well ive been reading the race gas thread for a few days and i had some questions about things so i went and found the answers to some of my questions. im gonna post them up for some of the other “less knowledgable” people!
The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like “regular” 87-octane gasoline) can handle the least amount of compression before igniting.
The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a “high-performance engine” has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight – that is what makes the engine “high performance.” The disadvantage is that the gasoline for your engine costs more.
the other thing i was wondering is that when you advance your timing a few degrees that makes a small increase in performence because the a/f is gettin compressed the slightest bit more before the spark ignites it. thats why when people buy “superchips” for their car its reccomended that they use 93 or greater octane. right?
also i was wonder what running a super high ocatane gasoline in a regular engine would do. im assuming nothing?
also fuck all of you that just thought im a stupid ass and im going to fill up my pretty much stock 240 with race gas because ill get more HP :hahano: :hahano: :)
when people sell chips and say you have to run 93, it’s simply because they advanced ignition timing and are probably riding the oem knock sensors… so if you have a super duper chip and ride knock all day on shaggy’s 86 turnpike octane, the performace won’t be there because it’ll pull down timing and pretty much drive like you don’t have a chip.
super high octane as in 104 or 130? race fuel in a car with no tuning will result in a better burn and more solid feeling motor… however, when running racegas you can crack up timing like a bastard and get it to haul…
running leaded gas on a car that relies on 02’s for fuel delivery is bad news… my 02 gti, for example, runs a narrowband o2 for fuel pressure adjustments under boost… so if i’m running racegas that’s leaded and kill those 02 readings… my fuel pressure will whack out.
i don’t know enough about it or i’d explain more… i know the concept, but i’m sure some guys on here know exactly what the deal is… they can chime in
you got it backwards, advancing timing makes the plug fire before the piston is at TDC, obv too much advance will cause detonation because the explosion is trying to force the piston down at the wrong time. when u ignite the a/f mixture it doesn’t instantly explode you get kinda a pre-burn thing goin on, with advancement it ensures the most power is being applied at TDC and not on the down-stroke basically not making any power. that’s why when you retard timing far enough you start igniting fuel in the manifolds because it’s still burning as the exhaust valves are opening. this can work as a “misfiring system” and spool turbos in between shifts(rally) and spool them at the line with a 2-step system.
