SVX Engine cooling "Again & Again"

[Huskymaniac]

Originally Posted by Johnybeas

ok so back on topic, my question is: With the modified exit to the radiator better aluminum radiator moved thermostat and enlarged pump inlet, would the modified y pipe on the engine be over kill or would it still be a good idea in light of future power increases and potential increased torque/power output later on?

I second this question! Earlier in this thread someone tossed out a hypothesis that came to my mind as well. Since this engine tends to run hot, and especially when revved high, is it possible that the high temperatures are contributing to some or most of the head gasket failures? When you consider that the cooling/heating is also believed to be uneven, that will also cause uneven expansion and mechanical stress. So you have potentially many cycles of large temperature swings on the gasket material plus mechanical stress.

Whatever can help to reduce operating temperature may help reduce head gasket issues. If there is a "kit" of hoses, an inline tstat, a specialized pump cover and maybe a radiator outlet expander, it could help us daily drivers. I was thinking these items could be added to a stock radiator or an upgraded radiator. Is there a parts list like this and someone that supplies each of the parts?

Any high stress reliability test includes two items; damp heat and thermal cycling. We have both in an engine cooling system. Now, if you have a cooling system that is marginal and restrict airflow to the radiator by, say, throwing a transmission cooler in front of it, you have to be making the problem worse. That makes an improved cooling system even more imperative, even for the daily driver.

[Dessertrunner]

I am convinced that if there are no other factor (leaking radiator, blown hose etc) at play the poor coolant flow is the problem to blown head gaskets.

Forget the standard radiator it won't cool the engine when you want more power,

The other question asked about top pipe etc, if you want to get the best cooling due to increased power you should consider changing to a cross flow radiator,
Thats my 2 bobs worth. Have a great day.
Tony

[Huskymaniac]

Originally Posted by Dessertrunner

I am convinced that if there are no other factor (leaking radiator, blown hose etc) at play the poor coolant flow is the problem to blown head gaskets.

Forget the standard radiator it won't cool the engine when you want more power,

The other question asked about top pipe etc, if you want to get the best cooling due to increased power you should consider changing to a cross flow radiator,
Thats my 2 bobs worth. Have a great day.
Tony

I tend to agree with, fellow Tony. For those that don't want to increase power, is there a simple and cheap way to bring down and even out the temperature? It sounded like svxfiles found some benefit by simply removing the tstat and relocating it, inline, to the radiator inlet side. Presumably, this helped avoid cavitation or some other source of air pocket generation. Summitracing.com sells some inline tstat housings. Can one just remove the tstat from the existing housing and re-install the housing with a new gasket?

I also looked into alternative pumps and discovered that the European SVXs have an extra nipple on the pump for an oil cooler. It wasn't clear to me if the nipple was on the positive or negative side of the pump. It also wasn't clear where the other line from the oil cooler went. It looks like it goes into the block. If that is correct, is it possible that this secondary path through the oil cooler helps to reduce or even out the engine temperatures by balancing flow or heat load load between the two sides of the engine? If so, I might consider replacing the US pump with a euro pump and oil cooler when the time comes for a pump replacement.

I have also been looking into better fans but have had no luck there.

The radiator could clearly be upgraded to the PWR but that is an expensive fix for something that may not even be broken!

And is there something that can be done with coolant and additive choices to even out or reduce temperatures? Redline's water wetter has gotten good reviews. When mixed with 50/50 coolant it brings the engine temperature down 8F. That isn't much but it may help a cooling system on the "edge". It also supposedly helps even out the temperature and that may be more important than the temperature reduction. Also, for those that live in warmer climates, you get about a 1F reduction in operating temperature for ever 1% reduction in anti-freeze. Going to a 45/55 mix will reduce temperatures by an additional 4-5F, for example. On the anti-freeze choice, wow, that is a confusing mess. Here is what I have been able to gather so far:

Aftermarket Green: Low silicate, zero phosphate inorganic ethylene glycol
Subaru Green: Zero silicate, zero amine, phosphated HOAT ethylene glycol
Yellow: Low silicate, zero phosphate HOAT ethylene glycol with nitrites to reduce cavitation
Orange: Zero silicate, zero phosphate OAT ethylene glycol dex-cool (bad stuff known to cause head gasket issues in GM cars)
Red: Zero silicate, zero phosphate OAT ethylene glycol with special anti-corrosion, anti-cavitation and anti-foaming additives
Pink: Zero silicate, zero amine, phosphated HOAT ethylene glycol
Blue: Not a lot of information on this new stuff but it may be propylene glycol and is known to not mix well with water wetter additives.

Propylene glycol is supposed to be less toxic and a better coolant because it has a higher heat capacity, lower viscosity and lower weight density. It also has a slightly lower thermal conductivity relative to ethylene glycol but that is supposedly out-weighed by the benefits.

It seems like the pink stuff (Zerex Asian, for example) is the only direct alternative to the Subaru green. The yellow stuff (Zerex G-05) appears to be an improved version of the aftermarket green stuff. Either greens or the yellow or the pink appear to be compatible with water wetters. A slightly reduced concentration of any of these plus water wetter could reduce engine temperatures by 12F or more and may help even out temperatures and avoid cavitation at high RPMs.

[svxfiles]

Originally Posted by Huskymaniac

It sounded like TomsSVX found some benefit by simply removing the tstat and relocating it, inline, to the radiator inlet side. Presumably, this helped avoid cavitation or some other source of air pocket generation. Summitracing.com sells some inline tstat housings. Can one just remove the tstat from the existing housing and re-install the housing with a new gasket?

That was Young Tom,
I have the crossflow rad with the 2" outlet for about six years now.

Picks in old locker.

[Dessertrunner]

If you start at cheapest and simplest first.
1 Move thermostate to top as Svxfiles did, this is the most important.
2 Change the inlet pipe to the pump, "Thermostate cover"
3 Bigger radiator.
4 Outlet pipe on radiator 50mm and noved to the centre of the bottom top (only if not a cross flow radiator).
5 Crossflow radiator.
6 Top engine pipe (this importance is determined by revs).
.

As regards coolant personally I don't think it will provide enough help to gain anything, the problem is one of flow but maybe I don't understand were the gain is.
Tony

[StatGSR]

^ Thank you, i was hoping somebody would just make a simple check list.

Also, where are you guys getting your t-stat relocation kits? what diameter? what temp t-stat are you using in it?

[svxfiles]

Originally Posted by Dessertrunner

If you start at cheapest and simplest first.
1 Move thermostate to top as TomsSVX did, this is the most important.
2 Change the inlet pipe to the pump, "Thermostate cover"
3 Bigger radiator.
4 Outlet pipe on radiator 50mm and moved to the centre of the bottom top (only if not a cross flow radiator).
5 Crossflow radiator.
6 Top engine pipe (this importance is determined by revs).
.

As regards coolant personally I don't think it will provide enough help to gain anything, the problem is one of flow but maybe I don't understand were the gain is.
Tony

Tony,
About #4.
What if the inlet is in the middle of the top?
It seems to me that would allow thw quickest path to the outlet with the least benefit of the radiator.
Thats whu on my next radiator the bottom/outlet will be close to the stock location.
Please feel free to correct me if I am not thinking correctly.

[Boxersix]

Originally Posted by Dessertrunner

If you start at cheapest and simplest first.
1 Move thermostate to top as Svxfiles did, this is the most important.
2 Change the inlet pipe to the pump, "Thermostate cover"
3 Bigger radiator.
4 Outlet pipe on radiator 50mm and noved to the centre of the bottom top (only if not a cross flow radiator).
5 Crossflow radiator.
6 Top engine pipe (this importance is determined by revs).
.

As regards coolant personally I don't think it will provide enough help to gain anything, the problem is one of flow but maybe I don't understand were the gain is.
Tony

I should post some updated stuff along with comments to above quote.

My car has been running excellent since this work. No overheating issues whatsoever and in fact, the car may be running too cool at the moment with the coler temps approaching. I can flog down a long road in these temps and be as low as 158F. that's with a 170 thermo in the housing. Again temps are dropping here and the airflow I have a the front of an impreza is qute different than that of an svx.

On the list above, #s 1-4 all go hand in hand. you really should be swapping out for a large aluminum core, and doing the subsequent housing and cover modifications all at once. To simplify things, one should have the radiator outlet position directly in front of the pump. This, coupled with appropriate 50mm connections, amkes the plumbing simple....just a simple 90 degree 2" id hose is all that's required. nothing fancy. Fan fitment will require work for stock fans, but at that rate one should be considering aftermarket slim units regardless.

[Dessertrunner]

The top of the radiator is under pressure and as a result the flow is less effected by pipe postion. The bottom pipe is under suction and has major flow problems related to pipe postion.
Give you an idea I had PWR built for me, a new design radiator about 6 months back. It had the top and bottom pipes made bigger 45mm but still at the standard position. When I put it on the test bench I near cried because at high revs you could see the air coming from the pipe at the radiator outlet. You can imagine how upset I was.
I was so frustrated that I installed a pump only no motor and sent the liquid around in a loop. I could get the pump to work air free at 9,000 rpm (had to change the thermostate cover to 45mm. The water was so clear that it was difficult to see that it was flowing. Then I went back to the engine, looped flow around and got Zero air.

As a result I changed the suction on the radiator to the centre and at 6,000 got Zero air above that had a bit.

Hope that helps, by the way I have to do a right up on MRT here in Australia about this when its done I will post a link for all to see.
Hope you all have a great day.
Tony

[svxfiles]

OK, Tony, the next rad I have remade will have the outlet in the middle bottom.

[Dessertrunner]

Originally Posted by shotgunslade

The greater the velocity of water through the radiator, the lower the temperature drop of the water. However, if the change in the heat transfer coefficient between the water and the radiator tube walls is ignored, the heat transferred from the water out the radiator is the same, despite the increased velocity because the greater velocity results in a greater mass flow. The two offset one another.

Q = M * U *p * deltaT

where:
Q = heat flux
M = mass flow rate
U = heat transfer coefficient
p = specifc heat
deltaT = logarithmic mean temperature difference.

Greater fluid velocity through the radiator, however, increases the heat transfer coefficient between fluid and radiator tube wall because the greater velocity erodes the static boundary layer between tube wall and flowing fluid. It is exactly the same phenomenon as wind chill factor. Increased air velocity (wind) erodes the boundary layer around your body, increasing the heat transfer coefficient, thus increasing heat transfer between your body and the air. Nobody ever claims that increasing wind speed makes you feel warmer because the faster moving air doesn't have time to heat up as it blows past you.

It is true that, with a greater coolant velocity through the radiator each cubic inch of coolant going through the radiator loses less heat and thus has a lower temperature drop, but the greater velocity also moves more cubic inches through the radiator per unit of time, so there is a greater mass losing heat.

The increased heat transfer coefficient between the fluid and the radiator tube wall actually results in a slight increase in heat loss through the radiator with increasing fluid velocity

Trevor never got this, and was adamant and even abusive in his defense of his own ignorance. This is basic fluid mechanics. It is not a theory.

Dan I need to thank you for jumping in with this post. It is brilliant and to the point as well as greatly appricated. When "Amber" started all this garbage again it made my blood boil. People don't realize how much time and money I put into finding out what caused the cooling problem and to just pointlessly debate with Trevor just burnt up time.

Have a great day.
Tony

[NeedForSpeed]

Originally Posted by Dessertrunner

Dan I need to thank you for jumping in with this post. It is brilliant and to the point as well as greatly appricated. When "Amber" started all this garbage again it made my blood boil. People don't realize how much time and money I put into finding out what caused the cooling problem and to just pointlessly debate with Trevor just burnt up time.

Have a great day.
Tony

Hey Tony,

Yes, I know how frustrating those pointless debates were, for you and for those of us trying to follow. Nothing positive about it, nearly unbearable.

Thanks for hanging in there, much appreciated.
Your work on this cooling fault was fantastic,
one of the best threads we've had here.

You were the right man to sort it out mate
Ron

[Johnybeas]

Originally Posted by svxfiles

OK, Tony, the next rad I have remade will have the outlet in the middle bottom.

and it'll go in my SVX

[Dessertrunner]

Hi all there is a story on the cooling on the MRT web site. I have tried to aklowledge everyones contribution. I wrote the artical trying to be a little light hearted with it as well. Thanks everyone for helping get this problem sorted.

http://mrtperformance.com.au/resourc...boiling-theirs


Hope you all in joy. Have a great day.
Tony

[SilverSpear]

Great article Tony.

Originally Posted by Boxersix

If people want I can fab a few of these 50mm pump inlets for those looking to do this. Will be a straight lip, you'll just have to modify your radiator to suit and use an appropriate 2" ID hose.

I am also interested in one cover, what do you mean straight lip?