Problems with Premium

[bradb08]

I have a new 427R and am running Premium in it however in Oregon we have Ethonal in all of our gas.

is there a product that can help me get rid of the knocking and pings?

[mln385]

You might want to contact Roush and ask them, they may reflash your ecm for this issue.

As I recall Roush does not recomend any octane boost for their cars as it fouls the plugs.

Marc

[superstang2]

We have ethanol in our gas in Virginia, and I have never had problems, tho' mine is Procharged with a 2007 GT500 fuel pump, low-temp Autolite plugs and Diablo Mafia..you might want to try some up-grades

[p47koji]

We have ethanol in our gas in Virginia, and I have never had problems, tho' mine is Procharged with a 2007 GT500 fuel pump, low-temp Autolite plugs and Diablo Mafia..you might want to try some up-grades

Yeah, we've got that corn-crap in our California gas. I hear that its more the atomization properties of the specific brand of gas has more of an influence on detonation. For instance, Arco has poor atomization so I avoid it, but it's cheap for a reason. As Marc and Superstang2 suggest, try giving Roush a shout? ;)

[Mrs. SuperSnake]

Not had any problems with either of our cars and all we can get is 91 octane...but no ping...good luck.

[Jus Cruisin]

I've been not having any detonation issues here in Florida. We can still get 93 octane Sunoco and Mobil.

[rheacerdave]

Regional mixes have a lot to do with it.
South East we get 93 octane with and without ethanol. (Phillips, Citgo, and Marathon don't use ethanol, yet) Not sure 10% or less is an issue.
I understand West Coast has 91 octane. May just have to try different brands to see which one works best.

[p47koji]

Hi, Dave, I hope the weather on the eastern seaboard is being good to you... We had a 5.5 earthquake here in southern California last Friday night... :(

Given your background and expertise in racing, is there any truth in the relationship between atomization quality of a fuel and detonation propensity? We only have 91 octane stuff down here... I do agree with your comments of just trying different gas but I'd be curious to hear your thoughts on the atomization... ;)

[aaholland]

actually i think the 91 octane stuff is just fine for most roush cars. i think and i stress think that roush tunes the blowers to 89 octane to make the 91 gas in all 50 states safe. just try to avoid the cheap stuff or any fancy boosters as i think they may foul your plugs.

[rheacerdave]

Hey, Koji
Haven't been around here much lately.
Yes, to your question.
Gasoline is pretty much gasoline, but the additives are what make or break it as a fuel for our cars. and vary from company to company.
Winter/ summer blends can complicate the formula
The Reid vapor pressure is the vapor pressure of the gasoline blend when the temperature is 100 degrees F. Normal atmospheric pressure varies, but is usually around 14.7 lbs per square inch (psi). Atmospheric pressure is caused by the weight of the air over our heads. If a liquid has a vapor pressure of greater than local atmospheric pressure, that liquid boils. For example, when you heat a pot of water, the vapor pressure increases until it reaches atmospheric pressure. At that point, the water begins to boil.

In the summer, when temperatures can exceed 100 degrees F in many locations, it is important that the RVP of gasoline is well below 14.7. Otherwise, it can pressure up your gas tanks and gas cans, and it can boil in open containers. Gas that is boiled off ends up in the atmosphere, and contributes to air pollution. Therefore, the EPA has declared that summer gasoline blends may not exceed 7.8 psi in some locations, and 9.0 psi in others.

A typical summer gasoline blend might consist of 40% FCC gas, 25% straight run gas, 15% alkylate, 18% reformate, and 2% butane. The RVP of the gasoline blend depends on how much of each component is in the blend, and what the RVP is of each component. Butane is a relatively inexpensive ingredient in gasoline, but it has the highest vapor pressure at around 52 psi.

In a gasoline blend, each component contributes a fraction to the overall RVP. In the case of butane, if there is 10% butane in the blend, it will contribute around 5.2 psi (10% of 52 psi) to the overall blend. (In reality, it is slightly more complicated than this, because some components interact with each other which can affect the expected RVP). This means that in the summer, the butane fraction must be very low in the gasoline, or the overall RVP of the blend will be too high. That is the primary difference between winter and summer gasoline blends.
You may notice more or less ping middle of April or middle of Sept (when blends change).

[p47koji]

Hey, Koji
Haven't been around here much lately.
Yes, to your question.
Gasoline is pretty much gasoline, but the additives are what make or break it as a fuel for our cars. and vary from company to company.
Winter/ summer blends can complicate the formula


Dave, so who gave you the hall pass? :) You were never excused from visiting this forum! :D

BTW, when you mentioned at the end of the info that you may notice pinging at a certain time of the year, it all makes sense now. I just hope the pinging doesn't escalate to marbles rattling around in a beer can...empty, of course.

Thanks for the info and y'all come back now, hear?:)

[LeeU]

One reason or possible solution is our cars have a crank case venting system or EGR, some have reported after modifying the oil return system with an air/oil separator their cars have stopped pinging. I have no clue if this is true but I suspect that the oil being returned into the supercharger where it becomes part of the fuel/air mixture which is a problem as our cars should be burning air and fuel not oil, oil could reduce the burn rate and in affect cause a ping similar to low octane fuel. I have been researching the best and most efficient oil separator but have not found any that I’m comfortable with yet. The oil/air mist entering our motors can cause carbon deposits on pistons and valves as well as slugging up intakes and especially intercoolers and should be removed even if it is not a contributing factor to a car pinging. IMO

I also run 91 high test with 10% alcahol, I have not had any problems. I wish we had 93 HT here but @5300 ft I'm told 91 HT is equal to 93 HT.

LeeU

[p47koji]

Lee, that's fascinating about the air/oil separator... How long have you been researching and are you leaning towards any product?