Hi all, Hope to get some input for thought. I have a water to air intercooler with the heat exchanger in the front bumper that's going roughly over 3/4 of the center opening of the 99 front bumper. Also I have larger oil coolers left and right plus oil thermostat and aftermarket aluminum radiator and fan shroud/fans and a Davies Craig ewp with thermostat delete. The whole thing is around a single turbo setup with an efr9180.Now to the data I see.Oil temp is solid around 83 degC. - happy with that. IAT - only going down under boost so far, intercooler is feeling pretty cold after driving, but I'm getting some heat soak while stationary - may want to look in another sensor.CLT - here I'm pretty unhappy. Even light throttle cruising around 130kph my fans are constantly running. Pushing it a bit towards 200kph, I see coolant temps rising, with fans running (setpoint 80 degC) and the speed. To me that looks like cooling system out of control. I usually let off once I see more than 96degC. Brand new engine that I don't want to cook.My radiator gives me an impression of being very hot and to me it feels like it's not getting rid of the heat. Is there anybody around who experienced similar behaviors?I'm mainly thinking aerodynamics at this point, ideally I wouldn't want to see the fans running at all at such speeds. So that would be ducting, where I didn't do anything at this point. Radiator being in oem position with undertray.I welcome all of your thoughts and ideas before throwing more sensors and effort on it. Thanks Falko

 

Are you sure your ewp works as expected? Maybe a voltage drop in its circuit..
Another thing to consider is the radiator size/thickness
Yet another thing to consider is your coolant level.. And you should burp it really good, otherwise you might get climbing temps.
I'd mention the undertray too, but you said you had it in place. Also your front mount heat exchanger would not be the root cause either. I had front mount intercooler before, and temps always were below 200f/93.3c.

 

How is your thermostat delete ? I had a similar issue with mine and that thermostat delete ended up being the issue

 

Hi thanks for the replies.
If the ewp wouldn't be working properly I would expect the radiator to be cold while the engine is hot. But radiator is hot. Will measure the size of it in the weekend and compare temps with a friend's car. I think he has the same radiator, but OEM water pump with thermostat.
The thermostat delete: I removed the thermostat and welded the bypass hole shut. I believe that was the consensus when I was doing it.
Did that change?

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provide some pictures of the cooling system. Depending on the undertray and the radiator/fan setup you may not get enough airflow to cool down the radiator.

 

I don’t see anything about how the Davies EWP is setup for control and what it’s doing during the issue?

Most t-stat deletes still need a restrictor; a t-stat gutted of the spring/plunger assembly, to serve as an orifice plate is typically a good place to start.

That said, you could just put t-stat back in again too. The general idea being if it flows too fast then there isn’t enough dwell time in the radiator to allow sufficient cooling on a recirculating system.

Because if a t-stat solves the problem, this means it’s not only restricting the flow, but also diverting some of the hot discharge back to the inlet if it’s anything less than fully open. Fully open = Bypass fully closed.

Depending on whether it has one or not. I suppose it should be asked if it has a bypass, and that it was either sealed/plugged or removed completely?
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What are you controlling the EWP with? The Davies Craig controller?
What coolant are you using? I assume you bled the system thoroughly.

As for the flow restrictor, I would suggest taking an infrared thermometer and seeing whether free flowing or restricted provides a better temperature differential between the hot and cold side of the radiator.

If all else fails, lower the front ride height of the car. lol.

 

My first thought is that a massive heat exchanger covering 3/4ths of the front bumper opening could be dropping air velocity before it hits your radiator. Did this similar setup used to have better coolant temps on the older motor?

 

Are your fans spinning in the correct direction?

 

Assuming there's airflow, fans are accomplishing SFA at probably half of that lower speed.

I'd say that's the case!

Sounds a bit like some FMIC set-ups when tracked........impossible to control engine temps. Not much of a fan of the Davies Craigs either, but that's coloured by experience of 25 years ago....hopefully better now.
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it’s just the typical internet forum malarkey.

you need to post pictures and/or provide very specific details beyond “ewp delete” to make sure the words match the actual scenario to avoid assumptions and confusion.

and from the old Mazdaspeed Motorsports rotary tech manual, it aplies to an EWP as well:



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and it was all discussed recently, you can either do the link belowor opt for the $1000+ ewp with integral t-stat discussed there as well

https://www.rx7club.com/3rd-generati.../#post12601864

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Interestingly, RB says the opposite. You’d think an electric pump wouldn’t need restriction, since it can control the rate of flow arbitrarily…

 

Hi,

First thanks for the many replies.
Pics I can do in the weekend. Traveling for work those days.

I put some effort in venting the system properly, but sometimes I still do hear air in the system. Ordered one of those large sealed funnels that should help venting.
Coolant is 50/50 water and the pink antifreeze. Forgot the brand.

I'm controlling the Waterpump with the ECU in this case an ECUmaster emu black.
I'm pulsing the pump below 60 degreesC higher than that it runs constantly. Water moving through the radiator too fast is an interesting point. Will try to measure that.
The thermostat is taken out and the bypass in the Waterpump housing is welded shut.
Actually temperature was the reason why I have a new engine in there. The old one overheated in summer. and being short on time I bought a new engine and put the old one on the shelve.
I used to drive the car only one or 2 weeks a year during holidays. But I plan to bring it back as the summer daily.
Also by now I'm not the biggest fan of the pump anymore, as it doesn't really allow speed control.
Considering a pierburg pump which can be speed controlled by pwm signal.
Probably also a BMW thermostat, with a heater in it to control the opening.
But however first I would like to figure out where is my shortage and you guys gave me some food for thought. Thank you

 

If you have air in the system, there is nothing to talk about until you get rid of it and see if you really have a problem other than air.

 

Hi all,

Bled it a few more times and put a few hundred kilometers on it. Even the fans are having difficulties to get the temps down
Here some pictures of how it looks like at the moment.
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And the inside. aluminum ast is hiding behind/under intercooler.

 

The restriction of thermostat is more helpful than most people realize. If you measure coolant pressure on the engine side of the thermostat while the water pump is running, coolant pushing against the restriction of the thermostat will increase the pressure of the coolant inside the engine. Increasing the pressure is helpful and important, because it raises the boiling point of the coolant. Increased boiling point is important to transfer heat and avoid localized hot pockets. This is why Mazda Motorsports (and others) will recommend a 'gutted' thermostat even though it would be easier to remove it completely. If you've removed the thermostat completely, I would find a factory thermostat and gut it so you can have the same flow as if it were fully open, but the coolant pressure inside the engine is correct.

I've heard good things about Pierburg electric water pumps, I haven't tested myself but I've heard they flow well when pressure/restriction is a factor.

 

Overheating radiator because you dont have stacked heat exchangers.

Air passes through the front mount IC heat exchanger and becomes very turbulent as it exits. It therefore has no inertia to penetrate the stock mount radiator, so the fans have to pull all the air through radiator.

This is the classic issue with FMIC on FD.
A good FMIC kit stacks the IC and radiator so airflow penetrates them together. A turbulent pocket of air in front of the radiator is a recipe for overheating.

 

Have pictures of your radiator ducting setup?
​​​​​​ Or is the ducting stock?

 

No ducting yet. Just the factory undertray. I'm doubting the whole setup to a point where I wonder if it's worth to invest the time into ducting, or do another layout.

 

Ducting is extremely important. If it's not virtually air tight from the bumper opening to the core, you will lose a lot of cooling efficiency. Especially with a big gap between heat exchangers like you currently have. Your setup would work a lot better if the bumper was sealed to the air:water beat exhanger and then from that to your radiator. It would also be much better if your best exchangers were stacked and sealed to each other with foam, and using air tight ducting from the bumper to the heat exchanger stack.

Thetr also may be issues with the EWP, thermostat/restriction. I was considering an EWP but I may play around with those once I know the performance of my new cooling system with the stock thermostat and pump.

 

Alright stacking them maybe worth a shot and actually may fit as well, look better and simplifies ducting a lot. Will try if I can fit that.
Or actually first remove the heat exchanger in the front and check water temps.

 

Too much thickness degrades cooling capacity because the air flowing through heats up through each exchanger, reducing the cooling effect as it goes. The air will also slow down as it passes through more restriction, further degrading cooling capacity.

 

Well but that's what we see at oems. Take M3/M4 and the likes. The cooling package of those look quite neat.