SVX Engine cooling "Again & Again"

[Dessertrunner]

Originally Posted by bazza

You've got good sized exit holes feeding a restrictive cross pipe outlet:

Incorrect Bazza,
everyone only thinks they are good size holes, I posted a photo years back that shows when you look in the hole the linner is blocking the hole. In other words bad flow, even if you removed the top pipe the flow through the engine would not increase much because of this restriction. You can do what you like on the top pipe and nothing will change.
Tony

[bazza]

Originally Posted by Dessertrunner

Incorrect Bazza,
everyone only thinks they are good size holes, I posted a photo years back that shows when you look in the hole the linner is blocking the hole. In other words bad flow, even if you removed the top pipe the flow through the engine would not increase much because of this restriction. You can do what you like on the top pipe and nothing will change.
Tony

It may show that it looks restrictive but how restrictive is it. That's the reasons I'm doing extra tests now to determine these extra bits of information.

I'm not convinced of your theory because viewing from inside and outside, the exit holes and the feed to the exit holes do look good and are 29mm. They would have to loose almost 50% of their flow rate capacity before the 30 mm cross pipe exit is less of a restriction and even though it's not an ideal flow path to those, I can't see that happening.

You can see one of the outlets here from inside and outside the engine:

[Dessertrunner]

You can't even fit you little finger in the bottom of the hole, it would lose more then 50% of the flow of that hole. I did measure the pressure loss between the jacket around the linner and the down stream of this port and it was substantial. From memory it had the highest single restriction of any part in the engine block.
Tony

[bazza]

Originally Posted by Dessertrunner

You can't even fit you little finger in the bottom of the hole, it would lose more then 50% of the flow of that hole. I did measure the pressure loss between the jacket around the linner and the down stream of this port and it was substantial. From memory it had the highest single restriction of any part in the engine block.
Tony

That's very interesting. Good to know.

[Dessertrunner]

Also Bazza I seem to remember measuring the pressure loss from the outlet of the left bank (the 29mm hole) to the end of the top cross pipe at the top of the radiator and the loss at 200l per minute was stuff all maybe 2 psi.
Tony

[SVXRide]

Originally Posted by bazza

I will add this to my site: http://diyracecar.com shortly but will add it here first.

In my previous tests you can see the water is being sucked from the bucket 70 cm below the pump. This gave me a false suction reading because of the extra work to suck the water "up-hill". So today I moved the bucket so it was even with the pump and radiator and got a better more accurate result and sure enough suction dropped to around 0.5 psi. When you view the gauges, it's pressure left, suction right gauge.


So my conclusions:

Three radiators tested had pressure drop of 2.5, 5 and 5 psi. Both 5 psi radiators were WRX radiators, one was sideflow and the other crossflow - both used the 34mm standard ID inlet / outlet. As the flowrate was very high - I'd expect a lower value in reality when the engine is running and I will test this soon.

It was also noted that a 27mm restriction inlet onto the pump caused the suction to increase. When the restriction was on the outlet side of the pump, the pump outlet pressure increased and this behavior is simply expected.

However, after getting a good idea of how a pump system works - a 34 mm thermostat housing may be the double edged sword. It is most likely the bottleneck after the pump and the bottleneck before the pump - increasing pressure on one side and increasing suction on the other side.

When this has been upgraded the bottleneck moves to above the radiator and to the cross over pipe where 2 x 29mm's merge to a single 30mm outlet - I'll investigate this next weekend.

Bazza,

Good stuff as it relates to the different characteristics of the radiators you used! Thanks for the link to your web site, it's now bookmarked in my "SVX Racing" folder. It would be great if your site could serve as the data repository for all the testing that you, Tony, and Tom J. have performed to date.

Bill

[Dessertrunner]

Bazza,
If you are going to do some more testing on the flows this week end you can borrow my guages if you want. Also if I understand you correctly you want to see how much coolant can flow through the standard top pipe as a stand alone test. Is that correct?
Tony

[bazza]

Originally Posted by SVXRide

Bazza,

Good stuff as it relates to the different characteristics of the radiators you used! Thanks for the link to your web site, it's now bookmarked in my "SVX Racing" folder. It would be great if your site could serve as the data repository for all the testing that you, Tony, and Tom J. have performed to date.

Bill

Cheers Bill. Will be adding a fair bit more soon.

Originally Posted by Dessertrunner

Bazza,
If you are going to do some more testing on the flows this week end you can borrow my guages if you want. Also if I understand you correctly you want to see how much coolant can flow through the standard top pipe as a stand alone test. Is that correct?
Tony

Yeap. This is what I'm planning to test, some of which simply to see the result my own eyes as I know you've done most of this already - I just need to understand it far better like you do
* Crossover flow and pressure drop
* Engine block flow and pressures
* 2 and 3 bypass lines flow and pressure drop
* Thermostat flow and pressure drop

Phase two of my testing will commence:
* Hot engine open system flow rate at various RPM with no radiator
* Add radiator to the hot engine system (open) and test various pressure locations at various rpm

I would not say no to borrowing some decent gauges

Also one of the major drivers for this is my sanity - the fact that this issue has never occurred in the STI's I just cannot get my head around having modified the sh!t out of STI's and their engines for nearly 10 years and flogged them to near death in all sorts of racing, never ever seeing any overheating issues. My friend who has the EG33/GT40 turbo setup worked at STI docklands as foreman (biggest Subaru owned STI workshop in Aus) and he agrees that it doesn't make sense for us EJ2X to EG33 converts and is very interested in what I come up with. Funnily enough he has the overheating issue already and thanks to what you found with the cover has saved him also several months / years of pain which he is most grateful.

[Dessertrunner]

Bazza happy to loan you the guages. In your work you may have to do like I did and set up a proper SVX pump and drive it with a electric motor as I am not sure you are going to correctly duplicate the behaviour of the svx cooling system unless you do that.

THe other thing worth doing is using clear pipe feeding the pump then you can see when the pump is cavitating because the water goes milky.

What KW is your pool pump? Also depending on have far in the testing you want to still use you pool pump we will need to get a flow chart for the pump. Every centrifugal pump has a maxium pressure it can pump up to. If that pressure is exceeded the pump drops flow.

I have a backing plate so you can bolt a SVX pump to the front with out the engine but you will need drive it with a electric motor.

Tony

[Dessertrunner]

Bazza and I spoke today and he made a point that the STI's never over heat so why. I think we need to buy a STI water pump and run some tests to compare the pump performance curves.
Tony

[bazza]

Originally Posted by Dessertrunner

Bazza and I spoke today and he made a point that the STI's never over heat so why. I think we need to buy a STI water pump and run some tests to compare the pump performance curves.
Tony

Tony, buy ?! come on :P

I've got about 3 sitting in the shed haha. You actually cannot tell them apart from the SVX pump without comparing the pulley offset.

[Dessertrunner]

Is there pulley larger or smaller then the SVX one?

[Dessertrunner]

Bazza the STI that you say runs cool do they have down flow radiator or cross flow? My exliberty had cross flow.

[bazza]

Originally Posted by Dessertrunner

Is there pulley larger or smaller then the SVX one?

It's wider as the EG33 has a wider timing belt. Diameter is the same.

[SilverSpear]

Why not exploring these...

TSM Water Pump

Crawford Water Pump