What fuel for 5.7

[securityguy]

Octane absolutely can offer better mpg and power if the engine is tuned to make use of it. Our engines for example are tuned best for 89, so if you use it over 87, you should see an increase in mpg and power. The whole point of higher octane is it reduces knock. In order to get more power, manufacturers will tune a motor typically with higher timing, however they will require a higher octane to prevent knock.

Now you are interjecting the "tuning" component that has yet to be brought up and is a separate topic in itself. All of the science that I have read states that higher octane does NOTHING for increased power or mpg...it's only to assist with knock as you commented above. Going from 87 to 89 or 89 to 93 does not produce any additional power or mpg which is a scientific fact. The higher the octane fuel, the harder it is to ignite. Google the topic and there are tons of articles all saying the same thing that I have posted.

 

[securityguy]

Exactly. Engine knocking/pinging ultimately leads to less MPG and less power.

https://itstillruns.com/bad-knock-sensor-affect-gas-mileage-12218387.html

Yes...we all know that you can hear pinging and knocking. However, that, too, is a different topic. If you have an engine that is pinging or knocking, you should upgrade the level of octane as that is specifically what octane is designed to address. If you are not experiencing these issues, then fueling up at the recommended octane (89 for the HEMI) is perfect. Increasing to 93 will show ZERO increase in performance.

 

[SD Rebel]

Now you are interjecting the "tuning" component that has yet to be brought up and is a separate topic in itself. All of the science that I have read states that higher octane does NOTHING for increased power or mpg...it's only to assist with knock as you commented above. Going from 87 to 89 or 89 to 93 does not produce any additional power or mpg which is a scientific fact. The higher the octane fuel, the harder it is to ignite. Google the topic and there are tons of articles all saying the same thing that I have posted.

Injecting tuning to the conversation? That's kinda the whole point of it. Manufacturers tune the motor for the octane, I mean you drive an RAM that is "tuned" for 89 from the factory. How is this even an argument?

Yes, that is the point of higher octane, it is to prevent knock. In order to make more power, typically manufacturers will add more timing. However that carries a risk of more detonation, which requires more octane. They can setup the motor so it can adjust timing based on how it's reacting to fuel. It will retard timing if it detects detonation, such as using 87 instead of 89 as recommended by RAM.

My BMW recommends 91 octane, however it states I can run 87 but that it will negatively effect performance and mpg. Why? Because the computer will retard the timing to prevent knock, which results in less power and mpg.

The very RAM you drive is setup the same, except for 89. It is optimized for best mpg and mileage with 89 octane, it will still run acceptable on 87 but you will get less power and mpg if you do.

 

[securityguy]

I was assuming that you were interjecting changing the engines tuning like adding a performance upgrade of which many will require higher octane fuel. I don't argue the other points and believe that we are now on the same page. The morale of the story...if your vehicle requires a certain grade of fuel...USE THAT FUEL. Using anything more will not produce more power or provide better mpg. You shouldn't be using anything less than what the manufacturer recommends as, YES, that will impact your engines performance which isn't rocket science to understand. If you are towing, and experience ping or knock based on the additional engine load, then upgrade the octane to compensate since that's what your vehicles engine is telling you. If you still disagree with these points then I am at a loss for words

 

[SD Rebel]

I was assuming that you were interjecting changing the engines tuning like adding a performance upgrade of which many will require higher octane fuel. I don't argue the other points and believe that we are now on the same page. The morale of the story...if your vehicle requires a certain grade of fuel...USE THAT FUEL. Using anything more will not produce more power or provide better mpg. You shouldn't be using anything less than what the manufacturer recommends as, YES, that will impact your engines performance which isn't rocket science to understand. If you are towing, and experience ping or knock based on the additional engine load, then upgrade the octane to compensate since that's what your vehicles engine is telling you. If you still disagree with these points then I am at a loss for words

Gotcha, I was only talking about factory tune for whatever octane they recommended.

I agree, if you vehicle recommends 89 or 87, using 91 or 93 isn't going to improve performance.

I think our disagreement was that I took from your statement that octane doesn't make more power or mpg, but the key detail is the factory tune requirement which we both agree is correct.

My original point is that if my truck recommends 89, but I can get (in my area) premium for less than 87 elsewhere, that is what I should be using. Between Costco 87 vs 91, I should use 91 since they don't offer 89 so I at least meet the recommended octane.

 

[ColoradoCub]

You are hearing things silver bullet, no way you are hearing pinging running 91 in these trucks. The PCM‘s won’t allow it even with 87 and you claim you hear it with 91? C’mon dude. I’ve pulled a 6,000 lb camper 6 miles up a 11,500 ft pass at 5,000 rpms with 85 octane and didn’t hear pinging. Some of you read too much into fuel quality and grade.

 

[RunsWithBeer]

The only gas with more power and better MPG is ethanol free gasoline, which is getting harder and harder to find.

 

[securityguy]

The only gas with more power and better MPG is ethanol free gasoline, which is getting harder and harder to find.

100% correct in that Ethanol is a killer to a fuels performance. I have it all over here in N. FL. However, I refuse to pay the ridiculous price they want for it and I am very happy with how my truck is responding to the 89 I put into it.

 

[Nails]

To poke the bear if you will.

Slight ethanol(normal %) and high octane mix isn’t a bad thing.

I’m just going to leave this here....
and sit at the table with sign that says change my mind lol

 

[Lake Ram]

Depends on where you get your gas. COSTCO down the street from me is $2.45 for 91. I paid $3.01 for 89 at a CHEVRON and 87 was like $2.69. COSTCO 91 is a bargain.

 

[SD Rebel]

To poke the bear if you will.

Slight ethanol(normal %) and high octane mix isn’t a bad thing.

I’m just going to leave this here....
and sit at the table with sign that says change my mind lol

The highest level ethanol fuel in the US is E85, which has a 108 octane rating. It's used by many tuners to make a lot of power and in racing applications. Pure ethanol has a 113 octane rating.

Where ethanol is a problem for gas motors is mpg. Fuel with ethanol is less energy dense do to the higher ethanol content, which lowers mpg.

It's also hydroscopic, which dries out rubber components in fuel systems and fuel lines not designed for it. Especially not good for older and small two-cycle and motorcycle engines.

 

[securityguy]

The highest level ethanol fuel in the US is E85, which has a 108 octane rating. It's used by many tuners to make a lot of power and in racing applications. Pure ethanol has a 113 octane rating.

Where ethanol is a problem for gas motors is mpg. Fuel with ethanol is less energy dense do to the higher ethanol content, which lowers mpg.

It's also hydroscopic, which dries out rubber components in fuel systems and fuel lines not designed for it. Especially not good for older and small two-cycle and motorcycle engines.

Exactly!

 

[SpeedyV]

The highest level ethanol fuel in the US is E85, which has a 108 octane rating. It's used by many tuners to make a lot of power and in racing applications. Pure ethanol has a 113 octane rating.

Where ethanol is a problem for gas motors is mpg. Fuel with ethanol is less energy dense do to the higher ethanol content, which lowers mpg.

It's also hydroscopic, which dries out rubber components in fuel systems and fuel lines not designed for it. Especially not good for older and small two-cycle and motorcycle engines.

That last part is key for my ‘68 BSA and its fiberglass tank. Fortunately, several nearby air and drag strips mean Sunoco pure gas all the way up to 112 octane is available. (Don’t put this in your Ram!)

 

[Jako]

That last part is key for my ‘68 BSA and its fiberglass tank. Fortunately, several nearby air and drag strips mean Sunoco pure gas all the way up to 112 octane is available. (Don’t put this in your Ram!)

Learned to ride on a 70 Triumph Bonneville, brother has 2 and maybe enough parts for a third. Pure gas is a problem in NYC. I believe it also likes lead.
http://www.todayifoundout.com/index.php/2011/11/why-lead-used-to-be-added-to-gasoline/

 

[RunsWithBeer]

To poke the bear if you will.

Slight ethanol(normal %) and high octane mix isn’t a bad thing.

I’m just going to leave this here....
and sit at the table with sign that says change my mind lol

Ethanol has 33% less energy than gasoline. Yes ethanol raises octane, but so do other additives that don't reduce energy content. It's cheaper because it's subsidized.

Ethanol damages elastomers, and binds with water pulling it into your fuel system.

Unfortunately, it's in nearly all gasoline now except aviation and racing fuel.

 

[SD Rebel]

That last part is key for my ‘68 BSA and its fiberglass tank. Fortunately, several nearby air and drag strips mean Sunoco pure gas all the way up to 112 octane is available. (Don’t put this in your Ram!)

Oh I'm familiar. The plastic tank on my Duc needed to be replaced due to E10 gas. Luckily the newer spec tanks were designed to be more immune to the effects of ethanol.

 

[silver billet]

You are hearing things silver bullet, no way you are hearing pinging running 91 in these trucks. The PCM‘s won’t allow it even with 87 and you claim you hear it with 91? C’mon dude. I’ve pulled a 6,000 lb camper 6 miles up a 11,500 ft pass at 5,000 rpms with 85 octane and didn’t hear pinging. Some of you read too much into fuel quality and grade.

Yes...we all know that you can hear pinging and knocking. However, that, too, is a different topic. If you have an engine that is pinging or knocking, you should upgrade the level of octane as that is specifically what octane is designed to address. If you are not experiencing these issues, then fueling up at the recommended octane (89 for the HEMI) is perfect. Increasing to 93 will show ZERO increase in performance.

Sadly I wish you were right. But I grew up on a 305 chevy that was 20 years old and that thing pinged incessantly. Once you hear it, you know what to listen for. These hemis do the same thing, and it's not just me.

For example, this guy on youtube, listen carefully, but it's very audible if you know what pinging is. Very audible around 48 seconds and following for at least another 10 more.

If you can't tell from that video what is pinging or what is interior/road noise, then you have no business discussing this. Anybody else who knows pinging, will hear it in that video. So yes, pinging is very real, very audible, and very bad on low octane gas.

My engine only sounded that bad when pulling a trailer with 87 octane. I got caught with my pants down and had no other choice in a small town with bad gas. But it's still there even with 91 octane.

 

[securityguy]

Sadly I wish you were right. But I grew up on a 305 chevy that was 20 years old and that thing pinged incessantly. Once you hear it, you know what to listen for. These hemis do the same thing, and it's not just me.

For example, this guy on youtube, listen carefully, but it's very audible if you know what pinging is. Very audible around 48 seconds and following for at least another 10 more.

If you can't tell from that video what is pinging or what is interior/road noise, then you have no business discussing this. Anybody else who knows pinging, will hear it in that video. So yes, pinging is very real, very audible, and very bad on low octane gas.

My engine only sounded that bad when pulling a trailer with 87 octane. I got caught with my pants down and had no other choice in a small town with bad gas. But it's still there even with 91 octane.

Not sure why you stated that you "wish I was right". What I stated above in your quote of me is 100% accurate and undisputed.

 

[silver billet]

Not sure why you stated that you "wish I was right". What I stated above in your quote of me is 100% accurate and undisputed.

I was responding to you both, neither of you is 100% right. For a start, pinging is very audible, and yes you can hear it with your ears. Secondly, if I can still detect pinging with 91 octane, and we know that pinging results in reduced performance, then it obviously follows that going to 93 octane will increase your performance. That gain in performance is not due to having more energy in the gas, but because it allows your engine to work at near optimum performance. Reducing the octane reduces the capability of your engine to perform optimally.

 

[RunsWithBeer]