Cooling System Design - Is My Thinking Right?

[JustinP]

I have been thinking about how I need to route everything cooling system wise on my R34 Neo build. I want to ensure that the correct coolant flow paths are maintained. I have been referring to this which has been quite useful:

http://www.sau.com.au/forums/topic/423082-rb25-coolant-flow-hose-swirl-pot-header-tank-setup/?hl=%2Bremove+%2Bheater+%2Bpiping

However my setup is a bit different and possibly pretty unique. I would really appreciated thoughts on my proposed solution. My setup will be as follows:

• Running a plenum similar to the Hypertune ones. It has no coolant hose connections at all, other than the ports coming out of the head and the radiator top hose outlet.
• I'm running an electric water pump which is controlled by a computer. The water pump is located inline on the bottom radiator hose.
• No thermostat is installed.
• Old water pump internals have been removed and a plate welded over the front to seal it up.
• The heater and heater pipes have been removed.
• Oil warmer/cooler and piping has been removed.
• No throttle body warmer will be used.

So basically I am left with just the turbo water return line and the IAC/AAC valve thing to worry about (I guess I might as well keep the cold start functionality). I want to keep things as simple as possible.

Originally I was thinking that I would need to route the turbo return and the IAC valve to either the hose connections coming out of thermostat housing (1 and 2 on kitto's pictures in the link above) or from the connection towards the rear of the block (3, 4 and 5). Due to my water pump setup / location I don't think this will work for my applications. I am proposing the following:

• Block the hose connections coming from the thermostat housing (1 and 2).
• Block the rear connection on the block (3, 4 and 5).
• Run the turbo coolant return line through the IAC valve (it has three connections, I will block the middle one).
• Plumb the outlet of the IAC valve into an adapter which will go into the radiator top hose near the plenum outlet.

I think I need to setup as above as the turbo will be fed coolant under pressure from the passenger side of the block and I will need to ensure the return goes back somewhere on the other side of the water pump. Given the location of my water pump I think this would be the best option?

I also no longer have the coolant bleed points and I was thinking of getting a swirl pot / breather tank, however I think the radiator cap will now be the highest point in the system, so I'm hoping I don't have to worry about that either? The only part of the system that I think might be around the same height will be the turbo water feed line (high mount turbo).

Sorry for the long post, but if any learned SAU members could give me some feedback i would greatly appreciate it!!

Cheers

[R_34]

Will you use a davies craig pump ?

We used at my work on an engine dyno to pump water through an oil cooler of a 2L diesel engine and a water to water heat exchanger. The pump was OK performance wise but it only lasted 400 hours before being replaced. It worked with only 50 to 70°C water temps and some fins broke or something as the pump was heavily vibrating.

And on another engine 2 stroke single cylinder petrol engine, still on an engine dyno an other pump but same model pump (EWP115) has been tested as a primary water pump. The coolant circuit was kept relatively simple : engine, a coolant flow meter, a water heater and the water to water heat exchanger.

The pump despite being fed with around 12.8v was not able to meet our coolant flow target.

Well the engine had a pretty restrictive flow path inside it but the pump was really weak for that use.

So my 2 cents is keep away of the EWP pump as a primary water pump for your engine.

But the EWP pump controller is worth a watch. I'm in the process of fitting one to control a electric motor that will power the STD water pump. As you I might remove the thermostat. It will remove a big restriction in the coolant circuit, allowing more flow but a lot less delta P before and after the pump leading to a lot less cavitation at high rpm.

As for your plate that replace the water pump beware that it might not let a lot of space for the water to go through between the plate and the block. The pump is making a canal with the block to allow the water to flow through. Your plate will make this path a lot narrower. I would look into fitting a emptied water pump if possible.

Iin the thermostat housing I would also block the by pass where the thermostat is being placed. When the engine is cold a part of the coolant goes through this by pass to allow a evenly warm up of the block. As you will control the warm up of the engine without coolant flow when it's not needed, you do not need this by-pass anymore and when hot you will put more "fresh" wate through the engine leading to a greater cooling capacity.

I will re-run the turbo water exit at the inlet side of the pump. It will lessen a bit the flow of cool water coming from the radiator but I prefer ensuring a good flow through the turbo. From factory it is plumbed exactly like that so I don't see as a real problem, just a small loss of efficiency. Given the gain that could be made with the rest of your setup if done correctly, I find this acceptable.

Once you change the intake manifold the highest point of the coolant circuit is effectively the radiator. My 20 is setup like that and didn't needed any precaution to be bleeded correctly.

Hope that helps.

[JustinP]

Thanks for the feedback, much appreciated. I will continue with my plan to plumb the turbo return back into the top radiator hose and won't bother with a breather tank.

The plate over the old water pump will be fine, the body of the old pump is still there so there is plenty of room for the coolant to move through. The plate is just to seal where the old clutch fan connected.

Yes I am using an alloy Davies Craig EWP. I will be happy even if it only lasts 400 hours, the car won't be driven much!

Edited January 1, 2015 by JustinP

[GTRNUR]

Just to clarify, you have plated off inside the pump where the mechanical impeller normally is right? So it is essentially just a passage from the thermostat housing to the main water gallery supply on the passenger side of the engine block?

You say your water inlet is via the thermostat housing (no thermostat). Where is the water outlet?

[JustinP]

Yes that is correct, the plate is actually on the outside of the pump to seal it back up with the internals removed. The coolant still goes in through the (now empty) thermostat housing and through to that inlet on the front / passenger side of the block, like normal.

The coolant then exits the engine / head via an outlet on the front of the plenum, pretty much like the stock setup. The only thing is the plenum does not have any other coolant inlet / outlets which is why I need to work out the best way to plumb in the turbo return / IAC valve plumbing.

Actually I should have just posted a couple of pictures of it, would have been much easier! Will take some now.

Cheers

Justin

[JustinP]

Pics:

[R_34]

Well then it looks OK for me.

Just take the most powerful pump from EWP and feed it with the highest tension you can.

I hope it will flow enough to cope with your power goal. Because you don't have the thermostat you should install 2 water temp sender, on at the inlet of the engine and the other on the exit to check the temperature rise. Ideally it shouldn't be higher than 10°C when the engine is at temperature and the controller is regulating, to get a correct cooling of the entire block, not just overcool the front cylinder while the lasts ones are burning.

If you have a delta too high, then the pump is not powerful enough. You'll need to install a second one or find another more powerful.

I know that pierburg are making some powerful pump which are used in wrc and on the last bmw //M. But they need to be pwm feeded if I remember correctly. The EWP controller can't do that.