The V8 Owners Forum -

Hello all,

I am trying to get the best cooling layout for my 4.6v8 (gems) type engine in a westfield, cooling is always difficult in these cars due to engine, space & radiator options are limited.

I trying to work out which of the rover V8 cooling layouts would be the best for my purpose.....the options are....

range rover 4.0/4.6 GEMS type which has a 3 port thermostat that fully opens at 92degc.

https://i.vgy.me/1R5Q8d.jpg

Discovery 4.0 bosch type which has a 2 port thermostat that fully opens at 87degc.

https://i.vgy.me/SmqZoa.png

I do have a heater, and it looks like the method i had originally allowed the water to bypass the rad and flow through the heater....and i am hoping to stop this somehow with the new layout.

Anyone know the advantages or disadvantages of each of the layouts above?

I would prefer a cooler thermostat as possible, as the engine on the gems runs at around 93-95 all the time.....

thanks
scott

On my Landie, which has a rad approx 550mm x 600mm (so quite small), I have used the standard P38 (Thor) coolant circuit with a valve in the heater circuit. This is OK because the top hose has a T piece so water can get to the thermostat either directly from the top hose (cold engine), or from the bottom hose (hot engine). Your drawing shows a similar arrangement for the P38 Gems engine, the difference being that the top hose does not have the T piece, instead the pipe to the thermostat comes from the inlet manifold next to the top hose connection.

I note that you have an incorrectly drawn arrow on the Discovery drawing - the one pointing out of the top port should be pointing in to the thermostat. That is how the water circulates when the thermostat is closed, in to the top and out of the side.

I have two vehicles with the P38 Thor cooling system, a Range Rover, and my Landie. I don't believe there is an issue with that arrangement provided everything is working OK. Clearly the margin between operating temp and catastrophic failure is reduced because of the higher running temp. But I have found the margin to be OK. (I have measured it running up to about 97C, but never over 100C).

Mark Adams from Tornado Systems is a huge advocate of the Discovery system, I think because you can run it cooler which is supposedly better for the engine block.

The Discovery layout also looks like you can close off the heater circuit without ill effect.

On my Landie, even though I put a valve in the heater circuit, I arranged it to not close off 100%, to try to avoid air bubbles building up behind a closed valve and causing the water level to fluctuate wildly. Really a bleed pipe at the valve would be better.

Both of my blocks are top-hat linered, so I hope the slightly higher temps are not an issue.

Chri.

I have already given you the part number for the 82deg stat used in the later Disco 4.0. in your previous post:
viewtopic.php?f=9&t=15769
I am using this in my 4.6 supercharged/intercooled Dax Rush - so harder cooling than your westy and it works great.


The only real difference is the heater return connects to the remote thermostat on the RangeRover - where as on the Disco it tee's into the hose before the remote thermostat.

Yes i now have that thermostat thanks, but as i had the 3 port one, i was just trying to find out which one is best......i am currently re-plumbing the system for the 2 port one you suggested.....so hopefully once the new pipes arrive i can test it.....its much less plumbing too....

Still think a new more efficient rad is in order too at some point, but currently its cheapest options first...due to life changes.....lol.

regards
scott

finally got the new layout plumbed in and working, as not any easy thing to get all the pipes in the spaces i had.....lol....

new 78degc 2 port thermostat installed, and plumbed as per the discovery layout.

Idles around 85degc, which is much cooler than before, seems much happier and cooler now.....hopefully this will help to solve some of the over heating issues.....

Might look at a thicker RAD next year, once a few other problems in my life are sorted.....

thanks all

scott

How thick is the current rad ?

Thicker is generally less efficient, although yes it can add capacity.

Ideally it's surface area you want, as much as possible, as thin as possible but usually there are limitations there hence thicker is more common.

If getting one made though, try and maximise that frontal area as much as possible in the design.

current rad is only 45mm thick.....there are ones that are 55mm, 60mm & 70mm.....although i am constrained by the size that will fit in the nose cone of my car....my current one is ally, but the same size as a volkswagen polo.....lol....so not the best.....

I thinking trying to the the layout right first might have been a good option....

So far the engine seems happier, but i will see what happens when i push it on the next hot day.....or i get stuck in traffic...

regards
scott

Seight-V8 wrote: ↑

Sat Sep 25, 2021 4:47 pm

current rad is only 45mm thick.....there are ones that are 55mm, 60mm & 70mm.....although i am constrained by the size that will fit in the nose cone of my car....my current one is ally, but the same size as a volkswagen polo.....lol....so not the best.....

I thinking trying to the the layout right first might have been a good option....

So far the engine seems happier, but i will see what happens when i push it on the next hot day.....or i get stuck in traffic...

regards
scott

Don't forget, even though the actual opening at the front may be small, the core can still be a lot bigger, just duct it appropriately.