Looking at the idea of making a restrictor plate to replace my thermostat. (maybe one for Summer and one for Winter...)

I was wondering if one hole of 25mm diameter (Surface area of 491mm sq) will let more water flow than 10 holes with an 8mm diameter ? (Similar overall surface area of the holes combined.)

Should I have multiple holes as this may offer slightly more overall resistance to flow and ensure the water is cooling the engine suitably. (Maybe need a few more holes / more overall surface area for flow)

Are there likely to be any issues with any sort of cavitation caused by the disturbance of multiple holes or is it likely that if the holes are over a minimum diameter the water will flow fairly well without major flow disturbance ?


And for a person with only basic tools available, whats the simplest waay to make up some 54mm circles of metal as templates ?


Thanks in advance,

Neil

Trial and error on the holes really.
Sure you could perform some complex flow analysis (hydraulics) on the holes but a vehicle cooling flow is relatively low tech, so turbulence caused by lots of holes and edges would have little effect unless the holes get really small.

As for material aluminium sheet would be easiest to work with basic handtools.

Thinking around the box I made some restrictor plates.

I basically cut the bottom off some pet food tins, used tin snips to get them to the right size and then clamped them to a board for drilling. I drilled a 4mm hole at the top of each and then a number of 10mm holes. I did three in the end... One with 5 holes, one with 4 and one with 3 holes.

Both 5 and 4 hole versions the engine settled on a run at 65 degrees.... With the 3 hole version it's running at 72 and can cope with engine heat when running at speed or pottering.

I may try a 3 holed 8mm version for curiosity soon but I'm happy with the current position. Ambient temps today were around 20 - 22 degrees.

Neil

And the dog is completely stuffed never having had to eat so much

Serioulsy less than 80 is too cool,
so tweak, get to 80+ .........then speak to me either 'come on down'....... or beg



Nige

What material are the Tins Neil?
as you don't want the plate rusting away,
when you drill through the coating you'll expose the steel and rusty mess will fllow

The tin bases are an experiment is to find out what I need Tony...

When I know what the engine requires to cool and then I can make a more permanent version.... Nige has offered me time on his lathe so I can turn out more permanent versions when I next visit him

I am aware long term I could be compromising the engine if indeed the tin bases rust. (Fingers crossed they won't be in there long enough.)

I think I'll make one with 3 X 8mm holes next Nige and see how that works tomorrow. I have also re-calibrated the temp sender for the ECU. (And checked the thermocouple with another one.. )
The VDO gauge and sender is reading several degrees hotter than the calibrated thermocouple.

I'll let you know how I get on. (And thanks for the warning Tony.)

Neil

Could always FAD of course

FAD??

Lost me there...

Fit A Diesel

Oh how we always get down to swearing in the end...

You should be made to wash your mouth out with Unleaded.... And soap! (but you can have a beer to remove the taste afterwards.)

The current PETROL engine can now pull the 110 past 100MPH quite happily. (Not on the Queens highway of course...)

With a bit of tuning who knows what it could do !

It can also crawl along quite happily with other Diseasel types under 50MPH. I may not have what you refer to asl "Economy" but I do have a nice loud pedal and a lorra smiles !
(All said in the best possible taste of course..)

Neil
(Now wondering if he just earned himself a lifetime ban.....)

Well I never... Moved down to 3 X 6mm holes with small bleed hole today...

Now runs at 74 degrees most of the time with a small climb when hitting hte engine hard for a prolonged period of time. It seems madness that it's not running hotter...

I'll try 2 X 6mm later in the week. I can't believe how muh flow I have to slow / restrict to raise the temperature by a small amount !

Neil

I have this sort of 1st, 2nd, 3rd attempt regularly
and this is what I now lovingly refer to as

"Three Bears Engineering"

Nige

I recon I'll be needing a restrictor plate without holes soon Nige !

Still, should be much easier to make if I head down to you again !

Neil

stupid question time......


why would you want to replace the thermostat?
Wont having a restrictor plate with simillar flow properties to a fully opened standard thermostat cause excessively slow warm up times?


also, to gauge how many holes and size you need - wouldnt it be easier to jam open an old thermostat and tape it to the neck of a 15l water can (or 40l aquaroll, if you are a caravaning type) and turn it upside down. Time how long it takes to empty. You then have the flow rate with the thermostat in 'fully open' position.
make your plates and do the same test. Saves mucking about with making and trial fitting and driving about to measure temps etc.

Quite a complex / can of worms subject this

Thermostats are really there on a road motor to assist in warm up times and help maintain temp
Often they do more harm than good, and on a V8 there are a selection of settings of thermostats you can buy

A good cooling system should be designed to actually "Overcool" the engine then a plate fitted to set and maintain at a predeterminaed limit - done via the size of the hole in the plate. Removing the thermostat completely is a seriously bad idea, apart from the effect on the cooling system it also affects the water flow which has other issues.

Many racing V8s have restrictor plates, yes the engine takes longer to warm up (esp on a really cold day) and should be born in mind to allow it to warm before driving off hard but the thermostats if they jam can see temp and core temp rise hugely and quickly, often damaging engines serverley, even new genuine thermostats have been known to cause issues....

The hole in the restrictor plate is reallyu dependant on many outside infulences, the engine itself, the cooling avaikable radaitor fans cowling all make a difference, a plate with the correct hole for the a specific 4x4 will not be the same in another, they are in effect tailored. You can buy a range of after market ones but best do the "3 Bears engineering" and work out what you need for yours, you can compensate within the 4x4 and get cooling that was previously a nightmare under control.

Lastly heat build up isn't a strasight line, there is a curve, when the heat buildf up in the system reaches a certain point the increase can almost become vertical, and you'll never get back on top of it unless you back off and pray, switching engines off at this pouint see the cooling system shutdown and the core temp goes through the roof . the trick is to map your cooling and ensure you pick a point where the cooling is well under control and has a saftey factor built it where it can still cope with more without "Losing it" . Some V8 racer aim for cooling between 65-85, kniowing that when they are screaming the engine 85 is top whack, but means its a tad cold at 65 for WOT. For racers again the temp is crucial for MAX BHP, as too hot see BHP lost, not key here but part of the "Why". V8s need to be run at a minimum of 80degrees part engine and on some partly due to fuel enrichment kicking in when you don't want it

Restrictor plates also help bleed the system super quickly, a 78 74 therm will normally get around 80 degrees V8 temp, a plate will with effort get you exactly what you wnat, and you have to also ensure the antifreeze levels are constant between tests as the mix can effect heat levels too. I have seen Aluminium ones but they tend to wear the holes bigger over time amazingly quickly, most I have seen thast you can buy (and mine) is just cleaned up steel plate

HTH

Nige

I thought of trying to measure flow using an open stat but the amount it opens varies on the temperature.

Just doing a vertical drop as Nicks90 suggests would not replicate the water flow to the same pressure / flow rate of a revving engine driving the water pump quite fast.

A fully open stat should replicate overheating and thus allow more cooling that is necessary to maintain a temperature.

My problem is that the stats I have tried (Eight of them) do not react fast enough to the build up of heat in the engine. I've looked at pressure release systems to allow water flow but that seems like overkill when there may be a simpler way of doing things.

The holy grail of a restrictor plate that will allow me to trundle at 70MPH all day (Apart from fuel stops of course) at 80 degrees is just a case of finding a way to optimise water flow to effect the amount of cooling required.

Neil

All you really need then is a bit of old steel with a nice adjustable hole fitted to it so you can change the temperature at will! Easy to buy from any hardware store- generally next to long waits (sp) and tartan paint!

Sod the coat the door is already hitting me on the @rse on the way out!!!

On a serious note I would suggest that a thicker plate with a larger single hole with the edges nicely rounded would be better for flow than a number of small holes with sharper edges- it would mean a less turbulent flow overall- although saying that the flow around the engine is probably fairly turbulent in any case...

Not really sure why you should be having problems, after all landrover made 1 or 2 of these engines and a few of them didn't overheat .
Why don't you go back to the system that was run on that engine with no problems at all which was a davies craig electric pump and controller. That way you can sit in the drivers seat and control the temp to whatever is deemed best without even switching the engine off.
Might be an easy fix for relatively little work / financial outlay.

Adrian

The current plates are only for experimentation as remarked upon further up the thread. Regards water flow, while on plate was still in place (held in by the gasket and a small amount of RTV sealant) I dumped several litres of water into the top of the rad through a large funnel and the water flowed through in a nice orderly fashion. I'll have the camera ready for the next version and see if I can replicate for you.
I believe if it were many small holes of 4mm or under, I'd agree, but having seen the flow throug 3 X 8mm holes, it's smooth and plentiful!

Nige has offered me some time in his inventing shed to make up the final version(s) which will have nice professional holes and maybe even rounded edges ! I'll be hoping to make from 3mm steel although Nige has probably already selected a nice piece of 12mm thick armour plate to make the job a goodun...

Neil

Hello matey, didn't see you there...

I did consider the way you ran it but I recon it would still need some sort of restriction, although not by the same amount maybe. So far the tin snips, drill and pet food tins are not a massive outlay and I still have a trustworthy stat on the shelf to fall back to, although it doesn't like closing too well once open!! May still be an option... Who knows.

Just for ref Adrian.. I pulled the old 3.9 airbox off I was using as a temp way of filtering some air.... Like a different engine. Nige suggested I might be strangling the thing and he was right. Pulls like a train right through the rev range now. Totally different to how I had it / had accepted it to be....(And I thought that was good..)
Visitng the V8 Dev boys this weekend to grab a ported inlet manifold and short trumpet base. Should be good for a few more smiles. If I am down your way I'll give you a call and you can have a crack in the truck. I think you'll recognise the engine alright now..

Neil

glad to see you are getting happier with it. might be worth a rolling road session sometime soon then, or try the old map back in it maybe

Always been happy with it.... Just at new levels now !

May try the old map like you say... Could be hairy!!!

Speak someday matey.

Neil