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Discussion Starter · #2 ·
> Another age old question...which is better,
> low (87) octane or high (93) octane?

Only run what you need, The stock Z's low compression will work just fine on low octane and I hear better than high octane. Now if you have higher compression you have higher combustion heat and it needs this to fire the higher octane.
There is a queston about octane I've had for some time though, my car is pretty modified and I like to run the timing a lot more advanced to the point of pinging and think the higher octane might help as running more advance runs a hotter combustion but I am finding that just going with a better advance curve and toneing down the advance to a few degrees under pinging seems it gives overall better power and driveability with regular gas. I'm going to add the capacitive discharging spark plug wires soon and they run best with a more retarded spark advance but that's another story.
If you have stock compression run regular gas, that's all you need and won't see any performance gain with high octane as far as I know and heard.
You can add a gas additive that contains Nitromethane, I know this adds a kick to the gas, it comes in 3 flavors by NOS, Street,sells for 5.99/Offroad 7.99/Race 11.99 prices as sold by Jegs (www.jegs.com) A great place for high performance goodies though they are mainly american car high performance supplies but a lot of their stuff can be run on the Z's as well. If you ever need a fantastic 4bbl carb than go there, they have some that almost make me want to run one on a Z if I could find a good manifold I would.
 

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107,695 Posts
Discussion Starter · #3 ·
> Only run what you need, The stock Z's low
> compression will work just fine on low
> octane and I hear better than high octane.
> Now if you have higher compression you have
> higher combustion heat and it needs this to
> fire the higher octane.
> There is a queston about octane I've had for
> some time though, my car is pretty modified
> and I like to run the timing a lot more
> advanced to the point of pinging and think
> the higher octane might help as running more
> advance runs a hotter combustion but I am
> finding that just going with a better
> advance curve and toneing down the advance
> to a few degrees under pinging seems it
> gives overall better power and driveability
> with regular gas. I'm going to add the
> capacitive discharging spark plug wires soon
> and they run best with a more retarded spark
> advance but that's another story.
> If you have stock compression run regular
> gas, that's all you need and won't see any
> performance gain with high octane as far as
> I know and heard.
> You can add a gas additive that contains
> Nitromethane, I know this adds a kick to the
> gas, it comes in 3 flavors by NOS,
> Street,sells for 5.99/Offroad 7.99/Race
> 11.99 prices as sold by Jegs (www.jegs.com)
> A great place for high performance goodies
> though they are mainly american car high
> performance supplies but a lot of their
> stuff can be run on the Z's as well. If you
> ever need a fantastic 4bbl carb than go
> there, they have some that almost make me
> want to run one on a Z if I could find a
> good manifold I would.

I would run the octane requirements that your engine needs to operate at the upmost performance. A common occurance is the you-get-what-you-pay-for syndrome. Which I believe is true in most aspects other than gas. Just because 93 octane is more expensive doesn't mean that it will make your z run any better. Bottom line: If you zcar will run without pinging with 87 octane, than use it and let your money go to other mods. If your engine practically screams for high octane (mainly because you have a compression ratio of 10.5:1)(in the lower altitude regions) then run it.
JN
 

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Discussion Starter · #4 ·
> I would run the octane requirements that
> your engine needs to operate at the upmost
> performance. A common occurance is the
> you-get-what-you-pay-for syndrome. Which I
> believe is true in most aspects other than
> gas. Just because 93 octane is more
> expensive doesn't mean that it will make
> your z run any better. Bottom line: If you
> zcar will run without pinging with 87
> octane, than use it and let your money go to
> other mods. If your engine practically
> screams for high octane (mainly because you
> have a compression ratio of 10.5:1)(in the
> lower altitude regions) then run it.
> JN

I used to run 87 octane in my 75 and is smoked alot and ran like crap. I changed to 89 octane and it made a big difference(Smoother idle, more power, no smoke). The original manual that came with the car recomends 89 octane.

Sam 75 280z
 
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