Still working on cooling

[Jeff K]

I shrouded the fans before I went on vacation. It made a big difference on cooling at low speed and in traffic. I had rode it for a few hundred miles before we left and everything seemed cool (pun intended).
But... As we started on our 5,000 mile vacation I began to see issues. I had never taken it on the super slab and wasn't pulling a trailer. It soon became apparent I had a new cooling issue. I was over heating at highway speed. Well maybe a bit more than "highway speed". I couldn't cruise at 85 for very long and the temp would start climbing. It would slowly climb to 240 and if I slowed down it would cool off. I was pissed. 5,000 miles to go and I couldn't travel over 65 without overheating. 
The ambient was high, about 95-100+ but I had never had this issue before. I vowed that if I made it through this I'd throw my wallet at it and finally get a bigger radiator made.
I called Griffin Radiator... and I called... and I called ... and I called... and I posted on their FB... I assume they have too much money, because I swear I've called them a dozen times in the past and recently and only got an answer one time. They were the ones that told me to shroud the fans before spending money on a new radiator.
So I called Ron Davis Radiators. Very helpful guys. He said I should draw up what I want and send it to them. I drew it up and sent them pics of what I have. After seeing the pictures and hearing my story they said “before you spend the money on a custom radiator ($800) let’s try something first. Based on the pictures you sent there may be a pressure build up in the shroud”. He suggested I put some flaps on the shroud to help vent it at speed.
I thought he was grasping at straws. But he told me that they had success with race cars that had the same issue.
So, I made some flaps. I was astounded at how much air didn't pass easily through the fans, even when the fans were under power. See the video below. I haven't had the chance to road test it yet but I should get a chance to test it tomorrow. It won't be 100 degrees, but I should have a good idea on how it is working.
I was holding the radiator over my shop blower

http://s287.photobucket.com/albums/ll126/kozmic1520/?action=view&current=MVI_1987.mp4	powered by Aeva

[BonS]

Very interesting Jeff, are those the "new" low profile fans? My new-to-me supercharged Valk and has the Mikuni HSR45 carb without the J-tube but has just one fan on the left side of the radiator. Have you moved your radiator out farther than the normal blown setup to accommodate the dual fans and shrouds? I like where this is going.

[Jeff K]

Very interesting Jeff, are those the "new" low profile fans? My new-to-me supercharged Valk and has the Mikuni HSR45 carb without the J-tube but has just one fan on the left side of the radiator. Have you moved your radiator out farther than the normal blown setup to accommodate the dual fans and shrouds? I like where this is going.

Yes I moved the radiator out a bit to accommodate the dual fans. But I've had dual and quad fans on in the past. I've had two pushing and two pulling.  I have never gotten it to be reliably cool in heavy traffic till now, but with only two fans pulling and shrouded. But keep in mind I'm running 8:1 pistons and 14psi boost.

You can get two of those fans in there pretty easily, but when you include a shroud it takes up even more room.

[BonS]

Yup, so far I'm okay at stock compression and 4-5 pounds boost but I haven't yet pushed it hard-and- long or low-and-slow for extended periods in the heat.

Do you have a manual fan switch? Do you get better cooling, at speed, with the fans on or off? At some speed might there be a break even point where they're better turned off?

[Jeff K]

I have a manual switch. I turn the fans on if I see traffic ahead. My EFI computer turns my fans on now, so I do have it set to come on early. But shrouded it doesn't seem to matter if the fans are powered up or not at speed.