Stuka wrote:MJMadness wrote:Stuka wrote:The OEM radiator has the output on the wrong side, so it will not work. Plus a cross flow aluminum radiator cools significantly better.
What issue did you have with novak? Everybody I know has had a good experience with them.
I dislike arguing on the internet, but there's no reason a cross flow radiator will cool better than a comparable up or down flow, although down flow has the inherent disadvantage of placing the radiator cap in what is probably the highest pressure point of the system; one can mitigate that issue if needed. A double pass (or more) cross flow radiator often will underperform a single pass radiator as the delta-T is the major driving factor on heat transfer, and the design of a double pass tends to lead to the least amount of radiator area being exposed to the highest delta-T; however the design may pick up some efficiency in regards to increased turbulence, but that's not normally the case.
The majority of OEM LSx radiators come in two types, up flow if the ports are on the same side, or single pass cross flow if the ports are on opposite sides. If it is a single pass they will use a long upper radiator hose.
I can see the upturn of the lower port being an issue with the OEM Jeep radiator. It might be hard to find a hose that would work with that and clear the fan. At this point in time I am not interested in using the OEM style radiator, so scrap that thought. I found a universal one made by Griffin that I think has some promise, and Griffin is IMHO one of the best aftermarket radiator manufacturers, however I am going to continue to look before committing. I've also found a bunch of Chicom Fleabay specials that would probably work fine, but build quality will vary... Neither of these options will use the OEM mounting system, which I am happy with as it is easy enough to build a cradle/tabs, and the OEM mount system doesn't seem ideal from the perspective of stressing the radiator if/when the body moves around.
Ideally I would rather use an OEM part from another vehicle, and use as few 'one off' or modified parts as possible, thus meaning replacement parts should be readily available in the future or in more remote locations. Hence the Trailblazer radiator is so attractive. I am concerned that it will not have the capacity to cool the engine with what I plan to be doing (big heavy truck with brick aerodynamics), although both the 6L and the high-zoot Trailblazer SS use that exact same radiator.
I'm not getting into my issues with Novak, it's water under the bridge.
A cross flow outcools an old style vertical flow in most cases.
The longer the coolant is in the radiator, the more heat is removed. In a cross flow the water travels width wise, meaning it has more heat removed from it. The novak radiator is a dual pass cross flow radiator on top of that. And there are chinese radiators that will work that are also dual pass cross-flow radiators. So it doesn't have to be a novak. Several here run the chinese ones.
This is why a dual pass radiator superior. As you can see in the diagram, the water is in the radiator for twice as long, meaning more heat is removed.
Pretty much every new high performance vehicle uses a dual pass radiator. I actually cannot think of any offhand that do not.
And I understand your point regarding delta-T. And there are cases where a dual pass may not work as well. The engine needs to be worked harder for it to pay off. But every design has some downsides.
See bolded.
Absolutely, the longer the water remains in the radiator the more heat will be removed from it. However, the issue is that the water is always flowing (assuming at operating temperature), and the rate at which it loses heat is primarily driven by the delta-T between the water (coolant) itself and the metal components of the radiator (which the temperature of is driven by the delta-T between the metal itself and the ambient air, but let's ignore that there's multiple layers of heat transfer for simplicity), and the water is ALWAYS picking up more heat (energy) while in the engine (as long as it is running). This relationship of heat loss vs delta-T is a exponential; when the difference is large the heat transfer is very fast, but when the difference is small the heat transfer is very slow. You can simulate (and I will use black and white units of temperature here) this simply by taking a glowing hot piece of steel and plunging it into a bucket of cool water; the steel will almost instantly go from 1300*+ to 400*~ (boiling, but black and scaling), and then much slower cool from 400* to below 212* (no longer boiling, only a few seconds to a minute depending on the size of the piece), and then much slower down to the ambient 70* of of the water (may take several minutes or much longer for a large piece). By forcing the water to take the longer route from one end of the radiator to the other, and then back across it again, the area in which the delta-T between the water and the radiator (or ambient air) is greatest is largely reduced. On a hot day you may see a 110* ambient temperature on the blacktop, and a thermostatically regulated outlet temperature of 200* from the engine. This means as the water hits the radiator there will be reasonably a delta-T of 90*, which is a large difference. This difference will rapidly reduce as the water cools; if the water loses 45 degrees crossing the radiator we have now halved the delta-T, and on the returning pass we will be lucky to see it reduce by 1/3rd of that (15*). Comparatively if you use a single pass radiator, you have twice the surface area to perform the initial maximum delta-T heat transfer, plus while maintaining the same flow rate the water is actually moving at half the velocity, meaning it still has the same amount of time spent in the radiator.
I also have to point out that flow is a good thing, or at least almost always it is. Flow is what stirs the coolant in the engine, as obviously the block/heads of an engine do not heat in any way evenly. If you have limited flow you will produce hot spots where the coolant in boiled; the LSx engines have provisions to help deal with this (steam tubes), but this is something that can largely be mitigated by keeping the coolant flowing. The long dual pass radiator WILL produce a larger restriction to flow than the same sized single pass; if you need a visual for this go to McDonalds and order a McDrink and ask for two straws, firstly take a drink with both straws side by side, then jam the two of them together lengthwise, bend them 90*, and take another drink. It will be much easier to take a mouthful of that tasty beverage with the two straws beside each other. Okay, maybe that analogy wasn't as good, I don't bat 1000.
Dual pass exists for two reasons. Marketing and packaging. For the LS with the outlet/inlet on the same side of the engine, packaging is a reasonable reason. Same if the radiator might be a goofy size, or it's another engine with same side outlet/inlet, or rear/side mounts, etc. Almost never will it make sense otherwise; see comments about turbulence, you can have issues where you induce what is essentially laminar flow within a single pass radiator, that is where the water is not mixing and only what is immediately contacting the walls of the radiator core is actually cooled. This scenario is rare, most radiators are simply not built 'clean' enough to allow for this to happen, along with the inherent turbulence from the water passing the vanes of the water pump, and through plumbing, thermostat (if in an older engine), etc. Otherwise they're common for the marketing reasons, because the guys with two teeth, a mullet, and a 'chebby three-fiddy for bolt mane with camel hump heads and a 3/4 race cam' saw Dale using that BEEP and thought it was a good idea, or the guys who sell radiators at the time knew they could make a few extra bucks pushing this 'latest advance' in radiator technology. Lots of racing teams do not use dual pass radiators, I can absolutely assure you that, hell sprint cars almost universally still use up/down flow radiators, most of the KOH cars aren't unless it packages better, and if you call Griffin and ask (they charge more for a dual pass) they'll tell you not to unless you need it for packaging...
But, I'm perfectly happy to agree to disagree. I won't order the Novak radiator, if there's another option I'd be happy to look at it.
