it should read 10.57. Thus additional fuel should be added by the UTEC to bring the target AFRs back into line. This should also reduce your EGTs.

By using the petrol AFR (14.7:1) this should mean that you can tune using your target numbers as before.

Does this make sense?

regards
Peter Chan
Electronics Engineer
TXS Pty Ltd
Phone : (+61) (2) 99870127
Fax : (+61) (2) 99870129
Email : peter@txs.com.au

 

Hard question. I think given the nature of the gas I would stay with 91. Here is an answer I gave to a guy on the PCA site. It has proven to be a real issue with older cars. You probably will not have an issue with the car in the short run, but prolonged use has shown no good.


"Ethanol in gas by nature would be harder to burn than say that without it. While ethanol may be burnable it is mixed with water. Cars don't like to try to burn water. They create a lot of it, but don't burn it. The fuel lines don't like it nor any other portion of the fuel system. In the long run I would have to believe that the ethanol mixed gas will be less in performance and mileage simply based on its contents and the ability to efficiently burn. I am not an engineer, so that and a 1.25 is worth a cup of coffee.

The use of Ethanol can be a real problem. It does serve the purpose of increasing the octane level by using it as an oxygenate.. The drawbacks may certainly outweigh the benefits though.

One needs to understand that Ethanol will cause problems with several areas of the fuel system. It will have a tendency to soften and attack all the rubber components in the fuel system. Anything that is not up to par will have a tendency to soften and start to dissolve. Those rubber particles will have to go somewhere, your fuel system.

The other issue with Ethanol absorbs water and will cause corrosion on the metals in the system that are not stainless steel. Once again this will cause a problem in the system. Other things to consider is Ethanol is to some degree a cleaner and will knock particles and dirt, varnish etc out of the system and send it down stream.

The best defense you have against this type of problem is to keep the filters changed on a regular basis. Don't be afraid to change the fuel filters in half the time of the recommend interval. Depending on how often you drive your car, twice a year is not out of the question. Inspect all the rubber seals and lines. Anything that is in question or looks odd, replace. If you are in doubt, replace it anyway. Also make sure you don't run the tank low. The content of Ethanol may cause particles to knock loose or corrosion to occur in the tank and send it to the rest of the system. You should regularly check the screen in the tank. Unfortunately the attention to the system will be higher, but by keeping an eye on it you will head off any potential problems. Not all of us have to deal with these issues. CA seems to be the biggest problem when it comes to Octane levels and boosters. Ethanol and 91 Octane are not the norm in the Midwest."

 

Use the 10% ethenol blend fuel and your engine will run cleaner and perform as designed. ALL major car manufacturers approve this blend including Porsche. Do not listen to the MYTHS that constantly circulate on boards like this. This blend DOES NOT eat at rubber lines or in anyway cause the fuel system to get dirty. It will keep your injectors cleaner and provide an antifreeze for the fuel line.

It has been used in the US for more than 25 years and billions of miles have been clocked using it. I have one car with close to 200,000 miles that has used nothing but ethenol blend and now that I think about it, it has the orginal fuel filter in it. Ethenol burns 100% and therefore cannot leave any residue in the engine like the waxes in gasoline can.

I think some people still read reports from 1975 about the initial problems with ethenol. This eporbelms do not exist anymore.

 

LOL, well sir you must not work on many CIS or older 3,2s. You might want to ask Bruce Anderson what CA gas has done to fuel lines and the likes. Many disagree with you.

 

Rather than give the opinion of someone else, please enlighten us as to a specific instance of how the new ethenol blend gasoline harmed a combustion engine. These blends do not cause any harm and are good for your engine. Your fuel combusts at a lower tempurature and also burns more completely. I'll take actual real world experience over paranoid theories everyday of the week.

Like I said earlier, the problems with this blend when orginally intoduced, such as vapor locks, corrosion, etc, have been eliminated. Any problems encountered on older cars were most likely a result of using this fuel over 10 years ago.

There is a reason you put fuel injector cleaner in your gasoline, Using an ethonol blend fuel eliminates the need to.