The last gas question - Toyota Yaris Forums

severous01 · 04-23-2009, 10:58 PM

wow, there's a LOT of seriously wrong info in this thread.

if you done your research, you know that higher octane DOES BURN SLOWER and is used in higher compression, more advanced timing applications for this reason....the spark is well before TDC for this reason, the fuel will start to burn well before TDC and then explode ATDC. higher performance engines REQUIRE this fuel because of advanced timing...and that's all you'll get with any of the aftermarket programmers....maybe a little fuel trim to enhance new timing. any way, the fuel is the same, and is actually has more addatives to make it lower octane vs higher...and lower octane fuel is cheaper than higher octane.

facts and myths: http://www.state.mn.us/mn/externalDo...ctaneFacts.pdf

octane rating is the percentage of resistance to knock....yes, even tho they have 102 and 104+ or whatever. the higher the octane the more energy required to cause a burn or release of energy.

when an engine senses knock it fixes the problem by retarding timing. if you know anything about old school (distributor ignition) you know you can do A LOT with a simple twist of the Dist...2 or 3* can net you up to 20 hp in some cases (5.0 mustangs for instance) but at WOT you'll need high octane fuel...hence the retarding issue from the factory. efficiency.

the higher the compression, the higher the temps. higher temps inside means a higher chance of pre-ignition or knock...or ping...or whatever you want to call it. and since all engines now are computer controlled and most have knock sensors....the pcm would much rather save the engine by retarding and fuel efficiency than popping a hole in a piston cuz your dumbass decided to ignore it or keep goin cuz you 'had to'. any way, do some more research on wiki or the site i provided.

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04-23-2009, 10:58 PM	#15
severous01 Drives: 2008 yaris, stripped, red Join Date: Jan 2009 Location: SE Texas Posts: 977	wow, there's a LOT of seriously wrong info in this thread. if you done your research, you know that higher octane DOES BURN SLOWER and is used in higher compression, more advanced timing applications for this reason....the spark is well before TDC for this reason, the fuel will start to burn well before TDC and then explode ATDC. higher performance engines REQUIRE this fuel because of advanced timing...and that's all you'll get with any of the aftermarket programmers....maybe a little fuel trim to enhance new timing. any way, the fuel is the same, and is actually has more addatives to make it lower octane vs higher...and lower octane fuel is cheaper than higher octane. facts and myths: http://www.state.mn.us/mn/externalDo...ctaneFacts.pdf octane rating is the percentage of resistance to knock....yes, even tho they have 102 and 104+ or whatever. the higher the octane the more energy required to cause a burn or release of energy. when an engine senses knock it fixes the problem by retarding timing. if you know anything about old school (distributor ignition) you know you can do A LOT with a simple twist of the Dist...2 or 3* can net you up to 20 hp in some cases (5.0 mustangs for instance) but at WOT you'll need high octane fuel...hence the retarding issue from the factory. efficiency. the higher the compression, the higher the temps. higher temps inside means a higher chance of pre-ignition or knock...or ping...or whatever you want to call it. and since all engines now are computer controlled and most have knock sensors....the pcm would much rather save the engine by retarding and fuel efficiency than popping a hole in a piston cuz your dumbass decided to ignore it or keep goin cuz you 'had to'. any way, do some more research on wiki or the site i provided.