I'm about to plunk down the bucks on an aluminum radiator -- I'm going to have the tanks customized to fit my rather unique needs, so I'm already leaning custom. WHy not go all the way? :p

Any comments on the difference between a single-pass crossflow radiator...
http://www.howeracing.com/images/radiators/radiators1/cflowf.jpg

...and a double-pass crossflow radiator...
http://www.howeracing.com/images/radiators/radiators1/34329rnf.jpg

The radiator, be space availability, is a little small for the desired application, so cooling is of concern. I'll be using some other tricks to allow engine-off cooling, but if going double-pass will help at all, I'd like to know this up front and plan ahead to incorporate it...

I don't want to talk about crossflow vs. downflow, my setup DEFINITELY mandates a crossflow radiator -- there's way more room on the sides for tanks than at the top or the bottom, and with this small a hole, I'm unwilling to give up any space for the actual core...

Randii

Randi,

I was talking with on the tech reps from Ron Davis Radiators about this issue last year and as I understand it the double pass is better than the single pass, but not quite as good as a bump up in tube size. I believe I was looking at a 26 X19 crossflow with I believe 1.25 tubes, I run a '68 Chevy 327 with > 10.5 compression, so it makes heat. The tech guy recommended a double pass instead of a 1.5 tube single pass. This radiator is also a little on the small side, but they were sure it would do the job if it was a 1.25" tube double pass.

Good Luck.

I don't have the equations to do the mathright now.. , but last time I was talking to a guy at fluidyne, he was saying ~20% better cooling with the double pass design.

I've been giving the phone a workout -- what I've been told by three different manufacturers is that the dual-pass design is not going to make a significant difference in idle or near-idle conditions (what we do on the trail)... one shop went so far as to say that the dual-pass setup is really only a matter of convenience for hose routing (in that both hosese route off the same tank). Both other shops believed that the dual-pass rad would cool significantly better at speed, though.

With no clear benefit in the operational window where I expect to have the most difficulty with cooling, I'm going to go for a custom single-pass crossflow radiator and save a few bones...

Thanks!

Randii