juju

Hello folks, I have just bought a 1989 S4 with a 928 Motorsports Stage 2 supercharger (intercooled Raptor V) with a standalone Autronics ECU fitted.

A 928 Motorsports radiator has also been fitted.

OEM exhaust has been replaced with ceramic coat headers and full twin system.

It is struggling to keep cool even under "mild" driving and weather (10 degrees celsius) conditions - temp gauge hovers in the low 90s.

I will post some photographs tonight however I think the problem originates from the stacked intercooler condenser --> A/C condenser --> 928 Motorsports radiator. There is a small push thermo-fan in front of the intercooler condenser and there are 3 small pull thermo-fans behind the radiators (can't fit a large fan or large twin pull fans because the supercharger is in the way).

Seems to me that cool air will struggle to get through to the radiator with this setup. What do you think? Any suggestions about how I can improve cooling?

Thanks very much in advance

Rob Edwards

What temperature do you register if you measure the upper and lower radiator hoses with an infrared thermometer? The gauge is not terribly accurate from car to car - my '90 GT and '93 GTS look like they differ by 20 degrees F when at operating temp but by the sharktuner datalogs they were within 2-3 degrees F.

Do you ever get an actual "engine temp too high" error on the digidash display?

hacker-pschorr

To add to what Rob said, do you know the thermostat is working? Are the thermostat seals good?

How is the engine tune? All other factors being equal, running lean will cause an engine to run hotter.

juju

Hi Rob: I just picked the car up a few days ago so I haven't done any diagnostics yet. The thermometer check is a good idea - I will have to acquire one!

I havent' seen any temperature error message yet but I've only driven it a few times and in very cool (sub 10 degrees celsius) conditions. But the seller did say that he didn't drive it in summer/hot weather and that he had experienced the temperature error message a few times when he had driven it in warm weather.

I checked to see if the cooling flaps were operating correctly but they've been removed.

juju

I will get the thermostat checked - I've booked it for a service and have suggested to the mechanic that a lower temp thermostat might help a bit, if one hasn't already been fitted.

As for the tune - I have no idea because the seller had not a single receipt for any of the work performed. All I know is that Richard James at RJP Motorsport in Perth fitted the supercharger/ECU/radiator etc. I have spoken briefly to Richard, he recalls the car and is a nice guy. I think I will drop by his workshop and have a chat with him to find out some more information about what work he did on the car, how is was tuned (I'd like to know if it was dyno-tuned, road-tuned or just has a standard tune setting with no actual testing) etc.

juju

This is almost identical to my 928's setup - the fan-cooled intercooler heat exchanger sits in front of the A/C condenser which sits in front of the larger aluminium radiator! I'm wondering whether it is possible to relocate the fan-cooled intercooler heat exchanger? The previous owner was going to remove the A/C condenser (and the entire A/C system) in order to increase cool air to the front of the radiator but he decided it was too big a job. I want to keep the A/C, removal is not an option!

hacker-pschorr

First things first, listen to Rob.

Verify your gauge is accurate, go from there.

h2pmr

if you want to reposition intercooler cooling rad it does fit behind the P/S -lhd- headlight, with its fan it clears the headlight by about 10mm.

juju

Will do and report back, thanks

FredR

A lower temp thermostat will not help you at all. As Rob says check the calibration of your dash gauge before believing it- then report back.

Oh -and check that you are reading the temp correctly- generally speaking the needle should sit to the left hand side of the last white line and even then there are variances example to example.

Rgds

Fred

juju

Thanks Fred, I've ordered an infrared thermometer and will check the radiator hose temps and report back. I believe I'm reading the gauge correctly but I will check and confirm. I have the Euro spec 1989 S4 with digital dash.

From memory the temp gauge has four indicators:

white block (marked 40)
1st white line (marked 80)
2nd white line (no number)
red line (marked 100)

My temp gauge reads about 1 - 2 needle widths to the right of the 2nd unmarked white line which I infer is "90" because the line is equidistant between 80 and 100

FredR

OK- on my example that is where my needle might be in the middle of summer pushing along"" in 44C heat with a/c flat out and I have a superior cooling system compared to stock [but no s/c setup].

When you get your IR gun boil some water in a pan or kettle and shoot the temperature to get a check calibration of 100 degrees C [assuming you are at sea level].

Rgds

Fred

juju

OK will do

Alan

This is what I am thinking too. That IC rad looks silly there, impedes airflow and heats up what it doesn't impede - but mainly it stops you putting a big pusher fan on the front - which I think you should consider also... take it in steps...

1) Measure accurately
2) Test functionally
3) Improve heat exchanges
- water wetter
- remove airflow restrictions
- ensure good flow through shrouding for the pullers
4) Remove additional heat loads
- intercooler rad
- add late model air/oil cooler before rad side tank to reduce oil thermal load
5) Better fans

The thermostat temp makes little difference - you either have enough cooling capacity or not - and if you don't: starting lower hardly has any effect - it has exactly no effect on the worst case conditions => always a waste of time.

Set the thermostat for the temp you want to run at for best results - and that isn't cold.

Alan

Carl Fausett

You could move the heat exchanger into the fender well - thats where we put it on the 16v cars. I saw a picture above that looked right. That would help.

Other ideas:

Use a Water Wetter or similar to bring the temps down, a lower thermostat that opens sooner, remove the temp switch from the fans and wire the fans so they are just ON when the key is on, make damn sure the radiator is sealed top, bottom, and sides so that air cannot go around it (common mistake), and check your coolant level and do not run a lower freezing point than you need to. Less anti-freeze and more water will lower your temps.