cooling problems

[khm]

i have built a car which i did donington track day with last friday for a first time out & had trouble with keeping it cool, it is a similar set up to ultima with a tuned rs4 audi (614 bhp) mid mounted & large ally rad up front
we have fitted an auxillary pump, but still don't seam to getting the flow we need, the engine running at 110 deg but the rad still at 70 ish
any ideas ?
cheers
keith

[Incorrigible]

I'm not an RS4 expert at all. But it sounds like (as you suspect) you're not getting enough flow to the front of the car.

I'm assuming you've got large (1.5 - 2 inch) ID water pipes running the length of the car ? I only say this as there must be a restriction somewhere. have you run it without a thermostat etc ?

What flow rate is the aux pump ?

[khm]

pump is a davis criag 80 but still running engine pump too, so should have plenty of push, 51mm pipes front to back
thermostat is going to be a git to get at, it's up to the bulkhead & needs the cam belt taking off to get to it - last resort !!

[stevieturbo]

khm said:

pump is a davis criag 80 but still running engine pump too, so should have plenty of push, 51mm pipes front to back
thermostat is going to be a git to get at, it's up to the bulkhead & needs the cam belt taking off to get to it - last resort !!

Likely the DC pump is restricting the OE pump. Use the mechanical pump only and try.

[khm]

tried that in the first place, hence we fitted the pump as the engine pump would not push the water through the rad

[anonymous-user]

Something sounds a bit fishey here!

Firstly, take the CraigDavid ;-) water pump and fit it to the bin!

Secondly, assuming you haven't used water pipes the size of drinking straws, the pressure loss from the rear-front plumbing will not be too excessive. I have NEVER found a std water pump unable to cope with the extra restriction! What actually happens is that the small reduction in flow creates a slightly larger deltaT across the engine, this restores the heat rejection to the correct value, and in fact, makes the radiator more effective as it has a larger DeltaT to ambient, and with a slower mean flow velocity more time to loose the heat!.

If you are seeing 110degC at the engine outlet, but only 70degC at the radiator top hose, then something serious has gone wrong, i'd put a few ££ on it being an airlock or similar (most mid engine front radiator cars end up with a pretty tortuous routing full of up/down / u Bends etc!

I would try a vaccumm bleed of the system as my first move.


(also, check if you have ended up bypassing the main rad? easily done if you have removed or altered the cabin heater loop etc??)

[khm]

thanks for that, where could i get a vacum bleed system from ?

pipes are 51mm front to back, pump is by the rad output to boost back ?!? but easy to remove again, heater is still in system as hopefully it will go on the road eventually

all help is appreciated

[stevieturbo]

As long as there are manual bleed points at the highest point where air could get trapped, and you have ensured there is no air, that should be fine.

I assume you also have the radiator plumbed correctly ?

ie, lowest hose is the pump intake.

I also see what looks like some corrugated hose ? bin it for proper smooth hose.

What is the header tank arrangement like, and heater if installed ? Are you sure the hot water is circulating through the rad as needed, and not bypassing it altogether via the heater or header tank ?

[khm]

the hose is smooth on inside, need to get car out & running up to temp & give it a good coat of looking at
you never seam to think straight at a track, always feel like you should be out trying something else

[stevieturbo]

And not forgetting the obvious...

I assume that air can actually get to and through the radiator ?? And that none of that frontal air, can escape and simply pass around the outside of the radiator ?

[Toilet Duck]

Sorry, I can't offer any help or advice, but would you mind posting some more pics of your car as it sounds very interesting? What have you done to the engine to get the power hike over standard? Sorry for the derail!

[khm]

rs4 engine, 600 injectors, rs6 stage 2 turbo's, inconel tubular manifolds, triple plate clutch, 6 speed sequential box, MRC re map

[anonymous-user]

WOW, that looks like a lot of fun!! (not to mention a bit of a handful lol)

On the cooling front, you might be well off fitting some more thermocouples into the cooling system at various points to understand what is going on before ripping everything up trying to fix it!

(remember, that basically, flow and deltaT are opposite, i.e. high delta = low flow and vise versa)

I would expect to see something like 6 to 8 degC deltaT across the engine if everything is flowing correctly (i.e. between bottom hose and top hose close to engine) (at high speed light load this can be much more, especially if the thermostat is mod'd / bust etc)

[stevieturbo]

Cool project !! must be nippy !

[Incorrigible]

Looks great

That rad top hose connector looks very susceptible to getting an air lock in it. Can you rig the rad vertically to test it

[garagewidow]

khm said:

thanks for that, where could i get a vacum bleed system from ?

pump is by the rad output to boost back ?!?

ah ha,if i interpret the above correctly i suspect you are getting pump cavitation.mechanical water pumps are pushers and not very good pullers.

Edited by garagewidow on Thursday 16th September 00:18

[khm]

Incorrigible said:

Looks great

That rad top hose connector looks very susceptible to getting an air lock in it. Can you rig the rad vertically to test it

it has a blled point on it

[khm]

donington track day pic's

[khm]

Max_Torque said:

WOW, that looks like a lot of fun!! (not to mention a bit of a handful lol)

amazing no !! stick's like sh*t to a blanket, even the damp sighting laps, got it onto boost in 2nd & it just went !!

[anonymous-user]

garagewidow said:

khm said:

thanks for that, where could i get a vacum bleed system from ?

pump is by the rad output to boost back ?!?

ah ha,if i interpret the above correctly i suspect you are getting pump cavitation.mechanical water pumps are pushers and not very good pullers.

Edited by garagewidow on Thursday 16th September 00:18

Can you confirm that the header tank feed is connected as close as possible to the water pump inlet side (min system pressure occurs at the pump inlet, so by ensuring the header tank connection is close (virtually no flow through h/tank, except for bleed returns, so no pressure drop , so you should se header cap pressure at that point)