Help with Rad in boot issues

[WabTheKing]

current set up

bottom hose from engine (theromstat outlet with thermostat centre removed) goes to the rear of the car via a davis craig water pump to the bottom inlet of the rad

top hose of the rad comes back to the front of the car into the two top hoses of the engine (splits to each head) with a bleed off pipe to the header tank

heater matrix is looped out

rear of the head water pipe work is standard with the header tank bottom hose connected

bleed point on the rad in the boot is siting about 70mm lower than the header at the front.

car did one lap of oulton park engine 95ish rad 75 - 80 ish

two laps and the header tank turns into a kettle but the rad goes cold (30-40)

rob suggested putting another header tank in the boot, what are other peoples advise/experiance with rear mounted rads?

thinking of doing a polycarb rear window with a full size rad air tunnel as the side naca ducts are far to restrictive

Cheers
Will

[terrybullwon]

Water passing through the rad to fast?

[Pirvu Eugen]

Electric pump pumping oposite the engine one?

[G60Rallye]

I haven't had mine run in anger yet so I cant comment fully on the issues your having. Mine does cool the car very well when stationary, when the fans are on it drops the temps very quickly.

Mine is plumbed differently to yours. Water manifold goes into the top of the radiator. Out of the bottom of the radiator through an electric pump forwards into the engine block. Vintage cars are plumbed that way around and work off a thermo-syphon system without a pump. Hot water rises and all that.

As for the air to the radiator i dont think you will get enough air to it with just 2 NACA ducts? Baz was struggling with 4 in his mk2 golf.

I only have the one inlet and outlet on the engine to keep it simple

[WabTheKing]

Water passing through the rad to fast?

rad goes cold more like an air lock but that was a thought earlier on in the day, think i ran it for a couple of laps without the aux water pump and it did help

[WabTheKing]

Electric pump pumping oposite the engine one?

it is a possibilty......... need to double check for sure

[bluequattro]

Davies Craig pumps go opposite direction iirc
Is header tank defo at highest point?
Tim cooper told me not to use water pump on
engine at all
Make sure pump runs on after engine off as
It ll boil header

[terrybullwon]

Yeah I removed my water pump blades also, but I know Hamish still uses his

[WabTheKing]

Should the bleed off pipe come from the rad or the top hose? Did both but that didn't work so just went with a bleed off from the top hose to the header

[volcano rs]

the reason you are having problem is because what you need to do is to totally get rid of the metal pipe that goes from the side of the block to heater matrix and block it off by putting a little rubber pipe and a bung .water is being pumped into heater matrix from both sides instead of inlet and outlet.
put a t piece somewhere by the water manifold exit that will go to the rad and connect the heater matrix outlet to that t piece .
i don't know if how i.m explaining it makes sense if in doubt call me on 07973 803367 jamil

[G60Rallye]

I think if you are going to have the radiator in the boot you should keep it simple and stip out the heater set up. I kept mine as simple as possible with regards to the plumbing I have plugged the pipe thats being talked about above.

I do have the water pump on the engine with the blades left on. Keith Edwards runs it this way in his hillclimb quattro and so did Keith Murray in the dialynx quattro. After seeing what my electric pump can do by itself I dont think it will make any difference.