333pg333

What engine management system are you using? Stock? That could be a number of things.
Spark, fuel, air. Work backwards.

Veloce Raptor

Frank, 100 octane is not "pump fuel". Which is it? 100 or pump gas? If 100 and you were ruunning on 93, of course it will retard ignition to prevent detonation, especially at higher RPM's. That combined with heat = much lower power.

Matt Romanowski

All fuel comes out of some sort of a pump....

Veloce Raptor

Pump fuel generally means gas station in the public domain, not race gas on private property.

d15b7

'pump' fuel? hands down the best (fastest most powerful etc) coming from a pump that the general public can use is E85. I've been running it in my turbo powered civic for 3 years now (used to run VP C16 race gas). I make more power on E85, and the price per gallon at the gas station where I buy it is about $3.40. C16 was up in the $12 per gal range. E85 is fairly widely available at a variety of gas stations near me (about 5 stations within 50 miles). so, the 'pros' for E85 are that it is very inexpensive (even considering that I burn 40% more E85 vs when I was tuned for C16), easiily available, and that it makes extremely good power, especially on a turbo car (due to the inherent cooling and evaporative properties of the alcohol). but, there are 'cons', too. you need to run much larger injectors and a bigger fuel pump due to the higher fuel flow requirements (I run 1150 cc injectors in my K24 2.4 liter engine and a Walbro 255 l/h pump). you need to retune specifically for E85, and can't run 'regular' race fuel, such as I was running before, without having two distinct maps. E85 will take a LOT more ignition timing than race gas, and the fueling maps, as stated before, are much different. E85 will clean out your fuel system (tank, lines, rails, everything) and if you have an older car that has run lots of miles, you might have some gumming and varnish issues (I had this problem initially). E85 doesn't store well; I drain it out and idle with a small amount of gasoline before storing the car for winter.

but, if you strictly are looking for the most power on 'pump' gas? hands down, there is nothing even close to E85 for that; I think the 'effective' octane of E85 is somewhere around 110 points. (C16 was 116 octane fuel, and I get more power out of the same engine running on E85).

Todd
ReidSpeed

dbf73

what do you choose when faced with the choice of 91 no alcohol vs 93 w/alcohol?

Steve Weiner-Rennsport Systems

93 w/ethanol, hands down!!!

Especially for any car with knock-sensors.

gums

When I say "pump fuel" I mean the stuff you can buy at any station.
Now, for my car I have two ECUs that I can interchange very easily. Both are custom flashed to optimize my particular motor, by Behe Performance in Maryland.
One is tuned for 100 octane and one for 93 octane.
But neither is for this ethanol crap, so I'm wondering now exactly what to do and I thank you guys for helping me on this. Ideas? I don't want to pay for race fuel if I don't have to.

dbf73

Steve - do I read your answer as octane uber alles and lack of alcohol is just a tie breaker? That's pretty much what I have been doing except for running no alcohol the last couple of tanks before putting the car up for the winter

PJorgen

Never understood how higher octane fuel will make an engine run cooler. Can someone please enlighten me?

Steve Weiner-Rennsport Systems

Your car runs best with 93 or better R+M/2 fuel. That provides maximum programmed ignition timing, thus best power.

Ethanol, while hygroscopic and miscible, is around 112 RON (a good thing, as noted) and 10% isn't going to be detrimental as long as you deal with the above by using Marine Stabil for winter storage and keeping the tank absolutely full to reduce condensation.

I store my own car with unleaded race gas, however that's not cheap to do.

Matt Romanowski

And don't forget that ethanol has a lower BTU content than gasoline, hence the required higher volume.

One of the major differences in race fuel and pump gas is flame front speed and propogation. Race fuels have specific burn rates that can help or hurt power production.

As to higher octane running cooler, I would love to hear the explanation on that as well.

Steve113

Frank for around $5 you can by a Ethanol tester or use mine any time. Very easy to use. Then you can check which gas stations have the lowest levels and use there gas

mrbill_fl

http://pure-gas.org/

just change the state, to NJ. (you may need to carry jugs to the fuel dock).

FWIW,
Some older boats had fiberglass fuel tanks.... ethanol starts to dissolve the resin and it goes into the engine destroying it.

plus some boats carry hundreds of gallons and can store them for long periods, so many marina get non E10 gas.

but I notice not many carry hi test, (93 octane. )


edit. NJ is not listed! not sure why... I'd call a big marina and ask...

http://pure-gas.org/extensions/map.html

Veloce Raptor

I did not say the engine would run cooler. I said it helps keep the cylinder head at a lower temperature on very hot days. This is unrelated to overall engiine IE coolant temp, which i do not believe fuel octane can influence much