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Searched the forum but found nothing about this. Didn't think about it before, but can't find anything that tells what MOPAR recommends for Octane on HEMI...do they state 87, 89, or 91? Anyone with a car and owners manual...would appreciate the info.
Thanks
 

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I've read that 87 is acceptable but 89 is recommended (no need to put premium in), at least on the Charger. I assume it's the same for the 300 and Magnum.
 

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I think 87 should be fine on the 5.7L because of the low compression, as long as timing is not really aggressive.

On the SRT 6.1L I think they might require 91 since the bumped up the compression and probably have more aggressive timing to reach the 425hp mark
 

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mnunes said:
I've read that 87 is acceptable but 89 is recommended (no need to put premium in), at least on the Charger. I assume it's the same for the 300 and Magnum.
Is that the same for the 3.5?
 

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I've heard that you get better gas mileage from 87.
 

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My mileage posted on a different thread were using 87 octane fuel. I just may have to run about 5 tanks of 89 to get a good average on that octane. Of course I will do that when I drive back out west in my charger from Georgia to run the same conditions as closely as possible. (Don't ya just love science!)
 

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JSA 007 said:
89


---------------
Man........I've just GOTTA start reading my manual!!! :embarrese
 

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ChargerR/T 1 said:
Yes 89 octane is the recommended rating for the 3.5 and 5.7 hemi.
My 2002 has the 3.5L and it was recommended to use 87 (which I do). It runs just fine with nary a problem for 32K+ miles now.

When all else fails, read the manual.
 

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rustypaws said:
I would put in 89 so you won't get a ping.
If you have a data logger that can monitor the knock sensor I would love to see some data on 87 vs 89..

In the summer I would be sure to run 89 with the high heat. But in the winter I would think 87 would be more cost effective with how high gas rates are.

I really want to start learning about the dodge engine managment system and about its learning curve. I know all about the ford ECU but nothing about dodges.

I assume like ford and many other cars ecu's if you always run 87 it will learn enought to reduce timing to manage any knock, that is until your battery dies or you disconnect it for more than a few seconds. Cause then it would have to relearn. (You would be amazed at how many guys that run nitrous in there cars that are made for 87 run 91 (even 93/94) all the time and then the car learns a bit so that timing is never retarded and when they go to use the nitrous they get premature detonantion and blow the engine. Its very common in Fl during the summer months
 

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I've read that 87 is acceptable but 89 is recommended......
You read correctly. That's per the manual.

I've heard that you get better gas mileage from 87.
Based on my experience, I get slightly better mileage with 89. Nothing substantial, but a little better.
FWIW, I tried 93 to be thorough, but it didn't do any better than the 89.

Besides, 89 is the recommended fuel so I'll spend the extra $0.10/gal for it. Even at a full tank (19 gallons) it cost $1.90 more to fill with the recommended octane.
How much money is spent on mods that are not proven, but claim to provide better performance? Is this not the same thing? If you average 25 mpg over 100,000 miles (4,000 gallons), that extra $0.10 will cost a total of $400. I'm willing to spend $400 to try to get the best performance and longevity from my engine. Judging by how many people have spent that much (or close to it) on a CAI, which are arguably only good for looks/sound, I'll bet most of people would spend $400 for 100K miles of ideal performance. No? Just trying to put it in perspective.
 

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You read correctly. That's per the manual.

Based on my experience, I get slightly better mileage with 89. Nothing substantial, but a little better.
FWIW, I tried 93 to be thorough, but it didn't do any better than the 89.

Besides, 89 is the recommended fuel so I'll spend the extra $0.10/gal for it. Even at a full tank (19 gallons) it cost $1.90 more to fill with the recommended octane.
How much money is spent on mods that are not proven, but claim to provide better performance? Is this not the same thing? If you average 25 mpg over 100,000 miles (4,000 gallons), that extra $0.10 will cost a total of $400. I'm willing to spend $400 to try to get the best performance and longevity from my engine. Judging by how many people have spent that much (or close to it) on a CAI, which are arguably only good for looks/sound, I'll bet most of people would spend $400 for 100K miles of ideal performance. No? Just trying to put it in perspective.
You want the lowest octane fuel without detonation. There are so many variables to that equation with temperature, compression ratio, actual motor octane value in the fuel....which is the M in the R+M/2 octane method.

However, octane doesn't give you better longevity. 87 or 93 and anything in between will have the same issues since there is no longer any sulfur, lead, or lubricity in the fuels. The only way to get real increased longevity is to provide the fuels with the ignition improving and lubricity that they lack.

This is part of the ACES IV introduction into the fuels.

Considering your example of 100,000 miles and 25 miles per gallon the difference between 89 and 93 is .22 cents per gallon around here. .22 x 4000 gallons is $880.00 more over that time period. Yet it doesn't impart any of the things necessary to really increase longevity.

Spend .31 per gallon with ACES IV x 4000 gallons and you end up with $1,240.00 over that 100,000 miles. But this time you get 6 times less ring and bore wear, 4 times less stem and guide wear and 5 times less valve recession. Yea, I know that hardened valves and hardened seats don't really have valve recession as such but do over time distort the edges of the exhaust valve because it is hammering on the seat without ANY cushion at all. So keeping the exhaust valve and seat long with the stem and guide will make a signficant difference.

That is truly worth the extra. But the other part is the increase in fuel economy using the 89 and ACES IV. With the extra 10% you get with the product you would save 400 gallons of that 4,000 gallons which would be $844.00 at $2.11 for the premium. So spend $1,240.00 and save $844.00 back from that and you end up spending $396.00 where you originally said isn't a problem extra to spend but are now getting the benefit of ACES IV.:beerchug:

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com
 

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You want the lowest octane fuel without detonation..... ......However, octane doesn't give you better longevity. 87 or 93 and anything in between will have the same issues since there is no longer any sulfur, lead, or lubricity in the fuels.....
But proper ignition will effect longevity. Therefor octane does effect longevity if 87 is more prone to detonation in the 5.7L than 89 (which is likely why it's recommended by the mfg).
 

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But proper ignition will effect longevity. Therefor octane does effect longevity if 87 is more prone to detonation in the 5.7L than 89 (which is likely why it's recommended by the mfg).
Agreed. Depends too on the compression ratio of the 5.7L If it is 9.6 to 1 87 is more than fine. If it is 10.5 to 1 Eagle motor you would be better with 89.

However, we have many thousands of vvt and non vvt engines running 87 for regular use with ACES IV and doing just fine for well over 100,00 miles.

All being equal, lubricity also makes a huge difference as it cools down the cylinders and therefore the propensity to detonate!:beerchug:

Regards,
Brian
BND Automotive LLC:driving:
440-821-9040
www.bndautomotive.com
 

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Besides, 89 is the recommended fuel so I'll spend the extra $0.10/gal for it. Even at a full tank (19 gallons) it cost $1.90 more to fill with the recommended octane.

I wish that was the case here. There is a $0.20/gal bump to go from 87-89 and a $0.50/gal bump from 87 to 93. Occasionally there will be a station with 91 or 92, but it is generally the same price as the 93
 
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