Custom Radiator Project

Send it to Mudder to "Review" lol

 

How much cooler do you think the ICE will run?

Do you plan on collecting data for the stock OEM radiator versus the custom aluminum radiator and share the data in this thread?

 

It will not run cooler if you keep the stock thermostat /

 

Unless, with the stock radiator, you were running it hard enough that the temperature exceeded the stock thermostat's fully-open temperature. That is a thing that can happen.

Not saying I have any idea how much cooler, if at all, it would run with this radiator. That would be a matter for controlled testing and instruments and reproducible data.

 

There you go Azusa, the only thing more predictable than cooler temps from an aluminum radiator are the answers from armchair engineers on Prius Chat.

 

..
Here's some reworded thoughts......

Cooling systems have indicated temperatures, actual temperatures. and large temperature gradients. They have an inlet water temperature and an outlet water temperature.

It DOESN"T MATTER, to outlet temperature, what radiator is installed in a car that is controlled by a thermostat. The outlet temperature will always be what the thermostat is designed for.

If the temperature sensor is mounted at the thermostat, you will never see a difference in coolant temperature indication even if you have a 500 gallon radiator attached to the engine.

Depending on the design of a replacement radiator, you may or may not have a lower temperature on the coolant being returned to the engine. IF you have a lower temperature coolant entering the engine, and the same temperature coolant exiting, the average temperature of the coolant must be lower than it was originally.

Think of it as two straight line graphs. Make the left vertical axis coolant temperature and the horizontal axis 100 inches of travel through the engine starting with the supply hose and ending at the thermostat. Two lines start on the left, one at 160F and one at 140F. (no, I do not know if these would be accurate temps for radiator outlets for a Gen 3) They both heat up over the 100 inches of travel until they both reach the thermostat in the upper right of the chart and are both 180F.

What true advantages this has are probably insignificant. Disadvantages? A higher thermal gradient across the engine. A thicker core? Hope that doesn't change the mounting points significantly for the fans/shroud/etc, since it may affect clearance between radiator and engine. Good, bad? who knows. Engines are designed to operate at specific temperature ranges. A passenger car will never know the difference between a properly operating OEM cooling system and a cooling system with a fancy aftermarket radiator, unless the new thermal gradient causes problems with clearances. Ignition systems work using indicated temperature, so there should be no change.

Pretty much every semi-modern passenger car can drive through the hottest desert or highest incline with the AC blasting and never exceed the thermostat setpoint or capacity of a stock OEM cooling system that is operating properly and lasts 20 years. High quality aftermarket DENSO radiators are available for <$100 if needed and will also likely last 20 years. For a prius? You'll never get an ROI on this mod unless you just want something to ohh and ahh over or impress your friends because you now have a shiny new aluminum radiator. To each, their own.

 

Nobody’s gonna explain anything to anyone’s satisfaction

 

True that it cannot cool the engine any lower than the thermostat set point (180F I think?).

But would it help with lower coolant temps after the thermostat is open?
Made up numbers and scenario: With the stock radiator on a big hill in the hottest desert and the coolant is at 220F, but with this "better" radiator it brings the temps down to 190F, thats still an improvement?
Or maybe in more mild climates it keeps the coolant temp below where the electric aux fan turns on?

I guess this is where doing some test drives before and after with OBD2 to capture coolant temps will show what kind of improvement it can provide..

 

It likely won't benefit. At absolute worst case, the extra temperature gradient will reduce engine clearances and cause wear, similar to what happens when driving during partial warmup. Pretty insignificant. Best case? probably nothing also. The car is still going to control engine outlet temperature at 180F, so the efi system isn't going to change how it does business. How heavy is the stock radiator? Most modern ones are aluminum with plastic side tanks. You're increasing radiator size and volume of coolant. Are you actually reducing or gaining weight overall? There's more to radiator design than just brass or aluminum. Just because a radiator is custom or aluminum doesn't 100% mean it's better for the car.

Overall, in the big picture, you're spending money to get a shiny new radiator that may drop your average engine temp a few degrees. Benefit? probably not measurable, except to the pocket of the guy who built the radiator.

How often have you needed extra coolant? Zero times? If so, what is the benefit of having more? carrying more weight?

How often have you had your OEM radiator break? I've had one car, a 2003 Santa Fe, that had an aluminum core/plastic tank style radiator develop a leak at the sealed joint at ~210k miles. So why would it matter whether aluminum is stronger than plastic? Aluminum develops leaks also. More radiator leaks are caused by accidents and impact damage than wear and tear. Is the aluminum strong enough to survive an accident?

 

Where is the discount code?

If Vsport endorses it and Blackj says thumbs up I think we should just report contrarians like Chapman (“armchair engineer”) and tmr-jwap. We can’t let science get in the way of a great innovation.

 

Hold the phone a sec. The thermostat lives in the water inlet elbow, where the water from the radiator is returning to the water pump, to be pumped into the block. The engine outlet is from the cylinder head and at the other end of the engine.

The sensor that gives the ECM its displayed engine temperature is at the outlet. But that doesn't control the thermostat. The thermostat is its own expanding-wax-pellet operation and only knows the coolant temperature right where it happens to be. (It is able to respond during warmup, when it's closed, because the bypass loop also returns there, the one that involves the cabin heater, EGR cooler, EHRS, and throttle body.)

The wax thermostat is opening between something like 83 and 87 ℃. Sure, if the coolant coming back from the radiator is cooler than that, the 'stat will close some to keep the temperature higher. But once the 'stat is fully open, there's no further effect it can have on how high the coolant temp gets.

 

I'll have to take your word on the Gen 3 flow path. When I'm not working directly on an engine, I have a habit of always envisioning old big block coolant flow paths when picturing coolant loops. Yes, mechanical thermostats typically start moving at the setpoint temp plus or minus a few degrees and will continue to open further if needed until they mechanically max out. IIRC, that max stroke is 10-15ish degrees higher than the start point, but is really never seen in a passenger car in normal use. Perhaps if one decided to tow 20 tons behind them with the gas pedal floored, it could make the thermostat go max open after a few minutes, and then a super duper radiator would come in handy.

 

Yeah, your memory is better than mine. Sho'nuff, Toyota says starts to open at 80 to 84 ℃, fully open at 95 ℃. That's a range of 11 to 15 Celsius degrees, even more if we were using Fahrenheit.

That 95 ℃, though, is exactly the temperature that turns the radiator fans on, so it's not an unheard-of temperature to reach in practice. (That would be ECM-detected outlet temperature though, not what the 'stat sees at the inlet.)

 

Have you tried water wetter/etc yet?

It increases the thermal transfer of coolant by a decent amount.

Also, running a 70/30 mix might be better for your climate.

 

You have a misunderstanding of what 2 row means.

 

and yes, as Chap explained about the location of the thermostat on a Gen 3, when located at the entry point of an engine, the thermostat has little control over the outlet temperature of the engine and it can vary several degrees depending on the load placed on the engine. Inlet temp maintained at 180 + varying power load = varying outlet temperature. Have you measured the temperature of coolant at the thermostat during the changing conditions? If it's maintaining in its normal control band, then a different radiator will make little difference, and you've found a solution for a non-existent problem. If it continually creeps up and goes outside it's normal control band, then those conditions are outside the ability of that system and a different radiator may help. But as I also said, to each, their own. Enjoy it.