R
Renno555
Guest
[quote author=FRAWLS link=topic=2413.msg22112#msg22112 date=1179856005]
Its just a matter of upping the duty cycle on the injectors and reducing the boost. No sweat for a mapper I would have thought. If there's a problem with the fuelling or boost ecutek will show this on the laptop so they can be fixed and the car mapped later.
So I cant see any ECU TEK mapper having any problem mapping them.
Frawls
[/quote]
Dave you would think so but apparently not. Id have agreed all day long until I spoke to certain people. Ive asked this question to a few mappers before, One of them gave me a fantastic / massive reply regards comp ratio etc which part of is below. The other thing is the B4 simply does not respond as well to mapping. Andy Forrest stopped mapping B4's for that very reason. They are notoriously over-advanced from factory and apparently on decent fuel "detuning" them can make decent gains as weird as that sounds. But they seem to suffer FAR worse DET then the Impreza on our fuel for some reason :dunno: In saying that Ive know people running them a long time with no issue at all so that kinda contrdicts some of it. Next B4 has a decat etc so see how that one goes or if it turns into another case of trying to save the engine. If it turns out ALL the B4's DET like mad on our fuel what would you take a guess its down to yourself ??? Would have to be something they all have in common rather then an actual problem on the car I would have thought but im no mapper :dunno:
Quote below.
"Anyone who claims that they can map out compression has obviously never tried it, or believes that the laws of physics do not apply to them. You can compensate to an extent, but if it's too high for the fuel then it's too high for the fuel. You can fuel dump to cool it down and broaden / flatten the cylinder pressure curve, but you're just making it less efficient rather than addressing the core issue... the compression"
"It's down to autoignition. There is a temperature at which fuel will spontaneous ignite, detonate if you will but that's not an accurate description (a detonation is indescribably more violent than what we get in engines, we're not talking broken ring lands, we're talking the entire piston being turned into dust!). Anyway, compressing air heats it up (try putting your thumb over a bike pump and allow the air to escape under pressure!). So as the piston compresses the air it gets closer and closer to autoignition. At some point before TDC we light the cylinder... the pressure then starts to rise much more rapidly... the sooner we light up (the more advance we run) the higher the peak cylinder pressure will be. This will be compounded by compression ratio. So we have to back off the ignition timing to keep the engine away from knock. Anything that we can do to either a) keep the cylinder temperatures down, b) keep the cylinder pressures down or c) increase the autoignition temperature of the fuel will allow us to place the spark more optimally"
Its just a matter of upping the duty cycle on the injectors and reducing the boost. No sweat for a mapper I would have thought. If there's a problem with the fuelling or boost ecutek will show this on the laptop so they can be fixed and the car mapped later.
So I cant see any ECU TEK mapper having any problem mapping them.
Frawls
[/quote]
Dave you would think so but apparently not. Id have agreed all day long until I spoke to certain people. Ive asked this question to a few mappers before, One of them gave me a fantastic / massive reply regards comp ratio etc which part of is below. The other thing is the B4 simply does not respond as well to mapping. Andy Forrest stopped mapping B4's for that very reason. They are notoriously over-advanced from factory and apparently on decent fuel "detuning" them can make decent gains as weird as that sounds. But they seem to suffer FAR worse DET then the Impreza on our fuel for some reason :dunno: In saying that Ive know people running them a long time with no issue at all so that kinda contrdicts some of it. Next B4 has a decat etc so see how that one goes or if it turns into another case of trying to save the engine. If it turns out ALL the B4's DET like mad on our fuel what would you take a guess its down to yourself ??? Would have to be something they all have in common rather then an actual problem on the car I would have thought but im no mapper :dunno:
Quote below.
"Anyone who claims that they can map out compression has obviously never tried it, or believes that the laws of physics do not apply to them. You can compensate to an extent, but if it's too high for the fuel then it's too high for the fuel. You can fuel dump to cool it down and broaden / flatten the cylinder pressure curve, but you're just making it less efficient rather than addressing the core issue... the compression"
"It's down to autoignition. There is a temperature at which fuel will spontaneous ignite, detonate if you will but that's not an accurate description (a detonation is indescribably more violent than what we get in engines, we're not talking broken ring lands, we're talking the entire piston being turned into dust!). Anyway, compressing air heats it up (try putting your thumb over a bike pump and allow the air to escape under pressure!). So as the piston compresses the air it gets closer and closer to autoignition. At some point before TDC we light the cylinder... the pressure then starts to rise much more rapidly... the sooner we light up (the more advance we run) the higher the peak cylinder pressure will be. This will be compounded by compression ratio. So we have to back off the ignition timing to keep the engine away from knock. Anything that we can do to either a) keep the cylinder temperatures down, b) keep the cylinder pressures down or c) increase the autoignition temperature of the fuel will allow us to place the spark more optimally"
