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850 Posts
Discussion Starter #1 (Edited)
I’ve been thinking about RZR cooling for some time but have put off this post off for months. If for no other reason I knew it spears a few myths and I‘d elected to avoid the whole thing. However, with recent discussion on intercoolers and several recent posts about over-heating I’ve decided to go ahead and post this. As always, this is mostly for my own thought clarity when I move on to other things. However, hopefully this also helps others too. I know I had a number of surprises in some of this, and I expect most of you will have a few too!

Most of this is fact supported by the links I’ve included, yet there are a few opinions snuck in too. There are also some things mentioned that I consider obvious enough to not need supporting links.

A favor please? I’m certainly fallible, but I’ll take is as a favor if before you suggest I’ve made mistakes (not just possible, but inevitable) or you elect to debate because you think you're right:
  • Read the reference links, the post, and do some of your own research first.
    • I hope I have a good reputation for chatting with:
      • Those do the research and want to chat at a peer level.
      • Those that ask for help.
    • I tend to, or eventually will, ignore those that want to argue but won't make the effort to ramp up.
  • Please remember correlation is not causation: “I wrecked my car in May” does not mean “May causes car wrecks”. “My ’04 Edsel overheats when I take out the thermostat” is also a correlation, not a causation. However, “because the water pump cavitated and took out my plastic water pump impeller” is a causation, as would be “I didn’t replace the housing gasket and the system couldn’t build any pressure”.
  • Play along in limiting stories - Telling this forum you run Coke in your radiator and “it works for me” is someplace between a story with no supporting science and a sentence that needs “so far” or “that I can tell” added to it. If you can explain why it’s a good idea, or why it flies in the face of normal best practice please share!
  • At the same time there are lots amazing folks here with great experience and incredibly useful insights, so this is a balancing act I leave in your hands. (of course there is always one...)
I will have certainly overlooked something vital. I’ll do what I can to make corrections to these first few posts as my inevitable oversights and mistakes come up. (errors and significant additions will be made in blue, at least for a time.)

Links if you want to dig deeper or see for yourself:

Post Topic Order:
Intro (post #1)​
Terms, Acronyms, and the "Disclaimer" (Post #2)​
Myth and Facts (Post #3)​
Intercoolers (Post #4)​
Overheating Tips (Post #5)​
What I’m thinking for my XPT (Post #6​
Performance Implications (Post #17)​
Misc Content or Learnings (Post #18)​

I hope you’ll find this interesting!!

850 Posts
Discussion Starter #2 (Edited)
Delta T:
Change in temperature. Lower delta t reduces radiator effectiveness.

Coolant Freeze Point. The temperature at which a coolant jells, but does not expand or become a solid.​

Coolant Burst Point: The temperature at which a liquid expands and becomes a solid.​

Just be aware water is the best commonly know liquid as regards heat capacity, and is “1”​

Ethylene Glycol, used to affect FP, BP, and boiling point. Heat capacity rating of .573, or 57% that of water. Highly Toxic.​

Propylene Glycol. Less heat capacity than EG, but not toxic.​

Waterless Coolants: (eg Evans):
The one and only time I’ll even mention them is here. Horrible heat coefficients, useless for us.​

Equilibrium Point - The temperature at which our engine BTU creation equals our cooling systems heat dissipation capability.​

f or F:
Fahrenheit. F is more accurate in single digit precision than Celsius simply because the f is a small unit of measure.​

c or C:

HOAT and etc:
Coolant types. HOAT itself has several grades, although we’ll care only about G-05. I’ve included some reference links if you want to dig deeper.​

Cylinder head temperature. One of two fairly important temperatures, and while it is affected by coolant temperature, CHT is typically higher than the measured water temperature.​

Surface area:​

Air Intake temperature​

Charge air Cooler - I’m using this to be clear we’re not talking about the intercooler radiator.​
There are a few types of readers I should caution:​
Some owners are by virtue of their mechanical experience, their risk/reward preference, or simply a KISS philosophy, better off following their owners manual. No harm in that, and this post will still have a few area's of value to you. Only you the reader can judge that.​
However, this post is most benefit to those that buy ECU tunes, look for better (not cheaper) oils, and are endlessly tinkering to make their machine "better".​
For the latter I remind you there is also an implicit need to suspend some of what you thought you knew. As I researched this I learned a number of things that required me to reset what I thought I knew. Fine with me, but I expect there will be those that can't accept some of these facts, yet won't take the time to bring ramp up to the subject matter either. No harm, but you're not going to gain much from this if you can't "make the leap" either.​

850 Posts
Discussion Starter #3 (Edited)
  1. Normal Operating Temperature - Fact
    1. I suppose there may be some variance between models, but in general our thermostats begin to open at 180f and are fully open by 203f. This sets our “normal range”, for we’re not at full cooling capacity until 203f (why yes, I would like a 170f thermostat).
      1. This doesn’t mean YOU will run at 203f, for we usually reach BTU equilibrium between engine and cooling system before then. However, you’re not “over-heating” nor out of cooling capacity before 203f.
      2. This means any report of ‘I did “XYZ” and my engine runs 10 degrees cooler” doesn’t mean you “fixed” anything “wrong” unless you were over 203f to begin with. You have only altered the EP.
        1. This is not to say lowering the EP doesn’t represent improvement. Anything that lowers radiator water temps should both reduce the EP and give us more reserve cooling capacity.
  2. Poo Coolant - Fact
    1. The current Poo coolant for our RZR’s (XPT) is #2880513. However, an older coolant used in at least some RZR’s is #2871323. Why do we care?
      1. The older was mixed, and installed in some RZR’s, at 60% EG. Todays its 50%, and most of us could use 33%! (more later)
      2. The current coolant, #2880513 is advertised as an OAT. Looking at its SDS its apparent (color and chemical composition) this is really a G-05 HOAT coolant available almost anywhere.
      3. Poo coolant is an EG, not a PG.
  3. Coolant - Myths (These are important, but it might also be time for the "I only follow the owners manual" crowd to get off the bus)
    1. Most of us believe the advertised “Freezing Point” temperature of our coolants is the point at which our engines may suffer damage from coolant expansion. Cracked blocks and etc. However, that’s not true.
      1. Gycol mixes don’t transition to a solid the moment they freeze like plain water does. They first turn into a slush. This “slush” temperature range varies but it’s usually quite large. Large enough most of us should be disregarding FP and using the unadvertised BP.
        1. Granted an engine should not be started while in coolant “slush” state, for coolant won’t flow through the system. Nor can slushed coolant be heated up by the engine (won’t flow), and in all probability the water pump(s) would be damaged.
        2. However, damage to a non-running engine doesn’t occur until something known as “Burst Point”. Lets take a look at a comparison table and see what we can learn:
          1. 655557
          2. We can see that coolant mixtures past 40% offer no additional engine protection from coolant expansion damage (BP).
          3. The reason most of us run coolant mixtures above 30% is to allow us to start and operate an engine (must be at FP or above) in freezing weather.
            1. But lets not forget we need at 25-30% to protect from corrosion and etc..
          4. Would you be one of the many that don’t run our RRZs in sub-zero temps? That BP protection only needs to be to -30f? (about 33% EG)
            • Great! At 33% EG to 67% water you’ve improved your radiators cooling capacity by 10%.
              1. You’ve just substantially improved the performance of any surfactant you add too! I project something like 13f reduction is possible just from the surfactant.
                1. Can you imagine what the ’16 XPT turbo owners are thinking right now?
    2. Many test antifreeze mixture with Hydrometers.
      1. As it turns out they can be quite inaccurate. A more accurate tool is called an antifreeze refractometer. Here’s the one I’ll buy this winter:
        1. Amazon.com: Robinair 75240 Coolant and Battery Refractometer: Automotive
      2. If you’re going to be playing the BP vs FP game I encourage you to be using an accurate tool!
        1. Since BP is a critical temperature, I plan on mixing to a -10f FP even though 0f is all I need.
          1. Just measurement error insurance.
          2. Should be 37-38% EG.
    3. Antifreeze wears out and has to be replaced
      1. Not really, but sorta. FP / BP / Boil protection is permanent. The anti-corrosion, seal lubricants, and etc. age out though, and so they need to be replaced. A G-05 grade EG mix should be replaced every 5 years, or a booster added.
      2. Was I running a reduced EG to water mixture I'd be inclined to change my coolant every 4 years just to be safe.
  4. Removing a working thermostat causes overheating, and/or “the water is going too fast to cool efficiently” - Myth
    1. I read this too often, and it’s simply not true.
      1. There can be other factors that may correlate and thus it appears the thermostat caused over-heating, but in fact water flow directly improves cooling.
        1. Obviously not as well as more airflow!
        2. In fact, small amounts, say a 20% increase in coolant flow, aren’t going to accomplish much.
        3. Notice however the curve steepens as water flow drops, and as air flow increases. Clearly you don’t want to be at low water flows if you’re over-heating.
        4. 655558
  5. Removing a properly engineered and working thermostat helps cooling - Sorta
    1. Despite above, and the fact that its potentially true, it’s not usually a good idea either:
      1. A thermostats primary purpose is to allow an engine to attain and maintain EP within optimum operating temperature (or more quickly) through dynamic adjustment of its opening.
        1. Most cooling system have some form of thermostat bypass. Better systems, like in the XPT, have a dynamic bypass that closes bypass flow as the thermostat opens.
          1. Allowing better CHT control = more timing = power.
          2. More cooling as we can close the bypass if needed.
            1. If the rest of the system can get rid of the heat.
      2. Pump cavitation can occur if the pumps see negative water pressure before the impeller. This can be destructive to the impellor and/or pump housing, and of course hurts cooling flow. Thus, a thermostats secondary purpose is to limit flow such that there is some back pressure on the pump.
    2. Clearly the loss of the thermostat removes dynamic adjustability thus removing engine temperature (including oil for the XPT) optimization and will either create cavitation problems or require a small full-time restriction. (looking at you HCT).
    3. Why anybody wants to run at non-optimized engine temperatures I leave to you. Personally, with ever tighter machine tolerances, I believe engines are best run in a controlled and relatively narrow operating temperature.
    4. Yes, I know I’m going to hear lots of “It works great” comments. Water cooled engines use thermostats almost universally, but if you’re convinced you know more than those engineers have at it. In advance, I’m letting those comments pass to others who may care to debate it.
  6. Airflow over your radiator can go too fast and hurt cooling - Myth
    1. Nope, see chart above. Air flow is more important that water flow (but SA will always be king)
  7. A deeper radiator creates more SA and so is as effective as a larger radiator – Kinda Myth
    1. No. Cooling efficiency drops as delta T drops. Thus:
      1. A radiator cools better as the engine gets hotter (assuming ambient remains the same delta T increased)
      2. A radiator cools worse as ambient temperature increases (rats)
    2. So frontal surface is a sort of 1:1 improvement, but fin depth is not as cooling media (usually air) gains heat as it passes down the fin reducing delta T.
      1. Fin depth is certainly the next best thing.
      2. SA isn’t really 1:1 either, as the water (usually) is also cooling as it passes and again delta T drops. But this a “single” delta T hit, not double (as it would be in fin depth) as the cooling media (air) didn’t increase in temp.
  8. Increasing fin quantity, assuming drag doesn’t matter, is generally very beneficial, but to a point - Fact
    1. Optimum qty per inch differs slightly by design.
    2. Is affected by tube size/flow as well. (more water flow equal more delta T equals higher returns on cooling).
      1. But affects airflow qty and resistance, so this too must be balanced.
As for optimum design then, of an air to water radiator, one would generally think that:
  1. Radiator frontal size is the most important, followed by fin depth.
  2. Optimized fin quantity is important so long as airflow resistance does not matter.
  3. Available air flow (volume and speed) has a significant affect. (and is often all we can address easily)
  4. Increasing water flow helps but is clearly at the back of the bus relative to SA and airflow.
Let’s not forget the implications of air density (altitude and air temperature) on cooling systems:

And of course we’ve not talked about coolant decisions yet, and that gets interesting too.

850 Posts
Discussion Starter #4
The pursuit of reduced AIT (air intake temp) at intercooler egress is oft talked about, but at what expense to boost pressure? While most of this discussion holds true for an intercooler radiator, for the CAC side one must also balance the fin design (style, qty, depth) over airflow restriction and resultant loss of boost. Even then, at what flow? A 170 HP engine may not demand enough flow to see significant pressure loss. A 240hp engine very easily could. Intercooler selection and testing then becomes a question of:
What is AIT temp drop (using the same water-cooling temperature and flow!)
At what CFM airflow?
At what airflow restriction (and corresponding pressure loss)
What is the water GPM of the IC? (more is better)
If too low it will heat soak the IC water, yet this could easily be missed in testing.

Of course it’s hard to lie to a dyno, and so I’m grateful for unbiased dyno any testing vendors are doing. Still, without addressing some of the above, and at CFM’s pertinent to those making such investments (typically the 200HP and up crowd), the information will have reduced value.

Question: Why does nobody offer a higher volume electric water pump for the IC side of the XPT? Sure water flow is back of the bus, but its also a bolt in upgrade. Perhaps it’s already pretty high and to make substantial improvements would require too much power? Or cost?

850 Posts
Discussion Starter #5 (Edited)
Overheating seems to come from five basic sources:
  • Inadequate capacity.
  • Blocked or degraded airflow.
  • We’ve reduced the effectiveness of the coolant.
  • We’ve lost water flow.
  • Lost pressure.
The ’16 XPT is an example of inadequate capacity. Poo elected to sorta add more airflow to the ’16’s (larger fan as I understand it), then correctly added more surface area to ’17 and up. The aftermarket added more surface area in various way (frontal, fin quantity, depth), and many enterprising folks added more cooling capacity via an oil cooler (for which the principals above apply) (I wonder how many problems would have been avoided running 33% EG?)

RE: Oil Coolers to increase capacity - I’m not getting into this here, for there a number of really good posts already on this. I do think any design needs to balance these aspects:
  1. Cooler Orientation:
    1. Line “Up” means you don’t have cooler fill issues at engine start, but then oil changes aren’t complete then.
    2. Line “Down”, aside from the reciprocal of above, adds “how much oil does it really take” to the equation.
  2. Flow.
  3. Reliability.
  4. Excess Cooling: In an XPT, where we have a water to oil intercooler, that’s mostly a non-issue. However, keep in mind a truly cold start is going to have to overcome a lot of remotely located thick oil in line “up” design. While a “bypass” oil filter can help here, not if it’s in line and past the oil cooler! Here the “sandwich” adapter is preferable to the fully remote. Meanwhile fully remote has ease of maintenance filter size on its side.
Personally, I’d make an additional oil cooler a “no other choice” kind of thing, much as the ’16 XPT guys did. But, after playing all other cards, an oil cooler is a highly effective solution.

Finally, there is a way to reduce cooling capacity requirement: I didn’t test for it, but I feel engine temps dropped as a result of eliminating the CAT when I build my new exhaust. I believe I reduced backpressure and exhaust heat, both leading to more power, which in turn led to less throttle opening for the same power settings. So yea, less heat created per HP, less heat retention, and less heat added to the CAC process. Add those up and why I felt like I was running cooler should ring true.

Blocked or Degraded Airflow:
By now it should be obvious that’s the kiss of death, so if you’ve over-heating concerns this is the first thing to look for.
  1. Blocked Airflow
    1. Have you placed something in the way?
      1. Can you move it? (This is a common, and fairly significant, mistake)
      2. Can you place a wing, duct, or air diverter to get air pointed back to the radiator?
    2. Ducting Sealing: Is there a way to gap seal the existing airflow so it’s forced past the fins rather than around the radiator?
  2. Dirty:
    1. Get the fins clean, but don’t bend them!
      1. I'm thinking Bar Keepers Friend right now. More if I hear back from them.
Coolant Effectiveness:
  1. Water is man’s most effective coolant. If you need not fear freezing, consider replacing your coolant with lower mixtures of antifreeze (refer to the “Coolant Facts” above)
    1. Realize we're leaving the safety of your owners manual here and getting into "at your own risk" area's.
      1. None the less, this is absolutely tried and true, as well commonly accepted practice.
    2. As an example, a 30% EG mix, the lowest you can go without corrosion concerns, should give more than a 10% cooling capacity increase.
      1. A wise man would add a surfactant to also help cooling, and to increase his corrosion and seal protection.
  2. All coolants are not alike:
    1. Ethylene Gycol based (EG), while toxic, has a higher heat capacity than Polyethylene and is preferable in a heat problem situation.
    2. Being north american based I see no reason to reject Phosphates (G-48), and I’d rather have those than silicates due to their more abrasive nature. That said I suspect a low silicate HOAT is just fine though.
      1. Of the EG’s, I discourage OAT, think HOAT is fine, and mildly prefer PHOAT formulations.
    3. I believe the current recommended Poo coolant is a G-5 HOAT EG coolant and don’t know that I see a reason to change despite my preference for P-HOATS.
  3. Water wetting agents (surfactants) improve water’s cooling effectiveness.
    1. Cooling System Additives - Turbo and High-Tech Performance Magazine
    2. I can find nothing compelling contrasting RP Purple Ice / HyperKuhl (same product) vs Redline Water Wetter performance.
      1. There is a concern w/ WW and “slime/sludge” creation with some coolants. Redline is aware but has no identified coolant that doesn’t do this. I’ll have to use something else.
        1. At this moment I plan on using Hy-Per Cool Super Coolant / Rislone Super Coolant.
      2. Such surfactants are well known, and resolve corrosion and seal concerns, even if you run 100% water!
        1. Read the instructions. Some ask for a refresh of the surfactant annually. Corrosion/Seal protection is why.
  4. How old is it? Old enough that scale or deposits might be forming? Time for a good flush and clean.
    1. While what water type has been battled over the years, best practice seems to have settled on RO water. Helpfully, Reverse Osmosis water is often sold in stores at “fill your own” stations.
  5. What of Altitude:
    1. It has no impact (aside from it can be colder) on freezing points, and altitude is addressed in a sister post, but keep this in mind: As we loose atmospheric pressure the relative pressure to our radiator drops (the radiator cap references against external atmosphere)
      1. This isn't tragic, but know that at 10,000' we've reduced your boiling point by as much as 20f.
        1. Once again the guys at altitude are in a tough box.
Water Flow:
  1. Are the lines and tubes still good?
  2. Coolant needs flow to be effective. Any chance the pump blades have eroded?
  3. And what of higher capacity water pumps for the engine? They aren’t as good as more airflow, or larger SA, but what if those cards are already played?
    1. https://bikemanperformance.com/mo-flow-water-pump-for-rzr-900-1000-and-turbos.html
    2. I’m a little surprised the 900 and the XPT use the same water pump. I’d have expected an attempt to push more water through the engine.
      1. A 20% water flow improvement won’t make much difference (look at the chart), but if there is nothing else and a few degrees will help….
  4. What of air trapped in the system preventing even water flow?
    1. A leak, an over-heat, even regular maintenance might leave an air bubble trapped in a coolant jacket.
      1. Your service manual will show you where and how to bleed air from the engine.
      2. Or use a vacuam driven pump to draw out trapped air. Perhaps like this one:
        1. Amazon has lots of them: Amazon.com : coolant vacuum refill kit
        2. Harbor Freights: Cooling System Test and Refill Kit
Lost Pressure:
Ugh, the one nobody wants: Blown or poorly sealed gaskets, bad radiator caps, leaking coolant lines and/or fittings, even holes in radiators.​

Many of the refill purge kits can be used to test for leaks. Otherwise pressurize the system and try spraying soapy water on suspects.​

850 Posts
Discussion Starter #6
So, what am I doing with my XPT as regards cooling? This winter I will be:
  • Working on my DIY split tank
    • Obviously I’m chasing reduced CAC temps / lower AIT here.
  • Flush, from the back, radiator fins after pre-soaking with Barkeepers Friend mixture
  • Draining both systems and refilling with EG G-05 HOAT to 38% EG: 62% water.
  • Adding a surfactant, probably Hy-per Lube’s/ Rislone’s Super Cool to both systems.
    • I’m chasing CHT reduction with the last two. I don’t overheat now, but I do sometimes get caught with lower octane fuels being all I can get, and the combination appears to deliver a 2 point octane requirement reduction. I’ll use that as a safety buffer, but it will be a relief having it.
  • Look for what I can do to seal the radiator ducting to force more air through it.
  • I’m going to think about a manual “Fan On” too. Present ECU settings of “Fan Off When Engine Running” at engine jacket water temp drop down to 190f is fine, but I certainly don’t like “Fan Off When Engine Off” is at 230f and below.
    • At break time my cool-down routine is to shut down when I see running water temps get below 190, then briefly restart a time or two, but I would really like to keep the fan on for quite a while longer.
    • This is complicated by the fact that I care about radiator water temp, and I suspect the temps Poo is monitoring is engine water jacket temp.
  • For now I’ve elected to drop oil cooler thoughts. I see more benefit from optimizing the existing system, and since I’m not at, or likely near, capacity I can skip it for now.

846 Posts
The only time my temps increase over 200 is during deep powder snow bashing; high rpm and low speeds combined with radiators getting packed with snow. Other than that I believe my 2018 XPT has been perfect in every other condition. Even more so with the AA tunes running the fan at a lower ON temp. For the most part I am 189-195degrees.

With that said I'll do a coolant flush this Fall and switching to Rotella ELC. From the diesel world it's fantastic stuff and anyone with a Powerstroke 6.0/6.4 knows how rugged and how well it works. What does that mean for a 2 cylinder boosted UTV engine? Probably not much, but I know it works and works extremely well.


850 Posts
Discussion Starter #10 (Edited)
Yea, I know right? I almost called it "What I did during quarantine" :):unsure::)

And I know I'll get a few "you're over thinking this". But here's the (two) things:

1) There are a lot of really good guys on this forum offering their experience to others just because. You, RW, Kevin, Dune, 185, Fling, and the list goes on. But once is a while somebody will take a few disjointed facts, connect them in maybe the wrong way, and share a flawed answer.

I don't like to tell people like that they're wrong, and I really loathe the whole classless "oh yea, prove it" kind of thing. Instead I try to just lay out the fact, and all the surrounding facts, so folks can see how it all fits and in turn reach their own conclusions. If along the way I clear up some myths then cool, maybe I've helped.

But yea, it can get interwoven pretty quickly.

Finally, I blame you, RW, Kevin, and etc.. And TV. See, we've talked about oil oolers, and split tanks, and intercoolers, and cooling and AIT, but my mind doesn't do that well. I need to see big picture first. And well, TV just sucks. So I read what interests me, and then I chase something related down, and then do it again,and well, this is what happens.

Hopefully it helps somebody. I know I straightened out a lot of my thinking on cooling doing it, for I at least was surprised by a number of twists.

All the best,


135 Posts
I think this is the best engine cooling write-up I've ever seen. No BS. Just facts with references.

Moderators need to create a new technical category like "Engine Cooling" and make this a sticky.

135 Posts
One concern regarding "coolant effectiveness" after reading this thread: Engine temps

The numbers vary by source, but a 50/50 solution provides freezing and boiling protection from -34F to 265F. My Polaris owners manual states to use a 50/50 ratio. Some manufacturers specify what the ratio should be or give you a range. For example, I read where Ford states "DO NOT ALLOW the concentration of antifreeze/coolant to fall below 40% or exceed 60% as engine parts could become damaged or not work properly."

I wouldn't post to the masses recommending running anything other than a 50/50 mix for two reasons. One, barring extenuating circumstance, it's masking a bigger problem. They need to focus on the root cause of the issue. And two (wrong, right or indifferent), it can give the dealership reason to deny a warranty claim. Peeps should follow the manufacturer's recommend ratio.
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62 Posts
And dont block radiator with light/s..lol. I added 4 extra holes in grill to aid in airflow. The hottest it's been is 204*.

99 Posts
Well, I ran Pepsi in mine because I heard that Coke would eat it from the inside out. I saw it on the interwebs. It's been working...so far.

850 Posts
Discussion Starter #16
My thanks for all the kinds words and the likes guys! Sincerely.

You bring up an interesting aspect. There indeed are those that have no business leaving the warm embrace of the owners manual. I can't think of a post I've made that was intended for that audience, but your point remains well made.

At this moment I'm leaning towards modifying the coolant mixtures section a bit too, for it would seem that's not quite clear enough also.

I'd mentioned I'd pushed this out to help a few forum members. Aside from poor proof-reading, there are some holes that need filled, and a section I'd not written yet. So, let me say these things:

Edits I make for clarity (like comments I'll add about some folks following the manuals), typo's, and what have you I'm just making.​
Edits I make to add content I deem of value to a section already posted , or to correct informational errors, will be made in blue and kept that way for a few weeks (at least).​
I'm going to drop now a placeholder post or two that will, when I get it written, hold a section to be entitled "Performance Implications". I suppose I'll use a bible reference or something as a placeholder.​

850 Posts
Discussion Starter #17 (Edited)
Performance Implications:

This particular section will look at:

An extension of some of Redline's WW link's and some information I may have to gain more support for you on regarding:

* CHT & implications on timing and Octane.
* Air density and how it affects performance (while always true, for XPT owners this matters more)
* ??

FYI, I'm get to go riding next week and will be gone for 5 days so this topic, and this post, is about to sit for a while. I'll be back (well, I hope!)

850 Posts
Discussion Starter #18
Job 13:5

For now though, I'm going to place a few random thoughts here that I may move back into the main post:

Radiator Cleaning:
  1. Radiator Genie looks to be a decent way of de-junking between our fins.
  2. For gunk that doesn't blow free A/C condensor coil cleaners are reputed to be a solid answer.
Fan Over-ride Switch:
  1. While potentially of great value, for '17 XPT and newer owners we can't play this card. Which sux's because we loose the ability to drag temp down on the IC radiator tank while we're taking a break. Crud.
  2. Everybody else can though, and for those that do occasionally over-heat (you don't really think every Poo made can take every heat situation possible do you?) Letting the fan run to cool down the engine radiator to near ambient temp would be really nice.
    1. https://www.amazon.com/KEMIMOTO-Override-Switch-Polaris-Ranger/dp/B07MXL77CX

850 Posts
Discussion Starter #19 (Edited)
For the causal reader that's overheating and has a correctly working cooling system (which most certainly happens), and is considering surfactants and running lower percentage antifreeze (thus higher amounts of water), let me help you a little bit with some of the FUD that comes with this:

As I've mentioned elsewhere, you'd do well to read the reference links and learn from them. However, to sorta get you started let me share a few thoughts with you:

1) 100% Antifreeze, be it EG or PG based, has roughly 5% dedicated to corrosion prevention, seal protection, and etc. The rest is pure EG or PG, and neither address those aspects.

2) The primary purpose of that 95% base antifreeze is to prevent freezing. Yes, it does raise the boiling point of water, but it's A) unimportant and B) an engine that needed such protection hasn't been made in your lifetime. Today's water cooled engines have pressurized radiators. Did you know 100% water needs to reach 250F to boil when at 15 psi (typical radiator pressure)? Well beyond the point we run our engines at.

But what of engine hot spots? A water cooled engines CHT (usually the hottest spot) will generally not exceed 20F of your water exits temperature (Which is why this works just fine even in racing). And remember, most of us have no business running our engines below 30% EG (and if you are, you're well aware of all this already). So what's the boiling point at 30% EG and 70% water? I could tell you, but know this: Virtually every antifreeze manufacturer prints that on his antifreeze!. Why? Because, so long as you can live within those freeze and boil points, it's a completely acceptable use of the product. (BTW, it's 260f @ 40% , or 265f @ 50% (@15 PSI over sea level. Not doing much right? I did tell you boiling point isn't an important aspect of antifreeze....)

Of course virtually every sanctioned racing event requires 100% water in their coolant, so unless you think you're working your engines harder than an F-1, Nascar, or etc engine, well..

Finally, let's say you don't believe me, the antifreeze manufacturers labels, or the racing industry. Would you believe, Redline, Barsleak, Royal Purple, Rislone or Amsoil? Every one of them makes an additive (a surfactant) that allows you to run, without corrosion or seal concerns, 100% water, or run reduced EG/PG mixtures. All you need do is select the freeze protection that you will be operating your engine at (FP) the coolest your engine will ever be without running (BP), and select the lower of the two.

Now again, let me caution you:

1) This is for ONLY those that need, or want, addition cooling AND understand how to do this safely.
2) There are those that are better off, or simply more comfortable with, sticking with your owners manual. That's certainly a safe feeling decision, although my opinion is that over-heating your engine is a worse idea.
3) You should ALWAYS address missing (or adding if you can) airflow first, and ALWAYs confirm your cooling system is otherwise operating correctly. But if you can't.....
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