GSlender's Track Beeotch!

[ndragun]

If you want to think that installing an electric water pump will return heaps of HP then start a new post and we can discuss the "science" there... not sure that demonstrating how fast it can empty a bucket is a measure of the watts used, nor do I believe that all OEM's for countless years actively agreed to over engineer something to the tune of 1,000x what is needed, but hey, will make for an entertaining discussion.

G

Grant, I think you're probably confusing yourself believing that a mech water pump is always robbing you of 10kw or whatever - which is not the case. As Dann said, the power draw squares with engine speed, so the faster it turns the more power it is taking. So at higher RPM its taking more kW from the system than at idle.

An electric pump wouldn't do this - it can be controlled to spin completely independently of the engine speed, and so the power draw is totally different. Its basically not comparable. You'd be better off comparing the power draw of a mechanical pump at engine idle, vs the electrical one.

Assuming that OEM's have 'overengineered' something 1000% is also flawed. Again - you might be sitting at idle on a hot day in traffic. A mech water pump has to be designed to handle that first and foremost. It spins at a certain RPM at idle to cool the system and has to be spec'd accordingly. It just so happens then, that at redline, it spins a whole lot faster and sucks a whole lot more power up there at the higher rev range. That's the way it has to be, since you can't ramp down a mechanical water pump at higher engine RPM.

Thinking about that - if you were worried about cavitation and whatnot - you'd be more likely to produce it with a mech pump at redline.

[gslender]

Thinking about that - if you were worried about cavitation and whatnot - you'd be more likely to produce it with a mech pump at redline.

Not convinced and this article kinda spells it out... at best, 8HP (5.9kW) on a 520+HP engine or 1.5% improvement.

http://www.hotrod.com/how-to/engine/hrd ... uck-power/

If you wanted an easier/cheaper way to reduce the top RPM parasitic loss than perhaps use a smaller pulley on the oem pump! Don't worry about idle as if it is a race engine, then chances are you are idling at 1,000rpm anyway so the loss in speed from an undersized water pump pulley at idle can be made up with higher engine idle speed. Just a thought and saves you from more wiring, extra pipe work and more things to break down and/or fail.

G

[gslender]

Had a run at the Street Sprints at lakeside and unsure if the car is still with cooling problems or not.

After 4 laps in the 35 deg heat, the car starts to get up to 98 deg and when pulling out to 6,000 or 7,000 rpm.... in various part of the track

When in the 5th cool down lap, the coolant climbs up to 106 deg when the engine revs drop down to under 3,000 and it won't come down at all after that.

This is at the 4th session at around 3pm.... it just gets progressively hotter and hotter each time.

I've got the top shroud and bottom tray installed, and I'm certain all the air is out of the system.

I'm now wondering if perhaps some other basic issue exists - maybe a coolant leak stopping the system from getting pressure. Hope it isn't the head!

Next step I'm going to pressure test the system because something isn't right!

G

[gslender]

Watch the below from 5:30 and you can see how under acceleration (gas pedal down) the cooling is fine, but as soon as I lift off (big vacuum drawn) the cooling races away to over 100... ???? and yet the car is still moving at over 100kph and the RPM is still high at over 4,000rpm ????

[Magpie]

Heat moves from hot areas to cold areas, you can't change this fact. Therefore if something spikes it is because it has absorbed heat. The issue could be is the heat spike local to the sensor or indicative of the whole system.

In addition at high RPM your water pump is spinning away however on lift off it drops to idle and hence water flow slows to idle. Hence the radiator is not cooling down the water as effective and the water is in contact longer with a hotter than idle engine. The Heat moves to the water and then to the sensor.

Where is your temp sensor located? Can you install another sensor the verify what you are seeing?

Have you tried the same thing with the heater core open and on full?

Whilst you do say that the RPM is still around 4,000 then a temperature spike could indicate lean condition of the engine on lift off throttle. Do you have any other data like AFR, EGT for a similar period when you get a temp spike?

[gslender]

Heat moves from hot areas to cold areas, you can't change this fact. Therefore if something spikes it is because it has absorbed heat. The issue could be is the heat spike local to the sensor or indicative of the whole system.

In addition at high RPM your water pump is spinning away however on lift off it drops to idle and hence water flow slows to idle. Hence the radiator is not cooling down the water as effective and the water is in contact longer with a hotter than idle engine. The Heat moves to the water and then to the sensor.

Where is your temp sensor located? Can you install another sensor the verify what you are seeing?

Have you tried the same thing with the heater core open and on full?

Whilst you do say that the RPM is still around 4,000 then a temperature spike could indicate lean condition of the engine on lift off throttle. Do you have any other data like AFR, EGT for a similar period when you get a temp spike?

Watch the video again - at around 5:30 ish...

The heat spikes with the RPM staying stable... the only variance is the throttle position (and heavy braking).

The temp sensor is at the OEM location which is the back of the head - of which I've been logging from this location many times before and never seen this issue. So it isn't a "it always behaves like this" thing...

You may not know, but the heater core is always on - the inside control only directs the air over the heater core... water is always flowing through the cores.

All engines go very lean on lift-off throttle etc. Normal

Keep thinking though !!

G

[Magpie]

Yep aware that it is just a flap on the heater circuit and also aware of the lean on lift off.

If it has not done it before what has been changed? Is the sensor operating correctly? Have you tried another sensor?

[madjak]

To me, it looks like the throttle is inversely related to the cts.... As you back off the throttle temp is rising almost instantly, as soon as your back on the throttle it drops. It does not look like its related at all to the rpm.

This means it cant be related to water pump speed (thats linked to rpm) which means its not related to water flow...

If it is actually happening, it means temps are rising as soon as you back off the thottle. The only thing that could do this would be vacuum pressure or something like it causing an effect on the coolant flow or something?

If its the sensor then it could be interference from coil packs, or some other signal that changes intensity with throttle.

I actually think something is causing interference with the CTS signal... for it to respond so quickly to changes in throttle it can't be heat transfer doing it as that would sure lag and be less responsive, plus its reverse to what should happen. WOT = heat

[madjak]

actually, looking at the video again, at the start you see this happen very clearly. 95 degrees @ 0 throttle > 88 degrees @ 100 throttle. By the end of the session your at 107 degrees @ 0 throttle > 99 degrees @ 100 throttle (about 7 degrees temp difference between 0 and 100 throttle the entire video)

I think your temp is actually going up from the start to the end by around 10-12 degrees... what the actual temp is depends on the sensor and how the ECU is reading it (it's just voltage down an unprotected wire, earthed through the engine), the fluctuation of up to 7 degrees due to throttle is just noise over the top masking the base signal.

[Magpie]

Thanks madjak, my thoughts as well however you were a little more succinct.

Try another sensor in another location and make sure that the wiring is not close to any electrical noise. Another source of noise could be the earth, is the ECU and the sensor sharing the same earth? In addition have you calibrated the sensor?

[madjak]

For reference, my coolant sensor is the stock one hooked up to the ECU (the green plug with two pins). This sensor has a separate earth so ignore what I said earlier, I was thinking of the dash sensor and Autometer sensor which have just one active cable. I see a steady arc of coolant temp across a session, so starting at 85 degrees and climbing to around 95 after 5 laps of the track with very little if any noise. By the end the curve is very flat with it sitting at 95 degrees for about 2 minutes of the 5-6 minute session. I think there is so much coolant and mass in the engine that rate of temp change should be very slow so you shouldn't see fluctuations like your seeing in your data log. This pretty much matchesto what I see on my Autometer gauge reading... when I get a chance to glance at it.

When I ran the wires from the ECU to the sensor, I twisted them together before wrapping them. This helps with interference much like lan cables / phone cables especially when running parallel to a high voltage or high frequency line.

[gslender]

I'm 1000% sure it isn't noise on the sensor and ECU signal. Given my background in electronics and ECUs I can be confident I know it isn't electrical noise. It is really climbing as quickly and succinctly as you are seeing in the video - the stock OEM dash gauge and sensor (using another location in the coolant system) mirrors this behavior and whilst it is an inaccurate gauge, that only gives you and indicator of cold, warm or hot - it is showing the same problem and is a completely independent sensor from the video.

The sensors are fine and correct - the problem is the coolant system but I'm unsure exactly as to what. I'm leaning towards it being some kind of pressure problem that perhaps is seeing engine keep the pressure up, and vacuum (no load) sucking the pressure out/away and allowing the system to boil over.

Once I've tested the system pressure I should know more... hopefully this weekend or early next week at the latest.

I'll update then!

G

[gslender]

If it is actually happening, it means temps are rising as soon as you back off the thottle. The only thing that could do this would be vacuum pressure or something like it causing an effect on the coolant flow or something?

My thoughts exactly.... and given the OEM dash gauge and other sensor behaves in the same way (I see it moving when I'm off the throttle coming in for the cool down laps) I'm fairly confident the sensors are correct.

If so, what then? Pressure test will hopefully confirm something.

G

[sailaholic]

If so, what then?

G

Easy, don't lift.


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[sailaholic]

G I know your 100,000,000% sure but if you get nothing back with a pressure test why not just throw in a mechanical temp gauge and see what it says?

Will it replicate by blipping the throttle while stationary.

What about with ignition on but engine not running?

I'm really struggling with water temp changing that much that quickly. But maybe not struggling as much as you are with interference.


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