Konan

Hi,


Car is a bug eye WRX.


During my last day at Snetterton, I found that my water temps were climbing on sections of track with sustained WOT/high RPM... or 'straights' as they're otherwise known


The temps came back down fairly quickly if I backed off a bit (shift at 5K)and during more technical sections.


I've not had this before. Unfortunately, a few things have been done to the car since it's previous outings and it's not possible to replicate these conditions on the road for troubleshooting purposes. I don't really want to spend out money on track time with a high risk of having to call a halt on it so I want to take some steps before my next outing.


So, I have a few questions.


1) I'm just using the regular dash temperate gauge. However, my searching is letting me down when trying to find out how these are calibrated. Is a large movement in the middle just representative of a couple of degrees C or, like my old shogun, is a slightly raised needle indication that your engine hot enough to be30 seconds to a cracked head?

The car has always run just above the lower mark (probably a shade under this.. http://www.electricsubaru.com/tempGa...ationMeter.jpg )- on road or on track. On this occasion, it gradually built up to the next mark up.


Any idea what kind of temperature rise this actually indicates? I didn't have any logging in the car and ECTs returned to normal by the time I got to the pit area.


2) Just had the cam belt done, so all the coolant dropped out and replaced (with Subaru spec stuff). It doesn't look (to me) like an airlock, there's no indication of this in normal driving. Are there any other issues I could look at with regards to coolant replacement?


3) I might have just been driving the car harder this time. I have the stock cooling setup and a mild tune to around 250bhp. Do people find these cars can suffer heat build up on track in the summer anyway or should the stock setup be more than capable at this relatively low power level? I'm happy to put an uprated radiator on, I just don't want to throw extra cooling at it if it's just masking an underlying issue.


4) I have pulled a bit of fuelling from the top end. Nothing I considered drastic. I started out targeting at 10.2:1 and now have 10.6:1 - The management did not register any kind of det during the day. However, I'm wondering if there's a knock on effect with less fuel cooling from running leaner / raised EGT.


Any thoughts appreciated.

TECHNOPUG

iTrader: (1)

1.) The gauge only shows "Below Acceptable Temp", "At Acceptable Temp", "Above Acceptable Temp". Trying to establish any more detailed information from the gauge is futile. I'd suggest fitting a proper Temp guage in the first instance and take it from there. If you don't know what temps it's hitting, then you don't know if it is an issue or how to troubleshoot it.

banny sti

iTrader: (68)

The gauge is useless it will sit at normal range from about 70c-110c then climb into overheating. It is most likely your oil temp climbing that is impacting your water temp too

trevsjwood

iTrader: (2)

it's serious territory if the OEM gauge moves up, as banny says it's probably overheating at that point and that can do damage.
If you're spending time on track, you should invest in some aftermarket sensors, oil, water and a boost gauge. The problem is, flat out straightline acceleration for sustained periods can send all intake temps soaring.
You could upgrade the rad thermostat to a 71deg one for the summer and that would help, the problem might then be low temps in the winter.
Trev

Konan

Thanks for the replies. All good stuff. I had a sneeking idea it might be being passed on from rather hot oil and that the regular temperature guage was going to be rough.

FYI - this is track on a budget. It's not my main car and, whilst I don't want it to die needlessly (that's really not good for the budget ), I also don't expect to also do 20,000 miles a year in it on top of track trips. It's also not so much of a worry about getting low temperatures for regular driving as it doesn't do all that much.

I do run 10W50 fully synth in it and swap the oil out around every 200 track miles. I've also got an oil pressure sender.

I assume that the tempreature reading that the ECU uses is pretty accurate? It's probably easier (and cheaper) for me to take that stright off the ODB and display it on an android device than to plumb extra gauges in. Same with boost (although I've done a lot of logging on boost whilst doing the mapping, so I'm pretty happy that it's well controlled).

I don't think there's an oil temperature sensor for the ECU is there? Certainly can't find any use of it in the map, just engine coolant.

Looks like the next step will be an oil temp sender/guage and double pod. I'll also have a look at a lower temp thermostat.

Danb85

iTrader: (1)

Oil temp and pressure gauges are a must.
Also with water temp (as said above standard gauge doesnt really move much for 30degs - its not great), you can use an obd reader - or if you are buying gauges - get a water temp one to match?

Also if you are doing track work, get an oil cooler installed - like you mines a daily driver and occasional track work - ive fitted an oil cooler with a thermostatic plate - so it only fully opens when up to temp - ideal for winter and shorter journeys.

Konan

Thinking about it, it's fairly obvious that the standard temp doesn't show small changes. I've never so much as seen the thing twitch yet I've come into the pit area with both engine fans running, which is something like 10 degrees C higher than the point at which they cut out.

trevsjwood

iTrader: (2)

the standard gauge serves the purpose it was designed for and for the average driver it's enough to keep the car safe. Take the car on track or up the power by 50 or 100%, that's very different and something much more accurate is required.

300gnspitzer

Mine's a bugeye WRX, STI engine about 330 bhp with an oil cooler. I get oil temp about 110-15 deg. but the standard water temp. gauge never moves from normal, just under halfway. Before fitting the cooler oil temp got to 120deg. Track use only

Blocks85

i can hopefully shed some light on this as ive been doing hard track miles in mine for the last 4 years, circa 10k track miles very hard and live on the door step to combe and that is hard on the car.

before i ftted an oil cooler i could get my water temps to go up to 3/4 in about 5/10 laps of combe with it sat on the limiter in every gear as it always get driven.

when mappping with martyn at enginetuner and asking about this he said its the oil temp takes the water temp with it and making the water temp rise.
after fitting an oil cooler this help dramatically, would take around 10 mins of very hard driving to get the water temp to move to 3/4 but never had any probelms with over hearing and have would do another 10 mins with the temp gauge there and gives no probs, soon as you let off coast for a bit it settles straight back down.

interesting bit now, i had a 2.1 built by andy @ wms and decided to remove the oil modine and now on track i get no increases in water temps at all.
At trax 2 weeks ago, rupz blob sti 360hp was running at 3/4 temp most of the sessions and mine was running solid half way even at 540hp with 2 bar of boost.
now proir to removing the modine ,i would have been up to 3/4 at least in 5 mins or more but now the temps dont move i can only think it is now the water is not going through the red hot oil modine causing the increases..
no change in cooling what so ever so must be removing the oil modine has made it more settled in the water dept..
hope this helps
cheers chris
This is the car

Steve Whitehorn

iTrader: (13)

I echo what Block and Banny and others have said here.
I have all the gauges AFR, EGT, oil temp, oil pressure, water temp and boost and two knock dectors.

And the mission critical one end of is Oil Temp.
(Closely followed by one of the Knock dectectors)

OK if the pressure gauge flickers then you might have problem...and perhaps gone past the point of no return.
Very very occasionally my EGTs have hit the warning area before the oil temps.
But invariably the oil temps 99% of the time get critical before the EGTs
And the high oil temps are what drags up water temps.

So two tips
1. Fit the oil temp sender near to the hottest part of the engine. (By No 3) That gives you a bit of extra safety
2. An oil cooler needs to be the right size for the spec of the engine and it is all about airflow. Many people fit them as a placebo ....You need to experiment with it and perhaps even get get some fabrication done. As the air flow out the back end of the cooler is an important as the air flow in. As you can stick it in at the front of the car but the air out of the back is dead.

Also running a five speed box or six speed box makes a difference to under bonnet temps, which can also be a factor

Hope this points you in the right direction
Cheers
Steve

Donnie Brasco 46

iTrader: (2)

You definitely need a oil temp gauge. I haven't taken my Impreza on track, but did with my 325ci and the oil temp went through the roof pretty quickly. All other temps rise in line with it as the engines worked hard, the brakes etc

Konan

Thanks for all the extra input. Looks like the first step is getting an oil temp sender wired in. Then I've got some proper figures to work with. Why is it that I feel positioning it near number 3 is going to be a delightful job?


Is a Sandwich under the existing cooler OK for picking up oil to send to a remote cooler?


On top of this, I've have given my coolant a good going over, as this was the first occasion I've had high temperatures. I just wanted to be sure I wasn't also suffering an air lock or similar.


I've fitted a lower temperature thermostat (since the standard oil heat exchanger is to the coolant, I figured it'd help nudge the oil temperature down a little, although from the info provided it doesn't sound like it'll be much more than a little 'help'). I'll probably tweak the RAD fans to run mode 2 at slightly lower temps/road speeds.


I also found that my new lower radiator hose was a little too long and had a bit of a kink in it. I've trimmed that down!

Konan

Update:

Still a work in progress (thermostatic oil cooler next) but with the stat fitted and fans reprogramed I can't get the water over 87. It's had a pretty good test as I've just done an airfield day with a 2 mile straight on it.