DIY cai?

Jordo!

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!

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synolimit

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.

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13 370z-