My best experiences with turbochargers have been with ball bearing equip ones and the logic's pretty hard to fault . The cost is a different story .

When you get right into what four stroke engines really like you can see inside the big picture .

To excite a turbine with a smaller or lower A/R turbine housing means the user is is artificially limiting the maximum flow potential of the exhaust side , the reason being that to have greater gas speed at lowish revs means even higher speed at high revs . Now you can believe what you like about the whole twin scroll process but the facts are that they like reasonably large A/R sizes so that they can help promote greater flow (hence power) at higher revs . Its all the little things that add up to significant things that make it worth the while . Things like a turbine dragging the chain (against oil sheer drag) that costs minor exhaust restrictions and that nice low down torque from extra ignition advance etc etc .

Anyhow I'm not interested in proving or justifying my reasons to anyone , I just want what I want and DON"T wish to be side tracked .

Generally to convert a cartridge from bush/plate to BB is not a major feat of engineering . Mostly the bearing housing is gutted and line bored to accept the larger diameter BB pack or races . I'd say the reason the British mobs ask for a low mileage core is so that the rear seal register is not worn out .
Now provided the turbine shaft fits the new bearings inner diameter about all that's left is the compressor spacing and seal assembly . To me 2G sounds like a lot to do this but then I don't now if shaft mods are required to make the bearings fit . Actually I'm wondering if any of the Subaru type BB cartridges could donate anything to the cause - are they IHI ?

Cheers Adrian .

 

I agree with TTP's viewpoint that the B.B. assemblies really shine on turbos with larger, high inertia compressors. But, the 16G's are such tiny turbos that as a practical matter you can accomplish essentially the same thing for a lot less money with a set of adjustable cam sprockets and/or by shortening the wastegate actuator rod. Of course, I realize that I am probably mistaken as I haven't yet grasped the "Big Picture".

 

Look I have just as big a problem with the cost as anyone else here , trust me if there was a way to get A Garrett GT BB cartridge to fit and retain the same twin scroll and integral wastegate features that'd be the way to go .

Just for the record I pm'd DB today to see if theres a way to achive the BB version whithout having to regut and rebuild the 9 turbo twice . If some of the cost can be cut then it may be in reach of more people . Also the numbers involved , economies of scale can alter production costs significantly in some instances .

Time will tell , cheers A .