Charge pipe size

[Reinhoud]

Busy building a new plenum, and idea's popping up, not sure if the idea's are any good..

 

I had/have a 2" pipe on it (from turbo to plenum), now I was thinking of putting a 2.25" pipe on it.

Will this improve performance?

 

Anyone been experimenting with this?

What size charge pipes are you guys running?

 

Thanks

[Arttu]

I was recently building a plenum and charge piping for a GSX-R1000, aiming for 400-500hp. Space was tight so I was using 50mm pipe but was a bit concerned if it would cause restriction. I found a quite nice web calculator where you can insert pipe diameters, lengths, turns and air flow figures and it calculated the pressure drop. If I recall correctly a 500mm long 50mm dia pipe with a couple of 90° turns resulted about 0.1 bar drop at air flow that a 1000cc engine takes at 12000 rpm.

So, I built that setup with 50mm pipe. Worked ok although total pressure drop from turbo outlet to the plenum was a bit higher than I was hoping, around 0.1 bar at full power. But there was also an intercooler cell in between so I have no idea how much drop the pipe alone caused.

In short I would say that 2" is probably fine unless you have long piping with plenty of turns. But on the other hand using bigger size shouldn't hurt anything either. So if you are building new one and you have space then bigger might be safer choice.

[Gixer1460]

As Arttu says it really is a minimal difference - 0.1bar / 1.5psi at max airflow (in his 12k example). I use 50mm (nominal) up pipe and have a IC that I understand has an approx pressure drop across the core of about 1-2psi, so for me, the saving of maybe 0.5psi using a bigger pipe is insignificant in the grand scheme of things. I'd actually prefer a 20 - 30 deg greater temp drop across the intercooler but that would induce a greater pressure drop . . . . . . nothing come free!

[Reinhoud]

So a bigger pipe what can move more air doesn't make a, or much difference?

It's more about pressure?

[Gixer1460]

You can pass 500cfm through a 100mm pipe or a 50mm pipe - the only difference is initial pressure and what the end pressure is in the plenum

[Reinhoud]

True...

 

Thanks guys, I'll keep it like it is then.