First, Don, since you can't enlarge the fans (no room) I'd contact Fred Hobe for one of his larger pulleys to drive the fans faster.
Another thing. I've found, contrary to what the GM boys say, that a full mud flap across the back AIDS in cooling. It forces the waste hot air out through the side louvered doors (if you still have them) that's the way the cooling system was designed.
I'm a little confused by your suggesting a larger pulley to drive the fans faster. Are you talking about a larger diameter crankshaft pulley, or a larger diameter squirrel cage pulley? Can you clarify your thinking on this?
Your comment about the bumper mud flap is intriguing, since you suggest that it tends to force air out the side louvered engine access doors. I don't recall ever seeing an MC-5A series with an OEM mudflap hanging off the rear bumper. All I can recall is just small mudflaps equal to the width of the duals directly behind the rear axle, and pics in Larry Plachno's book show the same.
It would be interesting to see what the slipstream airflow is doing when it reaches those side access doors, both with and without a flap. Perhaps one of you who own a 5A would be willing to experiment with some yarn tufts and a video camera in a chase car??Stan -
The point I was making (using the Turbo Corvair muffler as an example), is that sometimes powertrain engineers at the factory do things for reasons we, as the motoring public, are not aware of. The comment was not intended to confuse the issue. I'll agree that it wasn't focused directly on the repowered MCI MC-5A bus, but conceptually, the point is accurate.Don -
Another random thought just rattled around in my muddled mind: Possibly changing the water/coolant ratio. Depending on where you live, you may not need the freeze protection of a straight 50/50 mix. Perhaps a 60/40 water/coolant ratio might be better, since water conducts heat better than coolant, keeping in mind the correct SCAs(?) Detroit recommends.All -
I think that each and every one of us is aware that cooling a rear-engined vehicle is a unique challenge - from the factory engineers to the shade tree converters. Compounding the issue in a vehicle which has the aerodynamics of a brick that's got a souped-up repowered drivetrain, and the head scratching really begins!!
This has been an informative, interesting thread, and I think this is a good example of how so many things on our engines are inter-related - how changing one thing can end up with a large "ripple effect".
Eventually, Don will get his problem solved, we'll all learn something, and be entertained in the process!!
FWIW & HTH. . .