Originally Posted by GoldieLax
so the whole ringland failure thing is kinda caused by the alloy pistons, and the third ringland, but can be almost prevented by an oil catch and the ap. pretty neat stuff to me, those are definitely the types of upgrades id rather do to my car, ones that will help it last. so the ap can help fix the detonation timing, which is basically the whole lean vs rich gas/air combo, right? i never understood mapping/ how that was done, though it seems like the reflash thing on the ram could be solved by just adjusting the actual ecu and not having to technically bypass it with another ecu.. also the heavy load thing about the rpms, i guess thats what you were saying about no awd launches huh. cant believe the evo has forged pistons, you'd think subaru would have taken note of at least their own engine failure and fixed it over the last ten years or so? they've barely updated their engines it seems, or their interior..
so you say not to tune the access port, do you mean to stage 1,2 stuff or the base remapping too? ive read that the stock factory tune isnt all that great in the first place. with the reflash thing, so if your battery dies, you need to reset it? im probably not making sense, i just got off work. ill try and rewrite my questions another day when im thinking straight and comprehending the information better :)
I'm not an expert with tuning, just know the basics. But basically an optimum complete burn of gasoline happens at a ratio of 14.7 units of air to 1 unit of gas.This is called "Stoich", lower than this is a rich condition, higher is a lean condition. The saying is "richer is safer and leaner is meaner", self explanatory. Turbo cars tend to need to run rich to avoid pre-detonation 10-11 is considered optimal. Be advised, running rich might prevent pre-detonation, but it also increase exhaust gas temps, and could kill a catalyst converter, as well as create heat issues after the exhaust system. The subaru ecu are modern, and well understood, which is why the cobb ap is even available. It'll flash fuel map changes, as well as pull monitoring data from the factory ecu. Fuel maps should only be modified by someone who has a firm grasp. Definitely don't attempt to modify the base map yourself without learning it thoroughly, and if paying someone, research them, and previous customers fully. But yes, I'm saying avoid the stage1/2 upgrade/tune packages until you really learn the car inside and out.
Biggest problem with these types of platforms IMO, are the vast aftermarket parts available, which tempts new owners to chase easy HP, and other performance enhancements soon as they get one. Then start street racing, doing highway pulls, and blowing up motors/transmissions, and/or wrecking. It's a terrible order to do things for a newbie. The proper order should be to get maintenance things done first, despite not having issues yet. Then upgrading the car from the ground up as you learn to handle it's limits. Starting with tires, brakes, suspension, then maybe power modifications. Learning a car's limits should start with low speed, high technical racing like autocross, then moving up to higher speed track days.
Originally Posted by GoldieLax
ive been reading up on a FA20 engine with the avcs vvt, and the direct ports, sounds much better then the ej motors? though i guess it doesn't come in the impreza's. so this is the next evolution, is the vvt gimmicky?
vvt is basically what the popular "V-tec" is. I believe some subaru models, especially the turbo ones only have it on the exhaust cams, I'm not sure which though. It's not a gimmick. Direct port injection is exactly what it sounds like. Injects fuel directly into the combustion chamber, and not in the intake manifold. It definitely provides more potential for power and fuel economy. But it comes with issues of it's own. Primarily carbon buildup in the intake manifold (injecting fuel into the IM actually cleans it), which requires removing the IM and blasting the insides to clean the carbon buildup, not a simple or fun maintenance job. Another issue are the special fuel pumps required, which often aren't the best quality, especially when fuel demands are increased (more boost). DI requires fuel pressures well over 1000psi at stock boost, which is a big strain on the fuel pumps, and the fuel pump internals. I believe cobb offers upgraded DI fuel pumps and internals for a number of platforms. Lastly, DI doesn't have many options for increasing injector size for higher fuel needs (big boost + turbo upgrades). Last I checked, people were getting around this my drilling and tapping the IM, and installing a 5th injector, which complicates tuning further.
Edited by bigx5murf - 4/21/17 at 1:46pm