Hey guys!

I brought over a mazda cosmo for a parts car and am swapping the 20B into my car. I'm getting ready to build the header before I have the motor sent off for a rebuild (full bridge, new apex seals, etc, etc) and I'm a bit perplexed. If I wanted to run a divided housing, how would I route the primaries? Or is there even any benefit to running a divided housing with a 20b? Thanks

 

hmm 3 rotors, two turbine inlets. Nope, no good. If your cheap and or lazy it'll work fine, you'll need to run a collector for the 3 runners to the turbine flange. It's not optimal, it may hurt spool up and overall power slightly, but its a 20B lol. In time it may crack, I have seen the center dividers develope cracks were a non divided manifold was used with a divided tubine. If you aren't too cheap and or lazy, just replace the turbine with a open valute (non divided) one, their only $200~350 depending were you get it from NEW.

~Mike...........

 

I don't have the turbo I am going to use yet, I was just getting a feeler for weather or not I should use a divided housing. I went from an undivided to a divided GT4088R on my Honda and it made a huge impact in spool, but I guess if there's no effective way to divide up the exhaust pulses there's no point.

 

just run 3 turbos

 

The advantage of a divided manifold decreases as the number of cylinders or rotors increase. I don't think a divided manifold would make much difference on a 3-rotor. Besides, a divided intake manifold doesn't do much good if the turbine housing is not divided, and I am not aware of any aftermarket turbine housings partitioned into 3 chambers. I think the 3-turbo option would be pretty interesting, but probably not worth the money and effort.

 

How do you divide 3 into 2 nicely?


-Ted

 

you using something with a T6 footprint? i think it's needless worry on your part. if you're running a full bridge, i really don't see major problem with spool. if anything, and if you can work around space constraints, you might try playing with primary runner lengths going into the undivided flange.

 

I have been mildly entertaining the idea of a GT47-80, but I think I'll leave the gigantic turbo for my MKIV. Was thinking about a GT4294R, but if I don't need divided I found a T74-GTQ for quite cheap.