electric water pumps and turbo coolant flow
 

I've seen a lot of people install EWPs all in the same place (in the lower radiator hose).

I put mine in the same place, but I'm concerned that putting the EWP here moves the turbo coolant return from the suction side of the water pump to the pressure side of the water pump...

does this reverse the flow of coolant through the turbo? or stop the flow all together?

I've read of people having to put smaller booster pumps in heater lines to get them to properly move water after an EWP install... I don't see how the turbo is any different which has me worried....

anyone else look into this?

You are correct in that the coolant flow path will alter by moving the water pump the lower radiator hose.

In order to flow properly, any coolant circuit should be routed with an entry downstream of the water pump and the return upstream of the pump.

You will see that in the factory setup on all 13B and 20B turbo models, the turbo coolant return line is plumbed back into the lower outlet of the water pump housing via a barb fitting that points up directly towards the pump.

Ditto with the heater. In older Mazdas and FC models, the heater return line is on the lower radiator outlet. In the FD the heater return is also in the lower outlet of the water pump housing.

Now assuming you remove the thermostat and block up the bypass, then move the water pump to the lower radiator hose.

In my view it won't reverse the flow through the turbo - both entry and return are downstream of the pump. With the direction of the return fitting, what is likely to occur is you will get a very small amount of flow through the turbo circuit, based both on convection and negative pressure as the coolant is pulled through the engine and then down through the radiator. But the flow will not nearly be as much as if you routed the turbo coolant circuit to return to immediately upstream of the EWP. That's where the return should go. Same as the heater return. With that setup, no booster pump (EBP) is necessary.

Without an EBP, heater performance will suffer during warm-up times due to lack of flow, but this is somewhat offset by overall faster warming up times.

To hook this up, it's all quite simple. Davies Craig make a fitting that you can stick on the inlet of the EWP. OR you can tap a heater return into the lower radiator outlet. Stick in a T-piece and you can also re-route the heater pump. This will restore the factory coolant flow path.

The Davies Craig fitting is depicted below.


http://daviescraig.com.au/media/183/...5531020.s8.jpg

See: EWP Heater Return Kit (8380) -

Now, I've been using EWPs since they were first released in Australia in the early 2000s. After trying different setups, the best one I've found for a regular street car is completely different to what anyone else has done.

Basically, I have kept the bypass thermostat system. The problem with that is that, like the heater and turbo return, the bypass return is integrated within the pump housing itself. There is a channel from the bypass port back into the upstream side of the factory water pump. This means the bypass won't function properly and the coolant path will flow straight up the lower water pump housing outlet and directly out the bypass, minimising the flow path through the engine.

My solution was:
1. weld up the bypass return channel on the water pump side.
2. drill a hole from the outside of the water pump housing to tap into the bypass return channel
3. tap a thread into the newly drilled hole
4. screw in a barbed fitting
5. run a new return hose from the barb (thermostat bypass) and route it the heater return line (which on my series 3 RX-7 runs to the lower radiator hose)

Done!

This way I can run a factory thermostat with all the benefits. With the combination of Davies Craig controller and thermostat, temperatures are rock solid, warm up times are way faster than factory, heater performance is the same as factory and I get the benefit of the 3 minute run on with the EWP from the Davies Craig controller.

I did a write-up on this in my AusRotary build log years ago: AusRotary.com ? Login

Unfortunately, I hosted the images on ImageShack and they removed them all. I'll dig them back up again at some point.

Now, this is not as compact or lightweight as the simple inlet/outlet flange setup I see most people use. But without a thermostat, I found that temperatures were just too cool especially at nights on the freeway where temps would often drop back down from 85'C to 70'C in a few minutes - this is even with minimal flow from the EWP. You need that coolant circulation through the block to maintain and evenly distribute heat IMO.

that's what I figured thanks.

I'll just plumb the turbo into the feed pipe for the EWP...

I'm having a hell of a time picturing what you did with the thermostat. pictures would be awesome. It would be really nice to be able to maintain the thermostat functionality mainly for the overcooling possibility.

Here is my current setup (not quite finished obviously) and yes, it's an FC... I posted this in the FD forum because a lot more FD guys use EWPs.

https://lh3.googleusercontent.com/1G...=w1679-h944-no

https://lh3.googleusercontent.com/cs...=w1679-h944-no

https://lh3.googleusercontent.com/nj...=w1679-h944-no

Looks good to me.

I have a series 5 setup too. Just plumb the turbo and heater return (if you still have heater) into the feed pipe for the EWP as you suggested. Easy.

For my thermostat setup, I'll try to explain what I did using your pictures. You have plugged the bypass channel at the top. You need to do that when deleting the thermostat. So it's setup correctly for a thermostat-less operation. But with my setup, I've left it open at the top where the thermostat sits and blocked the bypass channel from the BOTTOM inside the recess where the factory water pump impeller sits. Now, the idea then is to get the coolant to run out of the water pump housing into to the EWP whenever the bypass is open (ie thermostat closed). To achieve that, I've tapped a fitting into the bypass channel and run a hose from that to a heater return inlet pre-EWP. I've quickly tried to do some annotations in the attached photos.

I think I got it.

How did you block off the bypass channel? Weld in a plate? I don't remember what it looks like...

it's a narrow tunnel basically. I had it welded up with aluminium filler. It's a contoured shape and difficult to access, so I couldn't really stick in a welch plug or something similar to what you have done.

Some more info on this.

The other option I've long considered is to use a remotely thermostat housing mounted in-line in the top radiator hose.

Moroso and a few other companies make universal remote thermostat housings eg Moroso Remote Thermostat Housings | JEGS The problem is that these lack a bypass and won't work properly on a rotary engine layout (that I can see). I think some OEMs use remote thermostat housings with bypass incorporated. I researched this years ago - maybe a MR2 Spyder and a Jeep?

If you could put a suitable aftermarket market product, then you could replace the entire water pump housing with the inlet/outlet flange like many race cars do and still have a thermostat controlled system.

If anyone is aware of such a product, I'd be keen to have more details.

Not exactly what you describe, but this company machines 3 holes into their thermostats to provide closed-condition flow.
http://www.stewartcomponents.com/index.php?route=product/category&path=61

That's a common practice in racecars to stabilize coolant temperatures and minimize trapped air. I've been doing that forever...

OP your oil fill thing is missing a nut or a bolt

Thanks guys. I hadn't seen those Stewart thermostats.

I have heard of drilling holes into the thermostat however. In fact, Davies Craig recommends that for using a conventional non-bypass thermostat when installing an EWP you drill one or two 5mm holes to allow proper circulation. It could work well in combination with the controller, but I still think the idea of recirculating warm coolant is a better option to reduce warm-up times, if possible. An elegant off the shelf solution may not exist.

OK. I managed to find the OEM solution again!

I was close. Not a Jeep and MR2 but a Land Rover and a Lotus Elise both of which use Rover K Series engines.

Land Rover Freelander 1.8L K series used a remote thermostat housing with a bypass: This is the Land Rover Discovery version (silver): Land Rover Discovery 180F Thermostat PEL500110
Similarly, the same Rover part was used in the Lotus Elise: https://www.eliseparts.com/products/...ef-thermostat/

https://www.eliseparts.com/img/up/e5/1_96643fd.jpg
https://www.eliseparts.com/img/up/ed/216-0c8c1.jpg

The second grey one is meant to be the improved design with better flow balance to prevent thermal shock when the thermostat opens. It comes with thermostat installed with an 82'C opening temp - factory spec for a rotary.

ABS plastic housing is not ideal though. We know what happens with the Mazda AST. But it not really an expensive service item and Rover parts are available everywhere.

I think this would work.

So, you could:

1. replace the entire water pump housing with an inlet/outlet flange and side mount the alternator. Or you could keep the alternator top mounted with the product Turblown is developing.
2. install the K series remote housing with 82'C stat in line in the hose from engine to top radiator inlet
3. run a bypass hose from the bypass port to a heater return fitting in the EWP inlet.
4. into that bypass hose, you also plumb the turbo return hose and the heater return.

When the thermostat is closed, coolant will run from engine directly to EWP, bypassing the radiator.
As the thermostat opens, the bypass also closes, gradually introducing cooled water passing through the radiator.
Once the thermostat is fully open, EWP is pumping according to engine requirements hitting full speed when or shortly before the radiator fans turn on.
Under all conditions, the turbo and heater return circulate, as this coolant path does not pass through the thermostat housing - it goes directly to the EWP.

Who wants to try it first?

Upon further digging, the factory Freelander / Discovery has a thermostat opening temp of 92'C - too high for a 13B.

Rover released a lower-rated t-stat for warmer climates that opens at the more useful operating temp of 82'C. Part no. is PEL500110.

Here's a link to a sample part: LAND ROVER DISCOVERY 2 1999-2004 THERMOSTAT & HOUSING 82C / 180F PEL500110 | eBay

Actually, this is designed to fit into the lower radiator hose. It would still work in the top, but you could also set it up on between the radiator and EWP like this:

Attachment 605272

The "from head" label is coolant from the outlet from the engine. You would need a T-piece in this hose, which would then also run to the top radiator outlet.

Here's how the factory system looks:

http://www.rimmerbros.co.uk/ItemImag...GRID001582.gif

Going off this diagram:

(3) goes to engine outlet
(8) goes to EWP inlet
(12) goes to radiator lower hose
(23) goes radiator upper hose

Even though it on the radiator outlet with cool coolant, the pump will circulate hot coolant around the thermostat to ensure proper opening temperature.

Some useful explanation is given here:

Am I just being a bit thick? 1.8T cooling system - Page 5 - The 75 and ZT Owners Club Forums

Finally, if you want something sexy and aluminium, these guys appear to make just about any inlet/outlet/bypass size configuration: Custom Remote Thermostat Housing

OK last one I promise and apologies for the multiple posts. Partly this is for more own reference later and partly to share the information to save others on the research.

BMW 2002 E10 and Fiat 124 also use a remote inline thermostat with bypass, but both are aluminium not plastic and therefore appear superior than the Rover ones. The Fiat is the best looking but more expensive. Not sure on thermostat options.

The BMW comes with 71, 75 and 80'C thermostat options and is dirt cheap. Found one brand new for US$16 without much research: http://www.autohausaz.com/pn/11531253249

Score!

http://www.autohausaz.com/images/11531253249.jpg

Part number for the 80'C t-stat is 1153146805680. For Australian players, Tridon makes an aftermarket version with 82'C thermostat (same as Mazda), Part no. TT260-180P - there are couple of other variations made by Tridon with different inlet/outlet sizes and shapes. Worth looking at Tridon catalogue.

What a great thread for anyone with a EWP! I will be giving the Fiat 124 remote thermostat a try. Should fit what I have going on perfectly.

is this really an issue or are we overthinking and complicating things needlessly?

does it mean that Turblown's or SBG ewp kits are incomplete and may cause turbo bearing to overheat?

I'm adding one of the ewp kits to my build and now I have this to worry about? i thought it was set it and forget it...

Turbos don't need to be water cooled at all.... most early ones were just cooled by the oil going through them. But water cooling is much better and it suggested by turbo manufacturers to extend the life of the turbo bearings...

As far as I can tell, with both Turblown's and SBG's kits they keep the stock turbo outlet location which means there is minimal coolant flow through the turbo with the revised pump location.

turbo life will be affected, how much? no one knows. but rotaries don't really run cool... there is a reason our stock turbos were water cooled.

For me it has nothing to do with water to the turbo as mine is oil cooled only. Car runs way to cold. Especially on the freeway.

i had something custom made. If there is enough interest I can see about a group buy. I will post a pic tonight.

Exactly this. Without a proper bypass there is also risk of thermo shock and possible engine damage from the EWP going from pulse mode to full operation there is a great temperature differential between the radiator and the block.

A proper bypass also ensures proper heater operation and turbo cooling as well.

Just make sure the Fiat temp rating is ok. The BMW and Rover have suitable alternatives but i couldn't find a rating for the Fiat. A lot of piston cars have 190-195F thermostats which is too hot for a rotary.

edit: according to this it's 180F - perfect!

http://www.partsgeek.com/mmparts/the.../fiat/124.html

The configuration is like the Rover. You fit in the bottom radiator hose before the EWP then create a T in the top radiator hose to feed the bypass. Here's how the factory setup looked:

Thanks for the video. Lets me see how this is going to work much clearer. Getting rid of the water pump housing is going to be nice.

Would this be a good flow path?

I deleted my heater core..

From my Rear iron to the feed of my turbo (old heater core line)
The return of my turbo back into the hot side of my radiator