On Mon, 9 Jan 1995, Glenn Mapes wrote:
>
> Hi marc
> I was ver y impressed with the article on preparing an MGB for autocross
> that appeared in the last issue of Motorsports.
> I am hoping you may have some insight on the following question: I have a
> 1968 MGB that needs a new radiator. What I want to do is have the radiator
> recored to save some money. The radiator shop will recore the radiator with
> the 1/4" core spacing (same as stock) or, for additional cooling, could use
> a 1/8" spacing core that is very high efficiency. Is there any problem with
> going to the 1/8" spacing?
Glen there are two aspects of radiator design that affect efficiency.
First is the row design. How many, how closely spaced, are they in line
or staggered? The more rows, the better heat dissipation, is a general
rule, but there are exceptions to that. Given two cores with the same
number of rows, the core with the staggered row design will work better
than the core with the in line row design.
Second is the fin design. What is the fin density? How are the fins
attached to the rows? Are the fins of a folded design, or are the
straight? The higher the fin density the better that core's heat
dissipation will be. It has been my experience that the straight fin
design (fins are flat and horizontal, and run from one side of the
radiator to the other) is much better than the folded fin design (fins
are folded back and forth between one pair of rows in a serpintine
fashion).
The factory MGB core is of the straight fin design and has three rows, in
line. I let a local radiator shop sell me a four row, staggered style
core with folded fins, once. They swore that with the higher row count
and the staggered desgin, it would outperforma my old stock radiator. Not
only did it not outperform my old core, the damn thing ran 20 degrees
hotter than it had with the old worn out, clogged core. I switched to a
fairly good, used, stock radiator I had. Like magic it was running cool
again. Just to make sure (the radiator shop told me I was nuts, that a
four row core will always out cool a three row core) I pulled the stock
rad back off, put their super duper rad back on and my car ran 20 degrees
hotter again. Oh well, take the sucker back off, get the old stock rad
rodded out and put it in my B. Now my car ran 30 degrees cooler with the
stock rad as opposed to the so called high performance rad.
If you can get a core with four rows, staggered, with straight fin
design, where the fin densitity (number of fins pre inch) is the same as
or higher than the OEM MGB rad great. Do it. If they are trying to sell
you a folded fin type core, don't bother. I have been told by a local rad
shop (a different one) that the flat fin style cores are used in large
trucks, so you might have a look in the truck rad catalog (not light
trucks like pick ups, big stuff), for a good core design.
One last thing to remember is that the heavier the coat of paint you put
on the rad, the less effective it will be. I know this sounds silly,
but I have seen resoration jobs where the guy just poured the paint
on. I have also seen guys who respray their rad every year to make it
look good again. They don't clean the old paint off first, they just
pile a load of new paint on over the old.
Thanks for the kind words about my article.
Marc Sayer
Performance Engineering
1070 W. 2nd Ave.
Eugene OR 97402
(503) 484-0904 Fax 746-0863
msayer@efn.org
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