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Engine cooling issues

 
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james911996  



Joined: 06 Jan 2022
Posts: 8
Location: UK

PostPosted: Wed May 11, 2022 7:38 pm    Post subject: Engine cooling issues Reply with quote

Hi All,

Had the new to me 924 2.0NA race car out for the first time this week at Donington Park for a track day.
Brakes and handling performed well. Only issue we had was engine cooling.
After about 5 laps from cold a cooling lap was needed as temperature was getting into the red. Then a cooling lap between every 2 laps or so.
(car also needs a lot of cranking to start up)
A local 924 racer at the track also thought the engine sound was missing some ‘bite’. He thought timing could be causing the overheating issue and the engine sound.

I've been advised to look at some ducting around the radiator.

Any thoughts on what could be causing this and what the best off the shelf cooling upgrades are ?

thanks for any help!

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924RACR  



Joined: 29 Jul 2001
Posts: 8605
Location: Royal Oak, MI, USA

PostPosted: Wed May 11, 2022 9:40 pm    Post subject: Reply with quote

For sure too much advance can cause overheating... without any details on the engine build, can't say if you need more substantial cooling mods.

It is a good idea to ensure the gaps around the edge of the radiator, against its surround, are filled - foam strips can work well here.

Also, you should definitely be running an oil cooler - not clear if you have any.
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Vaughan Scott
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'79 924 #77 ITB racecar
'82 931 Plat. Silver
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Cedric  



Joined: 27 Aug 2004
Posts: 2354
Location: Sweden

PostPosted: Wed May 11, 2022 11:07 pm    Post subject: Reply with quote

A standard 924 should easily be able to do a 12h endurance race, otherwise something is wrong. Timing could be of but the rad could of course be in rough shape, or a sticking thermostat. Upgrades and oil cooler helps, but it could be good to find the source of the problem first. And plan an oil cooler in the mean time.
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james911996  



Joined: 06 Jan 2022
Posts: 8
Location: UK

PostPosted: Thu May 12, 2022 12:35 am    Post subject: Reply with quote

Thanks both.

I should have started with this, engine is standard other than
- hotter cam
- there is an oil cooler
Regs limit any engine modes to minimum.

SO you think stock system should be enough and this is likely an issue within the cooling system rather than timing or air/ fuel mixture?
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Cedric  



Joined: 27 Aug 2004
Posts: 2354
Location: Sweden

PostPosted: Thu May 12, 2022 1:05 am    Post subject: Reply with quote

james911996 wrote:
Thanks both.

I should have started with this, engine is standard other than
- hotter cam
- there is an oil cooler
Regs limit any engine modes to minimum.

SO you think stock system should be enough and this is likely an issue within the cooling system rather than timing or air/ fuel mixture?


I've done 12h racing and 2x 45 minutes for example in 28 degree heat with bog standard cars, without any oil cooling, the needle didn't move. Its the same rad as a 924 turbo which put alot more heat into the system. Double checking the timing and fuelling properly is definitely a good idea anyway, those should always be in perfect order on a track/race car.
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Fifty50Plus  



Joined: 28 Feb 2008
Posts: 1266
Location: Washington DC area

PostPosted: Thu May 12, 2022 5:25 am    Post subject: Reply with quote

Same with both of my 924 race cars. 41 degrees total advance and higher compression pistons. I have a stock 924 radiator in both cars with no special ducting and temps are below the middle of the gauge while running. I have a switch on my two front fans that turn them on when I come into the pits to keep the engine below the half way mark.
If you have a stock 924 radiator, it may be slightly (or more) blocked. You can take it out and have it rodded (cleaned) and flow tested or replace with a 944 radiator. The 944 radiator is about 1 inch thicker and involves some finagling to install.
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car
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924RACR  



Joined: 29 Jul 2001
Posts: 8605
Location: Royal Oak, MI, USA

PostPosted: Thu May 12, 2022 6:03 am    Post subject: Reply with quote

Agreed, stock 924 rad should be fine for this if it's working right - which seems like maybe not, perhaps a system flush or the like are in need.
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james911996  



Joined: 06 Jan 2022
Posts: 8
Location: UK

PostPosted: Thu May 12, 2022 8:17 pm    Post subject: Reply with quote

Ok. I have a rolling road tune for fueling and timing booked in a couple of weeks.

So in the meantime it sounds like we should make sure the cooling system is flowing fully.
- radiator: cost of returning the existing likely to be more than an aluminium 944 rad, which I’ve been told can be fitted with a few brackets. They are less than 150 quid here in the UK. So might do that just to have peace of mind the rad is good
- thermostat: I have the fan on a switch on the dash like fifty50Plus, so would it make sense to just remove the thermostat for caution? (I’m not actually sure if it’s still in the car)
- can the heater matrix be a blocking point for cooling?
- then fill the gaps around the rad to make sur it is getting all the air: this is a nice to have but not a must have if the system is flowing right
- anything else to look at?
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924RACR  



Joined: 29 Jul 2001
Posts: 8605
Location: Royal Oak, MI, USA

PostPosted: Thu May 12, 2022 8:43 pm    Post subject: Reply with quote

Leave the thermostat in - replace with new if concerned about its function.

We also run a dash switch, in parallel with the stock rad fan switch, kick that on during the cooldown lap just to be sure (mainly to not forget it later).
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Vaughan Scott
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'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype
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