F430CS

Hi everyone,

This might sound like a stupid question, but is ethanol in ultra 94 bad for the car? What gas would you guys recommend?

Thanks

AM993

I have been running on Sunoco Ultra 94 for 1.5 year now / 1 tank per week (daily driver). Feels like my car likes it a lot...

Jaak Lepson

It's not bad ... less than 10% which is allowed by Porsche, according to the owners manual. The only issue is with your gas milage. It will be 10 to 15% less with ethanol than with normal gasoline.

I use Shell 91 ... seems to be ther best for both my vehicles according to my butt dyno. Of course YMMV ...

99three

It's been a steady diet for my high HP cars and still feed my 993. It saved my 700 hp TT from detonation a few times already.
OTOH-overboost is the phenomenon that this 'liquid gold' can't protect your motor from. Don't ask how I know.

99three

Jack...why 10-15% less gas mileage on 94 as opposed to the normal grades? Cleaner/higher RON should equate to better efficiency. Any stats/numbers on this?

Jaak Lepson

I have posted links in the past dealing with this subject. here's one of them ....>LINK GOV.

I have seen it with my vehicles as well. Ethanol does not have the same potency that gasoline has.

99three

That was good info Jack. This is something I didn't know:
"While a 10 percent ethanol blend contains about 97 percent of the energy of "pure" gasoline, the energy loss is partly offset by the increased combustion efficiency of the engine. This could increase fuel consumption by about 2-3 percent."

Also good to know that the GHG are reduced by using this stuff. I guess adding some C16 won't hurt.

Jaak Lepson

Before the drive clean test ... run a few tanks of the stuff ... and make sure it's in when going for the test. You will pass ...

mark '87 930

Ultra 94 does contain up to 10% ethanol. I confirmed this with Sunoco a few months back. I was having slight detonation issues last year in my car and although I'll be checking A/F ratios this spring, I will also be switching to Ultra 94 (I used to be a Shell guy). In speakign with various folks in the industry, the opinion is that Sunoco does have the best gasoline out there.

pzull

I did quite a bit of research on gasohol (benzene/ethanol blends) when doing an EFI project for my 965. Synopsis of my findings:

1) Ethanol has about 2/3 the BTU (energy) per volume compared to gasoline

2) Ethanol can be detrimental to certain car parts (usually older cars) not resistant to it. eg. rubber parts harden and crack, uncoated steel fuel tanks may rust, slightly more wear in fuel pump, faster deterioration of cat

3) Ethanol and Gasoline does not remain homogenous indefinitely ie. they start to separate if left sitting for too long

4) Gasohol has a faster combustion rate than plain gasoline

5) Ethanol has a higher latent heat of evaporation meaning it will create a cooler charge for the engine (good for power)

Most modern cars will run on gasohol without much drama but would not be optimised for it for the following reasons:

1) As gasohol has faster combustion rate, ignition timing needs to be changed. Cars with knock sensors may compensate for this a bit but depends on range of adjustments made by factory ECU

2) If a car is not running cliosed loop, engine will run leaner and hotter with gasohol. Few cars have ability to compensate for this and you will need a programmable ECU installed to tune the car eg. Motec, Autronic (which I used)

However if you have a programmable ECU and tune for it you can expect more power but higher consumption. The cooler charge due to more fuel being injected and the better cooling effects of the ethanol will increase charge density and increase power (drag racers use 100% alcohol)

Breakeven point in cost terms for higher fuel consumption in a tuned car is reached when gasohol prices are 4-5% cheaper than gasoline. Anything cheaper and you save costs.

In an untuned car, breakeven point is worse because consumption is much hiogher due to fact that car is not optimally tuned for characteristics of gasohol.

Anyway I'm no PhD physicist but this is what I learnt from research and implemented in my project and it worked really well. For many other reasons my 965 now has 420bhp (at 34 degrees C) compared to factory 320bhp. In lower temperature and humidity like in Canada (ie. 20C) I should get above 450bhp. No issues with pinging as car is optimised for fuel in where I live

PG993

There is an article published in "Excellence" on exactly this topic. "Ethanol and Porsches" september 2006, page 163.

pzull

I searched my P-mag pile and couldn't find this issue. Anyway you can post it or give a synopsis of the article?

NOBLEGT3

you think this guy will appreciate you posting his address on a web forum so spam crawler software can grab it and start spamming the crap outta him??

mark '87 930

Never thought of it that way, I guess I'm not that crooked!

I took down the file.. His address was on the Sunoco site...

Mark Lue

I was at a meet last monday night and over heard some guys from the Grand Am Cup Series saying that the Sunoco 94 actually gave less HP because of the ethonol but they have no choice but to run it as it was the spec gasoline for the series.

Correct me if I am wrong, if it cost more per litre and give less HP and milage than straight gasoline why the h3ll would we want to use it?