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Referenced from R&D's
"The IDI Turbocharger Thread" on FTE.
Looks like this thing would really start running out of boost capacity around 25-30 psi. 10-15 psi looks like it would put you right in the middle efficiency island.
It seems easy enough to calculate where you'll likely fall on the map at max fueling that your pump is capable of, but I'm still having trouble figuring out how to predict what turbo efficiency/boost is going to look like at partial throttle. I know there's some trial and error involved. Still, it looks like it couldn't be too bad on this turbo, especially with a smaller exhaust housing (diagram is for the 1.10 A/R).
Is there any reason not to drop head studs in by removing the head bolts one at a time and replacing with studs, without removing the heads? All are very easily accessible on the bus (I understand that the heads, or the motor, must be removed to do studs in a truck), and I've already had the heads off in the past year, so that might be part of my plan from the get go, if the turbo looks like it's going to be making more than 12 psi or so of boost.
I live three hours away from where the bus is currently parked, so I have trouble envisioning certain parts about the engine bay layout sometimes. I looked back at some photos I have, though, and found that the exhaust manifolds are nestled pretty well up against the frame rails. I had the idea to buy another of the stock 90 degree exhaust manifolds and flip both so the outlets point up-ish, then run up-pipes along to the back of the engine bay, toward the center to meet each other, and to a turbo in more or less the conventional location. But looking at these pictures, I am not even sure if there would be room to flip one of the manifolds due to frame rail clearance. Did it look like the Rayjay manifold was going to clear the frame rails ok?
Issues with firewall clearance, issues with frame rail clearance....such a big engine bay, so little room in the critical places for turbo pipe routing! When I get have the time and money to really work on the mods (which will probably be in the spring) I will see if I can flip one manifold or the other over--somehow this seems promising to me. But in another development of modification temptation....I found listed locally a running DT466 (180k mi, appears to have an MW pump) mated to an MT643. $3,000 for the pair. If I were a little closer to getting started on the mods timewise, location-wise, and finances-wise, I'd consider trying to make a deal and scrapping my IDI plans!