I have no use to bid for twins for a 3,9 liter 4BT. I thought I'd let you folks in on this ebay auction my friend happened to spot while browsing.

Item is a two-stage 'twin turbo setup' from an International VT275. Please see page 18/24 of this PDF document:
http://www.turbodriven.com/files/new...er_342_376.pdf

I made a few Excel spreadsheet calculations on airflows, and indeed this setup is perfect for Cummins 4BT.

These commercial two-stage turbocharging systems are not engineered to make even remotely as many psi's of boost pressure as you guys are familiar with. I'd say these setups push somewhat even 30psi and that's it.

One does only need to tweak out wastegate a touch further, and it'll make a decent boost where single charger cannot reach.
Making a measily 16psi out of both turbo's will result in 49,5psi overall boost pressure.


http://cgi.ebay.com/ebaymotors/USED-...mZ230059556622

 

That would be a sweet set up.