On the Subaru oil pumps when people uprate them to 11/12mm, which part of the pump is this referring to?

 

The rotor thickness.

 

Sorry to hijack this one but at which point is it wise to switch from a 10m pump and go to 11 or 12?

 

10mm on classic heads, 11m if you go to avcs heads and an oil cooler and 12mm for increased oil capacity and such like

 

Cool, thanks for that. I'm still on V3 heads and a fairly tame state of tune. I seen the group buy for genuine pumps and had thought about changing mine to 11/12mm if there was any benefit in doing so. As far as wear and tear goes, does the pump require replacement at some stage?

 

personally i would stick with 10mm and potentially go to a properly modded version

carry various in stock

 

My personal experience has been with under piston squirters on my 3k mile old forged CDB I found the modded 10mm pump didn't develop enough pressure (3.8 bar@4k rpm and 90C), even cold starts only produced 5.4 bar max. So I have upgraded to an RCM 11mm pump (other makes of pump are available ) which has given 1 bar more on each of those parameters. I know it's now more common to remove the squirters, but they're there so I have to cope with the extra demand.

 

Are the squirters found on all turbo engines or only the CDBs?

 

Not sure enough of my Subaru history facts to say, but I think they were fitted to all CDB engines, certainly not seen on all turbo engines. Someone is sure to be along with the right information.

 

2.1 cdb, with oil squirters, Using v2 sti heads and a oil cooler would it be wise to change to the 11mm pump or keep original pump?

 

You may be ok without AVCS, it's hard to tell until you fire it up and see what you've got.

 

Who sells the un-properly modded versions then as only a small handful sell them?
And by modded, do you mean valve?