Radiator for a track mk2 car

Discussion in 'Track Prep & Tech' started by HidRo, Oct 27, 2017.

  1. HidRo Forum Member

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    Trackday done.
    It was nice. Lot's of rain in the morning, cleared in the afternoon.
    Temps were always good on track, but whenever I stopped, it would raise up to 100+...
    On track, between 92C and 96C. Stopped to talk to a friend for 2m, and raised from 92C to 100C...
    So it behaves better pulling hard than idling.
    A friend said that might be a crack in the block or in the head.
    track.jpg

    Video of this happening.
    You can see coasting down the pitlane it went down to 90C, and then quickly raising to 100C+ while idling.
    [video=youtube;R3YinKZs6k4]https://www.youtube.com/watch?v=R3YinKZs6k4[/video]
     
    Last edited: Mar 20, 2018
  2. HidRo Forum Member

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    Just so you can follow what happening:
    Trackday done.
    It was nice. Lot's of rain in the morning, cleared in the afternoon.
    Temps were always good on track, but whenever I stopped, it would raise up to 100+...
    On track, between 92C and 96C. Stopped to talk to a friend for 2m, and raised from 92C to 100C...
    So it behaves better pulling hard than idling.
    A friend said that might be a crack in the block or in the head.
    View attachment 7147

    Video of this happening.
    You can see coasting down the pitlane it went down to 90C, and then quickly raising to 100C+ while idling.
     
  3. Jon Olds Forum Junkie

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    Its not running lean at idle is it?
    Jon
     
  4. HidRo Forum Member

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    Well, it's close to 14.7, but I can try to raise it to 13's, and see if it makes much difference. I was wanting to test this for some time, so I'll probably do it now, and see.
     
  5. Jon Olds Forum Junkie

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    I have had some problems with retarded ignition and lean mixtures causing hot running engines. It probably
    doesn't apply in this case, but sometimes a 'left of field' thought helps
    Jon
     
  6. rubjonny

    rubjonny Administrator Admin

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    tbh I dont think the temps are bad at all if you've just come off a hard track session and sit the temps will rise as the airflow stops. at what point does the fan kick in, and is it able to pull the temps back? If so I would be happy and move on.

    since the radiator is able to keep the temps to 92-96 while driving hard you know it has enough capacity for your usage. if you are unhappy with the fans ability to keep the temps back when sat then try a better fan or add another, and make up some shrouding so that when running airflow is forced through the entire surface area of the radiator not just the circle of it the fan covers
     
  7. HidRo Forum Member

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    The problem is exactly it does not pull the temps back when idling. Not even after an easy drive just to get the temps up.
    Prior to the trackday, I went for a spin and it was all good around 90c. Had to idle for a bit due to traffic, and it raised up to 97C. Only came down when starting to drive again.
    It already has 2 fans (1 slim that was added now, and one from a strakar, which pulls a lot of air).
    Adding a shroud might impact the overall flow on track, right? And if the engine is shut off, the temps will raise inside of the engine, showing an increase in the temp gauge (and megasquirt) but the radiator will cool down quickly.
     
  8. rubjonny

    rubjonny Administrator Admin

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    Ah so even with both the fans on full they cant pull the temps back down to about 1/2 on the gauge? If you have 2 on there covering a decent amount of surface area a shroud probably wouldnt help much, but have you offset them so one covers the bottom and the other the top if that makes sense? With larger VW shrouds they have little flaps/slats in which suck closed fans running, and open when the car is driving along so air flow is not restricted

    but yeah it does sound like you have an issue, give Jons suggestion a try :)
     
  9. HidRo Forum Member

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    Yeah, it's about that. It hardly ever stops the fans when they kick in while idle.
    Strange thing was that after we did some work on the car, disconnecting the pipes, and then, while idling it would raise temp, and back down and shut off the fans.
    After some more work, it stopped doing this, and again it was keeping the high temps...
    I don't believe it could be an air lock, if it would, I guess it would raise the temps while driving as well.
    I'll give it a go at lean idle thing, and see if it makes any improvements.
    Also, I have 18/20ยบ timing at idle. Don't think that would do any harm, and it's way over the retarded timing possible issue, I guess.

    Thanks for the updates on this!
     
  10. HidRo Forum Member

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    So, coming back to this.
    Changed the Radiator to a Toyota Celica one, like Nige has.
    Added an Oil Cooler, 16 rows.
    The temps were perfect, but I see a behavior that is rather strange...
    The water flow should be going from the radiator, to the t-stat, through the block, and out the flange on the side, into the radiator again, right?

    But I see that the water temp on the sensor goes lower than the t-stat, meaning that the water is flow backwards?
    The t-stat should close out at 82C or something, and I see temps low as 73C when hammering it on the straights.
    Picture from MegaLogViewer to ilustrate it.


    Coolant.png 20190223_110105.jpg 20190202_113521.jpg
     
  11. Terry47

    Terry47 Paid Member Paid Member

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    Just spotted this thread so I thought I'd just add a few words / observations about the cooling system I have in my rally car. Thankfully I've never had any coolant temperature issues when running even in the summer on 12 miles stages with an air temp around 80 degrees.

    I use a Davies Craig EWP80 water pump running constant and is activated as soon as the cut out switch is turned on. This is fed from a standard water pump which has had all its innards removed (so in effect it is just the casing) and no thermostat. It does not run a heater matrix so the original feed and return are connected together with a U bend pipe. The radiator is a custom built unit (from Brise Fabrications) and is a triple core aluminium one. It has an electric fan mounted to the back on the radiator to suck cold air through it. This is switch operated from inside, not a thermo switch. All this is mounted on the nearside of the car in front of the gearbox and is no wider than the gearbox. What fluid do I have in there, just normal tap water along with the standard VAG anti freeze. In addition to this there is also a 19 row oil cooler mounted on the offside of the engine bay under the air filter.

    I've had a look through my photos but cannot seem to find any of this installation, but if any one wants / needs me to add one then I'll to squeeze into the garage and take one.
     
  12. mec82 Forum Member

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    flow should be the other way around, top hose is engine out, bottom hose is pump inlet.
     
  13. HPR

    HPR Administrator Admin

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    @ mec82 Welcome back !
     
  14. mec82 Forum Member

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    lol, thanks has been a while!

    car is now back on the road after 4 year hiatus so enthusiasm is rekindled [:D]
     
  15. HidRo Forum Member

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    At this moment, I have no issues, as it was really low on temps. The only "strange" thing is the low temps when hammering it.
    My setup is similar, although the radiator size is almost the entire front of the car. Only space available is for the 16row oil radiator.

    That is what I meant with what I wrote, but might have come out a bit fuzzy. :)
     

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