View Poll Results: What is your typical fuel octane rating?
87 octane
42
30.88%
89 octane
10
7.35%
91 octane
33
24.26%
93 octane
51
37.50%
Voters: 136. You may not vote on this poll
Octane poll for 16V cars
12-08-2007, 12:40 AM
#31
Reanimator
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O.k., took a while since I read the start of this thread, and I'm not driving the car much yet. But after reading, the next fill was not premium, but middle grade 'plus' fuel, sign on tank says '89' octane. I'm now on my second tank, no knock, no ping. Runs fine. It's now December, next tank will be regular and I'll see how that goes. I keep a bottle of octane boost in the car just....in...case.
Don Bergmann
New Jersey, early '86 928 Meteor Metallic, auto
1990 Bronco (runs on plus)
1978 Yamaha XS11 (beast requires premium)
Don Bergmann
New Jersey, early '86 928 Meteor Metallic, auto
1990 Bronco (runs on plus)
1978 Yamaha XS11 (beast requires premium)
06-20-2008, 09:32 PM
#32
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Just an observation. I just ran my first tank of regular 87 Octane gas through the 81. Bad idea runs terrible and performance took a real hit. Now maybe just bad gas but I've run mid grade 89 octane since I picked it up. Not sure what this means but I won't be using 87 again fooosure!
06-20-2008, 11:07 PM
#34
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06-20-2008, 11:17 PM
#35
Rennlist Member
06-22-2008, 10:17 PM
#37
Rennlist Member
Lowest octane we get in Oz is 91, and on that my 83 (10:1 CR) runs absolutely fine AFAIK - no negative symptoms of any sort. No perceptible difference on 95.
jp 83 Euro S AT 51k
jp 83 Euro S AT 51k
06-23-2008, 12:53 AM
#38
We had a choice?
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Washed the 79, filled it up with 93 Octane $4.08/gallon and went for a spirited drive. I don't care if it hits $10.00/gallon,the 79 puts a smile on my face still after 7 years. Of course it always runs better after a bath
06-23-2008, 01:11 AM
#39
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06-23-2008, 01:27 PM
#41
Pro
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the lower the octane rating the more explosive it is, meaning that the flame travels faster.
You use/have higher octane when you have boost, or want to run more spark etc.
but on a NA engine with conservative ign timing from the factory, you will get marginally more HP and TQ from a lower octane.
You use/have higher octane when you have boost, or want to run more spark etc.
but on a NA engine with conservative ign timing from the factory, you will get marginally more HP and TQ from a lower octane.
Lower octane doesn't explose more violently than higher octane! The energy contain in higher or lower octane is the same.
Lower octane means it's more likely to explose from the compression alone than from the sparks.
Diesel is extremly low octane because it exploses from the compression alone.
You need high octane in performance car because you want to compress the gaz more before igniting it, giving a longer travel distance to your engine. If you put lower octane in an high pressure engine, you will lose an amazing ammout of power as the gaz will explode before the stroke has done it's complete motion.
From what I know, if you have a car with a 9.5:1 or 10:1 compression ratio, you should use 91+ octane, as you have high risk of having early explosion.
06-23-2008, 02:27 PM
#42
Three Wheelin'
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Hi 
I use 98 and if I used 95 I would have to connect the octane loop which retards the timing to cope with the lower octane...so less power....
Precisely as Martins table shows...mine is a UK ..86 S2 (16 V with 310 hp)
All the best Brett
I use 98 and if I used 95 I would have to connect the octane loop which retards the timing to cope with the lower octane...so less power....
Precisely as Martins table shows...mine is a UK ..86 S2 (16 V with 310 hp)
All the best Brett
06-23-2008, 03:51 PM
#43
What the hell are you talking about?
Lower octane doesn't explose more violently than higher octane! The energy contain in higher or lower octane is the same.
Lower octane means it's more likely to explose from the compression alone than from the sparks.
Diesel is extremly low octane because it exploses from the compression alone.
You need high octane in performance car because you want to compress the gaz more before igniting it, giving a longer travel distance to your engine. If you put lower octane in an high pressure engine, you will lose an amazing ammout of power as the gaz will explode before the stroke has done it's complete motion.
From what I know, if you have a car with a 9.5:1 or 10:1 compression ratio, you should use 91+ octane, as you have high risk of having early explosion.
Lower octane doesn't explose more violently than higher octane! The energy contain in higher or lower octane is the same.
Lower octane means it's more likely to explose from the compression alone than from the sparks.
Diesel is extremly low octane because it exploses from the compression alone.
You need high octane in performance car because you want to compress the gaz more before igniting it, giving a longer travel distance to your engine. If you put lower octane in an high pressure engine, you will lose an amazing ammout of power as the gaz will explode before the stroke has done it's complete motion.
From what I know, if you have a car with a 9.5:1 or 10:1 compression ratio, you should use 91+ octane, as you have high risk of having early explosion.
Lizard was talking about 16 valve cars (note the thread topic) which don't have 9.5 or 10 to 1 compression ratios. They were engineered to run on lower octane so any gains by running a higher octane would be minimal and certainly not enough to offset the higher cost.
Dennis
06-23-2008, 04:01 PM
#44
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Lightstriker,
Lizard was talking about 16 valve cars (note the thread topic) which don't have 9.5 or 10 to 1 compression ratios. They were engineered to run on lower octane so any gains by running a higher octane would be minimal and certainly not enough to offset the higher cost.
Dennis
Lizard was talking about 16 valve cars (note the thread topic) which don't have 9.5 or 10 to 1 compression ratios. They were engineered to run on lower octane so any gains by running a higher octane would be minimal and certainly not enough to offset the higher cost.
Dennis
06-23-2008, 04:38 PM
#45
6Mil928,
IIRC when using the M+R/2 method of rating our early 928's need 88.5 octane to run properly. i.e. stay away from the 87 octane unless you have manually retarded the ignition.
Dennis
IIRC when using the M+R/2 method of rating our early 928's need 88.5 octane to run properly. i.e. stay away from the 87 octane unless you have manually retarded the ignition.
Dennis