moparfreak77
Well-Known Member
Bought an 09 Ram Hemi last week and was reading the manual and it recommended 89 octane fuel but 87 was fine. We have ran 2 tanks of 87 octane through it with no issues, but what do you guys think?
87 or 89 octane in a new Hemi, does it matter?
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1968FormulaS340
Well-Known Member
87 will be fine but the engine computer will adjust for fuel quality....
So if you are running lower quality fuel than recommended it may pull timing out (or whatever those computers do), dropping power.
moparfreak77
Well-Known Member
would there be a mileage difference? Would it be worth the extra price to run the 89?
1968FormulaS340
Well-Known Member
More than likely you will lose MPG if you run a lower quality fuel than required.
One reason being that as it pulls timing out (and whatever else the computer is doing) the engine loses power. This is all done to prevent detonation (probably a knock sensor in the mix too).
The normal thing a person does to make up for this power loss is give it more throttle. More throttle = less MPG.
Driving habits play a part here.... Just run a tank of each (track your MPGs) and see what works best for you.
One reason being that as it pulls timing out (and whatever else the computer is doing) the engine loses power. This is all done to prevent detonation (probably a knock sensor in the mix too).
The normal thing a person does to make up for this power loss is give it more throttle. More throttle = less MPG.
Driving habits play a part here.... Just run a tank of each (track your MPGs) and see what works best for you.
jysnflem
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My 2007 Hemi ram stated the same. I've always used 89 and if a tow I use 93. I do believe I ran one tank once with 87 no issues. Jayson
fishy68
Tyr Fryr's Inc.
I bet 68formulas340 nailed it. Check your mileage with each fuel and do the math to see if your better off running the 89 or 87. That's what I did on my 02 Dakota with the 4.7L. When it was stock it ran fine on 87 octane and averaged 14.8 mpg. I bought a Superchips tuner and tuned it up and even though I now have to run 89 octane fuel at .10 more per gallon it offsets the cost by getting over 2 mpg more. AT 30+ miles more per 15 gallons of gas it's much cheaper to run the 89. And it runs better.
MoparJoe20
Well-Known Member
At least in my Ram MPG tanks on 87, 14-15 at best, 18-19 on 89 E10 and 20-21 on 89 Gas, this is pretty much all Hwy, I drive 100 miles round trip everyday.
AdamR
Big Member
My 04a owners manual says the same thing but my truck rattle bad on 87, Its fine on 89. Perhaps its had the computer reprogrammed.
swinger 367
A-body addict
I have a '03 Hemi Ram and I never understood the whole 87 vs. 89 business. The engine only has 9.5:1 cr and it has aluminum heads. Countless books and knowledgeable people on this site and others state that you can run more compression with an aluminum head than cast iron. Plus with modern design and engineering the quench should be optimized. If you can get away with 11:1 cr with aluminum heads on 92/93 pump gas, why can't i run 87 in my 9.5:1 aluminum head engine. (FWIW I always run 87 in mine)
I run 87 in my 08 Hemi Ram. No problems.
My 07 Charger is a different story, it has always been picky about gas quality. It sometimes pinged right before full-throttle upshifts. Seemed to be more associated with fuel quality rather than octane, it did that with every tune from OEM stock to the one I'm running now (Superchips 92 octane). I think when I changed the spark plugs things got better, though.
My 07 Charger is a different story, it has always been picky about gas quality. It sometimes pinged right before full-throttle upshifts. Seemed to be more associated with fuel quality rather than octane, it did that with every tune from OEM stock to the one I'm running now (Superchips 92 octane). I think when I changed the spark plugs things got better, though.
AdamR
Big Member
That depends on what the motor really needs for octane. Running a higher octane the needed will actually decrease efficiency lowering power and milage. You want the burn just hot/fast enough to slow a burn will loose power and millage to fast will detonate.
1968FormulaS340
Well-Known Member
You are talking about two totally different worlds there. One is a purpose built performance engine and the other is a mass market consumer grade engine.
The engine computer is programed and calibrated for a given fuel requirement. It is optimized (as far a factory programing goes) to deliver X MPGs, X Power and X Exhaust Emissions with that fuel.
Like was said above... You can run a lesser grade fuel but the computer will recognize it and make adjustments. The computer will protect the engine (they don't want to work on your engine under warranty because you run the wrong gas).
How much the computer plays with things varies (probably varies between same engines in the same application given factory production tolerances).
moparfreak77
Well-Known Member
I've never had to deal with this kind of thing before. I know today 89 was about 4 cents more a litre, but if it gets better mileage then I guess it's worth it. It got 22 MPG(Canadian) last w/e. At 4 cents more a litre, what would I have to get for mileage so it's worth it? Shoulda paid attention in math class.
Longgone
John/68 Barracuda & Dart
Congratulations on your new acquisition! :cheers: PICTURES?? Does Canada have an incentive plan like our "cash for clunkers" program to get people to start buying new cars again? My friend has an older Hemi Ram, ca. 2005?, and his manual recommends premium fuel. They must have made some changes in order to use a cheaper gas since his was made. I would err on the side of caution and use the higher grade gas. For the peace of mind I would pay a few cents more a gallon and reduce the chance of detonation.
moparfreak77
Well-Known Member
Chrysler is offering about $10 000 of the list price of Rams. We love the Crew Cab as we have a 15 month old a another due in December.
Burntorange70
Well-Known Member
The difference in price in 87-89 is .10 cents a gallon so if you fill up with 30 gallons of gas with 87 instead of 89 you save 3 dollars a fill up. If your that straped for cash that you cant cover 3 extra bucks a fill up you should of got a honda insted of a gas guzzling 3 ton truck. But thats just my .02
1968FormulaS340
Well-Known Member
I wasn't going to say that.... But.
That's the long and short of this entire thread.
cannucky
The Guy With No Birthday
You said it brother thats always been the jist of my answer when they ask what my cars get for mileage I tell em "If you have to worry about a few pennies in the price of gas buy a freakin 10 speed / bus pass and get off the road you'll help the enviroment and make room for the rest of us who budget it into our weekly nut instead of 100 dollar sneakers, fancy booze and designer clothes"
moparfreak77
Well-Known Member
But there is no sense of spending more than I have too. If thats the case why don't I put 91 octane through it? If I don't have to spend over $200 more year on gas than why would I? If I get better mileage with the 89 than it makes sense, but if I don't I'd rather have the $200+ in my pocket.
70GT
Burnt Orange Member
I always run 89 Ethanol Free in my Charger. REAL gas is getting harder to find.
fishy68
Tyr Fryr's Inc.
True. But you can get 40 opinions on the board here and still not know what is really going to happen until you go out and run both and do the math and see what's best. Then report back with the results so we'll all know.8)
fishy68
Tyr Fryr's Inc.
Man I haven't seen ethanol free 89 in 10 yrs. here. What station sells that? Even most of the 87 here is 10% Ethanol now.
70GT
Burnt Orange Member
Then I guess we're really lucky. We have one Phillips 66 in town that still sells REAL gas in all grades. I fill up my Dart there too...it loves it! I can't really tell any difference when I run it in my Charger.
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