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Old 03-08-2006, 04:49 PM   #1
Beanboy
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Default STI advertised output on 91 or 93 octane

Mazaspeed 6 fans are all up in arms about car mags testing MS6 and only using 91 octane gas when Mazda says 93 octane is needed for published HP figures. Seems that Mazda really tuned it to the edge... Thinking with 91 octane output is more like 254HP or so that the MS6 overseas and MS3 are rated for.

I know the STI in the owners manual mentions something along the lines that for optimum performance 93 octane or higher gas is to be used. Only other car I know of that mentions the use of 93 to the best of my knowledge. However, car mags never mentioned how the STI recommends 93 when they tested it. Hell, I can't remember any other car test that the mags mentioned octane issues like they did for the MS6.

So, are Subaru's specs of 300/300 on 93 octane? How much if a hit are folks seeing with using 91 or 91CA?

I know Cobb's published figures show a spread of 10HP from 91CA to 93, but that's aftermarket...

Thanks!

-B
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Last edited by Beanboy; 03-08-2006 at 04:54 PM.
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Old 03-08-2006, 07:04 PM   #2
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The STi manual recommonds 91 octane gas. yeah they hit 300/300 on 91
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Old 03-08-2006, 07:40 PM   #3
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The Mazda owners are actually finding maximum power created around 95-96octane owner if I remember correctly...kind of amusing.
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Old 03-08-2006, 08:44 PM   #4
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Quote:
Originally Posted by TravisSTi
The STi manual recommends 91 octane gas. yeah they hit 300/300 on 91
The manual clear states 93 but if 93 unaviable it is ok to use 91
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Old 03-08-2006, 09:23 PM   #5
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Quote:
Originally Posted by Your Owner's Manual

2.5-liter turbo models
Use premium unleaded gasoline with an octane rating of 93 AKI or higher. If premium unleaded gasoline with an octane rating of 93 AKI is not available, premium unleaded gasoline with octane rating of 91 AKI or higher may be temporarily used. For optimum engine performance and driveability, it is required that you use premium grade unleaded gasoline with an octane rating of 93 AKI or higher.
.....
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Old 03-08-2006, 10:17 PM   #6
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Right, so the STI doesn't produce 300/300 on 91, how much is it down? 10HP or so? What's the range from 91CA to 93?
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Old 03-08-2006, 10:24 PM   #7
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Well all I could find on Cobb's site was a 5HP drop, and no change in torque.
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Old 03-08-2006, 11:20 PM   #8
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the things that i have heard with the mazdaspeed 6 is that the intercooler on those cars heat soak like crazy

i also believe that i saw a dyno sheet showing it, they ended up using like 100 octane and placing ice in a container on the intercooler and getting the advertised numbers then a little higher [with the ice]

personally i feel that someone at mazda dropped the ball on that, but with it seeming that IC is the problem it could be fixed relatively easily, the direct injection allows for more
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Old 03-09-2006, 12:06 AM   #9
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Quote:
Originally Posted by TravisSTi
The STi manual recommonds 91 octane gas. yeah they hit 300/300 on 91
my manual says 93+ only and 91 temporarily if nothing higher is around
i will scan the manual if no one believes me

Last edited by 06blacksti; 03-09-2006 at 11:50 AM.
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Old 03-09-2006, 12:20 AM   #10
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Quote:
Originally Posted by 06blacksti
my manual says 93 only and 91 temporarily if nothing higher is around
i will scan the manual if no one believes me
Read a bit more buddy
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Old 03-09-2006, 04:53 AM   #11
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Quote:
Originally Posted by 06blacksti
my manual says 93 only and 91 temporarily if nothing higher is around
i will scan the manual if no one believes me
The owner's manual information has already been posted in this thread twice. Plenty of people believe you.
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Old 03-09-2006, 07:35 AM   #12
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Quote:
Originally Posted by TravisSTi
The STi manual recommonds 91 octane gas. yeah they hit 300/300 on 91


WRONG!!!! THE MANUAL STATES USING 93 OR HIGHER. Where do you guys get this crap from??

Read the entire manual please.

Thanks to whomever posted the page from the manual...I suggest reading it.

As for the MS6....I think heatsoak is the problem. A stupid design if you ask me.
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Old 03-09-2006, 11:49 AM   #13
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Quote:
Originally Posted by iamchris
Read a bit more buddy
what are you talking about
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Old 03-09-2006, 11:55 AM   #14
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Not disputing what the manual says, but does Subaru even consider that their cars are also sold in the Western half of the United States?
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Old 03-09-2006, 12:08 PM   #15
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[HIJACK]

Without raising the boost, would there be any benefit at all to using race gas? I've often wondered about this. I believe I have 104 and 106 available to me, but always considered it just as an added safety margin, not a power enhancer. Can an expert give their opinion on this? Dave? Scotty?

[/HIJACK]
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Old 03-09-2006, 02:31 PM   #16
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Quote:
Originally Posted by UltimateLurker
[HIJACK]

Without raising the boost, would there be any benefit at all to using race gas? I've often wondered about this. I believe I have 104 and 106 available to me, but always considered it just as an added safety margin, not a power enhancer. Can an expert give their opinion on this? Dave? Scotty?

[/HIJACK]

well im not dave and not scotty, but i would say no. if it did anything it would just help out with knock, if you had any.
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Old 03-09-2006, 02:32 PM   #17
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Quote:
Originally Posted by InvertedB
Not disputing what the manual says, but does Subaru even consider that their cars are also sold in the Western half of the United States?


Rest of the USA > California
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Old 03-09-2006, 02:33 PM   #18
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Quote:
Originally Posted by wrxblubayou
Rest of the USA > California
Exactly!
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Old 03-09-2006, 02:43 PM   #19
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Quote:
Originally Posted by layzienoy
the things that i have heard with the mazdaspeed 6 is that the intercooler on those cars heat soak like crazy

i also believe that i saw a dyno sheet showing it, they ended up using like 100 octane and placing ice in a container on the intercooler and getting the advertised numbers then a little higher [with the ice]

personally i feel that someone at mazda dropped the ball on that, but with it seeming that IC is the problem it could be fixed relatively easily, the direct injection allows for more
I told everybody the Mazda Speed 6 wouldn't put out it's advertized power. Mazda sucks they always have to lie about horsepower numbers. They do not know how to build a turbocharged car especially. They just throw crap together to make it turbo. The intercooler design on the Mazda speed6 is so crappy I think the car would do better without the intercoller at all
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Old 03-09-2006, 05:54 PM   #20
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oh no i stumbled into a INTERWEB warrr!
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Old 03-09-2006, 07:59 PM   #21
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canadian readily available 94 ftw!
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Old 03-09-2006, 09:39 PM   #22
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Using 91 or 94 won't change the power. The only way the power would be changed is if the engine detects pinging, then it would pull timming, and then you would loose power. If you don't ping with 91, you still have all your power.

The reason cobb has more power on the 93 map is because they were able to tune the engine a bit more, because the 93 has less tendancy to ping.

Bland...
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Old 03-10-2006, 05:58 AM   #23
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Quote:
Originally Posted by conker69


WRONG!!!! THE MANUAL STATES USING 93 OR HIGHER. Where do you guys get this crap from??

Read the entire manual please.

Thanks to whomever posted the page from the manual...I suggest reading it.

As for the MS6....I think heatsoak is the problem. A stupid design if you ask me.

Wow sorry guys I was looking at the 2.0 manual which says 91, but the 2.5 says 93 or 91 if no 93 available.
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Old 03-10-2006, 06:28 AM   #24
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Quote:
Originally Posted by wrxblubayou
Rest of the USA > California
You're an idiot.



California is not the only state stuck with 91 as "premium" fuel. In fact most, if not all of the mountain states in the west cannot get higher than 91. Its quite surprising to me personally. If you look at the percentage of vehicles registered in Colorado, Washingtion, Montana, Wyoming, Utah, Oregon, and Idaho I'd be willing to bet that there are more Subies there than in just about any eastern state. And these states all have 91 octane as their "premium."


You need to get out a bit and realize that the world does not revolve around the east coast.
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Old 03-10-2006, 06:34 AM   #25
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But that doesn't change the fact that California sucks more than any other state in the union.
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