legacycentral bbs

I am starting to plan for some mods on my new SS. The car is stock with the exception of an MBC. My plan is to run the car with the stock VF11, an aftermarket glass pack muffler (since my current muffler needs replaced) and a FMIC. I planned on setting the boost to 10PSI. My question is will I need a tune to take advantage of this setup? I understand that a tune will almost always net you more power, but I wanted to if I "NEED" a tune? I would be building a custom setup so I would keep the tubing as short as possible to eliminate lag. I was also wondering what diameter of tubing that I could use for the FMIC. I was thinking about using 2.5" since it will help with lag and then just stepping up the size when I get to the throttle body like the factory intake does. Will I be able to find a FMIC that will fit this style of thinking?

Disclaimer:
I am new to turbo cars so I am less familiar with some of these concepts. I have been working on Subaru's since my first car a 1993 Subaru Impreza L but this is my first Turbo Flat 4.

Add a Walbro 255lph wrx fuel pump to that list of mods and you can run 12 maybe 13 psi.

Your stock ecu csn adjust within these ranges. You won't need a tune (nor is it really an option anyway... gotta look at replacing the ecu -search for RobTune- or using a full standalone for higher power levels).

Fwiw, I have a fmic and the walbro pump and a slightly upgraded compressor and I run 15psi daily. It still runs quite rich, too...

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Also: exhaust piping makes for excellent ic piping. Plan out your paths and bends and you can probably have an exhaust shop make the majority of your piping for cheap. Make sure to get mandrel bends...much smoother than a crush bend. Also dont forget to have them roll the rims for you so the couplers have something to hold on to under pressure. I used worm clamps too and they work but T-bolt clamps would be optimal. They just expensive.

2.5" is a fine diameter for ic piping if you can.

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The greddy fmic kit I have is 2" off the turbo, 2.5" in the pass fender well to my ic. And 2.75" from the ic to the throttle body, which is the same size and the tb. Almost no pressure loss.

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Cool, Thanks for the input. Glad I wont need a tune. Walbro fuel pump eh? I still think that I will keep it around 10PSI but I will prolly add that to my list just for reliability sake. Good to know that I can go with small tubing to reduce lag this car is gonna be awesome. One more question. I am planning on tucking my IC in the bottom of my front bumper so to keep my sleeper appearance I want to paint it black. Is there a special paint I have to use? I don't want to reduce the effectiveness of the IC just to have it be black.

Honestly, even with a thick coat of paint, I still feel like the intercooler will be cool to the touch because of how much air is hitting it while driving.

Forgot to mention, to surpass 13psi you need a method to prevent fuel cut (13+ psi for > 3 seconds = fuel gets cut for safety, ecu thinks youre overboosting)

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Also - walbro fuel pump is a good idea nonetheless, even at stock boost levels...#3 cylinder is last in line for fuel and it can starve with the stock pump, running leaner than the other cylinders....

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Not to mention as old as these cars are getting it's a good idea to do a fuel pump anyway. I went to leave a buddies house one night last year, drove fine on the way there, fuel pump just said F-you I'm done when I went to leave, didn't even try to start.

https://www.youtube.com/watch?v=yWLibr0XKQY

Cool video on installing a FMIC on our generation Legacys.

Just upgrade to a TD04 while you're at it. Honesty not very hard and worth the while, especially if you're planning on running with a FMIC.


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