Dave/Joe,

what FMIC's are you running on your GF/GM body styles? I found the the cxracing one as seen below.
http://www.cxracing.com/mm5/merchant...egory_Code=WRX

are there any options out there?
if I was to go with custom piping what is largest core you think I could fit in there after trimming away the bumper? (Dave I know you know this answer)

Thanks

 

Since you have a new motor in an old shell, its hit or miss with any kit because the new TB sits further forward than the older models. The CXRacing FMIC kit might require cutting as I've seen from other builds.

You can go as large as a 3.5"-4" core. No BS.

 

that is the kit i went with. if i would have lined up my intercooler right i wouldnt have had to mod my piping, so put all the piping on then mount the intercooler. that is the biggest core id go 12x24x3 as there is not too much of the lower bumper left ill take some pics and post them up later

 

thanks guys....This local Korean guy I met out here is pretty good at fabricating piping I am thinking of talking to him to see what he can do for me also. my biggest concern was to figure out what the largest core would be to fit in the GM body. i really want to do the the WBR reverse flow on this setup or even go as crazy as to doing a reverse manifold.

Dave what size is the piping on your car?

 

it starts at 2" out of the turbo then when it gets to the fender well jumps up to 2.5"

 

^^ if you are custom fabbing the piping should be mat he'd to the diameter of your tb.

 

Dave is right on the money. You should match the compressor outlet OD to your hot side piping, use a step-up silicone adapter to your FMIC core, and depending on how big the core piping is, you should match it to follow all the way to the throttle body.

The morale of the story is: get the compressed air to the core faster with smaller ID piping, and use larger ID piping (core matched) out of your core. Do this and your fuel tip-in will match your air supply when you first crack the throttle wide open. Too many guys go big on piping compared to their compressor outlet and they complain about "lag", bwahahaha!!!

 

what is lag??

 

I think lag is a myth if you do it right.

 

Sorry for the haitus, but I was pretty frustrated at trying to help people here on Iclub and Subylife for free. I ended up having to beg people to look at their cars, knowing that they would have issues just from listening to the tuning process. Seemed to me like most people want to talk branding/naming rather than concepts, etc.. so I left Iclub pretty frustrated. I just don't understand consumer mentality sometimes I guess. I'm much better now though hehe

But I'd like to chime in on this.
I totally agree with you Joejoe69. Your argument is the generally accepted method to keep response high, at least from what I've seen through the years.


However I do have to say that there's lag (perhaps the more appropriate term is filling) from a flow standpoint, and then there's lag from a tuning standpoint. It all depends on the size of your compressor, hotside and type of fueling. From my experience on Subarus, the length of the MAF tract combined with the length of the FMIC piping (or volume if you want to get technical) presents a timing/latency issue. Subarus are unique in that the inlet is rather long, placing the maf rather far from the turbo. If you compare this to an EVO for example, the distance and volume of the inlet is shorter and smaller. The EVO ECU is timed for the added volume of a FMIC, so they don't really experience this issue much when they go with larger piping. The delta is not as great between an EVO upgraded piping and stock piping, as it is when a SUBY goes from TMIC to FMIC.

So MAF based tuning presents issues when turbos spool too quickly and the volume ratio between MAF to turbo and turbo to TB changes dramatically. Speed density can adapt quickly, however, as it's not reading flow.

When you add FMIC piping and change the volume post turbo to a SUBY however, you present a timing issue. If the turbo spools quickly, what happens is that the ECU begins injecting fuel before the air is able to reach the throttle body. On a log, you see this as an extreme rich spike. You can play with the tables to try and get rid of this, but it's hard to predict when and where the driver will gas it. It's hard though and takes time. I doubt most tuners will try to cure this. This rich spike will feel like a small dead spot, as the A/F goes to like 10:1 at peak boost, and then starts to lean out.

It's not a problem with the core filling. You'll see your boost gauge build quickly, but there won't be the same response as you would with the tmic, and it has nothing to do a lot of time with the FMIC. It's really the MAf and metering system.

This doesn't happen on larger turbos, as they spool slowly and the timing issue is not exacerbated or increased. I notice it a lot less on 35 or 30rs for example, greens and reds as well.

So if you run a stock a turbo or one that is designed for response, like any of the VF series, you totally want to pay attention to the amount of volume you're adding post turbo. Also, one other point is the ammount of pressure drop you'll get. For example, Steve's car, I believe STETS has it now, has rather large piping and core, and the pressure drop means that the small turbo can't keep as the revs climb, so the density at the throttle body is completely affected. I think that's a case where the large piping and FMIC actually kill peak power. I think that as the turbo is filling the core and FMIC, along with the pressure drop, the turbo is being pushed way out of its efficiency and flow range. He's getting the cooling, fo sho, but the compressor is just pushed into an area where it's not happy.

On the larger turbos, like a 35r, the pressure drop is not a super big deal because even though there's a 3psi drop for example, the compressor is still in its efficiency island, and you wont notice this large drop in power.


I guess in the end:
1) if you plan to stay with a small turbo (I consider 20g small), you definitely want to watch your piping AND core size if you want response (The rich lag spike is noticable, as when I remove it, the cars feel so much better)
3) if you stay with small turbo, a large core (mostly pressure drop) "may" rob peak power, so be careful
2) if you plan to go with a medium/large turbo, bigger piping and some pressure drop here and there wont hurt you too much as the larger turbo will make up for most of the pressure drop but still stay in its efficiency range.

 

wow nicely said Reid.....kick that knowledge!

 

If you want a better discussion, I think it's also nice to list your horsepower expectations, turbo choice and use, if you're going Time attack versus autox or even drag (we all know that you like to go drag ) for example.

Floating with generlizations is bad. It's cool when it's someone else's car, but if you're trying to plan it out, you probably want to be more specific, and then maybe ds and joejoe can give better advice too.

 

hey who told you I like to drag ......no but seriously I recently got dragged back into the drag scene (no real big secret) and I realized as light as my car is and as fast as I can get off the line. my current setup is showing its flaws up top.......I ask the question about a FMIC to Dave and Jon because i know they are running the specific setup on the GC/GF body styles. what I didn't mention is that I will probably going with a ATP 3076r as my next turbo upgrade (still toying with the idea and building my knowledge base).

although I love my low to mid end power I know I will loose a lot if not all my low end power (what I mean by power is my torque). I have asked questions about doing the 3076r on a TMIC, I even entertained the idea of going smaller with a 3071 and loosing some top end to gain low back some of the low. in the end everything is pointing back to the 3076r (so far) for what I want to do. anyhow i appreciate your opinion I like being armed with more ammo before going into a fight....sorry lame Army analogy....

 

Stay away from the 3071 IMHO.
The 20g is so much cheaper and has equal performance "most" of the time. I have yet to see a convincing dyno chart that shows me otherwise (at least on a 2.5l).


If you're not going rotated and staying stock location, I think that trying the TMIC wont hurt if you can get it to fit, unless you're having to pay for a retune from TMIC to FMIC (I can help you with that if you need it), in which case that would be cost prohibitive.
And then if it's not responding the way you like it, you can always switch to FMIC.
Anything like the 3076 and bigger, you shouldn't need to really micro think your FMIC selection and setup. You're going to lose the ability to build peak boost in parking lots for example, no matter what.




I don't have any experience with the ATP stock location turbos on Subies (some evo experience), but from a tuning standpoint, hotside size is really really important, more so on the subaru than any other car. The large compressor/small hotsides (green/red/dom), while putting up good peak numbers, have never impressed me with around town driving. The "real" garret 30 and 35rs build boost much more progressively and the dynos don't show that. Also with the larger hotside, the tuner can play with the AVCS more dramatically to build torque (good tuners always tune for torque and not spool). The AVCS tables are really dependent on backpressure. The less backpressure, the more that table has an actual effect on driving and power. The more restrictive, the less an effect it tends to have.

I can tell you that from my experience that an .82 35r (true garret) feels better than a high horsepower green on the street in the way that it builds boost and responds to changes in throttle input. The rotated kits offer the tuner a lot more options, but you won't see the dyno results, and the tuner has to get on the road with you to really play with those low load areas and transitions.

The peak numbers look "similar" from a pushed Red or green to a pushed 35r, but I've driven and tuned both and can tell you there's a difference. I think Jimi can chime on in this as well. With a well mapped map and a turbo with a good hotside and matched, you could convince someone that there was a much smaller turbo in there.

 

i dont think a 3076 is out of the question on your tmic.
dont get wrong a fmic will cool alot better and wont get heat soaked but i dont think it will be a problem to run a tmic and that turbo