View Poll Results: What kind of gas do you use?
Regular unleaded
45
90.00%
Super unleaded
1
2.00%
Premium Unleaded
4
8.00%
Voters: 50. You may not vote on this poll
What kind of gas do you use in yours?
11-22-05, 07:26 PM
#2
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Aperantly premium hurts the performance on a stock 7. Heavy mods requiere more octane to help reduce detonation. Higher octane less chances of blowing your motor when turbocharged.
11-22-05, 07:33 PM
#3
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Originally Posted by vacumLeeK
Aperantly premium hurts the performance on a stock 7. Heavy mods requiere more octane to help reduce detonation. Higher octane less chances of blowing your motor when turbocharged.
Oooh really? I've used premium since I bought it. The manual says to use high octaine (such a high amount that they don't use anymore) so I always have. Tonight was the first time I've put regular in it. Whoops
11-22-05, 08:14 PM
#7
REGULAR! are you guys just cheap or what? just kidding, I have never heard of premium hurting these engines. I have about 24k on a Factory Replacement Engine and have tried both. the car always runs better on premium. go figure.
Last edited by bad 83; 11-22-05 at 08:16 PM. Reason: misspelling
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11-22-05, 08:34 PM
#9
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Premium and regular have the same energy content! Only real difference IS, one pre-ignites or sends out detonation waves at a lower compression pressure+temp then the other! A non-boost rotary running 9.4:1 will never have a problem with running regular unleaded. If its got high compression like the renesis, then it needs higher then regular unleaded octane.
11-23-05, 12:13 AM
#15
In the eighties, mazda raced with 83 octane fuel. The lowest I can get is 87, so that's what I use.
Octane's only purpose (as many people here have mentioned) is to resist detonation (or premature explosion of the air/fuel mixture because of compression).
Two things can make an air/gas mix explode:
1. A spark
2. That mixture being compressed into too small a space
If your engine's compression ratio is high enough, there's a danger that #2 will cause your air/fuel mix to explode BEFORE you want it to, which pushes against the spin of the engine, causing running problems, loss of power and in many cases damage to the engine. To prevent this, using a higher octane fuel will make the mixture harder to detonate by compression and makes it so that only a properly timed spark will ignite it.
Higher octane = more pressure you can put the air/fuel mix under
When is this useful? High compression engines or forced induction (turbo, supercharger) engines.
The N/A rotary has a compression ratio of 9.4:1 (for the stock FB engines, both 12a and 13b).
This is not enough to cause a problem with premature detonation due to pressure. So the mixture will *always* fire only upon spark from the spark plug. Buying more expensive, higher octane gas makes absolutely no difference. The amount of power available to be extracted from 94 octane is almost EXACTLY the same as 87 octane *.
If you run turbo or super, don't use regular. Detonation = death.
So shake the common misconception that octane = power, and just buy the cheap **** for your car. It'll save you money, and your car won't notice the difference.
Jon
*ed note: (Some could argue that 94 octane has marginally lower amount of energy to release because adding anything is a dilution of the original gasoline. If that additive doesn't have more stored energy itself, the total stored energy of the diluted mixture would be less than the original gasoline. Of course this is so amazingly marginal that it really doesn't make any measurable difference either way)
Octane's only purpose (as many people here have mentioned) is to resist detonation (or premature explosion of the air/fuel mixture because of compression).
Two things can make an air/gas mix explode:
1. A spark
2. That mixture being compressed into too small a space
If your engine's compression ratio is high enough, there's a danger that #2 will cause your air/fuel mix to explode BEFORE you want it to, which pushes against the spin of the engine, causing running problems, loss of power and in many cases damage to the engine. To prevent this, using a higher octane fuel will make the mixture harder to detonate by compression and makes it so that only a properly timed spark will ignite it.
Higher octane = more pressure you can put the air/fuel mix under
When is this useful? High compression engines or forced induction (turbo, supercharger) engines.
The N/A rotary has a compression ratio of 9.4:1 (for the stock FB engines, both 12a and 13b).
This is not enough to cause a problem with premature detonation due to pressure. So the mixture will *always* fire only upon spark from the spark plug. Buying more expensive, higher octane gas makes absolutely no difference. The amount of power available to be extracted from 94 octane is almost EXACTLY the same as 87 octane *.
If you run turbo or super, don't use regular. Detonation = death.
So shake the common misconception that octane = power, and just buy the cheap **** for your car. It'll save you money, and your car won't notice the difference.
Jon
*ed note: (Some could argue that 94 octane has marginally lower amount of energy to release because adding anything is a dilution of the original gasoline. If that additive doesn't have more stored energy itself, the total stored energy of the diluted mixture would be less than the original gasoline. Of course this is so amazingly marginal that it really doesn't make any measurable difference either way)
Last edited by vipernicus42; 11-23-05 at 12:58 AM.
11-25-05, 05:35 AM
#19
Here, I found an awesome article on wikipedia which describes Octane wonderfully, and I've included a quote from it to finally quiet all the newbs.
Article:
http://en.wikipedia.org/wiki/Octane_rating
Article:
http://en.wikipedia.org/wiki/Octane_rating
Originally Posted by wikipedia
It might seem odd that fuels with higher octane ratings burn less easily, yet are popularly thought of as more powerful. Using a fuel with a higher octane lets an engine be run at a higher compression ratio without having problems with knock. Compression is directly related to power (see engine tuning), so engines that require higher octane usually deliver more power. Some high-performance engines are designed to operate with a compression ratio associated with high octane numbers, and thus demand high-octane gasoline. It should be noted that the power output of an engine also depends on the energy content of its fuel, which bears no simple relationship to the octane rating. A common myth amongst petrol consumers is that adding a higher octane fuel to a vehicle's engine will increase its performance and/or lessen its fuel consumption; this is mostly false—engines perform best when using fuel with the octane rating they were designed for and any increase in performance by using a fuel with a different octant rating is minimal.
11-25-05, 09:50 AM
#22
RX-7 Alumni
^^I'm with wikipedia--couldn't of said it better myself.
For rotaries:
NA=use the lowest octane available.
Stock turbo=87 or better (per FSM)
Modified turbo=91 or better
High boost turbo=you should know better without anyone telling you.
For rotaries:
NA=use the lowest octane available.
Stock turbo=87 or better (per FSM)
Modified turbo=91 or better
High boost turbo=you should know better without anyone telling you.
11-25-05, 07:25 PM
#23
regular 87, 86 if i can find it. I put mid-grade into my car because I had a $10.00 coupon for gas, and my performance suffered alot. The only time I put premium into any NA car that I drive is just after an oil change, with some Lucas fuel system treatment and lubricant to burn off as much carbon as possible (the higher the octane, the hotter it burns, the more carbon is taken out the exhaust pipe), and i drive the **** out of the car the whole tank to create as much heat as possible. After that all my cars run smoother, start easier, and get a 1-2 mpg bump in fuel economy.