Single pass radiator

wannaoc · Aug 23, 2003

Anyone have a part number or place to get one? Thanks.

wannaoc · Aug 23, 2003

Found this one , any comments or complaints?

Since87 · Aug 23, 2003

Some water flow test data by BillA on that particular heatercore is in this ProCooling thread. (Described as "Craig's 1-pass" about a third of the way down the page.)

One of the best heatercores there is if you have room for it.

cypher_138 · Aug 23, 2003

That's really nice. I might grab one myself.

altec · Aug 23, 2003

If you do not mind me asking, what is the benefit of a single-pass heatercore over one of the chevette cores?

wannaoc · Aug 23, 2003

From what I understand it has to do with flowrate mainly but I am not sure. I was going to get a new core anyway and this runs the same as a standard here and heard it helps.

Caffinehog · Aug 23, 2003

A single pass heatercore has no bends and twists. This causes less flow resistance.

Since87 · Aug 23, 2003

Assuming you don't put barbs on it, a 2-342 heatercore only has about 46% of the waterflow resistance that a (barbless) Chevette heatercore does. This allows for higher flowrates through the whole system, and particularly in the waterblock where it really counts.

The 2-342 only has about 29% of the waterflow resistance of a dual pass heatercore of roughly similar size. So, if you want a big heatercore, single pass is of even more benefit.

Since87 · Aug 23, 2003

Caffinehog said:
A single pass heatercore has no bends and twists. This causes less flow resistance.

Not really. Suppose you have two heatercores that are identical except for the fact that one is single pass and one is double pass. Let's say both have 14 flat tubes.

The pressure drop across the single pass heatercore will be a result of the coolant flowing through all 14 of the tubes in parallel.

The pressure drop across the dual pass heatercore will be a result of the coolant flowing through one set of seven tubes, and then through another set of seven tubes.

This gives roughly a factor of four difference in flow resistance between the two heatercores:

X2 for flowing through 7 tubes rather than 14
X2 for flowing through an additional set of flat tubes

A spreadsheet for calculating the flow resistance of heatercores is available for download in the last post of this ProCooling thread. (Same thread I linked earlier.)

wannaoc · Aug 23, 2003

So is there a big change in using a single after all? I mean my tubing design has to be changed more to use one so is it worth it? Anyone changed from a duel channel radiator to a single of the same size and have any results?

cypher_138 · Aug 23, 2003

I think they were compared at the link pro cooling Since87 posted.
I'm new at this but how do you run one barbless?

Since87 · Aug 23, 2003

In a lot of cases tubing can be slid over the inlet and outlet pipes of the heatercore directly. (Heating the tubing in very hot water can help.)

One of the pipes on the 2-342 core is 3/4". For that HC you might want to use a bit of 3/4" tube and a 5/8" to 3/4" barb-barb adapter, or solder/jbweld a 5/8" barb to the 3/4" pipe.

altec · Aug 23, 2003

Wow, I may have to look into getting that heatercore. Thanks for the link wannaoc. I guess the only problem is the shrouds for it...I have no skill with anything like that, and since that is bigger than the chevette cores, the tupperware shrouds wont cut it. Anyone want to make me some custon shrouds for one of those?

Edit: Looking at the pics of that thing again made me think of what a hassle it would be to find a way to fit it into the case and have it at a somewhat practical angle for the tubing and such.

cypher_138 · Aug 24, 2003

Thanks for the tips Since87. If I do get it I'll make us both shrouds if you want Altec.

Giblet Plus! · Aug 24, 2003

I'm getting one soon.

thorilan · Aug 24, 2003

the thing is since87 you are adding extra turns so though the same distance and tubes are used its the bend at the end that gives a small bit of resistance.

wannaoc · Aug 24, 2003

I am going to get it and build my own shrouds in the same manner used in the article on the o/c front page . I figure just measure in a similar way and there you have it, I built my single core using it and they work like a champ.

Since87 · Aug 24, 2003

thorilan said:
the thing is since87 you are adding extra turns so though the same distance and tubes are used its the bend at the end that gives a small bit of resistance.

What extra "turns"? Are you referring to the single additional turn in the bottom plenum chamber of a dual pass heatercore? (I suppose that could be thought of as additional "turns" if you consider the water exiting and entering each flat tube there a turn.)

That additional turn is of very little significance in comparison to the resistance of the flat tubes.

I wrote a spreadsheet to calculate PQ curves for heatercores. Here is a graph comparing BillA's data on four different heatercores, to the spreadsheet's results.

While the Big Momma results leave somewhat to be desired, the other results are fairly good IMO.

The only inputs to the spreadsheet are:

The length of the heatercore
The number of flat tubes in each pass
The ID of the input barbs

It would be extremely unusual for my spreadsheet to match the test data this well, if the relevant factors were completely different than I believe.

thorilan · Aug 24, 2003

thats why i said small bit of difference =)

Giblet Plus! · Aug 24, 2003

wannaoc said:
I am going to get it and build my own shrouds in the same manner used in the article on the o/c front page . I figure just measure in a similar way and there you have it, I built my single core using it and they work like a champ.

I think I'll just reuse my shroud.

Single pass radiator

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