First, if you haven’t read this thread: http://forums.offroadtb.com/viewtopic.php?f=27&t=3955 please do as there are many general cooling system subjects addressed in it as well as explanations of why I’m doing what I’m doing that I won’t repeat here.
So, the radiator. As many have noticed, we don’t have any better aftermarket radiators available for this platform. Ron Davis makes a couple for the SS, and I’m sure he’d move the outlet to the other side for enough money, but they’re already extremely expensive. Even more disturbing is the number of failures I’ve read about on what has to be a relatively small number produced. But if you want a “bolt in” installation as painless as possible, he’s probably your best bet (though it won’t be painless to your pocketbook). Other companies could surely custom make one but it’s not likely to be cheap. A local shop making one so they can simply make it to fit your vehicle may be the cheaper than having one of the big aftermarket companies do it to spec but could vary widely from shop to shop in both cost and quality.
Since there are so many decent aftermarket radiators on the market, I was convinced I could come up with something for much less even if it took a bit of fabricating to install. My 550 HP Camaro street/race car might “rate” a really expensive radiator but I really didn’t feel it should be necessary to spend that much money to keep this puny little 4.2 cool. The stock radiator is so tiny, the bar isn’t exactly very high to find an aftermarket radiator that is dramatically better. So I began looking for radiators on the market that were similar in overall size to our stock radiator. We’re basically looking for a downflow radiator, with the inlet on the passenger’s side and outlet on the driver’s side, with a core roughly 18” high by 27” wide. Unfortunately we can’t really make it taller or wider but we’re free on thickness (as long as the stock fan is removed) within reason.
I found that there are quite a few that are close. In particular, many late 60’s and early 70’s Mopars came with radiators almost exactly that size and they have tons of aftermarket units available. So if you accept it’ll take a little fabrication to install, we really have a large selection from which to choose. As with the fans, the one I chose and the way I chose to install it, etc, certainly isn’t the only correct way to do it but it should give those looking to do the same thing some valuable guidance.
There are what seems to be dozens of companies having “custom looking” aluminum radiators made in China (where many stock replacement radiators are made anyway) at what is likely the same factory, just with slightly differing options depending upon who was importing them. I found that the “factory code” 375 denoted a radiator fitment that works for us. If you search Ebay for “radiator” “375” you’ll see what I mean.
Here is the radiator I ended up with:
http://www.ebay.com/itm/Mopar-Big-Block ... 4a&vxp=mtr
Here it is shown next to stock (it’s really not shorter like that—it’s sitting at more of an angle):
It holds 1 ¾ gallons of water compared with a hair over ¾ gallon stock. Here’s a thickness comparison:
It’s a two row with 1” rows which is a very standard size across the industry used in countless racecars and other high performance applications and my back of the napkin calculations deemed it should be adequate.
Much of what he says on that page about the number of rows is true, but much is advertising of course. You could have a three row with 1” rows and it would be much superior but I do think most of those coming from China will have smaller rows and not be any better. If you want significantly better cooling than this, I think you had better bite the bullet and get a Griffin two row with 1.25” or 1.5” rows (and it should be higher quality as well) or equivalent from some other company—I wouldn’t expect any of the three or four row units on ebay with smaller rows to be any better. If you do get one with more rows, verify the size of the rows and make sure they add up to 2” or more total—many won’t.
I was quite pleased with the quality of this radiator for the price; the welds aren’t quite as nice and pretty as the ones on the BeCool in my Camaro but overall it looked pretty good. It sure looks less fragile than the stock one, that’s for sure. But only time will tell on its durability, I’ve had it on less than a year so I can’t say too much about that yet.
I can confirm this particular one comes with a plate-style transmission cooler vs. the simple “tube in a tube” type on many of the other brands (such as Champion, etc). Though if you get a decent aftermarket tranny cooler that point is largely moot. I’m currently bypassing the radiator’s cooler anyway and using only an external cooler with a thermostat.
If being made in China gives you the willies, there are plenty of other choices out there. Here’s pretty much the exact same thing by Ron Davis (which is likely much cheaper than his Trailblazer radiator):
![Image](http://www.rondavisradiators.com/1-18CH7072T.jpg)
Though as I said, given then number of failures I think I feel safer using the one made in China. A number of these brands that have been around a while (Champion, etc) actually have fairly decent durability reps if you do some googling.
Griffen makes a ton that are very close in size. Here’s one:
http://www.summitracing.com/parts/GRI-5-266GB-FAX/
Also available with 1.25” and 1.5” rows:
http://www.summitracing.com/parts/GRI-5-566GB-FAX/ ,
http://www.summitracing.com/parts/GRI-5-866GB-FAX/
And this one:
http://www.summitracing.com/parts/GRI-5-871GA-FAX/
A slightly wider core and different brackets, also available in other thicknesses. I think that’s the one I’d get (though probably just the 1.25” tubes) if I went with a Griffin, but please do your own measuring/planning using the exterior dimensions from Griffin before buying. They’re very close in size to the one I got but I can’t guarantee they’ll fit exactly like mine. Though once you’re paying that much, you may ask Griffin to at least put the correct inlet and outlet sizes on to simplify installation. Also, I think I’d get a Griffin without a tranny cooler as I really think the in-tank tranny cooler isn’t worth the trouble once you have a decent aftermarket cooler with thermostat (though that’s a subject for another thread) so you could save some money there. So as I said, there are lots of options available for people to choose the quality and cooling capability they feel they need or want.
So how much does a guy need? Is the one I got adequate? Most unfortunately, and it pisses me off greatly, even with all the testing I did in extremely harsh conditions last summer, I still cannot answer that question with 100% certainty.
I thought I could for a while, and the answer was “NO.” During the most extreme testing (sustained 80 MPH Second gear pulls up steep, long mountain passes in 100+ temps) the cooling system was failing to get the job done. However, I later discovered I had a faulty thermostat during all that time—the stupid thing would only open “a crack” and no farther, no matter how hot it got. So naturally, not allowing an increase in coolant flow rate with increased temps (which is its function) was like tying one of the cooling system’s arms behind its back. All those results have to be thrown out.
While this did have one beneficial side effect of making the cooling system hyper-sensitive so the effectiveness of other changes I made to the system could be measured easily (such as changes to airflow, etc), it makes all those test where the results were “less than adequate” meaningless.
Unfortunately, by the time I figured this out and replaced the thermostat the hot weather was done for the year so there was no way to re-do the tests. I was able to do some “room temperature” testing and the results were dramatically better compared with tests done in the same conditions with the faulty thermostat. So I’m very sure it’s “fixed” but I can’t guarantee it’ll pass those same tests until I actually try. So right now, I’m about 80-90% sure this radiator will get the job done no matter what I throw at it next summer, but I can’t guarantee it until it gets hot next summer and I confirm it.
What I can confirm is how well it did in the tests it did well in. If it passed a test with flying colors with a bad thermostat, it’ll only be better with a good thermostat (which is obviously not true visa versa).
In a good demonstration of radiator effectiveness, the exact test I mentioned in the Fan thread—70 MPH, level ground, 80 degrees, fans shut off—it passed easily. Where the stock radiator would send the temps rocketing toward the red, with the only change being the radiator it would stay right at 205+/- in the exact same conditions. With a hot tranny cooler and the AC on, it would run a few degrees warmer but still be stable close to 210 as long as the ground was level (and this was with the faulty thermostat and before any airflow improvements). That’s about as apples to apples as it gets comparing radiators. So it’s clearly a much better radiator than stock.
However, even with the new radiator in the above conditions, add an incline just enough to make the converter unlock (with stock programming and 33’s you don’t need much of an incline) and the temps would climb unless the fans were turned on. But with the fans it was no problem of course.
In extreme temps it did very well at lower speeds/RPM. Where many have problems in extremely hot weather in city driving/stuck in traffic type situations this setup performed beautifully. Even in legit 100+ temps in the shade, in those conditions this setup easily kept the engine temps right in the 205+/- degree range regulated by the thermostat, even with the A/C cranked—which was always nice and cold. So, success there. In these types of conditions this setup proved to clearly be much better than stock.
The only real problems were at high speeds going up steep hills. Pretty much no matter what I was doing, all I had to do was slow down to 60 MPH and it would be fine. But with 33’s, all the added weight and tremendous increase in air resistance I’ve added to the thing, the higher speeds are quite a chore for this little engine. Maintaining them up a steep mountain pass really makes it work. As I said with the new thermostat I’ve only been able to test this in “room temperature” conditions and it has done very well so I think it’ll still do well in hot weather but I can’t say that with 100% certainty yet.
The first test above proves the radiator is vastly superior, so (even with inferior fans) at high speeds where the fans don’t matter as much anymore it should be a much improved setup over stock, exactly what I was aiming for. Unfortunately I’ll need to wait for hot weather to return to prove it 100%.
So I can’t say this radiator/fan setup will get the job done for everybody, I’ll have to see how good it is in the hot weather to give a more informed opinion. If you can’t wait, I’d say if you live in the desert and/or have temp issues mainly at low speed/high RPM towing heavy loads where the loss of fan power will hurt you more, you may want to be safe and go with the 2.5” thick Griffin at least. Installation of the 3” thick might be a bit trickier but I’m still pretty sure it could be done. But that’s such ridiculous overkill I find it hard to believe any use would need that much radiator even with the electric fans. One nice thing about the Ebay radiator I got is it’s so cheap if one has to toss it for a better one you’re not out much money.
But for probably 95% of users out there, I’m quite confident this radiator/fan setup will get the job done. More testing next summer will give me a better idea about the last 5%. Durability-wise, it’ll be a while before I can say too much. I’ve had it on about 6 months now and it hasn’t leaked a drop, so far so good. That has included several 1600 mile highway trips in summer and winter as well as some pretty rough offroading. I also pressure tested the entire system a couple times by letting the engine heat up to the edge of the danger zone with no ill effects. But it is a cheap radiator, so if it doesn’t last forever I won’t be too surprised. There are plenty of more expensive units out there for those who want them, though I have a feeling there aren’t too many people here these days that want to drop such big money on a radiator.