Does the size of intake pipe and air filter affect turbo response?
 

I have 2 almost Identical 2nd gen 13b turbo sandrails and the turbo response is much quicker on one car. Could it be that the car with the larger 3inch inlet pipe and k&n filter flows more air to the turbo quicker? The other car has a silicone adapter 3inch to 2.5inch to a 2.5 inch inlet pipe and smaller k&n filter. The cars have different inter coolers as well. They are similar in size but are a bit different. Maybe this could be the reason? Some help please would be awesome. Again I think all of my questions are way out of league for the new member section and belong else where but until I have a certain amount of posts this is the only place I can post threads for now.

Generally, yes the intake affects turbo response in a big way.

Keep in mind the flow of an intercooler isn't as simple as size. The number of bends, the smoothness of the inside surfaces, the size of the internal passages, etc.

Dave

Would it be worth it to buy a larger inducer compressor housing?
 

Would it be worth it to buy a new compressor housing with a larger inducer like 4 inch rather than my 3 inch? Or should I just make a larger inlet pipe for my 3 inch and get a bigger cone filter?

I prefer to think of the problem like the size of a highway. Going 4" for a small section won't mean as much as being sure you have 3" everywhere. Remember that turbo response requires attention to the restriction of the exhaust as well as the restriction of the intake.

Also don't forget how length of tubing, sharpness of bends, and nozzles will add restriction. Going to a 4" piping might not provide any benefit if the extra size requires you to route it with greater complexity.

That's all a long way to say I'm not sure that the compressor housing inlet size matters as much as the balance of system.

Its amazing how much difference of a flow you have from 2 to 2 1/4 so yes it does and a good filter will do wonders

I've heard the rule for fluids is that flow is increased to the fourth power of a pipe diameter increase. so if you go from a 2.5 to 3in pipe you would think that was flowing 1/6 more or something similar when actually it flows way way more.

I would google or wiki if you actually want the real calculation though. I dont know it.

Face area (A) is pi*(d/4)^2

Q = UA, U being the velocity, Q being the flow...

In short, the less restrictive (lower pressure drop) the gas pathways are, the less the turbo compressor has to work to move that fluid. I think that David's "highway" perspective helps simplify the situation pretty well.