Duratecs & EWPs

[k80rum]

Out of idle curiousity, why are some folks using electronic water pumps on Duratec engines instead of the mechanical one?

 

The archives seem to show a few people fitting them, despite some technical posts arguing good cases against their use on grounds of decreased flow rates ( the mechanical pump seems particularly good in respect of its flow rate), worse thermal gradients, increased electrical load and all sorts.

 

Despite this, some owners seem to be using them and the SBD website goes so far as to say

We recommend the use of an electric water pump on the Duratec, we use this on all our engines.

I've dropped them a line asking why this is, so hopefully they'll be able to shed some light on the matter too.

 

Aside from the fact that at slightly higher revs than the original application the pump may be oversped, surely Ford/Mazda have produced a decent design? Perhaps the fact that some engines are developing 70-100% more power than stock a contributing factor to the need for a change but arguments against EWPs seem to disprove any huge advantage.

 

I'm trying to understand whether there's actually any issue with the mechanical coolant pump on this engine in a high state of tune. I find it difficult to believe there is because several high power engines, and indeed the R500 itself relies upon it. So what's driving some people to use them?

 

Darren E

 

K80 RUM Website and Emerald maps library

 

Duratec/SuperlightR hybrid

 

Edited by - k80rum on 20 Jan 2009 22:03:54

[Pendennis]

Hi Darren

 

An EWP is unnecessary in ANY road going spec, in fact probably not required in any going spec. However, I have specified a larger pulley for my refreshed lump, not because I have ever had any H2O temperature issues, but because I shall be revving a bit higher and my current H2O pulley is bent 😬 I did replace my water pump last year, but thats not bad considering the existing one spent all of it's life trying to keep up with an 8K engine

 

SBD, are a good company who achieve sales from extreme performance

 

What do you think is more reliable in the long run; (a) Ford/Mazda designed and manufactured part - or (b) An auxiliary retro component

 

Want to rent an 18th century Farmhouse in Rural Somerset?

[Willie.]

Darren,

 

My (Limited and simple) understanding is that the purpose of the water is just to conduct heat away from the combustion chamber/block/hot bits. Therefore, flow only needs to be great enough to accomplish this. Flow greater than necessary is wasted energy, and excessive flow will cause pressure in the waterways, which the pump is having to push against.

 

Too little flow, and the engine (Or particular areas of it) will overheat.

 

I've got an EWP, and intend to fit it, and possibly 2 water temp sensors, one on the in, one on the out. So long as there is sufficient flow to keep the exiting water within normal operating temp at sustained high revs, I think it will be a better solution that having a mechanical pump possibly over pumping and draining engine power at high rpm.

 

I may fit some kind of controller incase the necessary flow for high rpm is too much for idle and the engine runs cool. It would be very interesting to measure the flow rate of the existing pump at idle, 5k and 7k rpm. I doubt if Ford/Mazda designed the pump to be spot on right up to 8k rpm...but you never know.

 

The other advantages I see is that it could be wired in to run for 30seconds after ignition off, and it can make an engine install that bit easier and tidier.

 

Edited, before Peter C reads this, to add:

Its not flow that does the cooling, its the difference in temp between water and engine.

 

Willie

 

 

Edited by - Opposite Lock on 20 Jan 2009 23:14:05

[Pendennis]

Willie, when designing the correct pump and checking its compatibilty you need to know the water temperature entering the engine, thus you can identify it's heat transfer

 

Approximately, the Duratec needs to be between 85-92 to be productive, therefore energy submitted above these temperatures maintained maybe wasted, but by how much Because as power increases so does demand for cooling, so it would not be easy to calculate power loss, if any

The beauty of circulating coolant via engine speed is (if designed correctly) the water pump would ramp up in conjunction with heat build up. A process that would difficult to reliably and economically control via a EWP

 

I would be very surprised if Ford/Mazda had not tested their product beyond a RPM load such as 6k, which leads me finally into, 4 years of racing my Duratec with standard water pump without any water temp issues or pump failures (although last year got a whine so replaced it).

 

 

 

 

Want to rent an 18th century Farmhouse in Rural Somerset?

[Peter Carmichael]

Willie, I'm not going to pitch in particularly. I think your project is going about things in the right way. I'm a great advocate of multiple temp sensors in cooling circuits.

 

You are right. The temp diff between the cylinder head and the coolant does provide the heat transfer. Thing is if you don't get one bit of coolant out of the way so another bit can take its place, the temperature gradient disappears. For this to be the case, the flow rate needs to get the Reynolds number up > 4000. i.e. turbulent flow. I could go into the whole deal on heat trannsfer, digging out my Prandtl and Nusselt numbers, but.... pumping it as fast as you can usually gets you the result you need.

 

Your approach of measuring inlet and outflow temps is as good as it needs to be. It is exactly the empirical approach I would take myself. My main gripe at the EWPs is that Davies Craig insist on a load of hogwash about running a speed controller based on temperature recorded at a single location and they encourage the removal of thermostats. Both of these aspects has the bull****ometer off the scale.

 

I look forward to hearing about your progress.

[AMMO]

I think the EWP is a solution to a problem that doesn't exist.

 

The Duratec mechanical pump does a fine job. I have had larger ali water pump pulleys made to slow the pump down. This is to avoid cavitation as the stock pump is probably designed to bimble along with the engine at 4000 rpm whereas we tend to rev the engines way up to 9000 rpm. At 9000 rpm even if the pump didn't cavitate with the stock pulley it would probably sap power.

 

I fit the larger pulleys (which weigh less than the original smaller steel pulley) to my 300 + bhp engines and to date have had no problems. I even have one fitted to my road engine and have never over-heated in traffic.

 

The Duratec survives perfectly well on shut down without popping head gaskets or doing anything strange, so even the argument that the pump can continue to circulate coolant after shut down is one that doesn't hold water (is that a pun? Not sure).

 

The engine has probably undergone all sorts of testing to ensure that it survives some pretty extreme conditions. From frozen wastelands to deserts. A friend used to do destruction testing on Ford engines. They have to endure more than a shutdown when hot.

 

The EWP weighs more, takes up space, needs bracketry, bolts, extra hose and jubilee clips (more connections and potential leaks), adds complication, costs a hell of a lot more, saps electrical power to run it and is more likely to go wrong than the mechanical one that comes free with the engine.

 

The mechanical pump is very cheap, I've never seen one go wrong, weighs less, is less complicated, requires no electrical power to run it, doesn't need a controller etc. etc.

 

I would rather go touring (or racing) with a stock pump that can be bought anywhere in the world from a Ford dealer than an expensive electrical pump that can fail in a variety of different ways. To date I have never seen a Ford water pump fail.

 

I come from a background of 24 hour endurance racing so I don't like to fit anything that has the potential to go wrong.

 

There is more profit in selling electric pumps and controllers than telling people the stock pump is perfectly OK.

 

If there was a problem with the cooling system we would be looking for a way to fix it. As there is no problem why screw around with something that works?

 

My opinion only. Feel free to disagree.

 

Ammo

Raceco.com

[Jason Plato]

My Duratec water pump started leaking from the nasty cheap core plug on the front face. It started in the paddock whilst warming up to go to the grid ...... lost a race and probably a class win

 

I would suggest duratec users carry a spare pump and O ring in the support vehicle / garage > they are only about £40 from Ford

 

here is C7 TOP

Taffia joint AO with Al

 

[AMMO]

"they are only about £40 from Ford"

 

Exactly Dave.

 

As opposed to, I'm guessing, £300 for an EWP and controller?

 

 

 

Ammo

Raceco.com

[Darren Harrold]

I fitted a EWP. Why? One of the issues was overcooling at speeds above 5000rpm. Water pressure was forcing thermostat open. Yes, this could have been very easily fixed with a larger water pump pulley – a 15min Job, anyway, it got me thinking about EWP’s.

 

Whilst reliability has been raised– There is no reason why a well designed EWP using a brushless motor should be any less reliable than a standard mechanical water pump. The jury is still out on this one, however fuel pumps have been electric for a long time now.

 

I liked the idea of an EWP as it could give max flow independent of engine speed and provide run-on after the engine has been switched off. I never found an EWP that would give the same max flow rate as the std pump – but then again I don’t drive on the redline continually.

 

What I didn’t do was fit a variable pump speed controller or remove the thermostat. This concept gave me horrible thoughts of icy cold water from the rad entering the block at a trickle on a cold day as the pump slowed to maintain the output of the block at 85deg. Seemed a very bad idea to me.

 

So I kept the ford thermostat and rad bypass loop (Which controls the temp of water into the block by mixing water from the rad and bypass loop) and run the EWP flat out all the time. Plumbing PDF Here

 

Results are good. Temp gauge far more stable now. Even on the 3 track days during Le Sept last year where air temps were high 30’s. I am just in the process of fitting a 2nd temp sensor to the inlet of the Block.

 

I configured the ECU to give Rad Fan run on and also the EWP.(If fans were on) when the engine is switched off.

 

Darren

 

 

 

 

Edited by - Darren Harrold on 21 Jan 2009 12:21:32

[k80rum]

Thanks all

 

Some great feedback from both the adopters and those who wouldn't. Your first sentance Ammo, reinforces the conclusions I'd drawn so far which is reassuring to read.

 

I hadn't planned to fit one before now and I haven't read anything to change my mind on that score but it's been interesting to read why some have chosen to go this route.

 

I have an underdriven pump pulley by CFM which I could fit if necessary but I don't expect to be living at high revs a huge amount of the time so a nice high flow with the standard pulley gearing may be fine.

 

That said I also have the corresponding CFM billet crank pulley which I could use with the oversized pump pulley to keep the stock pump speed (I think. I need to compare the gearings from the stock and CFM pulley diameters to confirm this). I'm sure someone mentioned there had been one or two failures of the iron pulley? Given how many Duratecs are out there though and how few failures have been reported, I'm more than happy to stick with the stock setup but the CFM pulley combination might be worth fitting if I have it and it eliminates the chance of failure at all.

 

 

Darren E

 

K80 RUM Website and Emerald maps library

 

Duratec/SuperlightR hybrid

 

Edited by - k80rum on 21 Jan 2009 17:47:03

[Willie.]

I think the EWP is a solution to a problem that doesn't exist.

I fit the larger pulleys

 

Why fit the bigger pulley then? 😬

 

Willie

[paul jacobs]

I think the answer was in Darren's reply, in that the Duratec will drop water temp. over 5000 rpm, because of the build of of pressure forcing open the Thermostat. I can confirm that this does indeed happen, and very quickly too, and I do wonder if the much cooler water suddenly being pushed around a hot block will actually do some damage?

 

So, it seems to me that a larger pulley would slow down the pump at higher revs, as long as it maintains the flow needed at low revs. Maybe this is a solution I ought to be looking at - Ammo?

 

A very good question BTW Darren E 😬

 

Paul J.

Waiting to get my CSR back with it's new and remapped Omex ECU

 

Edited by - Paul Jacobs on 21 Jan 2009 17:37:23

[Willie.]

Darren E,

 

I should've said, the main thing people dislike about the EWP is the variable flow thing.

 

I know I mentioned it on my first post, but I dug out my notes and had a re-think, so ignore that bit.

 

I think its best (As Peter C says) to run the EWP flat out, and do the "cooling" via a normal mechanical thermostat. So EWP circulates water in bypass circuit, when this gets up to temp, the thermostat opens and lets radiator cooled water in as necessary to keep the temp constant.

 

Varying flow rate with a speed controller or something, to try and control temperature will just toast your engine and is bad. My thought earlier was to have, say 2 speeds, but on hindsight its got no real advantage.

 

My theory would be, use the EWP to circulate water around the engine fast enough so that its not freezing on one side and roasting on the other, but not so fast that the pump is cavitating/building up pressure in the waterways, and then you control the temp by feeding in coolant from the radiator circuit.

 

Willie

[The Pikey]

Hello gentlemen

 

I don't have a Duratec but I do use a EWP on my bec. I bought a Davies Craig and sold it after reading horror stories about them and then bought a Bosch of Powertec and sold that because it did not look like something I could rely on for thousands of miles. In the end I used one made by Stewart. It's amazingly well made and has a brushless motor and a ramped start which is supposed to extend its life.

 

I bought mine when the Pound was 2-1 so it worked out well. It's a dear bit of kit now.

 

Heres a link if anyone wants a noseStewart Pumps

 

Edited to say I run it flat out with the standard stat in and the bypass hose to a T before the pump. Works perfectly.

Jason

 

Currently, I am qualified to plead ignorance.

 

 

 

 

Edited by - Jason Fletcher on 21 Jan 2009 22:51:28

[AMMO]

First of all thanks Darren for posting your experiences and the .pdf schematic. That's very interesting. Thanks also Jason for bringing the Stewart pump to our attention.

 

I still stick to what I said originally. We are however all grown ups and free to make up our own minds on how things should be done on our own vehicles. There is more than one way to skin a cat and we should be able to disagree about what works best for us. I base all my decisions on past experience. I don't like complication that I think isn't neccessary.

 

I was discussing EWPs at work yesterday and the conclusion was that "the enemy of good is better".

 

I have an economical working solution for the cooling system on the Duratec so why complicate matters? Flogging engines can be a cut-throat business based on price. Increasing the cost of engines or installations in areas that I do not deem neccessary makes no sense. I insist on good cranks rods and pistons etc. EWPs are not essential for me, so I'm coming at it from a slightly different point of view.

 

We did agree that there are some classic engines where the power has been increased by quite a bit and the original coolant pump is under-specced. These do benefit from EWPs. We are fortunate that the Duratec has a pump that is over-specced. It is an easy job to slow it down.

 

Willie

 

I fit larger pulleys because we are revving the engines more, to avoid cavitation, to reduce parasitic losses and to save weight. The larger ali pulley is lighter than the original steel one.

 

I don't normally fit the large pulley to cooking / entry level engines that don't rev over 7500 rpm. They could be fitted and would work fine but the pulley would add to the cost. The stock pulley works fine on all the production road vehicles fitted with the Duratec I4. I guess there are quite a few million of them around the world.

 

To give you an idea how resilient engines can be I'll describe one of the destruction tests a friend of mine did when he worked at company called Scott Gibbin. He got the engines on the dyno at maximum rpm and temperature and would then pump 200 gallons of freezing cold water through. The engine had to survive this without popping the head gasket. A drop of a few degrees when the stat opens is no big deal in comparison to this.

 

Darren

 

I have seen the rubber on the cast crank pulley / harmonic damper deteriorate on high rpm engines. So I keep an eye on them and changed them once a year on customer's high rpm engines. I have since made some smaller steel crank pulleys /trigger wheels that I now use on high rpm engines like my 9000 rpm 2.2 conversion and the 8,500 rpm 2 litre race and road engines. I decided against ali for the crank pulley because i didn't want to reduce the weight too much on the nose of the crank.

 

I believe Caterham fit a stock pulley with the trigger wheel held on with three set screws rather than just rely on the interference fit.

 

Someone I know has dyno tested Duratecs a lot at high rpm has seen the pulleys crack. The timing wheel can then slip. Luckily he hasn't had one explode in the dyno cell. This is why I have made steel pulleys with trigger wheels bolted on with six screws as the stock one has the potential to fail.

 

Paul

 

I run the small crank pulley and large water pump pulley on engines that are spending most of their time on track. So I am slowing the water pump down even more. Danny LT did a two day open pit lane track day at Spa totalling 500 miles pretty much flat out with this set up on his 312 bhp 2.2 with no problems. Most of his other track days are only 200 miles a day.

 

On a road, road / track or purely track engine I would juggle the available crank, pump and alternator pulleys to do what wanted them to do depending on engine maximum rpm. You have to pay attention to choosing the right altermator pulley depending on what crank pulley you run.

 

On my previous 7,500 rpm and my current 8,500 rpm engines the large water pump pulley works fine. There is not a situation that I can think of or that I have encountered that I think it wouldn't work.

 

Ammo

Raceco.com

[paul jacobs]

Thanks Ammo, a very comprehensive answer and one that gives confidence to all Duratec users no matter what pump/pulley combo. they are running

 

Paul J.

Waiting to get my CSR back with it's new and remapped Omex ECU

[dannylt]

Just to echo what Ammo said, never had the temperature move above 85 degrees or so on track. I think the main reason we originally fitted the larger pulley was to get from 299 to 300bhp ages back .

 

However, the EWP on my Radical was one of only two times I've ever had to cut short a track day. The first sign I got was a cloud of steam in my mirrors. That was a Craig Davies pump, and the factory helpfully told me that they often failed, and supply a Bosch replacement. Thanks. Am sure they liked the £3k strip, skims and rebuilds!

[dannylt]

PS The only reason it had an EWP was because the oil scavenge pump took the place of the water pump.