Questions:
1. Without changing the oem IC, will just changing the pipes suffice to bring about better and larger air flow, and hence cooler charged air?
2. How much hp can the oem IC suport WITH oem pipes support?
3. How much hp can larger diameter aftermarket hard pipes support?
Point to note: I noticed the MME E9 by ST Powered uses the oem IC.
Answers
evolvix :
I guess the answer depends on which hardpipe kit you are looking at. Most aftermarket kits probably come with a bigger ID but the important thing to look out for is whether they come with less bends as well. From what I know, every single 45 degree bend slows down the air velocity significantly thus increasing lag and probably causing a pressure drop as well. Of course, bends that are greater than 45 degree are worse. In this respect, I think aftermarket kits help in maintaining boost pressure and reduces lag. As for enhanced cooling, I can't be sure but I will guess no.
To accomodate the straighter and bigger pipings, some kits require you to either relocate your stock battery or to use a smaller one. Personally, I will want a kit that has the shortest hence straightest pipings and one that's > 2.25" in diameter. I think its realistic to expect a power gain with these kits over the stock pipings simply because the stock pipings suck! Especially the stock lower piping between the compressor housing to the FMIC inlet. Picking up 'lost' boost pressure caused by the restrictive stock pipings should give you power liao!
As for the capability of the stock FMIC, I think there have been enough tests, even local ones, to prove there's substantial power gains to be had just by swapping it out for a more efficient unit EVEN on a stock Evo. Workshops can use what they want but no one can defy physics. Even assuming (optimistically) that the stock FMIC has a core that's as efficient as aftermarket ones, a bigger surface area will simply dissipate heat faster given the same amount of incoming airflow and the greater thermal mass will simply absorb more heat before being saturated. Look around, I'm sure you can find hard data and numbers locally.
Ideally, you should upgrade to a more efficient FMIC to lower your charge temp and use water injection to do in-cylinder cooling and detonation control. Remember though that a bigger FMIC works all the time while water injection requires constant monitoring, refilling and the jet size + spraying cycle really need to be tuned else you might lose power through the injection of too much water into your combustion chambers. Water injection systems can be unreliable too...pump failures, clogging of water lines, running out of water etc can cause damage to your engine if water injection is a critical part of your tune. Also, rem that although the in-cylinder cooling will bring about an increased density in air, the water molecules present in each intake charge (especially if you spray too much water or too often) will reduce its density too. In the end, you might face a compromised situation. Some says that the steam created in the chambers can also help in decarbonizing the engine but I can't be sure.
Personally, I will be setting up a 50-50 water/methanol injection system on my E9 soon. There's real benefits to using methanol so long as you are able to tune for it, and that the system is highly reliable and safe with all the monitoring measures and controls in place. I will not use 100% water because to me, there's too much hassle involved for too little gains. I guess as long as you understand what you are doing and know how to setup these systems, all should work as they are designed to. They are seldom mutually exclusive so I guess you can use all of them to bring about a greater effect to what you endeavour to achieve.
