In trying to find a reasonable solution to my cooling problem on my 1970 Buick GS 455 (siamesed cylinders, 0.030" overbore), I did a lot of reading and research on various bulletin boards and other sources. I came up with a simple scheme to rank or rate the numerous radiators. This is a simple, first order, tube-capacity type approach and doesn't consider all the variables (like fin heighth, etc.), but I think it'll get pretty close. The major contributor to cooling efficiency is tube capacity (up to some limit where stacking tubes on top of each other would result in little or no air flow) ignoring other airflow issues like a thick core and high fin count which lead to aerodynamic drag and drive up fan cfm requirements. Heat transfer characteristics of the specific materials were also not considered, as were issues with solder, epoxy, etc. My simple yardstick (index) is simply the total number of tubes, times tube depth (front-to-rear), times a flat/tube factor. This factor (FTR) penalizes smaller (say 3/8") tubes and favors larger (say 1.25") tubes, simply because in a smaller tube, there is less flat area to bond to the fins as opposed to a larger tube where there is more flat area and less area having no useable bonding area due to the ends being curved. In other words, there is more useable flat area on a single 1" tube than there is on two 1/2" tubes. It is calculated by dividing the total flat length by the total tube length. That being said here is my table, ranked by index: type #tubes tube length" tube-ins FTR index Griffin 78 1.25 97.5 .95 92.6 RonDavis 86 1.0 86 .94 80.8 RodneyRed 86 1.0 86 .94 80.8 BeCool 82 1.0 82 .94 77.1 Howe 82 1.0 82 .94 77.1 GDI3VX 135 5/8 84.4 .9 75.9 AFCO 80 1.0 80 .94 75.2 Griffin 78 1.0 78 .94 73.3 5HER 225 3/8 84.4 .83 70.0 PRC 70 1.0 70 .94 65.8 AC20778 46 1-7/16 66.1 .96 63.5 3X2K 135 1/2 67.5 .87 58.7 4HER 180 3/8 67.5 .83 56.0 4STD 120 1/2 60 .87 52.2 3HER 135 3/8 50.6 .83 42.0 3STD 90 1/2 45 .87 39.1 Notes: 3STD is the 3-row standard core (GM, Harrison, Modine, etc.), 1/2" tubes on 9/16" centers (vertically), 30 rows of tubes in a 16-7/8" tall core, 3 tubes per row, copper-brass (CB). 3HER is the 3-row GM High-Efficiency "HE" (or Modine "H", or GDI "VE") core, 3/8" tubes on 1/2" centers, 45 rows, 3 tubes/row, CB. 4STD is the standard 4-row, 1/2" tubes on 9/16" centers, 30 rows, 4 tubes/row, CB, like the Modine 1R365 or GDI 43-3165. 4HER is the 4-row GM HE core, CB, like the Modine 3R12353 or GDI 43-6015. 3X2K is the Modine 3-row X2000 core, 1/2" tubes on 3/8" centers. Available as a complete radiator only, 1R2332, CB. AC20778 is the AC-Delco 20778 (GM "P" truck) aluminum (AL) radiator, 1-7/16" tubes, 1 tube/row, also GDI 43-1363. PRC is the streetrodstuff AL rad, 1" tubes on 1/2" centers, 2 tubes/row, AL. 5HER is the 5-row GM HE (or GDI "VE") core, CB. Griffin is either 1" or 1.25" tubes, 2 tubes/row, AL. GDI3VX is the Go-Dan VX core, 5/8" tubes on 3/8" centers, 3 tubes/row, CB. Howe is a AL 1" tube core, 2 tubes/row. Be-Cool is 1" tubes, 2 tubes/row, AL. RodneyRed is 1" tubes, 2 tubes/row, AL. RonDavis is 1" tubes, 2 tubes/row, AL. Issues: I was quoted 1/2" vertical tube spacing and about 70 tubes by D. Z. on the PRC rad, can anyone with one confirm? I would guess that there are more than 70. The tube count on the AC20778 is a guess, starting from an estimated 3/8" tube spacing, can anyone with one confirm? Tube count for standard type core came from the Rodney Red website and is the same as the calculated count based on the 9/16" spacing. Griffin and Howe tube count were provided by the manufacturer. Be-Cool, Ron Davis, and AFCO tube counts came from a photo. Rodney Red tube count came from their website. Some sources have stated that 2 rows of 1.25" AL tubes have little or no advantage over 2 rows of 1" tubes, reasons were aerodynamic drag due to the thickness of the core and that the first tube transferred so much heat that the second tube was being heated up. It's interesting to note that the highest indexed CB unit is the GDI3VX. If anyone feels this data may be in error, please feel free to offer corrections, suggestions, comments, flames, etc.
I didn't include cost but the aluminum ones are usually more expensive. You can get "universal" type aluminum units from Jegs or Summit for $200 - $300. You can get the AFCO from ebay (new) for $200. But universal usually means some sort of fab or mod work to drop it in. Custom dop in aluminum units are $400 - $600 depending. I will probably go with the GDI VX core.
I just took my factory 3-core radiator to my local shop and they made up a 4-core radiator with hi-efficiency fins (15 per inch instead of 12). My car has about 500 hp, is a 462. With a 180 thermostat, my car stays rock solid on 180 degrees. I do put RedLine's water wetter in there. But I've never had any kind of trouble with overheating at all, not even at the track. Cost was about $210 or $225. Money well spend, IMO. There was also someone on ebay selling aluminum ones for our cars for about $275 if I remember right. Do a search and it should pop up. It was discussed about two or three months ago. I'll look and attach if I have time. Here it is: http://www.v8buick.com/showthread.php?s=&threadid=9741&highlight=ebay+aluminum+radiator
Did some price checking and listed below is what I found. Most were universal fit types, custom were usually higher. Also listed is part number and source: Griffin1.25 $295 55272 summitracing.com RonDavis $219 rondavisradiators.com RodneyRed $435 rodneyred.com Summit $180 380331 summitracing.com BeCool $290 65003 summitracing.com Howe $200 342E summitracing.com GDI3VX $350 local AFCO $170 80102N ebay.com Griffin1.0 $190 25272 summitracing.com 5HER $350 local PRC $325 100021 streetrodstuff.com 3X2K $361 1R2332 carparts.com AC20778 $187 (52479539) gmpartsdirect.com 4HER $240 43-6015 autozone.com 4STD $216 1R365 carparts.com
