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Thread: Simple question's about octane

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Posts: 11-20 of 26
2012-05-28 14:55:26
#11
^ sounds about right because our 1995 g20 dynoed at 131whp 100% stock w/87 octane (we always just use 87 octane --why go up when we won NASA TTF Nationals and have 12 current track records as-is?

We can go up to 150hp in TTF with the g20 BUT cannot do anything with internals without bumping to another class (so no cams, no change in trans, no cam gears, etc.) ECU tune is free but I seriously doubt we would see that much of a gain with 93 octane and a 'tune'
2012-05-28 15:21:32
#12
I'd be stunned if you gained 10whp from going to higher octane, maybe on a really really built motor.
2012-05-28 15:53:03
#13
^ realistic expectation was 3 to 4 whp with NA tune and 93 octane (not sure that was worth the price to get there so we haven't done it)
2012-05-28 18:36:20
#14
Originally Posted by Storm88000
I'd be stunned if you gained 10whp from going to higher octane, maybe on a really really built motor.


That's pretty much it. You run an octane that's high enough that it doesn't detonate prematurely. Doesn't mean there's more power in the gas, there's more power in the engine that it's running since that engine will likely have higher compression thus requiring the higher octane.

Octane is in no way, shape, or form, a measure of power. It's a measure of how much you can compress it before it goes "boom" on it's own. You're better off worrying about ethanol content.
2012-05-28 19:43:57
#15
You can gain 10whp by switching to 93 just by the different timing and tune ability. You can push the tune a little further without having to worry about knocking
2012-05-28 19:54:24
#16
Originally Posted by 92SentraSE-R
You can gain 10whp by switching to 93 just by the different timing and tune ability. You can push the tune a little further without having to worry about knocking


Be clear though, the tune is gaining the hp, not the gas. Tons of people are looking at it backwards like that, it's what causes most of the misconceptions about octane.
2012-05-29 06:06:55
#17
Originally Posted by WingmanSR20
Be clear though, the tune is gaining the hp, not the gas. Tons of people are looking at it backwards like that, it's what causes most of the misconceptions about octane.


Yeah by just having octane increased and no tune you wont gain anything, its all in the tune. Figured people would know that :o
2012-05-29 15:48:41
#18
Increase octane = Need more timing or you will be getting worse power/gas mileage.

How about some real numbers, our friend JP did an excellent test here:

Originally Posted by jpsr20det
Just to update some of the dynos... From a JDM p11 2j2 motor.

Dyno stock p11 timing at 13 (motor with more than 200.000-km)


Dyno-2 timing at 17


Dyno-3 timing at 19


Dyno-4 Timing at 20


Dyno-5 timing at 20 plus tuneup( bkr6e gaped at 1,1mm , tps at 0.45 volt ,new rotor , new air filter, MAF reground)


Dyno-6 timing at 20 Hotshot cai ,ground kit,3 inchs exhaust


Dyno-7 JWT ecu,cams s3r,ur pullies,Hotshot cai,hotshot header gen 3,apexi s-afc2 ,apexi itc(timing)2,25 inch crush bent exhaust wrx muffler.


Dyno-8 p11 stock vs p11 with cai,timing,exhaust
2012-05-31 05:16:21
#19
Cool thanks for all the input so far guys........now I'm a little curious, all fuels are not created equal......have any of you guys ever noticed that you were able to wring a little more power out of your car with a particular brand of gasoline, if so what brand did you use?

Originally Posted by WingmanSR20


Octane is in no way, shape, or form, a measure of power. It's a measure of how much you can compress it before it goes "boom" on it's own. You're better off worrying about ethanol content.


Can you go into this topic a little deeper why is ethanol content so important? Give me your take on it . My understanding of ethanol is that it's a chemical they place into the fuel pretty much used as a filler to double quantity sort of like flour in cocain, is their any benefits of ethanol in fuel?

Originally Posted by BenFenner
93 octane gets you pretty close to MBT I think.


What does the abbreviation MBT mean Ben?
Last edited by Topdog781 on 2012-05-31 at 08-08-23.
2012-05-31 05:28:07
#20
I only use ethanol free gas in my b13.
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