Pinging & 87 Octane
08-31-2006, 11:36 AM
#51
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I'm with the poster who said that you're most likely losing some performance using 87 over 91. Today's engine computers and management can monitor the octane of fuel and change the timing, etc. of the engine to compensate for fuel octanes.
I would think that any manufacturer would not produce an engine that won't destroy itself on 87. Manufacturers have to know that some customers will throw 87 in their engines regardless of what they say. Who knows what the long term consequence are though...
Put 89 in your car and see what happens. I'd feel safer putting that in my car than 87.
If you're concerned about saving money, do your own oil changes that'll save money to put 91 in.
I would think that any manufacturer would not produce an engine that won't destroy itself on 87. Manufacturers have to know that some customers will throw 87 in their engines regardless of what they say. Who knows what the long term consequence are though...
Put 89 in your car and see what happens. I'd feel safer putting that in my car than 87.
If you're concerned about saving money, do your own oil changes that'll save money to put 91 in.
08-31-2006, 11:39 AM
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Mazda told me that 91 is required. Using anything less could void my warrenty on the engine, even voiding the replacement of one for the recall deming it customer caused damaged before the recall was issued. It was phone call I made to one of the techs at my dealership. I know they cant make the discision but that is still a load of brown stuff they put on peoples noses.
08-31-2006, 01:51 PM
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Originally Posted by Fanman
Not really as much about FI'ed engine, as it is an absolute requirement for my setup, but if you look at a high compression engine such as the M3's, or ours, it needs the 91 octane as well to have the optimum timing. People point out previous threads on the RX7, but realize that those engines are very different than these engines. The compression ratios are far higher on this engine than previous 13B units. Not about gaining hp, it's about where the engine is set to run optimum timing.
Absolutely true. For some people the 10% might not even be noticeable if it is an everyday, freeway car. But some of the people are claiming no difference and that is not true. Some people don't care about 10%, some people do. It's up to the individual.
That's not the way it works. Essentially it doesn't mean that some Renesis give more hp on 87 & some on 91. The article has to do with different cars. Ones that are programmed (timing) to run on 87, run optimally on 87 and as such do not get much more hp from running on 91. Ones that are rated to run on 91, lost 6%-10% of their performance running 87. It's just what is your definition of performance ? For some people it is max hp. For some people it is smoothness, or better gas mileage, and 5%-10% less hp may be irrelevant. Butt dynos are notoriously inaccurate.
Absolutely true. For some people the 10% might not even be noticeable if it is an everyday, freeway car. But some of the people are claiming no difference and that is not true. Some people don't care about 10%, some people do. It's up to the individual.
That's not the way it works. Essentially it doesn't mean that some Renesis give more hp on 87 & some on 91. The article has to do with different cars. Ones that are programmed (timing) to run on 87, run optimally on 87 and as such do not get much more hp from running on 91. Ones that are rated to run on 91, lost 6%-10% of their performance running 87. It's just what is your definition of performance ? For some people it is max hp. For some people it is smoothness, or better gas mileage, and 5%-10% less hp may be irrelevant. Butt dynos are notoriously inaccurate.
In experimenting with different octanes, I never noticed enough of a difference in power to distinguish between which octane I am running. And again regardless of octane I am not experiencing detonation (that I can detect and I have had zero engine issues).
If I knew conclusively, on my own engine, that I was losing 5-10%hp by using 87 instead of 93 (premium available in Chicago) than I would use 93. That 5-10% estimate would be an approximate 10-20bhp on our engines. I just don't see it, and our PCM does adjust timing to compensate for 87. Also, within our community I have yet to see anyone conclusively prove or disprove such a theory that one creates substantially more or less power than another. The closest I've seen is the tuned Mazsport Interceptor on 87 providing more power than premium. That, to me, supports that this engine is very much in some ways like the previous 13B. It doesn't, however, support which provides more power on the OEM PCM tune.
08-31-2006, 02:58 PM
#54
Originally Posted by zeblien
Mazda told me that 91 is required. Using anything less could void my warrenty on the engine, even voiding the replacement of one for the recall deming it customer caused damaged before the recall was issued. It was phone call I made to one of the techs at my dealership. I know they cant make the discision but that is still a load of brown stuff they put on peoples noses.
Factory manual states 87 can be used.
08-31-2006, 04:38 PM
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Originally Posted by Red Devil
The last of FC models had 9.7:1 compression, pretty darn close to 10:1. But yes, this is a completely different engine.
In experimenting with different octanes, I never noticed enough of a difference in power to distinguish between which octane I am running. And again regardless of octane I am not experiencing detonation (that I can detect and I have had zero engine issues).
If I knew conclusively, on my own engine, that I was losing 5-10%hp by using 87 instead of 93 (premium available in Chicago) than I would use 93. That 5-10% estimate would be an approximate 10-20bhp on our engines. I just don't see it, and our PCM does adjust timing to compensate for 87. Also, within our community I have yet to see anyone conclusively prove or disprove such a theory that one creates substantially more or less power than another. The closest I've seen is the tuned Mazsport Interceptor on 87 providing more power than premium. That, to me, supports that this engine is very much in some ways like the previous 13B. It doesn't, however, support which provides more power on the OEM PCM tune.
In experimenting with different octanes, I never noticed enough of a difference in power to distinguish between which octane I am running. And again regardless of octane I am not experiencing detonation (that I can detect and I have had zero engine issues).
If I knew conclusively, on my own engine, that I was losing 5-10%hp by using 87 instead of 93 (premium available in Chicago) than I would use 93. That 5-10% estimate would be an approximate 10-20bhp on our engines. I just don't see it, and our PCM does adjust timing to compensate for 87. Also, within our community I have yet to see anyone conclusively prove or disprove such a theory that one creates substantially more or less power than another. The closest I've seen is the tuned Mazsport Interceptor on 87 providing more power than premium. That, to me, supports that this engine is very much in some ways like the previous 13B. It doesn't, however, support which provides more power on the OEM PCM tune.
You would say you feel the difference of say 10-20 hp, but would you really ? Some people put pullies on and claim they feel the difference. Later on the dyno they found it provided a whopping 1 hp. Or some people say they feel the difference when they put an intake, hi-flow cat & exhaust on, but found out it gave about 10 hp. Like I said the butt dyno are notoriously inaccurate. You put 87 in your car, and you want to justify that decision, just like the guy that might have dropped $400 on his pullies and wants to justify that cost.
I never said our ECU doesn't compensate for 87. As a matter of fact I said it does in my previous post. like I said, think of it as a range of 1-10, with 87 being a 1 and 91 being a 10. It can't retard the timing lower than 87 or it will get breakup, and it won't make it more aggressive than the timing of 91, so putting 100 octane in it won't get you more hp.
There was a guy from Europe recently that posted his results on using 87 octane vs. 95 octane, and the difference was substantial. The question is do you think our engine is tuned closer to an M3 or a Honda Accord like in the test.
09-01-2006, 01:54 AM
#56
I4NI
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Originally Posted by Fanman
Again, different engine like we had mentioned. This engine has little to do with the last FC engine. Not only is the compression different, but the factory tuning is different. In other words, if Mazda came in and said tune this thing to run on 87, I'm sure the engineers could have, but instead of touting 232-238 hp, would you have been as impressed if it ran on 87, but was only 220 hp ? They could have done it, but they set it optimally to get every last hp out of it & run the timing most aggressively at 91 octane.
You would say you feel the difference of say 10-20 hp, but would you really ? Some people put pullies on and claim they feel the difference. Later on the dyno they found it provided a whopping 1 hp. Or some people say they feel the difference when they put an intake, hi-flow cat & exhaust on, but found out it gave about 10 hp. Like I said the butt dyno are notoriously inaccurate. You put 87 in your car, and you want to justify that decision, just like the guy that might have dropped $400 on his pullies and wants to justify that cost.
I never said our ECU doesn't compensate for 87. As a matter of fact I said it does in my previous post. like I said, think of it as a range of 1-10, with 87 being a 1 and 91 being a 10. It can't retard the timing lower than 87 or it will get breakup, and it won't make it more aggressive than the timing of 91, so putting 100 octane in it won't get you more hp.
There was a guy from Europe recently that posted his results on using 87 octane vs. 95 octane, and the difference was substantial. The question is do you think our engine is tuned closer to an M3 or a Honda Accord like in the test.
You would say you feel the difference of say 10-20 hp, but would you really ? Some people put pullies on and claim they feel the difference. Later on the dyno they found it provided a whopping 1 hp. Or some people say they feel the difference when they put an intake, hi-flow cat & exhaust on, but found out it gave about 10 hp. Like I said the butt dyno are notoriously inaccurate. You put 87 in your car, and you want to justify that decision, just like the guy that might have dropped $400 on his pullies and wants to justify that cost.
I never said our ECU doesn't compensate for 87. As a matter of fact I said it does in my previous post. like I said, think of it as a range of 1-10, with 87 being a 1 and 91 being a 10. It can't retard the timing lower than 87 or it will get breakup, and it won't make it more aggressive than the timing of 91, so putting 100 octane in it won't get you more hp.
There was a guy from Europe recently that posted his results on using 87 octane vs. 95 octane, and the difference was substantial. The question is do you think our engine is tuned closer to an M3 or a Honda Accord like in the test.
Lets look at it another way. No two vehicles are exactly the same. Some cars run better than others. I'm sure some vehicles run better on 87 than 91. Everything Mazda has tested was in controled cond. We the people are running our 8's in different parts of the world and thinking everthings exactly the same as the guy who post next or live in japan(example) or somewhere high in the mountains in the US.
Last edited by Silver_Surfer; 09-01-2006 at 11:10 AM.
09-01-2006, 07:35 AM
#57
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Originally Posted by Red Devil
You are inferring these statements based on what? You act as if the answer for you is all encompassing. I run 87. I'm not strapped for cash. My car experiences zero detonation even under pretty extreme conditions. So why would I use 93? Because Mazda "recommends" premium? To me, that is just plain foolish. If my car was experiencing detonation with 87 octane, then I'd use premium, but it doesn't.
I guess I'll take my couple bucks of saved money a week and have a Guinness at the bar. Cheers.
I guess I'll take my couple bucks of saved money a week and have a Guinness at the bar. Cheers.
09-01-2006, 08:26 AM
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Originally Posted by Fanman
You would say you feel the difference of say 10-20 hp, but would you really ?
I'm curious to see, got a link for the memeber in Europe (Rasputin, maybe?) that posted the difference between regular and premium?
And again, Mazda may have tuned for 91. But Scott countered by saying optimal after his tuning was 87...I think we could argue about this all day. I'm content to say I'll run what I run and be happy with it.
09-01-2006, 08:48 AM
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I didnt read that, but considering the dealership is the guy who says "sure we will fix that under warrenty" I guess i dont have much choice". But I will ask him why it says 87 in the book.
09-01-2006, 08:48 AM
#60
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Originally Posted by Silver_Surfer
Nubo, that is a terible looking plug! This is the kind of stuff I'd wanted to see/here when starting this thread, not the here say/read that stuff. Can you tell me about your 8. Mods? If any.
The plugs were still functioning. Color and deposits looked ok. The only thing I'd noticed was a bit of stumbling at very low speeds. That prompted me to change the plugs, and the performance went back to normal.
09-01-2006, 11:16 AM
#61
I4NI
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Originally Posted by Nubo
No performance mods.
The plugs were still functioning. Color and deposits looked ok. The only thing I'd noticed was a bit of stumbling at very low speeds. That prompted me to change the plugs, and the performance went back to normal.
The plugs were still functioning. Color and deposits looked ok. The only thing I'd noticed was a bit of stumbling at very low speeds. That prompted me to change the plugs, and the performance went back to normal.
I'll have to pull my plugs to check. I do get an intermittent stumble at low rpm's but seems to clear out with a redline buzz(wooot)
Hmmmmmm? Lucky I got a long weekend 
Thanks 
09-01-2006, 03:05 PM
#63
Here is another take on it, Mazda designs the engine to run under 87 oct, after testing a small portion of cars build up a deposit that cause some pining. Is it easier for Mazda to fix the deposit pinging problem or just slap a use 91 oct across the board to protect themselfs from warranty costs?
Originally Posted by Fanman
Again, different engine like we had mentioned. This engine has little to do with the last FC engine. Not only is the compression different, but the factory tuning is different. In other words, if Mazda came in and said tune this thing to run on 87, I'm sure the engineers could have, but instead of touting 232-238 hp, would you have been as impressed if it ran on 87, but was only 220 hp ? They could have done it, but they set it optimally to get every last hp out of it & run the timing most aggressively at 91 octane.
You would say you feel the difference of say 10-20 hp, but would you really ? Some people put pullies on and claim they feel the difference. Later on the dyno they found it provided a whopping 1 hp. Or some people say they feel the difference when they put an intake, hi-flow cat & exhaust on, but found out it gave about 10 hp. Like I said the butt dyno are notoriously inaccurate. You put 87 in your car, and you want to justify that decision, just like the guy that might have dropped $400 on his pullies and wants to justify that cost.
I never said our ECU doesn't compensate for 87. As a matter of fact I said it does in my previous post. like I said, think of it as a range of 1-10, with 87 being a 1 and 91 being a 10. It can't retard the timing lower than 87 or it will get breakup, and it won't make it more aggressive than the timing of 91, so putting 100 octane in it won't get you more hp.
There was a guy from Europe recently that posted his results on using 87 octane vs. 95 octane, and the difference was substantial. The question is do you think our engine is tuned closer to an M3 or a Honda Accord like in the test.
You would say you feel the difference of say 10-20 hp, but would you really ? Some people put pullies on and claim they feel the difference. Later on the dyno they found it provided a whopping 1 hp. Or some people say they feel the difference when they put an intake, hi-flow cat & exhaust on, but found out it gave about 10 hp. Like I said the butt dyno are notoriously inaccurate. You put 87 in your car, and you want to justify that decision, just like the guy that might have dropped $400 on his pullies and wants to justify that cost.
I never said our ECU doesn't compensate for 87. As a matter of fact I said it does in my previous post. like I said, think of it as a range of 1-10, with 87 being a 1 and 91 being a 10. It can't retard the timing lower than 87 or it will get breakup, and it won't make it more aggressive than the timing of 91, so putting 100 octane in it won't get you more hp.
There was a guy from Europe recently that posted his results on using 87 octane vs. 95 octane, and the difference was substantial. The question is do you think our engine is tuned closer to an M3 or a Honda Accord like in the test.
09-02-2006, 05:33 PM
#64
I4NI
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Just got done checking my plugs. Very nice coco color. The only thing I found odd was my leading lower plugs were RE7C(lower) & RE9B(upper) like wise trailing set. Thought "N3" type plugs were put in new. About 15,000 miles now, guess my 8 likes 87
09-02-2006, 06:42 PM
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Originally Posted by Red Devil
I'm curious to see, got a link for the memeber in Europe (Rasputin, maybe?) that posted the difference between regular and premium?
09-02-2006, 06:45 PM
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Originally Posted by Raptor75
Here is another take on it, Mazda designs the engine to run under 87 oct, after testing a small portion of cars build up a deposit that cause some pining. Is it easier for Mazda to fix the deposit pinging problem or just slap a use 91 oct across the board to protect themselfs from warranty costs?
10-05-2006, 08:34 AM
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Im surprised that throughout the thousands of posts about octane (I've read most of them) no one has mentioned altitude. Altitude dictates air thickness which would have an impact on why some of the members here say that 87 is ok for them and some say it isnt. Along that same line, I believe I only read 1 post that mentioned air temperatures also (same effect). Interested to hear from the rotary gurus about this one...
10-05-2006, 10:18 AM
#69
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Originally Posted by Nubo
No performance mods.
The plugs were still functioning. Color and deposits looked ok. The only thing I'd noticed was a bit of stumbling at very low speeds. That prompted me to change the plugs, and the performance went back to normal.
The plugs were still functioning. Color and deposits looked ok. The only thing I'd noticed was a bit of stumbling at very low speeds. That prompted me to change the plugs, and the performance went back to normal.
I'm brand-new to rotaries, but from what I've read, what I infer, and what seems pretty clear these things can be damaged pretty quickly by deto (well, so can a recip engine) and you may not know it until too late.
I'll buy off on the idea that some of our cars run well on 87 octane, with the knock sensor providing some protection from deto. But that very variability in the response of these engines to octane does not, to me, justify using the lower grade until I've run low-grade and then seen the inside of my combustion chamber. Or my spark plugs, as in the case of Nubo's. A plug damaged like that is often the precursor to more significant damage.
Is there any rotary equiavalent to melting the top of a piston? Do rotors fail that way?
Pilgrim
10-05-2006, 11:14 AM
#70
I4NI
Thread Starter
Originally Posted by zeblien
Beter then never detonating. That would make for a very slow ride 
.
Realy though since gas as come down to $2 I really dont mind paying for 91oc.
.Realy though since gas as come down to $2 I really dont mind paying for 91oc.
I'd pay $5.00 if I thought it would make a differents...
fyi: It's 3.85 here in the peoples republice of hawaii
10-05-2006, 11:15 AM
#71
I4NI
Thread Starter
Originally Posted by M23RX8
Im surprised that throughout the thousands of posts about octane (I've read most of them) no one has mentioned altitude. Altitude dictates air thickness which would have an impact on why some of the members here say that 87 is ok for them and some say it isnt. Along that same line, I believe I only read 1 post that mentioned air temperatures also (same effect). Interested to hear from the rotary gurus about this one...
Sea level.
10-05-2006, 11:22 AM
#72
I4NI
Thread Starter
Originally Posted by Pilgrim
Some of the worst deto I've experienced was in a Harley engine I built, and it was absolutely silent. Even a young friend with good ears who rode it didn't hear anything. But when I took the heads off the pistons were badly eroded around the edges and the combustion chamber looked sandblasted around the exhaust valve.
I'm brand-new to rotaries, but from what I've read, what I infer, and what seems pretty clear these things can be damaged pretty quickly by deto (well, so can a recip engine) and you may not know it until too late.
I'll buy off on the idea that some of our cars run well on 87 octane, with the knock sensor providing some protection from deto. But that very variability in the response of these engines to octane does not, to me, justify using the lower grade until I've run low-grade and then seen the inside of my combustion chamber. Or my spark plugs, as in the case of Nubo's. A plug damaged like that is often the precursor to more significant damage.
Is there any rotary equiavalent to melting the top of a piston? Do rotors fail that way?
Pilgrim
I'm brand-new to rotaries, but from what I've read, what I infer, and what seems pretty clear these things can be damaged pretty quickly by deto (well, so can a recip engine) and you may not know it until too late.
I'll buy off on the idea that some of our cars run well on 87 octane, with the knock sensor providing some protection from deto. But that very variability in the response of these engines to octane does not, to me, justify using the lower grade until I've run low-grade and then seen the inside of my combustion chamber. Or my spark plugs, as in the case of Nubo's. A plug damaged like that is often the precursor to more significant damage.
Is there any rotary equiavalent to melting the top of a piston? Do rotors fail that way?
Pilgrim
Only seen rotors melt with extreem boost cases. I would think the apex seals(rings) would be one of the first things to go.
10-05-2006, 11:29 AM
#73
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My manual (06) only has 91 for the fuel recommendation. 
Anyway, I calculated the cost for me if I were to use regular versus premium and it's right around $10 a month, so it's not really significant. I'm sure it would probably be okay if I absolutely had to run 87 in it, like on a cross country trip where I've noticed a few different gas stations in the recent past only had regular and diesel for choices. I wouldn't make a habit of it, especially since my car seems to run differently depending on brand. I use Chevron all the time and the car runs great. I have had to fill up with Shell twice. Both times my mileage went down and the car didn't run as smoothly as otherwise. The only thing that changed was the brand of gas, so apparently additives make a difference.
Anyway, since somebody said their mpg was good at 19-20 with regular, I get 23 average with mine on Premium. I just took a road trip over the weekend up to the Seattle area and got 27 with mixed driving but mainly highway.
I know you won't see improvement using higher octane gas than your car is rated for because it is programmed to run at a certain octane level. So, it would make sense that if your car is programmed to run at 91 (per the manufacturer's recommendation to use that grade) it isn't going to do as well running lower octane, since it was programmed to use higher.
After seeing the damaged plugs, I think I'll stick with my premium.
Anyway, I calculated the cost for me if I were to use regular versus premium and it's right around $10 a month, so it's not really significant. I'm sure it would probably be okay if I absolutely had to run 87 in it, like on a cross country trip where I've noticed a few different gas stations in the recent past only had regular and diesel for choices. I wouldn't make a habit of it, especially since my car seems to run differently depending on brand. I use Chevron all the time and the car runs great. I have had to fill up with Shell twice. Both times my mileage went down and the car didn't run as smoothly as otherwise. The only thing that changed was the brand of gas, so apparently additives make a difference. Anyway, since somebody said their mpg was good at 19-20 with regular, I get 23 average with mine on Premium. I just took a road trip over the weekend up to the Seattle area and got 27 with mixed driving but mainly highway.
I know you won't see improvement using higher octane gas than your car is rated for because it is programmed to run at a certain octane level. So, it would make sense that if your car is programmed to run at 91 (per the manufacturer's recommendation to use that grade) it isn't going to do as well running lower octane, since it was programmed to use higher.
After seeing the damaged plugs, I think I'll stick with my premium.