87,89 or 91 Octane?
Thread Starter
Senior Member
Joined: Sep 2001
Posts: 318
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From: Calgary, AB, CA
87,89 or 91 Octane?
I just got my 88 N/A a while ago and I didnt' get a users manual with it. I'm wondering if there is any advantage in using 89 or 91 octance gasoline? What does it say to use in the manual?
87 is a fair bit cheaper, and that would add up to a significant saving for a student like myself.
Its not like I'm racing or anything, so I don't need top performance. I just want to make sure I won't be hurting the engine by putting in 87. Thanks,
Nima
87 is a fair bit cheaper, and that would add up to a significant saving for a student like myself.
Its not like I'm racing or anything, so I don't need top performance. I just want to make sure I won't be hurting the engine by putting in 87. Thanks,
Nima
Uhm, I've had my 86 N/A for almost 2 years now, and Ive put nothing but 91 octane in it since then. Are you saying that the car would perform better on 87, or that a higher octane just isnt necessary? I just assumed that the higher the octane the better, is my reasoning wrong, and if so, why?
Rotary Freak
Joined: Aug 2001
Posts: 2,267
Likes: 3
Originally posted by Rxmfn7
Uhm, I've had my 86 N/A for almost 2 years now, and Ive put nothing but 91 octane in it since then. Are you saying that the car would perform better on 87, or that a higher octane just isnt necessary? I just assumed that the higher the octane the better, is my reasoning wrong, and if so, why?
Uhm, I've had my 86 N/A for almost 2 years now, and Ive put nothing but 91 octane in it since then. Are you saying that the car would perform better on 87, or that a higher octane just isnt necessary? I just assumed that the higher the octane the better, is my reasoning wrong, and if so, why?
Octane is simply a measure of knock resistance. 91 octane gas is not "better" qualitatively; just harder to ignite inadvertently. 87 octane is all your NA will ever need (unless you buy an aftermarket ignition setup and advance the hell out of your timing).
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NA Powah, Every Hour!
Joined: Mar 2001
Posts: 1,302
Likes: 0
From: Sacramento, CA, U S of A
Yo,
From Felix's Rotary FAQ:
What's the best fuel for my rotary car?
It depends. If your rotary Mazda is equipped with a turbocharger, all the normal rules about octane apply. Use the highest available octane premium fuel for best power and best protection against the ravages of detonation. You may find slighly better fuel mileage using lower octane, but you need to be very careful about using the available power on lower octane. If you are good at exercising restraint, you can save a little money on a long trip using regular, but it's probably best to stick with premium for normal use.
WIth the normally aspirated (NA) rotary, the highest octane you should use is US pump (AKI - anti-knock index) 87, typically RON 91 outside the US, no matter how heavily your engine is modified. Octane in excess of any engine's actual requirement is always wasted. The issues of purity and additives in more expensive fuels are entirely separate issues. There's no reason not to want either in the NA rotary.
The rotary engine's high turbulence combustion chamber provides a very high resistance to detonation. Its duration of combustion is also longer, remembering that the rotors turn at 1/3 of the tachometer reading, and the slow burn* of high octane is undesirable in it. Pump 80 octane is more than sufficient for most of them. Best power and mileage is usually produced with the lowest available octane.
Many serious rotary racers bring their own low octane gasoline to tracks that supply only racing gasoline. From "How to Modify Your Mazda RX-7", by Dave Emanuel and Jim Downing, HP Books, 1987, p 47-8: ". . . the best results are obtained with conservative spark-lead calibrations provided the engine is fed a diet of low-octane fuel. The fact that both 1985 and 1986 IMSA Camel Lights championships were won with low-octane fuel is a rather definitive statement . . . ."
So if you want best performance from your NA rotary, you want lowest octane. The lower cost of it is a nice bonus.
* Note - the time allowed for combustion at high RPM is measured in ten-thousandths of a second. Some literature ascribes lower volatility rather than a slower burn as the characteristic of a higher octane value. In contrast, consider the following: From "14-to-1 compression", By David Green, NASCAR Winston Cup Scene: "One problem that has developed in the 9.5-to-1 engine is high exhaust temperatures, due to a less-efficient burning of 108-octane gasoline in the lower-compression combustion chamber." (emphasis supplied)
You can find his whole FAQ at:
http://mrmazda.members.atlantic.net/...html#RENESISHP
It's a great resource.
KS
1989 GTUs "No rear wiper"
From Felix's Rotary FAQ:
What's the best fuel for my rotary car?
It depends. If your rotary Mazda is equipped with a turbocharger, all the normal rules about octane apply. Use the highest available octane premium fuel for best power and best protection against the ravages of detonation. You may find slighly better fuel mileage using lower octane, but you need to be very careful about using the available power on lower octane. If you are good at exercising restraint, you can save a little money on a long trip using regular, but it's probably best to stick with premium for normal use.
WIth the normally aspirated (NA) rotary, the highest octane you should use is US pump (AKI - anti-knock index) 87, typically RON 91 outside the US, no matter how heavily your engine is modified. Octane in excess of any engine's actual requirement is always wasted. The issues of purity and additives in more expensive fuels are entirely separate issues. There's no reason not to want either in the NA rotary.
The rotary engine's high turbulence combustion chamber provides a very high resistance to detonation. Its duration of combustion is also longer, remembering that the rotors turn at 1/3 of the tachometer reading, and the slow burn* of high octane is undesirable in it. Pump 80 octane is more than sufficient for most of them. Best power and mileage is usually produced with the lowest available octane.
Many serious rotary racers bring their own low octane gasoline to tracks that supply only racing gasoline. From "How to Modify Your Mazda RX-7", by Dave Emanuel and Jim Downing, HP Books, 1987, p 47-8: ". . . the best results are obtained with conservative spark-lead calibrations provided the engine is fed a diet of low-octane fuel. The fact that both 1985 and 1986 IMSA Camel Lights championships were won with low-octane fuel is a rather definitive statement . . . ."
So if you want best performance from your NA rotary, you want lowest octane. The lower cost of it is a nice bonus.
* Note - the time allowed for combustion at high RPM is measured in ten-thousandths of a second. Some literature ascribes lower volatility rather than a slower burn as the characteristic of a higher octane value. In contrast, consider the following: From "14-to-1 compression", By David Green, NASCAR Winston Cup Scene: "One problem that has developed in the 9.5-to-1 engine is high exhaust temperatures, due to a less-efficient burning of 108-octane gasoline in the lower-compression combustion chamber." (emphasis supplied)
You can find his whole FAQ at:
http://mrmazda.members.atlantic.net/...html#RENESISHP
It's a great resource.
KS
1989 GTUs "No rear wiper"
Rotorhead
Joined: Feb 2001
Posts: 9,136
Likes: 39
From: Charlottesville, Virginia, USA
Originally posted by Ryde _Or_Die
Ha ha, ha ha, you have to pay more for gas!! Sorry have to point it out when I have some sort of advantage over you TII people, however small it is
Ha ha, ha ha, you have to pay more for gas!! Sorry have to point it out when I have some sort of advantage over you TII people, however small it is
HyperREV.com
Joined: Mar 2001
Posts: 1,162
Likes: 0
From: Oregon
Originally posted by Ryde _Or_Die
Ha ha, ha ha, you have to pay more for gas!! Sorry have to point it out when I have some sort of advantage over you TII people, however small it is
Ha ha, ha ha, you have to pay more for gas!! Sorry have to point it out when I have some sort of advantage over you TII people, however small it is
yoru still slow biotch
Eats, Sleeps, Dreams Rotary
iTrader: (1)
Joined: Jul 2001
Posts: 3,383
Likes: 3
From: Stinson Beach, Ca
and BTW, why the **** am i awake
its 5:08AM
I go to school
oh yeah, thats right, 4 day weekend and today is day 1/morning of day 2
WOOOOOOHOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
its 5:08AM
I go to school
oh yeah, thats right, 4 day weekend and today is day 1/morning of day 2
WOOOOOOHOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
HyperREV.com
Joined: Mar 2001
Posts: 1,162
Likes: 0
From: Oregon
Originally posted by Node
shutup and waste your modding money on premium while i save up for a Turbo II so I can waste my modding money on premium too!!!!
TAKE THAT!@$!@$
shutup and waste your modding money on premium while i save up for a Turbo II so I can waste my modding money on premium too!!!!
TAKE THAT!@$!@$
Eats, Sleeps, Dreams Rotary
iTrader: (1)
Joined: Jul 2001
Posts: 3,383
Likes: 3
From: Stinson Beach, Ca
Originally posted by RX-7 GT
im kiddin man..relax node
im kiddin man..relax node
wow, what will i scream about when i get my rx-7
Full Member
Joined: Sep 2001
Posts: 162
Likes: 0
From: Marietta, GA
Originally posted by Evil Aviator
The 87-88 TII can use 87 octane just fine, so I guess its the 89+ folks who have to pay for their extra HP at the pump.
The 87-88 TII can use 87 octane just fine, so I guess its the 89+ folks who have to pay for their extra HP at the pump.
Personally I have NEVER put anything less than 93 Octane in mine...
Rotorhead
Joined: Feb 2001
Posts: 9,136
Likes: 39
From: Charlottesville, Virginia, USA
Originally posted by Brian_TII
Also you HAVE to run premium if you start modding it.
Also you HAVE to run premium if you start modding it.
It has all the ghetto mods:
HKS Super Mega Flow Intake
HKS Turbo Timer
Racing Beat FCD
Auto Meter Ultra-Lite Pillar-Mount Boost Gauge
CFDF Clutch
Custom Straight-Through Catback Dual Exhaust (No Mufflers)
Gutted Pre-cat (Expansion Pipe)
I also have the HKS VBC, but it is not hooked up because the previous owner blew 2 engines with it (no fuel upgrade - go figure), although the car did manage an impressive 13.6 1/4 mi time. I would upgrade the fuel system, but this car isn't worth my time, and I'm probably just going to sell it. Anyway, I can still run 87 octane without the VBC.
hambre y sueño
Joined: Feb 2001
Posts: 300
Likes: 1
From: 80* >
Originally posted by RarestRX
Yo,
From Felix's Rotary FAQ:
What's the best fuel for my rotary car?
It depends. If your rotary Mazda is equipped with a turbocharger, all the normal rules about octane apply. Use the highest available octane premium fuel for best power and best protection against the ravages of detonation. You may find slighly better fuel mileage using lower octane, but you need to be very careful about using the available power on lower octane. If you are good at exercising restraint, you can save a little money on a long trip using regular, but it's probably best to stick with premium for normal use.
WIth the normally aspirated (NA) rotary, the highest octane you should use is US pump (AKI - anti-knock index) 87, typically RON 91 outside the US, no matter how heavily your engine is modified. Octane in excess of any engine's actual requirement is always wasted. The issues of purity and additives in more expensive fuels are entirely separate issues. There's no reason not to want either in the NA rotary.
The rotary engine's high turbulence combustion chamber provides a very high resistance to detonation. Its duration of combustion is also longer, remembering that the rotors turn at 1/3 of the tachometer reading, and the slow burn* of high octane is undesirable in it. Pump 80 octane is more than sufficient for most of them. Best power and mileage is usually produced with the lowest available octane.
Many serious rotary racers bring their own low octane gasoline to tracks that supply only racing gasoline. From "How to Modify Your Mazda RX-7", by Dave Emanuel and Jim Downing, HP Books, 1987, p 47-8: ". . . the best results are obtained with conservative spark-lead calibrations provided the engine is fed a diet of low-octane fuel. The fact that both 1985 and 1986 IMSA Camel Lights championships were won with low-octane fuel is a rather definitive statement . . . ."
So if you want best performance from your NA rotary, you want lowest octane. The lower cost of it is a nice bonus.
* Note - the time allowed for combustion at high RPM is measured in ten-thousandths of a second. Some literature ascribes lower volatility rather than a slower burn as the characteristic of a higher octane value. In contrast, consider the following: From "14-to-1 compression", By David Green, NASCAR Winston Cup Scene: "One problem that has developed in the 9.5-to-1 engine is high exhaust temperatures, due to a less-efficient burning of 108-octane gasoline in the lower-compression combustion chamber." (emphasis supplied)
You can find his whole FAQ at:
http://mrmazda.members.atlantic.net/...html#RENESISHP
It's a great resource.
KS
1989 GTUs "No rear wiper"
Yo,
From Felix's Rotary FAQ:
What's the best fuel for my rotary car?
It depends. If your rotary Mazda is equipped with a turbocharger, all the normal rules about octane apply. Use the highest available octane premium fuel for best power and best protection against the ravages of detonation. You may find slighly better fuel mileage using lower octane, but you need to be very careful about using the available power on lower octane. If you are good at exercising restraint, you can save a little money on a long trip using regular, but it's probably best to stick with premium for normal use.
WIth the normally aspirated (NA) rotary, the highest octane you should use is US pump (AKI - anti-knock index) 87, typically RON 91 outside the US, no matter how heavily your engine is modified. Octane in excess of any engine's actual requirement is always wasted. The issues of purity and additives in more expensive fuels are entirely separate issues. There's no reason not to want either in the NA rotary.
The rotary engine's high turbulence combustion chamber provides a very high resistance to detonation. Its duration of combustion is also longer, remembering that the rotors turn at 1/3 of the tachometer reading, and the slow burn* of high octane is undesirable in it. Pump 80 octane is more than sufficient for most of them. Best power and mileage is usually produced with the lowest available octane.
Many serious rotary racers bring their own low octane gasoline to tracks that supply only racing gasoline. From "How to Modify Your Mazda RX-7", by Dave Emanuel and Jim Downing, HP Books, 1987, p 47-8: ". . . the best results are obtained with conservative spark-lead calibrations provided the engine is fed a diet of low-octane fuel. The fact that both 1985 and 1986 IMSA Camel Lights championships were won with low-octane fuel is a rather definitive statement . . . ."
So if you want best performance from your NA rotary, you want lowest octane. The lower cost of it is a nice bonus.
* Note - the time allowed for combustion at high RPM is measured in ten-thousandths of a second. Some literature ascribes lower volatility rather than a slower burn as the characteristic of a higher octane value. In contrast, consider the following: From "14-to-1 compression", By David Green, NASCAR Winston Cup Scene: "One problem that has developed in the 9.5-to-1 engine is high exhaust temperatures, due to a less-efficient burning of 108-octane gasoline in the lower-compression combustion chamber." (emphasis supplied)
You can find his whole FAQ at:
http://mrmazda.members.atlantic.net/...html#RENESISHP
It's a great resource.
KS
1989 GTUs "No rear wiper"
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