87 vs 93.
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From: miami
87 vs 93.
i have a s5 n/a and i noticed big difference when i pumped with 93 sonoco vs 87.
Ive read that some companies will have a higher btu level in premeum gas.
Give it a try and see if u notice something, and try sonoco.
Ive read that some companies will have a higher btu level in premeum gas.
Give it a try and see if u notice something, and try sonoco.
premium fuel is just a higher octane rating and in most cases more additives. a higher octane rating means it is harder to ignite. so im older cars with lots of carbon build up it will not ignite until the spark plug ignites. and it has better burning characteristics. so yes it will have a smoother combustion. maybe a little more power if your car is old and was igniting the 87 gas a little early. this is also why in turbo applications they say to run premium so you don't have detonation. as for higher btus i have no clue
^ Ditto lol.
Typically higher octane gas has less btu's per gallon, which is why it often gives lower mpg.
Normally (for reasons completely unrelated to btu's per gallon) it is best to run low octane gas from a good brand on the N/A. See www.toptiergas.com for a list of retailers. If anything it's b/c you used Sunoco/Conoco, though I suspect this is all subjective.
High octane gas should only be used on vehicles that need the extra detonation protection, such as certain high compression or turbocharged engines. Otherwise it is worse (but still relatively harmless). And if you have detonation on an NA rotary, something is horribly wrong with your car b/c they come from the factory with tons of protection. They really shouldn't need high octane gas.
Typically higher octane gas has less btu's per gallon, which is why it often gives lower mpg.
Normally (for reasons completely unrelated to btu's per gallon) it is best to run low octane gas from a good brand on the N/A. See www.toptiergas.com for a list of retailers. If anything it's b/c you used Sunoco/Conoco, though I suspect this is all subjective.
High octane gas should only be used on vehicles that need the extra detonation protection, such as certain high compression or turbocharged engines. Otherwise it is worse (but still relatively harmless). And if you have detonation on an NA rotary, something is horribly wrong with your car b/c they come from the factory with tons of protection. They really shouldn't need high octane gas.
Last edited by ericgrau; Oct 31, 2008 at 07:14 PM.
If you actually want more power rather than just wasting your money on expensive gas you could advance the timing curve with the CAS and test for gains on the butt dyno or a real dyno.
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From: Newnan, Ga
I asked about the same question...This is the best response,
You would be wasting your money.
The octane rating of gas is the resistance to pre-detonation. So higher the octane, the less likely that when the gas is compressed it explodes without a spark.
Octane has absolutely nothing to do with how much power a gallon of gas can provide.
And you wouldn't get any better gas mileage, as again, the BTU (power output) of 86 octane is the same as 89 or 92 octane.
The only cars that would see additional power are cars that are tuned to run higher octanes with higher compression or forced induction or radically advanced timing. These cars need the higher resistance to detonation (higher octane) to prevent either the timing being retarded due to the knock sensor (if equipped- and non turbo FCs are not), or prevent engine damage (pre-ignition or detonation will destroy a rotary engine very very very quickly- in the case of some mis tuned turbo rotary's, two or three pre-ignition events are all is needed to crack and break the apex seals).
Also because of the bathtub combustion chamber found on rotary engines, the lowest octane you can run will provide you with the most power. On a reasonably stock FC that is 86 or 87 octane.
Again the mis-conception that you might be getting more power from higher octanes or better burn is actually the opposite of what is happening.
Another draw back is that higher octane may not completely burn and you end up dumping more down the tail pipe as well as coating the rotor faces with soot (since typically mid and high grade gasoline also have higher additive packages as to give the consumer the concept a more expensive grade is a better grade).
The octane rating of gas is the resistance to pre-detonation. So higher the octane, the less likely that when the gas is compressed it explodes without a spark.
Octane has absolutely nothing to do with how much power a gallon of gas can provide.
And you wouldn't get any better gas mileage, as again, the BTU (power output) of 86 octane is the same as 89 or 92 octane.
The only cars that would see additional power are cars that are tuned to run higher octanes with higher compression or forced induction or radically advanced timing. These cars need the higher resistance to detonation (higher octane) to prevent either the timing being retarded due to the knock sensor (if equipped- and non turbo FCs are not), or prevent engine damage (pre-ignition or detonation will destroy a rotary engine very very very quickly- in the case of some mis tuned turbo rotary's, two or three pre-ignition events are all is needed to crack and break the apex seals).
Also because of the bathtub combustion chamber found on rotary engines, the lowest octane you can run will provide you with the most power. On a reasonably stock FC that is 86 or 87 octane.
Again the mis-conception that you might be getting more power from higher octanes or better burn is actually the opposite of what is happening.
Another draw back is that higher octane may not completely burn and you end up dumping more down the tail pipe as well as coating the rotor faces with soot (since typically mid and high grade gasoline also have higher additive packages as to give the consumer the concept a more expensive grade is a better grade).
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From: Hixson, TN
Why? You're are only going to get butt-dyno impressions. If I spent 15% more for gas I'm going to have the feeling "well I payed for it so it has to be better" thought, and then you THINK that it's better, when it's the same if not worse. It's been discussed, and the scientific mumbo-jumbo is out there. The only way you are going to prove different is to have dyno results. And since changing gas is going to require emptying the tank and filling with the other, so many factors in between runs will change that may alter any affects you will see on the dyno.
Where's your proof of "pullling"? Maybe you should check your timing. What facts do you have that 93 has more additives? You are a marketer's dream.
That's one of the stupidest things I've heard in a while. Again, where is your proof?
That's one of the stupidest things I've heard in a while. Again, where is your proof?
Rotorhead
Joined: Feb 2001
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From: Charlottesville, Virginia, USA
1. Psychological
2. The 87 fuel was contaminated or stagnant.
3. Your engine has a lot of build-up which creates 'hot spots' that are causing pre-ignition with the 87 octane fuel.
4. Your engine has screwed-up ignition timing.
5. Your engine has a slight clog somewhere in the fuel system.
6. Your engine has low fuel pressure.
A stock engine in good condition will run the same with any octane grade.
Example:
Chevron premium unleaded (UTG-96) = 18,400 BTU/lb * 0.740 specific gravity = 13,616
Chevron regular unleaded (UTG-91) = 18,500 BTU/lb * 0.735 specific gravity = 13,597.5
Crunching some basic numbers (without getting too far into the weeds)...13,616/13,597.5 = 0.136% gain for Chevron super unleaded, which in theory would calculate to a whopping 0.21 bhp increase for your engine. Well worth the extra $150/year that you would pay for it... not so much.
I don't have any Sunoco numbers, but they should be similar in that there would be very little difference between the energy content of the fuel octane grades. If you contact them for the information I can decipher the numbers for you. I am not a chemist so I have my limits, but I do have many years of experience working with international fuel contracts as well as some experience running a fuel farm.
What modifications does it have? It sounds to me like it has issues.
Most fuel companies put the same additives in every grade of their pump fuel. I am only aware of Shell putting more in their premium unleaded, but I suppose that Sunoco could do the same. However, as long as it meets Top Tier standards, it should be just fine. I don't see how one tank of high-detergent gas would make any immediate noticeable difference in performance, but it would most likely help over the long term.
Totally false. Many of the rotary-powered endurance race winners used low octane fuel. Also, there is no quality difference between the various grades of a given fuel vendor.
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From: miami
There are several possible reasons for this:
1. Psychological
2. The 87 fuel was contaminated or stagnant.
3. Your engine has a lot of build-up which creates 'hot spots' that are causing pre-ignition with the 87 octane fuel.
4. Your engine has screwed-up ignition timing.
5. Your engine has a slight clog somewhere in the fuel system.
6. Your engine has low fuel pressure.
A stock engine in good condition will run the same with any octane grade.
As stated earlier, most of the time the premium fuel has less BTUs than the regular unleaded fuel. Sometimes the premium fuel does have more BTUs if it is rich in aromatics, and sometimes a difference in density can make a difference since fuel is metered by volume rather than weight. However, the energy content is pretty much the same regardless, and would not be noticeable with the butt dyno.
Example:
Chevron premium unleaded (UTG-96) = 18,400 BTU/lb * 0.740 specific gravity = 13,616
Chevron regular unleaded (UTG-91) = 18,500 BTU/lb * 0.735 specific gravity = 13,597.5
Crunching some basic numbers (without getting too far into the weeds)...13,616/13,597.5 = 0.136% gain for Chevron super unleaded, which in theory would calculate to a whopping 0.21 bhp increase for your engine. Well worth the extra $150/year that you would pay for it... not so much.
I don't have any Sunoco numbers, but they should be similar in that there would be very little difference between the energy content of the fuel octane grades. If you contact them for the information I can decipher the numbers for you. I am not a chemist so I have my limits, but I do have many years of experience working with international fuel contracts as well as some experience running a fuel farm.
What modifications does it have? It sounds to me like it has issues.
Most fuel companies put the same additives in every grade of their pump fuel. I am only aware of Shell putting more in their premium unleaded, but I suppose that Sunoco could do the same. However, as long as it meets Top Tier standards, it should be just fine. I don't see how one tank of high-detergent gas would make any immediate noticeable difference in performance, but it would most likely help over the long term.
Totally false. Many of the rotary-powered endurance race winners used low octane fuel. Also, there is no quality difference between the various grades of a given fuel vendor.
1. Psychological
2. The 87 fuel was contaminated or stagnant.
3. Your engine has a lot of build-up which creates 'hot spots' that are causing pre-ignition with the 87 octane fuel.
4. Your engine has screwed-up ignition timing.
5. Your engine has a slight clog somewhere in the fuel system.
6. Your engine has low fuel pressure.
A stock engine in good condition will run the same with any octane grade.
As stated earlier, most of the time the premium fuel has less BTUs than the regular unleaded fuel. Sometimes the premium fuel does have more BTUs if it is rich in aromatics, and sometimes a difference in density can make a difference since fuel is metered by volume rather than weight. However, the energy content is pretty much the same regardless, and would not be noticeable with the butt dyno.
Example:
Chevron premium unleaded (UTG-96) = 18,400 BTU/lb * 0.740 specific gravity = 13,616
Chevron regular unleaded (UTG-91) = 18,500 BTU/lb * 0.735 specific gravity = 13,597.5
Crunching some basic numbers (without getting too far into the weeds)...13,616/13,597.5 = 0.136% gain for Chevron super unleaded, which in theory would calculate to a whopping 0.21 bhp increase for your engine. Well worth the extra $150/year that you would pay for it... not so much.
I don't have any Sunoco numbers, but they should be similar in that there would be very little difference between the energy content of the fuel octane grades. If you contact them for the information I can decipher the numbers for you. I am not a chemist so I have my limits, but I do have many years of experience working with international fuel contracts as well as some experience running a fuel farm.
What modifications does it have? It sounds to me like it has issues.
Most fuel companies put the same additives in every grade of their pump fuel. I am only aware of Shell putting more in their premium unleaded, but I suppose that Sunoco could do the same. However, as long as it meets Top Tier standards, it should be just fine. I don't see how one tank of high-detergent gas would make any immediate noticeable difference in performance, but it would most likely help over the long term.
Totally false. Many of the rotary-powered endurance race winners used low octane fuel. Also, there is no quality difference between the various grades of a given fuel vendor.
Regardless its a good antiknock protection, since its not a brand new rx7.
premix 2 once per gal will decrease 0.5 octane.
Why is the rotary-powered endurance race car, mazda rx8 3 rotor use 98 octane?
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From: London, Ontario, Canada
premix 2 once per gal will decrease 0.5 octane.
Why is the rotary-powered endurance race car, mazda rx8 3 rotor use 98 octane?
Rotorhead
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From: Charlottesville, Virginia, USA
The Renesis engine has a higher compression ratio, and even the stock engine has a minimum octane rating of 91 vs. the 87 of the 1986-1992 RX-7s. Also, as Aaron stated, it could have something to do with spec fuel or highly advanced timing. I am sure you can get a better answer on the RX-8 forum.
Smoke moar
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From: The yay, California
I used to add a bottle of octane booster once n awhile (My dad started this trend) the gas millage goes down but in the higher rpms it seems to have more power, I was just driving around the block a few yrs ago gave it like half throttle and the tires started cherping and it shot right up to the redline faster then it does today with exhaust/drop n filter.
im not sayin its better but maybe in the higher rpms the higher octane runs alil better? My dad used to watch mpg and with higher octane gas's he said you loose alot of mpg which would be performance loss, but he never went above 3.5k rpm or so (automatic :P)
Anyways how do you adjust the timing?
im not sayin its better but maybe in the higher rpms the higher octane runs alil better? My dad used to watch mpg and with higher octane gas's he said you loose alot of mpg which would be performance loss, but he never went above 3.5k rpm or so (automatic :P)
Anyways how do you adjust the timing?
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From: miami
Hey, it's your money, spend it as you wish. In my case, I have owned rotary-powered cars since 1988, and have never blown an engine. I choose to spend my extra money on maxxing out my Roth IRA and 401 plan each year.
The Renesis engine has a higher compression ratio, and even the stock engine has a minimum octane rating of 91 vs. the 87 of the 1986-1992 RX-7s. Also, as Aaron stated, it could have something to do with spec fuel or highly advanced timing. I am sure you can get a better answer on the RX-8 forum.
The Renesis engine has a higher compression ratio, and even the stock engine has a minimum octane rating of 91 vs. the 87 of the 1986-1992 RX-7s. Also, as Aaron stated, it could have something to do with spec fuel or highly advanced timing. I am sure you can get a better answer on the RX-8 forum.
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From: miami
If your car is knocking, something is very wrong.
Which is TWICE as much premix as you should be using. This will cause smoke, stink and fouled plugs. Also likely to reduce power.
Hm, my guess is because it might be a highly tuned race car running at the ragged edge of a tune with likely A/F ratios running just at the edge of being too lean and probably 40+ degrees of timing? Just a thought though....And don't racing classes usually have a spec fuel?
Which is TWICE as much premix as you should be using. This will cause smoke, stink and fouled plugs. Also likely to reduce power.
Hm, my guess is because it might be a highly tuned race car running at the ragged edge of a tune with likely A/F ratios running just at the edge of being too lean and probably 40+ degrees of timing? Just a thought though....And don't racing classes usually have a spec fuel?
The car had original motor before i rebuilt it. It was leaking oil at high rpm pass the oil seals. detonation.
Joined: Feb 2001
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From: London, Ontario, Canada
I go wide open throttle on my stock 87 TII quite often. The grade I use is 87 octane. Been using it for years with no problems. I even experimented with 92 for several weeks. Guess what, I didn't notice a damn thing.
Oh, car pulls harder in cold temps lol, I notice that. Sorry, can't prove that.
Oh, car pulls harder in cold temps lol, I notice that. Sorry, can't prove that.
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From: Onanole, Manitoba Canada
Yes, but let's bring ethanol into the equation. What about gasoline with 10% ethanol? I found with my 95 Jeep Cherokee 6 cylinder that the mileage went from 28 miles per CDN gallon to 20 as soon as they introduced the stuff here in Manitoba. I tried Premium gasoline with no ethanol in my 88 RX7 Vert last time I filled up, seems to me the car ran smoother.
Any comments on ethanol containing gasoline?
Mike
Any comments on ethanol containing gasoline?
Mike
Rotorhead
Joined: Feb 2001
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From: Charlottesville, Virginia, USA
If it is an RX-8 and it requires high octane fuel, then one of many reasons could be that they wedged Renesis 10:1 CR rotors in the engine with advanced ignition timing. However, that is just speculation on my part. Most 3-rotor race engines use 9.7:1 CR rotors. If you really want to know why a given race team uses a certain fuel, you will need to contact them for the answer.
Banned drag race fuel.
That means the engine is not running correctly.
With a standalone EMS.
Yes
That is actually a myth.
Ethanol has less energy content than gasoline. Therefore, if the engine does not need the extra detonation resistance of the ethanol, then the more ethanol in the fuel the less performance the car will have.
Banned drag race fuel.
That means the engine is not running correctly.
With a standalone EMS.
Yes
That is actually a myth.
Ethanol has less energy content than gasoline. Therefore, if the engine does not need the extra detonation resistance of the ethanol, then the more ethanol in the fuel the less performance the car will have.
Rotorhead
Joined: Feb 2001
Posts: 9,136
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From: Charlottesville, Virginia, USA
It is also highly volatile. This is not a good thing unless you are a terrorist looking for a good component for a fuel-air explosive.
What about focusing on driving skill and proper tuning rather than looking for some magical elixir?
What about focusing on driving skill and proper tuning rather than looking for some magical elixir?