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Wednesday, March 25, 2020

Radiator : Nissan Skyline GT-R 2020 Upgrades : Hoses : Fans : Coolant : Anti Freeze : Water Pump

RB26dett with an aftermarket aluminum radiator. #bluecar

The purpose of a radiator is to take waste heat from the engine, and introduce it to the atmosphere. An internal combustion engine is inherently inefficient. A radiator is also called a heat exchanger, as in it exchanges heat from one medium, water, to air.   A radiator is a misunderstood part.  In reality you want the smallest radiator, with the minimal amount of exposed area, that can keep your engine cool enough, or in its operating temperature range.  However when you start making horsepower, lots of heat energy that is left over, or wasted in the engine is converted into heat that the radiator must carry away.

Modern gasoline engines have a maximum thermal efficiency of about 20% to 35% when used to power a car. In other words, even when the engine is operating at its point of maximum thermal efficiency, of the total heat energy released by the gasoline consumed, about 65-80% of total power is emitted as heat without being turned into useful work, i.e. turning the crankshaft.[1] Approximately half of this rejected heat is carried away by the exhaust gases, and half passes through the cylinder walls or cylinder head into the engine cooling system, and is passed to the atmosphere via the cooling system radiator.
Engine efficiency- Wikipedia
C& R Radiator in the R34 GT-R race car. Also visible, stock intercooler, and some of the ducting

So again, in theory you want the smallest radiator possible, you want the smallest openings possible to be able to maintain your engine within its safe operating parameters.  Anything larger is just weight, its just aerodynamic drag.

RB26dett Coolant flow diagram. Notice the inlet and outlet paths


Water, pure water boils at 212 F/100C at 1 atmosphere. However under pressure, water boils at a higher temperature, and actually the inverse is also true. At higher altitudes water boils at lower temperatures. Why is boiling point of water important?  It is because water does a lot better job of carrying waste heat away from engine components than air. However most street cars run a glycol mix, normally something around a 50/50 mix.  Any air, or boiling water in the system means your cooling system will not operate to its peak capacity.

Like the fuel system, the radiator is one part of an entire cooling system. Street cars have lots of obstructions in front of the radiator, from the design of the nose, to the air conditioning condenser. Even the A/C fan, and the hood latch may obstruct air.   I like people to understand that things are a system, not just a single component.  Replacing one part, may or not fix an issue you are having. It may just kick your problem down the road.
Aerodynamics of an R35 GT-R. 


Cooling System

  • Radiator
  • Coolant Temperature Sensor 2 wire and 1 wire
  • Aftermarket Radiators
  • Radiator Cap
  • Thermostat
  • Water/Fluid/Coolant/Anti Freeze/Glycol/Cooling Medium
  • Overflow
  • Swirl Pot/High Side Breather/Bleeder
  • Hoses
  • Fan
  • Fan or Radiator Shroud
  • Fan Testing
  • Ducting
  • Water Pump
  • Oil Cooler
  • Intercooler
  • Tuning/Ignition timing

OEM Radiator

OEM R32 GT-R radiator with aftermarket upper radiator hose, and a Nismo radiator cap. 

The purpose of the radiator is to transfer waste heat energy captured by the cooling medium, and transfer it to the air. The OEM R32, and R33 radiators have composite or plastic end tanks. The early R34 have all aluminum radiators. However the later ones, 2000 up go back to composite/plastic end tanks. I asked Tamura about that, and he said in order to get the carbon fiber hood on the later cars, to save money elsewhere, the radiator went back to composite end tank. Give and take, even in the OEM world.  


Coolant Capactiy (liters)
RB20/RB25DE/RB25DETRB26DETT
Capacity~9~9.2


Nissan Skyline Radiator Cooling System Fill and Bleed Procedure
Nissan Skyline Radiator Cooling System Fill and Bleed Procedure


Coolant temperature sensor 2 wire and 1 wire

Two wire coolant temperature sensor for an RB engine. According to NZ EFI, this fits about 50 different Nissans. 


The 2 wire sensor, is the sensor that the ECU uses as an input. It is a very important sensor. It effects startup, and running of the car.  We often see the cooling system not bled right, and an airpocket forms at the sensor. When this happens, the sensor may show 250F-300F. When this happens, the ECU thinks the car is hot, and it may not fire the injectors, based on the tune. So if you have hot start problems, that go away once you crank for a bit, the CTS is a good thing to look at, then the bleeding.  This gets back to having a Consult datascanner, so you can see what the ECU is seeing. Makes troubleshooting much easier. 

The 1 wire sensor only drives the gauge in the dash.  A cool fact, R32 and R33 are different resistances. You find these things out later, when you start a car up, and have the wrong sensor in. Then about 2 minutes in, the gauge pegs, the car is fairly cool.  NZ EFI says that the R34 is also different, need to look that one up. 

Nissan Water Temp Gauge Sender – S13, Z32, R31, R32 from NZ EFI



Nissan Water Temp Gauge Sender – R33, R34, S14, S15


Aftermarket Radiators

Factory all aluminum radiator on an early R34 GT-R

Please don't buy a crappy radiator. The stock one probably does a better job, fits better, allows the use of the fan shroud, and won't leave you stranded. I don't care what kind of warranty they offer, only buy from trusted brands. Most aftermarket radiators are aluminum. Honestly aluminum is not the best conductor of heat.  Copper/Brass is a better conductor, but if you built one that worked well, it would be so heavy, it would probably outweigh any benefits. More information about copper vs aluminum radiators.   Flex a lite has this to say about copper vs aluminum vs their radiators.  In the end copper while in theory works better to transfer heat, in the real world, it isn't durable, light enough, or pressure resistant enough to work in an automotive environment.

Heat rejection is the term for measuring the ability of a material to transfer heat to the air. This is what a radiator's job boils down to: Take engine heat that has been transferred to the engine coolant and transfer it to the atmosphere. Heat rejection is measured by the amount of British Thermal Units (BTU) per hour the system can dissipate. Higher BTU/hour means more heat transfer and better cooling.
Brass radiators came in nearly all vehicles until the '80s. A typical original-equipment brass radiator rejects heat at a rate of about 1,500 BTU/hour. That's pretty good, and this is why brass was chosen as the material for radiators. In the '80s, car manufactures wanted to reduce costs and lower vehicle weight. This led to changing the radiator design to use composite (plastic) tanks with an aluminum core. The plastic tanks transfer about 1,000 BTU/hour; considerably less than the traditional brass construction. Next we come to aluminum radiators. It might surprise you to learn that the typical, smooth aftermarket aluminum radiator tanks dissipate heat at a rate of about only 700 BTU/hour! That's less than half the BTU of brass sidetanks!
Leask Spec Radiators - triple bypass mod and non triple bypass mod side by side

Radiator flow.  So you have your normal type flow which is top end tanks, and the inlet and outlet on the same side.  Then you have something like what is called a cross flow, where the inlet is on one side, and the outlet on the other side of the radiator.

Modifed radiator in this Garage Saurus built R32 GT-R. 


The radiators above, modified by Leask Spec, have some cool features. One has what is called a triple bypass mod.  By making the coolant spend more time in the radiator, you can usually control the amount of heat it will give up to the atmosphere.  In addition to that mod on one of the radiators, he also puts an electric fan, and rubber flapper doors in a shroud.

Rubber flapper doors are closed at idle, but open to allow air to pass through at speed. 


Koyo - Koyos have been around a long time. They are a well priced radiator that fit like stock, and just work. If you are on a budget and looking for something good, this is your radiator.




C&R - These guys build NASCAR radiators. We had them build us a radiator for the R34 GT-R race car when we ran World Challenge. Their stuff is top notch. C&R is actually part of the PWR Group now.  https://www.crracing.com/aftermarket

PWR- These Aussies build some good parts. Another well liked, raced, and proven part.
https://www.pwr.com.au/products/radiators/radiators-faq
https://www.pwr.com.au/portfolio/nissan-car-radiators

HPI - They are popular in Japan

ARC - Awesome parts, expensive, but some stuff is worth it.

Nismo - They source some of the best parts. Expensive, but may be worth it to you.

Ron Davis - Located in Arizona, Ron Davis made us an R32 GT-R Radiator in the past. They don't list one, but you can probably call and ask, or draw them up for them to make for you. - http://www.rondavisradiators.com/radgallery.htm

Radiator Cap

Nismo old logo radiator cap. This one is 1.3 kg/cm2 or 18.4 psi cap

The radiator cap is a relief valve. It has a spring,and it allows pressure to build in the cooling system, until the pressure overcomes the cap. The higher the pressure in the system, the higher the boiling point of the fluid/medium. As the pressure of the cap goes up, also the stress on the cooling system goes up.  The RB26 has a ton of coolant lines under the collector.  You really don't want to stress test every single one of those connections by putting a cap with excessive pressure on it.


21430-4B700   0.9 bar (13 psi)  OEM R32
21430-7999C    88 kPA (12.7 psi)   Superceeds 21430-4B700
21430-54P00    1.2 bar (17.4 psi) 300zx

Koyo SK-C13 1.3 bar (18 psi) radiator cap.
Nismo 1.3 bar (18 psi) radiator cap

From Engineering Toolbox

Thermostat

A thermostat is a flow control valve. It opens/starts to open at a certain temp, and it allows for coolant flow though the radiator.  The OEM thermostat is the same as the VG.

OEM Thermostat opens at 76.5C or 170F.  21200-42L0A

A cooler rated thermostat, does not make your car run cooler in most cases. What it does, is open at a lower temperature, but once its fully open, its up to the rest of the system to keep the car cool.

Water, Coolant, Anti-Freeze, Cooling Medium


Water is better at transferring waste heat energy than coolant. However glycol has a higher boiling point than water.  Check out this article from Hot Rod Magazines Marlan Davis.

The specific heat capacity of ethylene glycol based water solutions is less than that of pure water; in a 50 percent solution, ethylene glycol's specific heat capacity compared with pure water is decreased at least 20 percent at 36 degrees and about 17 percent at 200 degrees. Propylene glycol, another common coolant, has an even lower specific heat. Assuming a 100-gpm (gallons/minute) coolant flow rate and an energy loss through the coolant system of 189.5 hp, the water temperature increase would be 10 degrees, the ethylene glycol water mix would gain 20 degrees, and propylene glycol would gain 33.3 degrees.

I run water and water wetter in my cars.  Many tracks don't like you to run glycol as its much harder to clean up than water.  Some people run distilled water, some run tap water. There are a few theories out there. In the end you do have dissimilar metals in the system, that will cause some amount of galvanic corrosion. So you do want some kind of additive in the system. If you are anywhere that it freezes, or transporting your car though anywhere that freezes, you want to put some glycol in it.

In the past, we have experimented with waterless coolant, like Evans NPG. The theories are great, but never saw anything that said- this is 100% the way.  Will explore that again in the future. 

Hoses

Hoses from HPS

R32 GT-R

Upper Radiator Hose  21501-05U00

Lower Radiator Hose  21503-72L00

So what do you do, if you just lost a hose, on the side of the road in the middle of nowhere?  You can always take the old hose to an autoparts store.  They normally have racks of hoses. Find one with a similar shape, or a section with a similar shape, and cut to fit. You can also use a hose repair kit, to at least get you back on the road.

Red coolant hoses from HPS, remember kids, red is faster
There are a ton of hoses under the collector, a few that run behind the engine, and then you have the turbocharger coolant supply and return. There are a lot of places that coolant can leak from an RB. None of them particularly fun to fix.

Overflow Tank


 Overflow cap - these seem to leap away from you, when you remove them. A new one is only $3.




Swirl Pot/High Side Breather/Bleeder


There is a 10mm bolt on the forward part of the balance tube, that you use to bleed the air out of an RB26. Caution. if you loosen it too much, or don't realize what you are doing, boiling hot liquid will come out. The 10 mm bolt will drop down into the engine/collector abyss, and you will be wondering why you did, what you just did.

JUN high side venting and coolant flow


Over the years I have seen some pretty crazy high side venting of the head.  As the engine is tilted, some people think that it is very important to have extra bleed ports on the intake side of the head.  JUN used to do a pretty insane setup.







Fan


I like the stock clutch fan. Lots of people ask about electric fans, but honestly I have not(yet) seen an electric fan, that works good enough to replace the stock clutch fan.  At speed, the fan really shouldn't be doing anything, but at idle, with the air conditioning on, in hot temperatures, you need that fan to move as much air past the air conditioning condenser, and through, not around the radiator as possible.   The stock fans crack around the base. Inspect your fan, if its 30 years old, it probably needs to be replaced.

If you are going to replace your stock clutch fan, check the clutch for proper operation, and an R34 fan is a good upgrade for R32, and R33.

R34 Fan - 21060-5L300
Clutch coupling  R34 -21082-24U00

https://www.flex-a-lite.com/blog/the-truth-about-airflow-and-amperage/


GK Tech sells a replacement fan they say flows 40% more air than stock.  We have one on the #bluecar
The GKTECH high-performance engine fan has been designed and engineered in Australia with the intention of pulling more air than the factory item.

When tested on a dyno the GKTECH high-performance fan took less than half the time to cool down from 90 degrees to operating temperature (good for next time you're on the start line at the track).Super easy to install, simply remove your factory fan (4 bolts) and install the new fan, it is a direct replacement clutch fan to suit SR, KA, RB, VG enginesAn adapter is needed to fit RB/VG engines, as seen here: https://us.gktech.com/rb-vg-clutch-fan-adapter
- Direct replacement of the standard fan- Pulls 60% more air than the factory SR fan- Pulls 40% more air than the factory RB fan

Electric AC fan testing

Fan or Radiator Shroud



If you don't have a damn good reason to remove the shroud, DON'T.  If you don't know what it does, then DON'T remove it.  If your radiator makes it not possible to mount a shroud, return that POS ebay special, and get a radiator that allows a shroud. If your radiator is too thick to allow a shroud and fan package, then that is for you and god to sort out.

The R35 has great ducting, and even some cool features, like the flapper doors on the fan shroud. Anything blocking airflow could cause a choke point, so Nissan designed the shroud with doors that stay closed at low speed. Then the electric fans are more efficient. At a point air pressure will overcome the doors resistance and the doors will open. It is pretty basic, but cool to nerds that notice things like this.

R35 fan shroud with dual fans and flapper doors. 

R35 fan shroud with dual fans and flapper doors.

R35 fan shroud with dual fans and flapper doors.


Ducting

R32 GT-R radiator lip, this one is aftermarket and superior to the OEM Nismo lip spoiler

Air must go through the core for the radiator to do its job efficiently.   Read this paper on ducting and its effects on cooling.

 https://www.beta-cae.com/events/c1pdf/05_chacko_radiator_efficiency_paper.pdf

We were running the Garage Defend radiator panel in the blue car. This panel extends all the way across, behind the headlights
Air wants to take the path of least resistance. We want it to pass through the radiator core. A radiator panel will help to direct air from the grill though the core. The more sealed the better, but not always practical.



R34 race car with ducting. Carbon fiber side ducts. Lower ducting you can see here. The top panel is removed. 

R34 side and lower ducting is visible here

Side ducting from the top

Lower ducting

The other side of the ducting and the C&R radiator. Yes this car has no shroud, I know. It isn't a street car. 

OEM R34 foam, trying to make air pass through the core

OEM R34 foam, trying to make air pass through the core

OEM R34 foam, trying to make air pass through the core

Leask Spec Radiator Ducting. This is super important to help airflow though the radiator. A crappy radiator with ducting, is better than the best radiator with none. 

Leask Spec Radiator Ducting. This is super important to help airflow though the radiator. A crappy radiator with ducting, is better than the best radiator with none. 

Leask Spec Radiator Ducting. This is super important to help airflow though the radiator. A crappy radiator with ducting, is better than the best radiator with none. 

Leask Spec Radiator Ducting. This is super important to help airflow though the radiator. A crappy radiator with ducting, is better than the best radiator with none. 

Leask Spec Radiator Ducting. This is super important to help airflow though the radiator. A crappy radiator with ducting, is better than the best radiator with none. 

Water Pump


Can you describe the shape of the water pump gasket for us? Oh no gasket, just liquid gasket











  • Water pump
  • Water Pump - 21010-21U26
  • N1 Water Pump - 21010-24U27

  • N1 water pump in the background, normal in the forground.  Notice the top bolt hole. This is an issue if you dont have an N1 block.  It can be filled in a number of ways. Just make sure you do it before you install it. 

    So some people say they have problems with N1 water pumps at idle. Over the years, not anything that we have noticed, but we are investigating it.  The N1 pump has less blades, but they are larger, and it has a anti-cavitation plate on it.  Cavitation causes weird things to happen, like bubbles, so you want to minimize that if possible.

    N1 water pump
    Standard water pump
    I have to look up if there are flow numbers for the water pumps anywhere. I looked into a flow tester at one point, but never got much further than that.   We have a friend that runs an electric water pump with a rear mount radiator in a drift car, and although it sounds like it would be the way to go, so far it seems to be pretty far from that.

    Oil Cooler


    RB factory oil cooler. Coolant lines are green. 


    On a stock RB26 there is an oil/water heat exchanger on the right side of the engine. The oil filter attaches to part of the assembly. If you have an R32 with Hicas, you know how fun it is to get to the oil filter.

    You have a lot of factors that contribute to oil temperature in an RB26dett. It is honestly near an oil cooled engine. The higher you rev it, the more temperature you add. At a point you can't cool the oil enough, and it breaks down. When it breaks down enough, you kill an engine. An RB26 has a long crankshaft with 7 main bearings. Each bearing is adding lots of heat at high rpm. Cams, turbos, oil squirters, and more.
    More oil cooler information here


    Intercooler


    The intercooler plays into the radiator as its a major component that blocks airflow to the radiator. It is also a heat exchanger, but air to air in most cases.  The biggest thickest intercooler, may cause your car to overheat, especially if the air isn't ducted after the intercooler.

    Factory intercooler and ARC oil cooler on the R34 race car. 

    Tuning/Ignition Timing


    If you don't run enough advance in the ignition timing, you can cause overheating issues. If you use a lot of the two steps, as the cool kids do these days, with things like anti-lag you will put a ton of heat into the cooling system.  Plan your days accordingly.


    Buy USA Legal R32 Skylines at Importavehicle.com!
    Buy-R.com for Nissan Skyline GT-R and GT-R parts.

    This page isn't done yet, but I am done working on it for now. I think it has a lot of useful information, but it will be expanded in the future.  - March 2020.





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