I did a little snooping around on porting the ROE manifold and did a compromise between how GG opens them up and how they were stock. Basically opened them up quite a bit on the outside (head side and corresponding runner) but not to the extent Greg does on the intake side. He really fillets the runner on the manifold side. I also port matched the hogged out ROE to the heads. Also did a bowl smoothing, unshrowded the valves, and cleaned up the valve seats and associated intake/exhaust transitions. What I think really is making a difference is the centerline rib I put in the manifold along with some corresponding mesh air deflectors to assist with calming the internal airflow while still not restricting any inherent flow out of the manifold. Before, my boost gauge was bouncing around once I got over 10 PSI. Indicated to me a lot of turbulant air. Now the gauge just reads a steady pressure...12 PSI. I was hoping for more but that is a big engine and with the cam and mildly ported heads, I can see its breathing better. So inthe final analysis, probably could have gotten by with the standard 2.8 blower vice the 2.8H. Really don't gain any efficiencies at under 15 PSI boost wit the 2.8H. As far as heat sink. Same as the 2.4. I haven't seen any real difference in basic functoning of the system other than boost is even more instantanious with a little bit more whine. Oh and I'm running the old #10 pulley from my 2.4 to get the current 12 PSI. I don't think you can spin it any faster than that without running the DW crank pulley. I think the belt might not agree with that however. The #10 pulley is pretty small as it is and I doubt ROE develped anything smaller. It would be interesting to know the limits of how fast one can spin the 2.8 however....
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