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RCZ · 02-26-2010, 12:31 PM

Nah, here's the quick and dirty. The octane rating of say gasoline, whether its 89 or 93 or whatever refers to how easy the fuel is to ignite. The lower that number, the easier it is to ignite.

When you have a car that is tuned for high performance, whether its high compression or boost or even just a lot of stress from driving on the track; that causes the cylinders to get really hot. Hotspots are created at different locations inside the combustion chamber. All that heat can cause the air/fuel mixture that you car burns to ignite prematurely. That is NOT a good thing, it creates a lot of stress on all the components and if done repeatedly will lead to engine failure. This pre-ignition is called pinging, knocking, detonation, etc. Its all the same thing.

So to battle this premature ignition problem, you can make the fuel mixture harder to ignite, that way it wont ignite before it is supposed to (when the sparkplugs fire). That is the purpose of running race fuel with higher octanage and of injecting methanol or water into the mix. It just raises the octanage, making it less likely for premature ignition to occur.

So race gas/meth/water will NOT give you more power, it just allows you to run a bit more boost or squeeze a little bit more performance out of the car. Because you can run more boost (in our case) then you can make more power without knocking. Of course in forced induction applications, that "little boost" can be a few more psi which can mean as much as 50whp+ over regular gasoline.

FYI, the leading cause of detonation is leaning out the air/fuel mixture. When you lean out, you are running more air in the mix than you should be. The more oxygen you have to burn, the more power, the hotter your cylinders get. So when you lean out, chances of knocking increase dramatically. Thats why they say its safer to run on the rich side. (rich = more fuel). So when someone says their AFR is 12. There are 12 parts of air per part of fuel. SO if you say your AFR is 15, then you are running comparatively more air, therefore leaning it out as compared to running the same car at 12.

So no, its not cooler, its just safer. I run 50/50 mix of pump gas and race gas at the track every time to ensure that my car isn't detonating

02-26-2010, 12:31 PM	#17 (permalink)
RCZ A True Z Fanatic Join Date: Nov 2008 Location: Miami Posts: 6,403 Drives: '09 370Z Rep Power: 1118	Nah, here's the quick and dirty. The octane rating of say gasoline, whether its 89 or 93 or whatever refers to how easy the fuel is to ignite. The lower that number, the easier it is to ignite. When you have a car that is tuned for high performance, whether its high compression or boost or even just a lot of stress from driving on the track; that causes the cylinders to get really hot. Hotspots are created at different locations inside the combustion chamber. All that heat can cause the air/fuel mixture that you car burns to ignite prematurely. That is NOT a good thing, it creates a lot of stress on all the components and if done repeatedly will lead to engine failure. This pre-ignition is called pinging, knocking, detonation, etc. Its all the same thing. So to battle this premature ignition problem, you can make the fuel mixture harder to ignite, that way it wont ignite before it is supposed to (when the sparkplugs fire). That is the purpose of running race fuel with higher octanage and of injecting methanol or water into the mix. It just raises the octanage, making it less likely for premature ignition to occur. So race gas/meth/water will NOT give you more power, it just allows you to run a bit more boost or squeeze a little bit more performance out of the car. Because you can run more boost (in our case) then you can make more power without knocking. Of course in forced induction applications, that "little boost" can be a few more psi which can mean as much as 50whp+ over regular gasoline. FYI, the leading cause of detonation is leaning out the air/fuel mixture. When you lean out, you are running more air in the mix than you should be. The more oxygen you have to burn, the more power, the hotter your cylinders get. So when you lean out, chances of knocking increase dramatically. Thats why they say its safer to run on the rich side. (rich = more fuel). So when someone says their AFR is 12. There are 12 parts of air per part of fuel. SO if you say your AFR is 15, then you are running comparatively more air, therefore leaning it out as compared to running the same car at 12. So no, its not cooler, its just safer. I run 50/50 mix of pump gas and race gas at the track every time to ensure that my car isn't detonating Last edited by RCZ; 02-26-2010 at 12:33 PM.