Cylinder head cooling, thermostats and expansion tanks: Discussion...

[watoga]

The best point maybe to move the radiator to the rear of the car as you will benefit from that by increaseing the amount of coolent in the system and you could also duct the air to and from the unit via the side and rear window.....rules permitting .

Does anyone know how much (roughly) the typical coolant volume will increase when this is done? Assuming a 35mm diameter hose going the full length of the car (~4m) and back again to the engine adds about 7.5 litres of coolant, but I'm sure this is an overestimate. Regardless, does the added amount of coolant that the pump needs to push around the hoses affect its longevity and/or reliability? Are there any other complications that need to be overcome (other than feeding cool air to the radiator and hose plumbing)?

Cheers for the advice,
Dave

 

[campbellju]

I used to run a standard Nissan bonnet with the bracing removed and a slot cut along the front that rested just above the rocker cover. Probably around 40cm wide and 8cm deep with open sides. The bonnet was free so it didn't matter hacking it about. Was pretty effective in getting rid of hot air as being metal there was no gap needed between it and the rocker cover to stop damage. I had to chuck it out when the car was stored :-(

The original inspiration I took from Mike Kojima's Sentra race car. No different in principle to the big hole on top of Evo's that use a front mount.

 

[PobodY]

I don't think so. - Fundamentally it's still just moving coolant in a circle; it's just that there's a longer resonance time.

Obviously more hose means more chance of leaks, but I'd guess you'd be running it at 1.1-1.3bar pressure so that makes no difference.

I guess if you were going to do this, it's not much more effort to blank the water pump and run an electric one instead.

 

[Jon Olds]

Had experience of the davies craig elec pump. When they 1st came out I converted my mk1 golf rally car, and had 3 pump failures in 2 years. 1st 2 covered under warranty. Converted back now. Still not convinced about them as they have reduced the warranty period they offer right down.......

 

[watoga]

I don't think so. - Fundamentally it's still just moving coolant in a circle; it's just that there's a longer resonance time.

I was thinking more along the lines of where the pump actually is in relation to the bulk of the coolant. I suppose if you run the extra coolant lines relatively inline with the rest of the system, you'll not be increasing the work required to circulate the coolant. Plus, if the pressure and flowrate are the same, then the pump will still be operating at the same power. Maybe it's time to use that water-pump blocking plate I bought a while ago............... :-D

Dave

 

[The Doc]

Its a sealed system, so all the pump does is to circulate the water. The volume will have no consiquence or affect and there is not enough head height to affect it either.

 

[watoga]

Its a sealed system, so all the pump does is to circulate the water. The volume will have no consiquence or affect and there is not enough head height to affect it either.

Cheers Doc! :-D
Dave

 

[Jon Olds]

Holey thread revival....
Just picked these gems of info from another thread, from someone with a lot more know how than me;

The cooling system for this car was designed when it was effectively a rally car, and as such forced to run with a 34mm turbo compressor inlet restrictor. As such, the compressor pressure ratio is extremely high, even for what would normally be fairly moderate boost, and that means your compressor is un-avoidably inefficient. This results in high compressor outlet temperatures and the requirement to reject quite large amounts of heat from the intercooling system.

Added to which, the main water radiator is heavy (it's full of water!) so mounting it low and the much lighter I/C rad high is sensible. By steeply angling the main water rad, the overall package height is also reduced and you can get some benefits from non forced convection cooling at low vehicle speeds (typical of UK stage rallying). As a radiator only requires something like 50-60% of it's core area as intake area (because the core itself reduces the flow area, and it uses highly turbulent flow to get good heat transfer) by tilting the main rad, and packaging the IC rad above it both rads get a nice cool air flow close to ambient temp (rather than have them sandwiched and the rear rad gets hot(ter) air)

The exit area is more than sufficient for both radiators, it's just a question of subjugation to avoid upheat at low speeds!

It's really noticeable with this cooling layout, that with the vehicle not moving, the cooling rad fans hardly even cut in at idle. In effect, there is enough convection driven cooling to remove the engines idle heat flux without cooling fans.
So, that's more info to dwell on for my pulsar rally car, also on 34mm restrictor...
Comments appreciated (its rare to get anyone to comment on the effect of compressor inlet restrictors)
Jon