I have a low boost pulley 120mm Kraftwerk C-90, what is the next pulley size upgrade?
I know a few upgraded to 95-90mm pulley, anyone trying to get rid of their old pulley?

I don't know what is next size after 120mm, but anything other than what I got I'm interested.

 

For Kraftwerks, the high boost pulley is 100mm for 10 lbs boost. You can get replacement pulleys (6 rib) from superchargerrebuils.com for about $100. A 90mm will net about 12lbs boost.

 

Thanks benb --- just to clarify, is the pulley that I need to replace is the crankshaft pulley or the rotrex pulley?
I went to superchargerrebuild.com and what I saw is the crankshaft pulley...sorry I'm confused.

 

For the ap1 the high boost pulley (10 lbs) is a 110mm...for an ap2 it is a 100mm (10 lbs). If you want more you could try a 90mm (12 lbs) but it is NOT recommended or advised from Kraftwerks. These are all for the C30-94 rotrex blower not the crankshaft.

Brian

 

Thanks Brian you are right. Also if you are contemplating going to a smaller pulley or even keeping your kit you should do some upgrades to make it more bulletproof. The main one being upgrade the diverter valve. There are several threads on this.

 

I know this thread is old. I will try calling your memory
Do you remember what was the crankshaft pulley diameter on these old C30 KW kits ?

 

On the original KW kit the blower was driven in-line with the rest of the OEM serpentine system (one drive belt for the entire system and uses the OEM crank pulley). I do not currently know the diameter of the OEM crank pulley. I'd have to measure one.

 

This is the point I had not understood !
I will measure my OEM crank pulley. Many thanks!

 

You're very welcome.

 

I juste measured: The oem crank pulley has a diameter of 140mm on the "lip" and about 130mm on the head of the grooves, where the belt comes.

So the old KW kit high boost C30-94 for ap1 was equipped with 130(crank)/110(rotrex) pulleys, and made 10psi.

My old TTS supersport C30-94 kit with 125(crank)/105(rotrex) pulleys should obviously provide the same boost. Except if the fmic and piping are more restrictive. We'll see.