Thanks

Decided to change out my cai system that uses the OEM MAF section. It's only 2.35" ID which matched the throttle body. Now that my TB is 2.48", I need to have the piping bigger. From the way I understand it, your intake should taper down in size and not up. Tapering down would increase air flow like air going through a compressor on a turbo. I'm going with 2.75" OD pipe or about 2.63" ID. That should have the system bigger than the TB and really help. I bought new MAF housings and they showed up today. Only $40 on ebay. I'm still waiting on the pipe. I'll post pics soon.

http://i39.photobucket.com/albums/e1...ps893593c6.jpg

I could be mistaken, but I think narrower inlets are better to maintain part throttle velocity (or the incorporation of a butterfly of some sort), whereas gradual stepping up to wider diameter as you move towards the intake manifold would be ideal for optimal cylinder filling at WOT...

I could be wrong though... worth doing a little additional research on this, but I'm pretty sure that IM and EM runner designs almost always step UP in diameter from flow entry to exit, not down.

If it's unclear, I'd keep the diameter the same, and maybe incorporate velocity stacks at the intake inlets before the MAF's.

Anyway, be prepared to do a lot of rescaling the MAF voltage tables.

Good luck!

Stepping up when the TB is the choke point won't do anything I don't think. No need to have a bunch of air stuck in a dam and can't get through. The stillen uses a 3" filter, tapers to 2.5" OD all the way to the TB. You wouldn't want a 2" filter and step up. Nothing will get through a 2" because it's far away from the TB and it will choke out. A velocity stack can be small but that'd be attached to the runner so no pipe equals no choke. It'd suck all the air it could. Like a turbo compressor you want to have a bigger size going to a smaller size to speed up the velocity but ending at the smallest size. The taper rate depends on the length of pipe and the diameter from start to finish. I believe Megan's cai does this. You also wouldn't want to go to small then back up at the TB size. This or just run the smallest part of the system the whole way, again like stillen. But I can't do this because aluminium pipe doesn't come in a 2.48" ID size. So better to run 2.63" all the way through till it's forced down into the 2.48" TB. It's still going to act like a dam because the taper will happen in 2.5 inches but better than nothing. All I know is I don't want the MAF section I have now because it's the smallest part at only 2.35" ID.

Ok all done.

Instead of running the CAI like the Stillen I had before, I decided to change it up a bit. Since my piping is now bigger I also want it to flow faster and better. So I took out the 90* bend the pipe took to sit behind the bumper and kept my 45* coupling and ran the filter down into the wheel well. Bigger, better, faster, more power!!!!

http://i39.photobucket.com/albums/e1...ps67250005.jpg

http://i39.photobucket.com/albums/e1...ps7a02e025.jpg

Since I won't be able to drive to the tuner with the new MAF housing I modded the system so I could drive there with the OEM MAF housing and right on the dyno I can swap it out to the new MAF housing. August 8th can't come soon enough!

http://i39.photobucket.com/albums/e1...psf50506a1.jpg

http://i39.photobucket.com/albums/e1...ps67dc8ef9.jpg


Here's everything I took out. I even re-ran the AOS lines which saved some weight haha

http://i39.photobucket.com/albums/e1...psfc5649b4.jpg

i just stumbled on this thread. how did your dyno tune go?

fine. i guess the tuner had some issues with the 13 ecu not wanting to play well with UPrev but the timing, AFR etc are all ok. we dynoed with everything on the car but the new CAI, then installed the bigger MAF tubes, then tuned everything with a rescale of the MAF etc. picked up like 15/15 which is normal i think for a NA tune.

any close pics of the bend going to the wheel well

Funny wish I saw this before, Great write up, I made my own also Z1 tubes but I kept the stock boxes and attached piping to the rad support that feeds the stock box. been running it for a few weeks now and have a dyno I HOPE for this Saturday

I can try when I wake up. It's just a 45* bend. Nothing special.

Any dyno or street test results yet?

Search his name, he posted them.

So what would happen if you put jwt pop chargers in the bumper with the mafs up there on the oem sized pipe then ran 3" intake piping all the way back to throttle bodies?

Answered in PM.