For the guys who think they get more power with 91 octane fuel

[dhay13]

Years ago I was at a swap meet and a guy pulls up in a beater van. I had a set of 12.5:1 pistons from my 454 on the table. Guy says 'looks like the ones in my RV'. I laughed and said 'yeah I don't think so'. He then says 'well obviously you don't know who I am'. So I ask. He tells me he was an engineer for GM back in the late 70's and his team was trying to improve MPG. They took a 350 out of a 1974 Camaro and he says they had it running on 27:1 A/F ratio (Air/Fuel), about 1/2 of a standard ICE. He said they were making big gains but started getting death threats and were told they would be at the bottom of the ocean if they continued their research. He did say that GM cut the project so his team continued on their own and the threats weren't until after they had parted from GM.
His premise was that they could run higher compression if they ran a high overlap camshaft profile to bleed off compression. Not sure if this guy was a real genius or an idiot that was blowing smoke...lol

 

[dhay13]

The good ole days of drilling holes in the throttle plates so you could keep the throttle blades closed enough,they weren't uncovering the transition circuits,lol.

Yep, drilled out a few throttle plates too

 

[dhay13]

I don't notice much, if any, difference going 87 to 89 octane but man when I get the non-ethanol my truck sure does run nice. I camp each summer at a remote place that only sells non-ethanol and it's nice. Sure, I can find it at home but it's usually $1-2 more per gallon so I'll pass.

Speaking of ethanol in gas I always remember what I read on one of these forums once.... A guy who had spent his life working in the fuel business as an engineer, etc. He knew a ton about fuel, refining and distribution. His opinion was that most vehicles get 10% less MPGs with 10% ethanol and the only reason it was mandated by our govt. in our gas was to keep corn farmers in business. I'm just the messenger but don't find it hard to believe that our govt. would do something that stupid.

I had heard years ago that when they started installing catalytic convertors they had to make the engines run 'dirtier', lowering fuel economy, in order to get the cats to work properly

 

[16WhiteQC]

My truck runs very different between my custom 87tune and the 93tune, more power for sure....more MPG's not so much lol.

 

[CanuckRam1313]

I'm here in Ontario Canada and I too use 91 in my truck!
Costco is a super saver indeed, especially because I have a 32 gallon tank.

I'm not into snake oil or wasting money on frivolous purchases, but from my experiences in 33 years of driving and having had over two dozen vehicles from old carb units to modern day HEMI's, 91 fuel with no ethanol works best.

I notice hands down that if I put 87 in my truck is runs like S@$T!!! And I've done it purposefully over the 3.5 years I've had my 19' Ram just to test this.

My understanding, albeit unqualified, is that 89 at the pump is just a blend of say 70% regular and 30% premium done at the pump, and that refineries don't actually produce 89 as standalone fuel (is this true??)

My truck is properly maintained, and I put new plugs in every 60,000KM's or so just to ensure I have a great running vehicle. Clean the TB properly, new PCV Valve, use synthetic oil that is changed every 6,000KM's, etc....

I too get better MPG from the 91 and a much happier and more responsive engine too. I have zero knock on 91, whereas on 87, especially on a hot summer day with the A/C on there is knock at times, especially when dropping the hammer to the floor and loading up the engine for maximum takeoff...lol.

The difference in cost on a fill up of 87 vs. 91 is maybe $10 to $20 a tank more expensive using the 91. For what the 91 does for my engine in terms of more efficient operating and a little MPG increase (not that I really care because having a HEMI inherently means one consumes fuel regardless), it is hands down worth it for me as I am invested long term in my ownership experience.

Now, were I leasing it for a 2 to 3 year term and just flipping it back in for another lease, well, different story. I did lease vehicles once upon a time in my driving career, and just used 87. But with leasing there are too many restrictions, requirements, and limitations, and I like to mod my vehicles and I drive a lot as well. So it doesn't make fiscal sense to me to lease.

Besides, with proper predictive and preventative maintenance, there is no reason one couldn't achieve a dependable 500,000KM's or more on our trucks.

 

[Burla]

Rick, you are losing this one, lol. You cant win them all bud...

 

[A_mod_too_far]

Lol, I use 85 sometimes 87, havent noticed anything, I guess I'm blissfully unaware of how a hemi should run

 

[Docwagon1776]

His opinion was that most vehicles get 10% less MPGs with 10% ethanol and the only reason it was mandated by our govt. in our gas was to keep corn farmers in business. I'm just the messenger but don't find it hard to believe that our govt. would do something that stupid.

Common sense tells you that unless ethanol has 0% energy, a 10% blend won't get 10% less work output. An engineer should know better.

Regardless, I think people tend to look at these things in a vacuum. Ethanol and farm subsidies aren't perfect by any means, but are a national security measure with the idea of a peer or near peer war making commercial shipping and imports unreliable. Food and energy security, including alternate sources should major refining centers be damaged or destroyed, could be rather important at some point. Most common military motors are 'flex fuel' and designed to run reliably on any number of fuel sources. It's the same reason the military pays way more money for boots than it otherwise would, to support a domestic source, and why there are rules in place that mandate US port to US port shipping be done by US ships, to support a domestic ship building industry. We've lost sight of that in other areas (like semiconductors, note the damage done) but have been smart enough to know you can't go to war with someone making your boots, boats, and bullets.

 

[Docwagon1776]

Lol, I use 85 sometimes 87, havent noticed anything, I guess I'm blissfully unaware of how a hemi should run

You don't have enough oxygen to be aware of a how a hemi should run since you're elevation is somewhere just shy of space.

 

[demonram]

I have always used 93 octane in my truck, ever since it was new. Well, let me back up a little; the first few times I gassed up, I used 87 octane, and there was a very noticeable knock, especially when going under a load, such as going up a fairly steep incline or hard acceleration. I then switched to 93 octane and only tried 87 again when gas was priced at nearly $5.00 a gallon. Once again, I had to ignore the difference in price and go back to 93 octane.

 

[Dodge Lover]

I've been running Mobil 87 since the prices climbed. I have not experienced any lack of performance and am getting better mileage. Mobil's Extra is 89 and Premium is 91 to 93.

Most of my driving is at less than 1000 feet elevation. I was told by another RAM owner to switch to a higher octane if I were to go into the mountains.

Walt

 

[brilliantnick]

You all should watch engineering explained's take on it;

Never Use This Gas In Your Car!

How 85 Octane Fuel Can Destroy Your Engine And Void Your WarrantySubscribe to Engineering Explained for more videos! - https://goo.gl/VZstk7Recommended Books...

www.youtube.com

as well as project farms take on shell vpower nitro+ vs cheap

Shell V-Power NiTRO+ vs Cheap Gasoline. Is it better? Let's find out!

Is Shell V-Power Nitro+ better than cheap gasoline? Shell claims that it cleans better and contains 7 times the amount of detergents required. So, will She...

www.youtube.com

Several key points;

-Higher Octane = less knock... it does not necessarily mean more or less anti-wear/anti-sludge additives

Octane rating does not relate directly to the power output or the energy content of the fuel per unit mass or volume, but simply indicates gasoline's capability against compression.

-knock = when gas is pre-detonating in side the chamber due to exceeding compression + heat limits of the fuel
-pre-detonation/knock = bad news for engine

-Engines come with knock sensor to limit knock and damage, they do this by retarding power (less air+less gas = less pressure)

-Higher elevation = less air = less compression = less knock = lower octane offered for 'regular' in the state

-Those states that offer less than 87 octane, because the likely average elevation of the state meant that they could during the days of carburetors
--Colorodo
--Idaho
--Montana
--New Mexico
--Nevada
--South Dakota
--Utah
--Wyoming

-Ford 2021 says you engine is built to run on a minimum pump rating of 87, use of fuels below 87 could result in engine damage that will not be covered by vehicle warranty.

-Ford 2021 engine is likely turbo, plus modernized computer controlled fuel and air management, so elevation really does not matter as much anymore, which is why the 'requirement' to always have 87+

Conditions that are less likely to have knock;
-old carbureted car
-naturally aspirated
-high elevation
-eco-conscious driving

Conditions that will have a higher likelihood of knocking;
-Modern cars (meaning anything past 1987)
-turbo
-lower elevation
-petal to the metal / towing


In short,
-its about how you drive-
petal to the metal / towing = higher engine loads and pressures = higher likelihood of knocking = engine retarding power in the event of 85 octane.
If you don't tow or climb mountains or ram the throttle... odds are your not going to notice the difference.


That said
I had a 1998 Ranger, I went to one gas station and running on their 87 octane gas typically resulted in some weird sticky ticking noise from the engine.

Switching to shell's 87 made the noise go away.

Its was about the additives and the 'top-tier' standard rather than the octane.

Nowadays, I dont notice a difference between 92 or 87... unless I'm towing heavy uphill like I do when hauling firewood.
Which is why Ill always fill up with top tier with 87 for normal driving and 89+when towing no matter what state or elevation I'm in.

 

[HEMIMANN]

I don't notice much, if any, difference going 87 to 89 octane but man when I get the non-ethanol my truck sure does run nice. I camp each summer at a remote place that only sells non-ethanol and it's nice. Sure, I can find it at home but it's usually $1-2 more per gallon so I'll pass.

Speaking of ethanol in gas I always remember what I read on one of these forums once.... A guy who had spent his life working in the fuel business as an engineer, etc. He knew a ton about fuel, refining and distribution. His opinion was that most vehicles get 10% less MPGs with 10% ethanol and the only reason it was mandated by our govt. in our gas was to keep corn farmers in business. I'm just the messenger but don't find it hard to believe that our govt. would do something that stupid.

The government was bought off by the agribusiness lobby. This is decades old news. Politicians can be bought by anybody with enough money.
And it's not an opinion - it's a fact that alcohol is less energy dense per unit volume than gasoline. It's just material properties, available in any chemistry book.

 

[Wild one]

I've been running Mobil 87 since the prices climbed. I have not experienced any lack of performance and am getting better mileage. Mobil's Extra is 89 and Premium is 91 to 93.

Most of my driving is at less than 1000 feet elevation. I was told by another RAM owner to switch to a higher octane if I were to go into the mountains.

Walt

You got that backasswards,higher elevation means you can get away with a lower octane fuel.Less atmospheric pressure at higher elevation means there's less air going into the cylinder,which translates to less cylinder pressure,which means the engine won't require as high octane to stay out of detonation

 

[CheechDogg.0n37s]

I've been running Mobil 87 since the prices climbed. I have not experienced any lack of performance and am getting better mileage. Mobil's Extra is 89 and Premium is 91 to 93.

Most of my driving is at less than 1000 feet elevation. I was told by another RAM owner to switch to a higher octane if I were to go into the mountains.

Walt

I seriously doubt you are getting better MPGs with 87 but I will give you the benefit out of the bout lol ..

As to you not experiencing lack of performance, ok I will say you probably don't notice it , but I guarantee you that if you switch it up to 91 you will definitely feel the difference ... you will see what the HEMI engine is supposed to fee like opposed to being ******** by the lower dirty 87 and 89 octane ...

Again just to save a few bucks to me it's not worth it ... those people who choose to go with lower octane gas to save money are the ones that drive the speed limits and don't ever feel or experience the capabilities of these trucks and cars ... thus they are driving in a way that is also going to save them money ....

Those of us who really don't mind spending the money on 91 or even 93 like someone just stated probably drive these trucks without care or much care for MPGs .... I like to feel the full potential of my truck's HEMI, I don't mind spending the extra money to get that.

So to make it a little more clear for those that might of gotten confused, most people that want to save money use lower octane gas, 89 or 87 ... those same people won't drive their vehicles like people who don't care about the gas prices and love to drive their vehicles to experience full potential ... Those people who want to save money will never really notice their engines knocking because they are not being pushed to the limits or near the limits, so you really can't tell that the knocking is happening anyways because those vehicles are already being driven to save money lol ....got it? ok ...

 

[Wild one]

The only thing i have that doesn't require 91 or higher fuel is our 300,and it doesn't notice any differance between 87 and 91.It gets the same milege on 87 as it does with 91,and will pull 165mph wide open on either fuel.It's bone stock other then having the speed limiter opened up,and the idle raised to 700 rpm,i also run a catch can on it,which helps with keeping the fuel octane where it should be.I think alot of you guys who claim theres a differance also probably aren't running a catch can,and the crap sucked through the PCV system effectively lowers the octane of the fuel going into the engine. The stuff sucked through the PCV dilutes the fuel and lowers it's effective octane rating

 

[Burla]

You got that backasswards,higher elevation means you can get away with a lower octane fuel.Less atmospheric pressure at higher elevation means there's less air going into the cylinder,which translates to less cylinder pressure,which means the engine won't require as high octane to stay out of detonation

Wouldnt you have more air since it has less o2? Seriously a q I dont know the answer.

 

[Wild one]

Rick, you are losing this one, lol. You cant win them all bud...

Hell Mike it's no differant then being at home,i don't remember the last time i won with the wife either,even if i'm right,i'm still wrong,lol

 

[Burla]

thank god wifes aint running this thread, lol

 

[Wild one]

Wouldnt you have more air since it has less o2? Seriously a q I dont know the answer.

A naturally aspirated engine really notices atmospheric pressure,and the higher the elevation the less air pressure there is being forced into the engine.An engine operates alot like the human body does in regards to elevation,the higher you go up the side of the mountain,the harder it is to get air