Theoretical Octane Question
08-17-07, 06:51 AM
#1
Theoretical Octane Question
Alright, I searched and haven't found this question yet and I'm just too curious to not ask. It's a bit theoretical so it might be a stretch to ask.
What octane would be best for a stock S4 N/A?
Now I'm not talking about just what you can get at a pump. I'm talking if you could put ANY octane gas into the engine to burn (ex. 70, 82, 84, etc.).
What octane would be best for a stock S4 N/A?
Now I'm not talking about just what you can get at a pump. I'm talking if you could put ANY octane gas into the engine to burn (ex. 70, 82, 84, etc.).
08-17-07, 08:07 AM
#2
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Alright, I searched and haven't found this question yet and I'm just too curious to not ask. It's a bit theoretical so it might be a stretch to ask.
What octane would be best for a stock S4 N/A?
Now I'm not talking about just what you can get at a pump. I'm talking if you could put ANY octane gas into the engine to burn (ex. 70, 82, 84, etc.).
What octane would be best for a stock S4 N/A?
Now I'm not talking about just what you can get at a pump. I'm talking if you could put ANY octane gas into the engine to burn (ex. 70, 82, 84, etc.).
08-17-07, 08:21 AM
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^^IIRC that is sort of correct. (not ****, the other one... sup ****? 
)
From what I remember to be a fairly detailed discussion on this, they are tuned to run at most 87. Let me clarify this some, however. I believe the number was actually around 84, but I don't actually remember. I do, however, remember that the "max 87" number (keep in mind I don't mean this is maximum recommended or w/e, that's just a number I know for sure it was tuned to run under) was RON. We use AKI or R+M/2. The difference here in these ranges is generally 3-4 octane.
This means that if it was tuned to run on 87, then here in the states we would use 84 or so octane. If it was tuned to run 84, then 81 or so. I believe the final calculated R+M/2 number that the thread came to was in the 82-83 range but... again... years ago.
I hope this helps.
)From what I remember to be a fairly detailed discussion on this, they are tuned to run at most 87. Let me clarify this some, however. I believe the number was actually around 84, but I don't actually remember. I do, however, remember that the "max 87" number (keep in mind I don't mean this is maximum recommended or w/e, that's just a number I know for sure it was tuned to run under) was RON. We use AKI or R+M/2. The difference here in these ranges is generally 3-4 octane.
This means that if it was tuned to run on 87, then here in the states we would use 84 or so octane. If it was tuned to run 84, then 81 or so. I believe the final calculated R+M/2 number that the thread came to was in the 82-83 range but... again... years ago.
I hope this helps.
08-17-07, 08:36 AM
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Well I was reading over a post that AaronCake had posted (I think on his website) and he was mentioning that for an S4 N/A best octane is the 87, if you go higher you are going to actually lose power and there will be greater carbon build up. I used to think that if i put 91 octane it would make it run better but after doing some searching looks that 87 is the best for S4 N/A.
08-17-07, 08:41 AM
#7
Well I was reading over a post that AaronCake had posted (I think on his website) and he was mentioning that for an S4 N/A best octane is the 87, if you go higher you are going to actually lose power and there will be greater carbon build up. I used to think that if i put 91 octane it would make it run better but after doing some searching looks that 87 is the best for S4 N/A.
^^IIRC that is sort of correct. (not ****, the other one... sup ****? )
From what I remember to be a fairly detailed discussion on this, they are tuned to run at most 87. Let me clarify this some, however. I believe the number was actually around 84, but I don't actually remember. I do, however, remember that the "max 87" number (keep in mind I don't mean this is maximum recommended or w/e, that's just a number I know for sure it was tuned to run under) was RON. We use AKI or R+M/2. The difference here in these ranges is generally 3-4 octane.
This means that if it was tuned to run on 87, then here in the states we would use 84 or so octane. If it was tuned to run 84, then 81 or so. I believe the final calculated R+M/2 number that the thread came to was in the 82-83 range but... again... years ago.
I hope this helps.
)From what I remember to be a fairly detailed discussion on this, they are tuned to run at most 87. Let me clarify this some, however. I believe the number was actually around 84, but I don't actually remember. I do, however, remember that the "max 87" number (keep in mind I don't mean this is maximum recommended or w/e, that's just a number I know for sure it was tuned to run under) was RON. We use AKI or R+M/2. The difference here in these ranges is generally 3-4 octane.
This means that if it was tuned to run on 87, then here in the states we would use 84 or so octane. If it was tuned to run 84, then 81 or so. I believe the final calculated R+M/2 number that the thread came to was in the 82-83 range but... again... years ago.
I hope this helps.
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08-17-07, 09:12 AM
#10
I have an S4 NA with an Intake and a RB headers, High flow cat, and a cat back what and I have been using 93 the whole time I noticed a difference from 89octane to 93 it ran smoother but it could of been a placebo(I dont know how to spell) effect what should I be running?
08-17-07, 09:14 AM
#11
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Edit ^^^ Run 87 octane only in an NA. As stated below if I could find 80 I'd run it.
Yeah, they run pig rich. I'd run 80 octane if I could find it.
Interesting tidbit though... adding premix lowers your octane. I don't know by how much, but it does. The thread I'm talking about had calcs for it.
I'm positive that these motors are tuned for no higher than 84 R+M/2. 100% guaranteed that number is not higher. I'm pretty sure it's a little lower though.
Or you could just get a fuel management system and wideband, and tune it for whatever you're putting in.
Yeah, they run pig rich. I'd run 80 octane if I could find it.
Interesting tidbit though... adding premix lowers your octane. I don't know by how much, but it does. The thread I'm talking about had calcs for it.
I'm positive that these motors are tuned for no higher than 84 R+M/2. 100% guaranteed that number is not higher. I'm pretty sure it's a little lower though.
Or you could just get a fuel management system and wideband, and tune it for whatever you're putting in.
08-17-07, 10:13 AM
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^^ OR
You could get a wideband, and properly tune your car. I think for an NA you're shooting for 13-14 AF's depending on condition.
Edit: you also need a fuel controller (SAFC, Rtek, Emanage, or a full EMS like Haltech, Microtech, Wolf3D, Megasquirt).
If you aren't going to tune your car this way (too expensive or w/e) then just fill it with 87 and enjoy. You aren't hurting anything.
You could get a wideband, and properly tune your car. I think for an NA you're shooting for 13-14 AF's depending on condition.
Edit: you also need a fuel controller (SAFC, Rtek, Emanage, or a full EMS like Haltech, Microtech, Wolf3D, Megasquirt).
If you aren't going to tune your car this way (too expensive or w/e) then just fill it with 87 and enjoy. You aren't hurting anything.
08-17-07, 12:38 PM
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There have been a couple messes that I don't even like to mention anymore despite what's in them. I don't remember that one being terrible though. Some of the supercharger wars get downright nasty.
08-17-07, 01:06 PM
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He did, he just diverged some. The flame fest he was talking about involved people arguing about anything from 80 to 110 octane gas. The argument ranged from which octane is best to the proper or improper calculations for converting to/from RON and AKI or for mixing.
The result of the argument was that 87 was the best to use as far as pump gasses. I know that's not the answer you want, but they came to that conclusion based on optimal being between 80 and 84 AKI. Heck it might have been in the high 70's. I know it was significantly lower than we can purchase at most stations. That is the tie together that he was making with that thread and this one.
The result of the argument was that 87 was the best to use as far as pump gasses. I know that's not the answer you want, but they came to that conclusion based on optimal being between 80 and 84 AKI. Heck it might have been in the high 70's. I know it was significantly lower than we can purchase at most stations. That is the tie together that he was making with that thread and this one.
08-17-07, 01:16 PM
#19
He did, he just diverged some. The flame fest he was talking about involved people arguing about anything from 80 to 110 octane gas. The argument ranged from which octane is best to the proper or improper calculations for converting to/from RON and AKI or for mixing.
The result of the argument was that 87 was the best to use as far as pump gasses. I know that's not the answer you want, but they came to that conclusion based on optimal being between 80 and 84 AKI. Heck it might have been in the high 70's. I know it was significantly lower than we can purchase at most stations. That is the tie together that he was making with that thread and this one.
The result of the argument was that 87 was the best to use as far as pump gasses. I know that's not the answer you want, but they came to that conclusion based on optimal being between 80 and 84 AKI. Heck it might have been in the high 70's. I know it was significantly lower than we can purchase at most stations. That is the tie together that he was making with that thread and this one.
08-17-07, 01:32 PM
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Ok, so... I'm stupid. I'm not very stupid, but... I am in fact stupid TWICE.
I do have a fairly good reason to be stupid though.
I make a partial *** of myself in this thread, because I was at the time misinformed on what the manual said. I had been told at the time that the manual stated 87 RON for a rotary. I was corrected on this. I still don't know what this guy thinks linear approximation means, but... see the last few pages of this thread.
https://www.rx7club.com/showthread.p...hlight=kontakt
According to this next link, the S5 manual states 87 AKI or above. The reason that I've got a good one to be stupid, is that this manual is wrong... ish. The manual means that it will run the way Mazda tuned it (rich) on 87 or higher octane gas. This does not, however, tell you what I thought we were talking about in that thread, and that we ARE talking about in this thread. That is at what octane fuel are you no longer running pig rich.
https://www.rx7club.com/showpost.php...0&postcount=42
Here is another VERY informative thread, that at least touches on octane. It's mostly abouth alky/meth injection, but has some very bright minds.
https://www.rx7club.com/showthread.p...hlight=kontakt
I do have a fairly good reason to be stupid though.
I make a partial *** of myself in this thread, because I was at the time misinformed on what the manual said. I had been told at the time that the manual stated 87 RON for a rotary. I was corrected on this. I still don't know what this guy thinks linear approximation means, but... see the last few pages of this thread.
https://www.rx7club.com/showthread.p...hlight=kontakt
According to this next link, the S5 manual states 87 AKI or above. The reason that I've got a good one to be stupid, is that this manual is wrong... ish. The manual means that it will run the way Mazda tuned it (rich) on 87 or higher octane gas. This does not, however, tell you what I thought we were talking about in that thread, and that we ARE talking about in this thread. That is at what octane fuel are you no longer running pig rich.
https://www.rx7club.com/showpost.php...0&postcount=42
Here is another VERY informative thread, that at least touches on octane. It's mostly abouth alky/meth injection, but has some very bright minds.
https://www.rx7club.com/showthread.p...hlight=kontakt
08-17-07, 01:43 PM
#22
Ok, so... I'm stupid. I'm not very stupid, but... I am in fact stupid TWICE.
I do have a fairly good reason to be stupid though.
I make a partial *** of myself in this thread, because I was at the time misinformed on what the manual said. I had been told at the time that the manual stated 87 RON for a rotary. I was corrected on this. I still don't know what this guy thinks linear approximation means, but... see the last few pages of this thread.
https://www.rx7club.com/showthread.p...hlight=kontakt
I do have a fairly good reason to be stupid though.
I make a partial *** of myself in this thread, because I was at the time misinformed on what the manual said. I had been told at the time that the manual stated 87 RON for a rotary. I was corrected on this. I still don't know what this guy thinks linear approximation means, but... see the last few pages of this thread.
https://www.rx7club.com/showthread.p...hlight=kontakt
I guess for clarification though, shouldn't it be (R+M)/2 instead of R+M/2?According to this next link, the S5 manual states 87 AKI or above. The reason that I've got a good one to be stupid, is that this manual is wrong... ish. The manual means that it will run the way Mazda tuned it (rich) on 87 or higher octane gas. This does not, however, tell you what I thought we were talking about in that thread, and that we ARE talking about in this thread. That is at what octane fuel are you no longer running pig rich.
https://www.rx7club.com/showpost.php...0&postcount=42
https://www.rx7club.com/showpost.php...0&postcount=42
Here is another VERY informative thread, that at least touches on octane. It's mostly abouth alky/meth injection, but has some very bright minds.
https://www.rx7club.com/showthread.p...hlight=kontakt
https://www.rx7club.com/showthread.p...hlight=kontakt
Might as well make the info public.
08-17-07, 01:49 PM
#23
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08-17-07, 09:41 PM
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All 2Gen RX-7's are rated for a minimum (R+M)/2 octane rating of 87 with no more than 10% alcohol. Due to variances in fuel, engine condition, and tuning, Mazda recommends that you stick within these parameters. Much like the stress rating on a bridge, aircraft wing, etc., there is a fudge factor built into those numbers, but it is best to stay within the given parameters for safety and reliability.
The octane rating is only an anti-knock rating. It has nothing to do with energy content, acceleration, deposits, emissions, gas mileage, chi, juju, mojo, or anything else. See here:
http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm
If you are looking for a fuel with more power, you need to ask the manufacturer for the "energy content". Assuming the same fuel density and air-fuel ratio, a fuel with a higher energy content will produce more power than a fuel with less energy content.
My car runs a lot better when I use the gas from a particular gas station with a green sign. Therefore, you guys should really be using gas from a station with a green sign if you want your car to run the best. Do you see a problem with that logic? Good, now apply that to the octane rating and you will be at one with reality.
http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm
If you are looking for a fuel with more power, you need to ask the manufacturer for the "energy content". Assuming the same fuel density and air-fuel ratio, a fuel with a higher energy content will produce more power than a fuel with less energy content.
My car runs a lot better when I use the gas from a particular gas station with a green sign. Therefore, you guys should really be using gas from a station with a green sign if you want your car to run the best. Do you see a problem with that logic? Good, now apply that to the octane rating and you will be at one with reality.