I use the MP viscous clutch and fan set up on a number of cars. Never a problem, always does the job, never an issue, used with the stock shroud and radiator.
Most powerful mill to date was a 475hp - 360 cube engine.
I run this set up on my Dart. It along with a FlowKooler water pump have been on my 340, 408 and now my 434. The 340 was in the 450-475 hp range, the 408 was approaching 600 and the 434 dynoed 703, although I'd say it's in the 650 range. This set up has kept all three engines well under 200° even when making back to back to back runs at street car shoot outs. In the summer heat they all have ran around 175° while cruising.
I tried electric fans when I built the 340 over 15 years ago, it didn't work out well. I bought two new radiators and two electric fans along with the above mentioned pump and it still ran hot. I was ready to pull the engine and tear it down as I thought there was a problem, then someone suggested a MP viscous fan. A buddy of mine had a new one that he made me a deal on. I had a shroud for a factory 26" radiator that I cut into four pieces to fit my aluminum radiator. No overheating since then.
Just out of curiosity has anyone ever checked how much power it takes to run the alternator when one of them monster fans kicks on? I know with the last one I bought it would cause the ammeter to peg on fully charging when it kicked on.
To the OP, I ran the valley tray in my 340 when it was first built. Can't say if it helped or not but the intake bottom had no oil stains on it after five years, for whatever that's worth.
