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Using regular gas


old guy

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I posted in another thread about a week ago that we had no problem using regular (85 octane at 5000 ft) with no ping. It was my belief that running low octane fuel was ok as long as there was no detonation. Because of the retarded timing I expected (and got) less performance. LuLu replied that damage could occur over time with inaudible ping.

 

Let me clarify that this is Pauline's daily driver, and she drives about 60 miles per day on the highway at normal highway speeds, so getting the last drop of performance out of the car is not her priority. She bought it because she liked the way it looked and she wanted something to bring to shows when I brought mine.

 

I have since told Pauline to start putting hi-test in her car (she always does what I tell her to do,) but I have scoured the internet and have spoken with a couple of engine builders about this, and they all say the same thing... that ping is always audible because it is actually the vibration thru the engine that is caused by preignition, and the anti-knock sensor will pull the timing back far enough to prevent any detonation. If it doesn't, you will hear it.

 

I am not doubting LuLu's explanation and Pauline will continue to use hi-test until or unless this is disproved, but I really want to understand this. If there is no detonation, how can damage be caused. In all my years of driving and, more importantly, flying small planes where detonation can cause premature or unexpected engine failure, I have never heard of anything like this. Detonation is caused by the fuel igniting before the piston reaches the top. Pushing the timing back delays the spark. Unless there is high enough compression or a hot spot to ignite the gas, there is no preignition, and if there was it would be audible.

 

Can we get a discussion going on this? Thanks.

 

EDIT: Here's a link to the original thread...

 

The discussion starts at post #6

 

http://www.teamshelby.com/forums/index.php...hl=pre-ignition

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One thing to remember is - 91 octane is "required". If there were to be some issue, during warranty, does Ford have a way to check the fuel octane - or would the computer reveal the octane used and/or pinging?

 

I doubt I would hear pinging anyway, just because my ears have always been a little deficient on picking up sounds like those.

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Retuned my SGT for 87 last Sunday. Filled up with 87 on Thursday morning and down to 1/2 a tank right now. Not a single ping or rattle even at W.O.T. - so far.

I'm driving it today so that's first hand information and I drive it a a lot harder than my wife does.

 

Must be genetics. :rockon:

 

I'll post up the first sign of anything out of the ordinary.

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Retuned my SGT for 87 last Sunday. Filled up with 87 on Thursday morning and down to 1/2 a tank right now. Not a single ping or rattle even at W.O.T. - so far.

I'm driving it today so that's first hand information and I drive it a a lot harder than my wife does.

 

Must be genetics. :rockon:

 

I'll post up the first sign of anything out of the ordinary.

 

Stump, what exactly is that hypertech tuner you have?

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One thing to remember is - 91 octane is "required". If there were to be some issue, during warranty, does Ford have a way to check the fuel octane - or would the computer reveal the octane used and/or pinging?

 

I doubt I would hear pinging anyway, just because my ears have always been a little deficient on picking up sounds like those.

 

 

The 91 Octane requirement is Shelby's, not Ford's. Ford recommends regular gas in the Mustang GT. I don't know the answer to your question. I guess I'm asking if there will, in fact, be damage. If there is, in fact, something that would cause damage, then using hi-test would be a no brainer. But if not, then there are people who wouldn't mind a bit less power because of the price of high test. If any warranty work is necessary, it would be up to Ford to prove that using low octane fuel in an engine that normally requires it actually caused the damage, no matter what the owner's manual says.

 

There is no doubt in my mind that Shelby requires premium fuel, at least in part, so the computer will advance timing and give the advertised HP. The question is, is there any other reason they require it? There are no internal mods to the engine.

 

Again. I am just trying to understand.

 

By the way... I think you would probably be able to hear the "ping" (more like marbles rattling around in your engine.) It would be very noticeable, especially under WOT or going uphill.

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Stump, what exactly is that hypertech tuner you have?

It's the Hypertech Max Energy. It also updates online but you have to put the stock tune back in the car, update and then retune. I used to think it was really vanilla. I'm thinking different now. It's also super easy to use, just yes and no questions and nothing an engineer has to figure out.

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I've read in a number of Mustang magazines (MM&FF and 5.0) over the years that detonation is not always heard.

 

I've read that too, but it is usually in the context of an aftermarket anti-knock sensor not "hearing" the knock because the unit is not a good match for a particular engine. I would hope that Ford has engineered their sensors for the engine.

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I posted in another thread about a week ago that we had no problem using regular (85 octane at 5000 ft) with no ping. It was my belief that running low octane fuel was ok as long as there was no detonation. Because of the retarded timing I expected (and got) less performance. LuLu replied that damage could occur over time with inaudible ping.

 

Let me clarify that this is Pauline's daily driver, and she drives about 60 miles per day on the highway at normal highway speeds, so getting the last drop of performance out of the car is not her priority. She bought it because she liked the way it looked and she wanted something to bring to shows when I brought mine.

 

I have since told Pauline to start putting hi-test in her car (she always does what I tell her to do,) but I have scoured the internet and have spoken with a couple of engine builders about this, and they all say the same thing... that ping is always audible because it is actually the vibration thru the engine that is caused by preignition, and the anti-knock sensor will pull the timing back far enough to prevent any detonation. If it doesn't, you will hear it.

 

I am not doubting LuLu's explanation and Pauline will continue to use hi-test until or unless this is disproved, but I really want to understand this. If there is no detonation, how can damage be caused. In all my years of driving and, more importantly, flying small planes where detonation can cause premature or unexpected engine failure, I have never heard of anything like this. Detonation is caused by the fuel igniting before the piston reaches the top. Pushing the timing back delays the spark. Unless there is high enough compression or a hot spot to ignite the gas, there is no preignition, and if there was it would be audible.

 

Can we get a discussion going on this? Thanks.

 

EDIT: Here's a link to the original thread...

 

The discussion starts at post #6

 

http://www.teamshelby.com/forums/index.php...hl=pre-ignition

 

 

Owning a Shelby is a sacred trust. If you are not prepared to do what it takes to care for it properly, you should sell it to someone who will. This is a scandal! Shelby abuse!

 

 

:redcard:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

:hysterical:

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Hey old guy. Here's is my experience with the 87 on a Shelby tune, take it or leave it. When I bought my car the dealership filled the first tank with 87. I left there in a cloud of smoke so-to-speak and noticed no problems with the car. I had to go back a few days later for something and they were going to put more gas in the car. By now I had read the book stating 91. When I asked if they were putting 91 in the car I was told no, Ford recommends 87. We argued briefly, I showed him the manual and he showed his manager. They were or seemed to be surprised. I say all that to say this, when the car was Shelby tuned, I ran 87 in the first tank without any noticeable problems. I switched to 91 because of the manual.

 

My Hypertech is a different story though. It was tuned for 91 and I got some (I assume) cheap or mismarked gas that caused horrible pinging. An expensive bottle of Octane booster later and all was well.

 

I just remembered that situation sitting here at work and didn't know if it might help.

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The 91 Octane requirement is Shelby's, not Ford's. Ford recommends regular gas in the Mustang GT. I don't know the answer to your question. I guess I'm asking if there will, in fact, be damage. If there is, in fact, something that would cause damage, then using hi-test would be a no brainer. But if not, then there are people who wouldn't mind a bit less power because of the price of high test. If any warranty work is necessary, it would be up to Ford to prove that using low octane fuel in an engine that normally requires it actually caused the damage, no matter what the owner's manual says.

 

There is no doubt in my mind that Shelby requires premium fuel, at least in part, so the computer will advance timing and give the advertised HP. The question is, is there any other reason they require it? There are no internal mods to the engine.

 

Again. I am just trying to understand.

 

By the way... I think you would probably be able to hear the "ping" (more like marbles rattling around in your engine.) It would be very noticeable, especially under WOT or going uphill.

 

 

Interesting post.....With the cost of fuel we all need some no BS information if we can use regular fuel or it has to be premium that we must use. I have been hearing of fuel stations putting regular in premium tanks and overcharging.....what are we to do in such situations???? I have been using fuel from my local BJ's club which is currently at $4.15 a gall and they only have two types of fuel,reg 89 or premium 93 so who knows what can be mixed up or not,good point about the GT using regular fuel,I mean is 319HP really that much more than the advertised 300HP GT? HMMMMM..... :talkhand:

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Owning a Shelby is a sacred trust. If you are not prepared to do what it takes to care for it properly, you should sell it to someone who will. This is a scandal! Shelby abuse!

 

 

:redcard:

 

:hysterical:

 

There's always one in every crowd, isn't there??? :slapfight::)

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Hey old guy. Here's is my experience with the 87 on a Shelby tune, take it or leave it. When I bought my car the dealership filled the first tank with 87. I left there in a cloud of smoke so-to-speak and noticed no problems with the car. I had to go back a few days later for something and they were going to put more gas in the car. By now I had read the book stating 91. When I asked if they were putting 91 in the car I was told no, Ford recommends 87. We argued briefly, I showed him the manual and he showed his manager. They were or seemed to be surprised. I say all that to say this, when the car was Shelby tuned, I ran 87 in the first tank without any noticeable problems. I switched to 91 because of the manual.

 

My Hypertech is a different story though. It was tuned for 91 and I got some (I assume) cheap or mismarked gas that caused horrible pinging. An expensive bottle of Octane booster later and all was well.

 

I just remembered that situation sitting here at work and didn't know if it might help.

 

Thanks for relating your experiences. They match my own. This is why it is so confusing.

 

I would guess that the Hypertech tune has a higher minimum timing parameter than the original tune.

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According to the writeup on the Bullitt(which has the same FRPP tune on it), you can run it on 87 Octane. I have attatched a link to the PDF for the Bullitt. That info is in the engine section. I guess there is a new adaptive spark ignition system on the 08's. I do not know if there is any real difference from before but it says you can run 87 and the car will be fine.

 

Bullitt Features<<<<LINK

 

 

Gib

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When the car is delivered from Ford to the Shelby factory, what octain fuel does Ford ship in the car. This is the same fuel that is used when the car received the tune. I would guess its regular, 87 octain. I wonder if that would that have an effect on the tune?

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According to the writeup on the Bullitt(which has the same FRPP tune on it), you can run it on 87 Octane. I have attatched a link to the PDF for the Bullitt. That info is in the engine section. I guess there is a new adaptive spark ignition system on the 08's. I do not know if there is any real difference from before but it says you can run 87 and the car will be fine.

 

Bullitt Features<<<<LINK

 

 

Gib

The Bullitt has a different FRPP intake so I don't think it has the same tune. Ford Racing states "premium fuel only" for the M-2006-FR1 Power Upgrade Package used on the Shelby GT.

 

http://www.fordracingparts.com/parts/part_...rtKeyField=9398

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Try this tip to save about 5 cents a gallon on average. Fill up at about 1/3 to 1/2 tank and alternate b/w 93 octane premium and 89 octane mid-grade. The blended mix will yield about 90-92 octane at all times. I've been doing this for some time with no problems. It's not much of a savings but every little bit helps.

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A fellow Denver area SGT owner recently got the Service Engine light because he was running 87 rather than 91. Sounds to me like that car really doesn't like anything but the premium stuff.

 

Rick - I think that was inconclusive. He said that he had climbed 5000 ft and got the check engine light. He had been running 87 in it for quite some time. A loose gas cap would definitely cause that with the pressure change. AAA says that when you fill up you should get at least 4 clicks to guarantee a good seal.

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Rick - I think that was inconclusive. He said that he had climbed 5000 ft and got the check engine light. He had been running 87 in it for quite some time. A loose gas cap would definitely cause that with the pressure change. AAA says that when you fill up you should get at least 4 clicks to guarantee a good seal.

 

I don't know if the altitude was the issue or a loose gas cap but in the future I will be running 91 octane in my SGT. I have dreamed of owning a Shelby since I was 18 and don't want to risk a major failure to save a few bucks. In the long run the engine life will be better if I follow what Shelby reccomends. Old Guy I agree I'm not sure the 87 Octane was the issue but why take the chance? Great discussion it will be good to get to the bottom of this issue, see you on Saturday for breakfast at Mimi's!

Mick

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I run high octane super unleaded even in my cars and motorcycle that don't require it. I know it costs more per gallon but even my older cars run better with the higher octane fuel. To each his own but my personal opinion is to heed the Shelby recommendation for the super unleaded (high octane).

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I'm running Colorado 91 (93 to the rest of you flatlanders). By the time I go from 85 (your 87) to 89 (your 91), going to our highest just doesn't make that much of a difference. But then I've only got a little over 600 miles and not even three tanks in it yet, so it's not a huge investment. I'm still averaging over 21MPG even with my aggressive little trip up in the mountains last weekend.

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I don't know if the altitude was the issue or a loose gas cap but in the future I will be running 91 octane in my SGT. I have dreamed of owning a Shelby since I was 18 and don't want to risk a major failure to save a few bucks. In the long run the engine life will be better if I follow what Shelby reccomends. Old Guy I agree I'm not sure the 87 Octane was the issue but why take the chance? Great discussion it will be good to get to the bottom of this issue, see you on Saturday for breakfast at Mimi's!

Mick

 

+1 It's not worth the risk. The difference between 87 and 91 is only $3 or $4 per tank. Pay the extra few bucks and avoid the chance of detonation.

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I'm running Colorado 91 (93 to the rest of you flatlanders). By the time I go from 85 (your 87) to 89 (your 91), going to our highest just doesn't make that much of a difference. But then I've only got a little over 600 miles and not even three tanks in it yet, so it's not a huge investment. I'm still averaging over 21MPG even with my aggressive little trip up in the mountains last weekend.

 

 

Exactly... and let me make it clear that I agree for most of us here high test is the way to go, but for those who use their cars as their daily driver and are putting 1500 easy miles a month on the cars (reread my first post for a reminder of why I brought this up in the first place,) they probably wouldn't mind giving up a little performance to save a few bucks as long as there is no chance that the engine will chunk.

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