Car Question

[galt11]

I was hoping to draw from the vast knowledge out there for another interesting couple of questions. This first is has anyone heard of adding acetone to the fuel in your car to increase the MPG? I have searched this one out on the internet and most in not all the info says it works. The person who originally told me the idea is someone I trust and he said it works by deceasing the fuels surface tension with the cylinder itself and it therefore able to more completely combust.

The other question is also fuel related. Which will make an engine hotter, regular (87) octane fuel or Premium (91 or better) octane. I have been told that running 87 in a car not designed for it will damage the catalytic converter because the gases coming out of the engine are much hotter. This may be true, but I can't see it getting hot enough to damage a ceramic material. The engine in a friends plane, which is basically a Porsche 911 engine could re run above 1500 degrees F before the manufacturer said to even worry about valves. Surely a ceramic material could withstand much higher temps.

Thanks for any info.

Adam

[GentlemanJim]

Any unleaded fuel is ok...lead kills cat converters.

I would not put acetone in fuel it will melt certain plastics used in fuel injections...or your plastic fuel tank

In normal fuels octane rating will have no effect on eng temp and very little if any in EGT.

Jim

[JaredB]

Octane rating is essentially a measure of gasolines resistance to detonation. Cars that are meant to be run on higher octane generally have a higher compression ratio and more advanced timing.

The higher the compression ratio the more heat that is generated from pressure.

If you put low octane fuel in a engine that is meant to run on high octane fuel you run the risk of detonation.

Detonation is bad mmmmkay.

[George]

Ifn'ya hear the can-o-marbles shakin' under the hood, you need more octane rating in yer' gas ;-) Driving in Mexico will make ya' familiar with the sound of an engine pinging unless you travel with a case of octane booster additive. I swear some of the gas I have run across in Mexico almost wouldn't ignite with a match!

[EricW]

Higher octane fuels burn hotter than lower octane. Not the converse. It's easily demonstrable by putting 100LL in an airplane that is rated for 80. You'll see it in higher cylinder head temps and EGTs.

There will not so substantial effect in a car during normal driving.

Acetone will also make your engine run hotter. I have used it to clean the crud out of my pickup truck. Better mileage? Nah....

[galt11]

Thanks all for confirming what I either knew or suspected. What confused me was talking to a rep from BMW at the NY auto show who told me that filling the 335 with regular fuel will damage the catalytic converter. When I asked him how, he didn't explain.

I was also concerned because I just had to replace the cat on my VW. It says it needs 91 or better but for the last year or so I have only been filling it with 87 and using a fuel system cleaner every so often. Fortunately, the cat was covered under warranty, but I was curious what might have caused the problem to begin with.

Adam

[galt11]

This is the website my friend referred me to in the first place.

http://peswiki.com/index.php/Directory:Ace...a_Fuel_Additive

Adam