[ChallyTatum]

Have driven my six-speed 5.7 on 89 for ten years with no issues. I only recently learned that the manual called for 91. The salesman had told me 89 and I guess when I read the manual myself I missed that.

So the knock sensors prevent any serious damage but running 91 will prevent the PCM from pulling timing due to knock so you will have more power available with 91.

 

[creamsicle]

I use 89 as recommended(auto trans), and it runs fine. I did use 93, and get a few more mpg. Riding down from NY, 93 was 'cheap' in the mid southern states, thru N Fla So why not?.

 

[Frank Julian]

So the knock sensors prevent any serious damage but running 91 will prevent the PCM from pulling timing due to knock so you will have more power available with 91.

Mine were turned back because the headers are noisy and make the sensors think it is knocking.

 

[ChallyTatum]

Mine were turned back because the headers are noisy and make the sensors think it is knocking.

Actually most SC'er tunes I have seen do this regardless of headers. In fact, the diablo 93 canned tune also does this as well.

 

[mopardude9]

No, by changing the voltage tables in the tune.

Most people swear they don't feel a difference between 87 and 91 probably because their butt only detects the thickness of their wallet but do a log of long and short term knock in the summer and see how much timing is pulled. Every degree is worth maybe a couple of ponies.

My butt dyno never noticed a difference in octane with my 5.7. But 93 prevents knock with my M6 if I stall it out in first gear.

My 09 3.5L ran way better on the butt dyno with 89 vs 87

 

[SubzeroAWD]

Burn the 93, I do 89 in my V6, did 93 in my Scat

 

[lws43]

if your car is tuned for 87 you will gain nothing with 93. Your timing curve is set up to be conservative with 87. If you ran 85 it might pull some timing and you will loose power but its conservative program probably isnt going to induce any spark knock with 87 and if you put in 93 it will not advance the timing to take advantage of it. Only way to do that is with a tune. That is basicaly what a tune does is maximize timing advance for the fuel your using. Run the gas the manufacture says your car is tuned for. Only advantage with a stock car to running higher octane fuel is youll be a bit lighter because youll have less money in your wallet.

 

[Frank Julian]

Actually most SC'er tunes I have seen do this regardless of headers. In fact, the diablo 93 canned tune also does this as well.

I had to get a tune edit after my cam and header install because they were not tuned down. I thought once you did mods to car and wrote a tune for that engine with those mods, you could just use that tune on all engines with the same mods, I was wrong. Every tune is written from scratch and some may get tweaked a little more in some areas than others.

 

[ChallyTatum]

if your car is tuned for 87 you will gain nothing with 93. Your timing curve is set up to be conservative with 87. If you ran 85 it might pull some timing and you will loose power but its conservative program probably isnt going to induce any spark knock with 87 and if you put in 93 it will not advance the timing to take advantage of it. Only way to do that is with a tune. That is basicaly what a tune does is maximize timing advance for the fuel your using. Run the gas the manufacture says your car is tuned for. Only advantage with a stock car to running higher octane fuel is youll be a bit lighter because youll have less money in your wallet.

The 5.7 is tuned for 89...87 is acceptable but it will pull timing (non-MDS 5.7...aka manual trans equipped engines) is tuned for 91. Again if you guys want to see if timing is being pulled or not start logging for LT/ST knock.

 

[lws43]

The 5.7 is tuned for 89...87 is acceptable but it will pull timing (non-MDS 5.7...aka manual trans equipped engines) is tuned for 91. Again if you guys want to see if timing is being pulled or not start logging for LT/ST knock.

odd thing is then is that my ram 5.7 is tuned for 87 and still puts out more hp. Have you actually seen proof timing is pulled or just other peoples opinion. From what ive seen in factory tunes there very conservative and you see very little knock even running 87 in a car they claim is tuned for 91or 93. They know somebody is bound to put regular in it and they dont want to pay out warantee claims do to parts getting beat to hell with detonation. Id like to see an actual comparsion on the same car on a dyno with a 5.7 running regular and one running premium and id bet if anything theres no more the 2 or 3 hp difference. My real guess would be none.If they were actually running the ragged edge you wouldnt see crap for gains with a tune. When in fact theres a good 15-20hp available with a tune that actually makes running premium mandatory and even then many tuners go a bit conservative so you can imagine how conservative that factory tune is. Fact is that was proven to me with snowmobiles on a dyno is if your using higher octane then what your motor is tuned for you can actually loose a small amount of hp. .

 

[ChallyTatum]

odd thing is then is that my ram 5.7 is tuned for 87 and still puts out more hp. Have you actually seen proof timing is pulled or just other peoples opinion. From what ive seen in factory tunes there very conservative and you see very little knock even running 87 in a car they claim is tuned for 91or 93. They know somebody is bound to put regular in it and they dont want to pay out warantee claims do to parts getting beat to hell with detonation. Id like to see an actual comparsion on the same car on a dyno with a 5.7 running regular and one running premium and id bet if anything theres no more the 2 or 3 hp difference. My real guess would be none.If they were actually running the ragged edge you wouldnt see crap for gains with a tune. When in fact theres a good 15-20hp available with a tune that actually makes running premium mandatory and even then many tuners go a bit conservative so you can imagine how conservative that factory tune is. Fact is that was proven to me with snowmobiles on a dyno is if your using higher octane then what your motor is tuned for you can actually loose a small amount of hp. .

Unlike others that claim 87 is fine and they have not felt any issues...Yes, I have data...see link below where I show knock on my 2013 JGC 5.7 (89 recommended but 87 acceptable) running 87 on a hot summer day. BTW I doubt your 5.7 RAM is tuned for 87...it is more like 89 with 87 being acceptable.

Gas mileage

There was a thread last week about a guy getting really low mileage on a new SXT. Like most I've gotten pretty good mileage. Last week I drove to Texas from San Diego for Thanks Giving. It was the first long trip with my Hellcat repops and the 275x40 tires. I was getting only 25MPG most of the...

www.challengertalk.com

BTW I wish others would also log knock instead of giving opinions or what they read somewhere. Also when people fuel up on higher octane, pull the PCM fuse so you can reset adaptives.

2015 dodge ram owners manual - 89 recommended. The 87 acceptable can be found in FSM.

Premium Gas

I've been putting super unleaded gas in my 2020 Challenger Scat Pack and wondering if I am doing the right thing. I do just mostly normal driving. Do you guys use regular or super in your cars with the 6.4 Hemi?

www.challengertalk.com

 

[lws43]

I would think that because that ram has a much more of a chance to be in a heavy load situation if it was tuned like that they would say 89 minimum because as we both know heavy load is what brings on detonation. Read too in the manual you posted that it said that there is NO benefit to using anything more then 89. So are you telling me if 90 will do nothing and its detonating at 87?? Thats some ragged edge tuning. then tell me how a dyno tune with 89 can put out so much more power without detonating. Like is said any reputable tuner is going to put a safety factor in there unless you tell them absolutely not to because they dont want you running around saying you broke a piston because of there tune. My guess is if you were showing detonation with some poor grade of 87 that wasnt 87. By the way there are 10s of thousands of rams and challenger 5.7s running around on 87 that have 200k on them. I guess maybe nobody tell them that they should be spending 30 cents more a gallon to get a bit more alcohol in there gas or there going to blow there motors up. Me? I use 87 in my ram and in my jk and 91 in my challenger but its a 392. Remember too that same ram owners manual you have there tells you to change your oil every 6 months even if you dont start it and move it out of the garage. So if they though it would save them paying out a warrantee claim theyd say 89 minimum period. But its your car. You can run av gas in it if it makes your feel good. Just dont thinks its giving any hp without a tune. Im out of this now ive only been doing this for 43 years and i guess ive learned nothing.

 

[2012 White R/T]

That is not correct. 87 is acceptable on a 5.7 auto. Running 93 octane on a 5.7 auto is overkill unless you want to ensure little to no knock is experienced. I used to run 93 on my 2013 5.7 JGC and between 87 and 93 there was noticeable less fish bite feel (happens when PCM detects knock and pulls timing) when accelerating hard on a hot summer day or towing the boat.

Premium Gas

I've been putting super unleaded gas in my 2020 Challenger Scat Pack and wondering if I am doing the right thing. I do just mostly normal driving. Do you guys use regular or super in your cars with the 6.4 Hemi?

www.challengertalk.com

I get why you think it's not correct. I re-read it and it does sound like I was talking about 87. I was actually refereeing to 93 and the NN being able to adjust for it. Actually, now that I think about it, you'd have to clear the adaptives to feel any benefit. Not sure that would even work.

 

[ChallyTatum]

I would think that because that ram has a much more of a chance to be in a heavy load situation if it was tuned like that they would say 89 minimum because as we both know heavy load is what brings on detonation. Read too in the manual you posted that it said that there is NO benefit to using anything more then 89. So are you telling me if 90 will do nothing and its detonating at 87?? Thats some ragged edge tuning. then tell me how a dyno tune with 89 can put out so much more power without detonating. Like is said any reputable tuner is going to put a safety factor in there unless you tell them absolutely not to because they dont want you running around saying you broke a piston because of there tune. My guess is if you were showing detonation with some poor grade of 87 that wasnt 87. By the way there are 10s of thousands of rams and challenger 5.7s running around on 87 that have 200k on them. I guess maybe nobody tell them that they should be spending 30 cents more a gallon to get a bit more alcohol in there gas or there going to blow there motors up. Me? I use 87 in my ram and in my jk and 91 in my challenger but its a 392. Remember too that same ram owners manual you have there tells you to change your oil every 6 months even if you dont start it and move it out of the garage. So if they though it would save them paying out a warrantee claim theyd say 89 minimum period. But its your car. You can run av gas in it if it makes your feel good. Just dont thinks its giving any hp without a tune. Im out of this now ive only been doing this for 43 years and i guess ive learned nothing.

Stop reading manuals and start logging. I am not telling anyone to run 93 but the recommended octane (89 for 5.7 auto and 91 for 5.7 manuals). In my area 89 is not as readily available as 91 which is not as available as 93. Running 87 won't hurt the motor as there are knock sensors to prevent any significant damage...but if you plan to tow a heavy load run the min or next octane level up.

Now that we are done talking about octane...I assume the next topic will be oil brand and/or viscosity?

I get why you think it's not correct. I re-read it and it does sound like I was talking about 87. I was actually refereeing to 93 and the NN being able to adjust for it. Actually, now that I think about it, you'd have to clear the adaptives to feel any benefit. Not sure that would even work.

You were incorrect about the 87.

According to your manual, 87 is not recommended for long term use.

Manual does not say anything 87 and long term use.

 

[2ndgen]

View attachment 1073774

It says right there: "This engine is designed to...provide satisfactory fuel economy and performance when using...octane number range of 87 to 89..." Nothing in those paragraphs indicate anything other than that 87 is just fine for long term use. It /recommends/ 89 for optimum performance (it's going to need the least knock reduction on 89), but does not have any language discouraging or disparaging 87.

 

[ChallyTatum]

It says right there: "This engine is designed to...provide satisfactory fuel economy and performance when using...octane number range of 87 to 89..." Nothing in those paragraphs indicate anything other than that 87 is just fine for long term use. It /recommends/ 89 for optimum performance (it's going to need the least knock reduction on 89), but does not have any language discouraging or disparaging 87.

Are you directing this response to me? I hope not because I was pointing out to 2012 white RT that the owner's manual does not say 87 is not recommended for long term use.

This all stems from another thread BTW.

Premium Gas

I've been putting super unleaded gas in my 2020 Challenger Scat Pack and wondering if I am doing the right thing. I do just mostly normal driving. Do you guys use regular or super in your cars with the 6.4 Hemi?

www.challengertalk.com

And again, this is only true for 5.7 MDS (aka auto trans equipped).

 

[2ndgen]

Are you directing this response to me? I hope not because I was pointing out to 2012 white RT that the owner's manual does not say 87 is not recommended for long term use.

No, I was agreeing with your post--just highlighting the other portion from the manual--that 87 is just fine for that engine with the auto trans.

 

[Magnumite]

Untuned, my ‘13 M6 R/T ran better on 91. The 93 made it a little sluggish.

 

[ChallyTatum]

Untuned, my ‘13 M6 R/T ran better on 91. The 93 made it a little sluggish.

93 is less prone to detonation compared to 91...so less chance of timing being pulled due to knock...so more available power. So don't see how the engine would run sluggish at a higher octane?

 

[87GN]

93 is less prone to detonation compared to 91...so less chance of timing being pulled due to knock...so more available power. So don't see how the engine would run sluggish at a higher octane?

I think the 20 cents/gal. savings provided the power of suggestion.