620R cooling

[7 wonders of the world]

Modify yours one to accept a bypass outlet underneath  - same as the Burton one.

[7 wonders of the world]

where is your bleed pipe taken from to feed the expansion bottle..? 

[7 wonders of the world]

Bypass hose

https://caterhamparts.co.uk/other/2406-water-by-pass-hose-duratec.html?search_query=duratec+hose+&results=404

 

[7 wonders of the world]

https://www.uk.mountuneracing.com/products/cast-water-outlet?variant=36319296074

[Mark w]

Re # 52

of the top of the return rail .

[Mark w]

#54

solves one problem but leaves no home for the water temp gauge connection . This would need to find a home in a submarine pipe .

[Mark w]

Re #53 
 

may not be needed ? The bypass could possibly be

Teed into the existing pipe that runs from the expansion bottle to the thermostat housing .

[Mark w]

I might be interested in trying this but just want to understand a couple of things 

By introducing this larger bypass pipe from the back of the block to the thermostat housing it follows basically the same path as the bleed pipe via the expansion bottle . Larger flow but the same path . 
what benefits does the larger flow give ? 
 

All the plastic HE14 thermostat housings I've seen place the bypass connection next to the cold feed from the radiator . The 620 has a metal connection to the block .This seems distant from the thermostat . Will the thermostat still operate correctly using this connection or will one just end up with a large volume of water circulating round and round the block ?

Not looking to be awkward here just trying to understand the implications of changing the rear connection manifold .

 

 

[7 wonders of the world]

Increased water flow Mark, the T'd off via the expansion bottle pipe flows tro a 3-4mm hole, the bypass is a 16mm hose, the response time of the hot water from the head to stat is quite different, it also allows for a much better warm up circuit too.

 

No, the 16mm plastic connection on the stat hosusing is the return line from the expansion bottle and heater - usually the bottle is T'd into the heater return, the bypass is the gold colour metal pipe pressed into the block itself which directs hot water straight onto the wax capsule, this circuit is open to flow during warm up and as the stat opens in response to the hot water from the bypass the stat then closes this bypass off in favour of the 32mm return from the rad - but should the stat receive too much cold water from the rad it will start to move in the opposite direction thus reopening the hot supply form the bypass this blending effect much like a domestic shower maintain your base temperature.

[Doctor]

OK, what about the stat end, what needs to happen there?

[Mark w]

So just to be clear , bypass from new back plate to connection shown in this photo ( black pipe ) 

[7 wonders of the world]

yes bypass is gold pipe to gold pipe with nothing else in this pipework.

has the new cnc stat housing got a provision for a 16mm hose..? if not we need to locate a suitable point for the bottle return to feed into.

[Doctor]

#62

and where would that be? Can they be connected into one? 

[Titanium7]

There's currently no provision built into or onto the engine at the the outlet or Inlet end for a bypass pipe.

[Mark w]

re 62

Theres no 16mm connection on the cnc stat pipe and theres no room there to fit a plastic thermostat housing with two inlets .Too much supercharger pipework in the way .

What about fitting the expansion bottle return pipe  by way of a T into the bypass pipe ? After all thats the way it runs now ?

[Mark w]

On a related matter , The casting shown in photo ,post 48 appears to have a blanking plug where the bypass elbow would fit . ( need to take it off to fully check but that appears to be the case ) 

Does anyone know a source for the elbows ? If found the existing back plate could be modified .

 

[Titanium7]

I've just checked mine and yes there's a downward facing spigot which looks like it could be drilled and tapped.

[Doctor]

The plug on the bottom of the bolted water outlet at the back of the head is just pressed in. You can specify one of the products advertised here whether you want it with the bypass outlet on the bottom or without - the plug would be pressed in instead. The issue of that particular outlet is that it only offers thread for one temp sensor while we do have two in there. It looks far more feasible to modify our water outlet with the knee for a 16mm water hose.

[7 wonders of the world]

You could add a 16mm elbow to the housing, I haven't had the opportunity to study at length the clearances for the Rotrex plumbing, but I feel with a little patience you could rework the housing to accept something suitable.

 

 

[Titanium7]

Found this from SBD Motorsport. I find the second paragraph quite interesting as it may be the cooling strategy Caterham originally used although they also don't use the bypass hose.

 

The cooling system shown is the design as used by SBD Motorsport, when using a mechanical water pump. The most important part of the cooling system is the orange recirculation pipe. When the thermostat is shut, the coolant passes through the engine, reaches the closed thermostat, the coolant flow is then directed through the front of the cylinder head to the water outlet on the underside of the inlet manifold and the coolant is then drawn back in to the engine by the water pump. This keeps the coolant flowing through the engine maintaining an even temperature. As the temperature rises within the engine, the thermostat slowly opens allowing the coolant to pass into the main cooling system to the radiator. The thermostat is a 2-part stat and as the thermostat slowly opens, the second part of the stat begins to slowly close the entry into the recirculation part of the cooling system and as the temperature begins to fall again, the thermostat begins to slowly shut. This maintains an even temperature throughout the engine.

Important Note: Some engines used in specific race car championships (Formula 3, etc) do not use thermostats. They carry out extensive testing, design the radiators and cooling system around their design and quite often change the water pump design and even on occasions use restrictors. This is not something recommended for a single user. If you get your cooling system design wrong, the water could flow too fast or too slow causing hot and cold spots within the engine, creating damage to the engine itself. In many cases this problem may not be visible straight away and may become more apparent over long periods of time. We do not recommend this set up.

The most common mistake when designing a cooling system is to misunderstand the flow of the cooling system itself. The mistake normally made is when connecting one of the following: the header tank outlet (green), the heater outlet (red) and the recirculation outlet (orange). These pipes must separately be fed into the blue water pipe shown flowing from the radiator outlet and going towards the back of the water pump. DO NOT attempt to T any of the pipes together, this will completely destroy the water flow causing a major problem with your cooling system.

[7 wonders of the world]

 

Running a road car with no thermostat control in cooling ot oil circuits is madness.

Whilst space is very limited it does shows a lack of understanding from CC in removing the bypass circuit and using it to feed the header tank into, 

Love to get my head under the bonnet,

Ti 7 could you BM me as I think were not too far apart 

 

[7 wonders of the world]

NB the above diagram does not represent a Duratec as the return from the header is not correct as it would feed into a dead end until the thermostat opened.

Easy to mis interprest the water pump for the thermostat housing and blur the understanding.

 

[Doctor]

How about putting the bypass hose back in place and connect the fill of the expansion bottle to the radiator itself?

There is bottom bolt on the right and top on the left (I think) and it should be easier to banjo either one of them. 

[ChrisC]

On the first page of this thread there is a picture of the 620 stat housing.  Isn't the cut out at 6 o'clock providing a cooling circuit while the stat isn't open, all be it through the radiator?   Without a picture including the stat it's difficult to tell.  

[7 wonders of the world]

Chris - hard to establish as I don't know if they use a conventional stat to the same OE model, I think the former as there is no form of retention for the later in the housing photos I've seen.

Doctor - no as if the correct stat is used this circuit is closed off during warm up - the feed needs to be in a constant circuit, and a feed from the top of the rad is effectively another bleed we need a return from the  bottle.

I have a few ideas but really need to see a 620 to do a reality check