Turbo water cooling, am I flowing too much water?

[RedMist]

Brief history. I'm running two GT2560r-4's on my 3.5 ltr Nissan V6. I've been chasing overheating issues all season and wondered if I'm simply flowing too much water through the turbos. I run two completely independant water systems to and from each turbo using dash 4 lines. Each has reasonably short water lines and is without bend or any restriction.
Anyone know if I could place a restriction in the line to prevent water flow or if I'm flowing enough water as it is?

[fivebob]

I doubt you would be flowing too much water through the turbos. More water should give lower overall water temp if your radiator can cool it sufficiently.

Where is the temp sensor in relation to the turbo water outlet(s)?

[fivebob]

Also just thought... how much are you going to restrict dash 4 pipes which are already pretty small anyway (1/4" OD so I'd guess around 3-4mm ID).

[RedMist]

The gauge sender is only 20mm upstream of the turbo outlets. The ECU sender is approximately 250mm upstream.
The car will broach 127 degrees c on the ECU sensor and over 300 f on the gauge after 10 -15 minutes of hard running.
Unfortunately I have very little frontal area for the radiator. The radiator that I have in the car (behind my head) is a Ron Davis professional racing radiator. It's very close on the biggest rad I can fit in this area.

[fivebob]

The differences in the gauge and ECU measured temps seems to indicate that the water coming out of the turbos is (artifically?) raising the temp. To me that would indicate that there is not enough water flowing through the turbos and the water coming out of them is too hot and as it mixes with the other water it cools down.

Do you have any way of measuring the water temp as it exits the motor? As that would give a better idea whether or not you have an overheating problem.

[IH8TEC]

-4 seems tiny for a turbo water feed, i run a -3 for my oil feed and thats tiny.

[RedMist]

The ECU sender is placed at the jointer on the water outlet between the heads. It would be as close to engine temp as possible. I would have to agree, the differentiation between the gauge and ECU senders would point to there an issue with turbo temperature. Hence my question. I had hoped to expel some of the heat through the exhaust.

[darkwolf]

When you say you are running independent water systems for the turbos are you saying you have independent feeds for each turbo or that the water cooling system for the turbos is completely separate to the engine cooling system. (Possibly a n00b question but I have method to my madness)

If it is the first one. It could be that the water temperature feeding the turbos is already hot. I.e. can you measure the temperature of the water entering? Or alternatively where abouts are you getting the water for the turbos directly from the water pump or from the radiator or from somewhere else in the engine. (I'm not too sure on the flow of water in a engine and the placement of the pump)

The logic behind my theory is that if you are cooling the turbo with already hot water then the water temperature coming out will be higher than the temperature of other water in the system. This would in theory be a flow on effect causing the overall temperature of the water to rise in turn causing the temperature of the turbo water to rise also and so on and so forth.

Also is there anyway that you could increase the amount of airflow that your current radiator is getting. I.E cooling panels etc to direct air past the radiator.

[RedMist]

Water is taken from the water system post water pump and is placed back in the water system just before it hits the rad. Two individual feeds, two individual returns.
I'm already attempting ducting. I've mocked up some side panels that will effectively create a funnel between roof, side panels and the fuel cell. I'm also going to change the exit ducting that has a single 16 inch fan on it at the moment with one that will allow more area behind the core and will be terminated with two 12 (or 14 if I can fit them) inch fans
I'll also remove and replace the stainless mesh on the front of the radiator as soon as I can find something appropriate with a larger mesh size.
HOWEVER, all these modifications don't really allow for dirty conditions. I need considerable manoeuvring room when it comes to cooling. Intercoolers are bound to be blocked, some of the radiator will also be blocked. The only coolers that won't receive copious amounts of dirt are the trans and engine coolers, and they are in relatively dirty (heat wise) air. I have to do something regarding cooling, I can't keep on winning races while short shifting!
I had thought that oil was the primary cooler for turbos? If anything I'm probably heat exchanging between the oil and water temps while passing through the turbos. Greater the flow, greater the heat exchange.

I might have to bite the bullet and get a rad made up that’s approximately 18 square inches larger in core size. Other than that, I’ll have to create some larger side pods and mount them formula style, one in each side pod.

[matt dunn]

Water is taken from the water system post water pump and is placed back in the water system just before it hits the rad. Two individual feeds, two individual returns.

so the in and out from the turbo are both on the same pipe between the water pump and radiator?

As we used to run the two feeds to the turbo's one from each side of the radiator, and found that too much flow through the turbo's bypassed the radiator basically.

And be wary of too many fans too.
At high speed radiator fans fans are a restriction to airflow,
wether they are turned on or not.
But of course are necessary at low speed and idle.

Interestinmg radiator theroy we used to run on our old corolla,
was two radiators in front of each other,
back one like a pre-cooler, and then through the front one.

Also double pass radiators are an option,
and in my experience tripple pass are too much restriction to water flow.

[RedMist]

Turbos are water fed from the block drain just post the water pump and feed back into the water system in a connection block just prior to entering the radiator. They could be flowing too much water, I just don't know. However the water temperature exiting the turbos is substancially hotter than the engine water temp.
I think I should be replacing the rad with something as large as I can shoehorn in there. Which isn't much bigger than I currently have! Presently I can't get the existing rad out without removing the throttle bodies and intake plenums.

[jaypines]

my guess is that you might have air in the system... try bleeding out the air first and see...

[KinLoud]

- Are you using anti freeze? You will get a bit more heat exchange using pure water - you would need to put anti freeze in after each race to prevent corrosion then back to water for race day.
- Water wetter - I've heard some people swear by it.
- Gap between fan and radiator... pretty sure you have an alloy panel the fan bolts into. You might need to increase the space between radiator and the panel to give a bit of a plenum to let the air escape from the radiator fins easily before going through the fan.
- Is the cockpit a low pressure area, reducing the pressure difference across the radiator?
- mount radiator 90 degrees to airflow and fab suitable ducting to direct the air upwards through radiator, exit ducting will help create low pressure area. Mounting at 90 degrees could reduce probs with mud blocking and the need for screen before radiator.
- same idea for intercoolers... mount at 90 to air/mud flow

- Install a baby radiator inline with turbo water outlet before going into main radiator

My ten cents worth

Ken

[Si]

Looks like all the pics are gone from your project thread so cant remember exactly how everything goes.

As kinloud said could you install small radiators after the turbos? Perhaps in place of the intercoolers and use water injection to lower cylinder temps to negate some of the loss of the intercoolers?

(Although im not to sure how much water you would need on an enduro )