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this is because they must running ecus like a link or a vipec which doesnt need an afm and uses a map sensor , which i think is installed near the throttle body

for the power fc u require an afm and the z32 is a good choice

Where it should be, at the factory position, turbo inlet.

You'll notice most of the "enthusiasts" (I used that word loosely as most of them don't have a brain) on boostomgcruising will extend their AFM cabling and hook up their AFM on the cold side of their FMIC, totally acceptable provided you retune your aftermarket ECU's injection map as the air is denser, which many if not all never do. I'll leave the rest up to your imagination on why that would do such an exercise on their VL turbos.

A 4inch inlet on a GT30 is only there because its a surge slotted housing....

The actual intake of the turbo would be around 3inches.

So i cant see how a 3 inch Z32 air flow meter would be a restriction....

post-32514-0-55506300-1295230647_thumb.jpg

well in front of the compressor is sea level pressure, and after compressor outlet is boost + sea level pressure, known as psia

yeah i can see how the anti surge slots need a wide snout, but 4" just sounds so big, specifally if you are running 3" std piping after the compressor

well in front of the compressor is sea level pressure, and after compressor outlet is boost + sea level pressure, known as psia

yeah i can see how the anti surge slots need a wide snout, but 4" just sounds so big, specifally if you are running 3" std piping after the compressor

It would actually be under vacuum in front of the compressor and pressure after the outlet...

My point being PV=nRT... So if the pressure increases the volume can decrease to flow the same amount of air :)

Thus you should technically have a larger inlet than cooler piping!

Edited by SimonR32

So a 4-2.5" reducer sitting on the comporessor intake wouldn't be considered a restriction?

depending what size bend you can get you can either put a 4"-3" (2.5" is too small) reducer straight on the turbo and then a 3" pipe to the afm (leave it before the turbo, its not a restriction) or you can run a 4" pipe to the afm and then have a reducer joiner the afm to the pipe (this is what i've done and it works well).

map sensor for the win, the afm pissed me off to no end.

the volume will decrease proportionally provided the temperature doesnt increase, but yeh generally the air is alot denser on the intercooler side, so it makes sense that the inlet side would need a bigger sized pipe to flow the same amount of air, also considering the pressure differential is probably alot smaller on the intake side as well.

Always sounds good in theory but probably only makes a bees dick of difference, although it makes it easier to run a larger air filter which probably helps as well.

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