SVX Engine cooling "Again & Again"

[Huskymaniac]

Originally Posted by Huskymaniac

Couldn't you just install a bypass line in the cooling system with a pressure relief valve inline? When inlet-vs-outlet pressure of the radiator gets too high, the valve opens and partially bypasses the radiator to semi-equalize the pressures. That would create a situation where there is a maximum coolant flow through the radiator equal to the bypass pressure divided by the flow resistance of the radiator. If this maximum flow is good enough to provide sufficient cooling, there shouldn't be a problem.

Hmmmm, Trevor said to expect no response.

How about this folks. Instead of simply bypassing the radiator through a pressure relief valve, send the bypassed coolant through a secondary cooler, similar to the transmission coolers, and then back to the radiator outlet. Hell, you could even go through a secondary cooler and then through an engine oil cooler sandwiched between the oil filter and block. Then you would would be eliminating excessive vacuum, increasing cooling AND cooling the oil.

[Dessertrunner]

Originally Posted by Huskymaniac

Hmmmm, Trevor said to expect no response.

Sorry I didn't realize you were speaking for Trevor.
By pass valves by there nature require back pressure to cause them to open and ther for have a pressure loss accross them. In hydrulic system they are only used to control pressure that may damage the circut like pressure spikes. If they used them permently they would cause the oil to over heat.

As regards bypassing through a bunch of other things like oil cooler it may be a option but you will still have to control the maxium amount that the pump can pump other wise the system will fail again.

Tony

[Huskymaniac]

Originally Posted by Dessertrunner

Sorry I didn't realize you were speaking for Trevor.
By pass valves by there nature require back pressure to cause them to open and ther for have a pressure loss accross them. In hydrulic system they are only used to control pressure that may damage the circut like pressure spikes. If they used them permently they would cause the oil to over heat.

As regards bypassing through a bunch of other things like oil cooler it may be a option but you will still have to control the maxium amount that the pump can pump other wise the system will fail again.

Tony

I'm not speaking for Trevor. He saw my posting and predicted the response.

I don't think you have a thorough view of bypass pressure relief valves. This problem has been solved before by a bunch of truck driving rednecks:

http://competitiondiesel.com/forums/...hlight=version

To avoid high temperature operation I would suggest doing something similar to what these guys did which is to bypass coolant from a high pressure point soon after the water pump back to the area where you think you are getting cavitation. There are even taps that can be placed inline in a coolant hose. Watts sells a variety of BYPASS valves which operate at various pressures and are adjustable.

[Tireiron]

What are the thoughts of when I have my PWR radiator made, that I have them build it to the SVX size, use a 45 or 50mm lower outlet (depending on the thermostat cover enlargement) in stock location (need to be sure and clear my under engine mounted alternator in the middle), but have the upper inlet moved to where the WRX inlet is or even a little further over to clear the fan mounts. This would allow me to use the longer WRX upper radiator hose as seen in this picture. Looking at the SVX radiator you could almost just swap the positions of the inlet and cap and they would be in the perfect locations. Also use the straight inlet from the WRX instead of the angled inlet of the SVX. Swapping the cap to the other side shouldn't affect anything in the radiator from what I can see.



This would allow more room for my upper thermostat housing as it is quite a tight fit in the current upper hose seen here. It also makes it easier to get upper hoses when needed from many different sources.



Thoughts?
-Jason

p.s. keep in mind this build is not a racecar, but a nice fun touring cruiser that can blow the pants off most things I come across, as you can see from the full engine bay with nothing stripped out of it.

[Dessertrunner]

Current PWR radiator to suit a SVX has the bottom radiator mounting pins in the wrong/right place. As a result it means the radiator has to sit further forward which results in the power steering coole have to be put some were else other wise it cuts a hole in the radiator. I find this mistake to be really good because the clearance between the fans and the engine is greater. What you could do is still get the version with the transmission oil cooler and plug the power steering into that. PWR will also weld in a larger outlet for you at the bottom just be aware you will need to cut the bottom of the fan a bit to get it to all fit.
The design they have that has the fault is the bottom pins are in the centre of the bottom tank interms of front to back direction.

This way you will get more room at the top in front of the engine as well.
Tony

[Tireiron]

OK that sounds good. I don't mind trimming fan shrouds. I already use a different PS cooler because mine rusted out so its not a problem to move that. When I talk to them about making it I will leave out the tranny cooler, use the larger outlet at the bottom stock location, and see about swapping the cap and inlet positions and using the straight inlet they use on the wrx/sti GD radiator. That should give me exactly what I need. Unless someone thinks having the cap and inlet positions swapped will cause some odd undesired behavior. I don't think it would change anything though.

Jason

[Dessertrunner]

Hi Jason,
I looked at moving the cap once and no can do it doesn't clear the bonnet. Have a close look and you will see what I mean

[Tireiron]

I took a look at the underside of my hood and it is symmetrical. It has the same indent on both sides for the cap clearance so as long as they move it the same distance to the right of the car as it is currently to the left it should fit just fine. I do see what you mean about possibly moving it to either side of the center though without the indent for the cap. Ill contact PWR in a week or two and see about having things made up the way I want after I have my water pump housing back and know exactly what size it ends up.

[Dessertrunner]

Have decided to pull this.

[bazza]

Originally Posted by Dessertrunner

There seems to be a suggestion that I have changed my mind on the direction of what needs to be done to fix our engine. The key point being that I have done a total about face in the last 4 months. This is not correct so I am going to quickly list what needs to be done. In order of most important, if you want to track the car for any extended periods you will need to do the lot. In support of this we have a track car running some trials over the next couple of months.
1- Upgrade the radiator size.
2- Increase the size of the suction so larger pipe size from the radiator and larger thermostat cover.
3 - Move the thermostat to the top of the engine,
4 - Use a smaller ID thermostat at the top to help restrict the amount of coolant being sent around at hi revs.
5 - Only for long race periods or if you are going to rev the engine around 8k for any extended periods you need to add a expansion tank that has a radiator cap.

Over the last x years we have added things but have not taken back any of the original suggestion. The reason for that is to try and look after the cooling at 10,000rpm.

Tony

I'd probably do things a little different. The concern I have with thermostat on the top of the engine is it's not proven and may even be a little dangerous to engine health. I've tested and have seen the pressure spike to 30-40 psi which may be enough to blow a heater core apart. Also when testing it blew my top hoses off several times. With a smaller thermostat up top, this may make the pressure spike problem worse - those hoses really don't like 40 psi. So I probably wouldn't do the above. For interest sake I found and ordered a far bigger lower thermostat for some future testing - 30% increased flow over stock so I'll see how that performs also.

Anyway back to the turbo header tank - at Winton when I tested my setup, the RPM sat between 4000-7000 rpm per lap. NO overheating. The issue after each session was air pockets in the system. Afterwards I realised I had not plumbed the radiator TOP into the header tank - the turbo WRX's have a breather line from the radiator to the header tank and I reckon if I did that, problem solved. That day for interest sake I was running a huge radiator with minimal pressure drop, 2" lower thermostat cover (no thermostat in system at all). It was a very hot day (well I did 3 days straight) - so was quite a good test.

Now back to the original problem - a mate of mine has his brand new EG33/GT40R setup in his WRX making over 550 bhp. He sat his car on the dyno for 5 mins and held it at 6000 rpm. The annoying thing is he didn't find a single issue - no cavitation, no overheating, no airpockets. Standard thermostat cover and inlet.

Further my own SVX has been flogged about and I handed the keys to the current NSW Rally State Champ (mate of mine) and he flogged it and was living on the limiter for minutes - again not a single issue... it he did it multiple times.. think he enjoyed my SVX with plated rear diff lol.

Of course, I never actually had any cavitation issues with my EG33... I simply upgraded the thermostat cover before any testing which is rather annoying for me as it means I've never actually got to see this issue.

So it has me scratching my head - why do the 4 cylinder EJ's not have this issue with the same impeller, drive ratio? Why do only some of the EG's have this issue!! Just doesn't make sense. A few guys think the speed of the pump might be to fast but then why can an EJ spin to ridiculous rpm and have no cooling issues... this is a fellow in WA (Aus), 9500 rpm, stock WRX or STI pump and cover (500 kw atw):

http://www.youtube.com/watch?feature...&v=nRPdQCksEEE

So in the near future I'm hoping to get some more testing done and determine answers to all these questions and more. I'd also like to determine how the psi rating of the cap can help in conjunction with the turbo header tank system. If increasing the flow from the pump or increasing the flow back to the pump helps. What happens if we install the 3rd pump inlet (from the oil cooler location). Ideally it would be nice to have a fix that didn't involve moving thermostats, enlarging covers and custom radiators. Hopefully we can get there.

[Dessertrunner]

Also pulled this, I am going fishing and watch from the side lines.

[bazza]

Originally Posted by Dessertrunner

Bazza,
I think you need to point out that you had no lip or feral on the top thermostat just hose straight on to a straight pipe. No wonder it blew off. I seem to remember you posting before that the return pipes were on the suction side so had no pressure.
Tony

That's right, the lips didn't exist at the time on a couple of the joins which is a weakness but then it comes back to why run 30-40 psi through a "heater" type hose designed for 14 psi? When we start talking those pressures with air in intercooler piping we tend to double clamp, use heavy duty silicon hose and many other things which cost money. The cost to upgrade the radiator inlet hose to heavy duty or silicon (if we do it properly) and the complexity is getting up there plus we've got to look at why we're introducing problems in the first place and ensure we're doing it for the right reasons. Bare in mind my same system ran for three days at Winton without drama (thermostat removed from the inlet) - pressure around 14-15 psi IIRC. The only time the system blew apart was testing with thermostat up top.

If we knew that the hot water return to the radiator needed a restriction and without a doubt fixed the issue then it might be far smarter to add a little restrictor to the aluminium outlet. However then we still are pressurising the **** out of the heater core - so not so good when they cost $500 and take several hrs to fix. It might come down to putting restrictor plates on the two engine outlets on the top of the block if we know that will actually fix the problem. In my testing, I might find that shutting these down to the same size as the EJ outlets might fix it. If this is the case then it's a rather easy and very cheap fix. No complications, no moving thermostats about, no enlarging covers and radiators etc. This is the type of fix I think everyone would be interested in.

[Alcyone Lunacy]

Been lurking on this thread for a while now, very informative.

Been thinking about one of these if it is able to fix the cavatation issue. Carbing is a very reputable tuning company and I think this may be the answer to the issue. If someone here could advise a proper install, not sure where how exactly to place on the SVX engine as the install guide they give is very generic.

http://www.carbing.co.jp/internation...eservoir.shtml

What do you guys think?

[Dessertrunner]

Its a good idea

[BackWoodsBob]

So the solution is

40+mm thermo inlet
Cooler thermostat OR one located to the top rad hose?

I'm running a griffin 2.5" aluminum dual row cross flow and my car hit 230f yesterday. It's done it a few times, still no blown head gasket thank god but this temp is ridiculous. Stock thermostat which I've replaced 2x thinking it was stuck closed....High flow pusher fans in an 01 legacy sedan chassis.

I have a spare thermostat housing but welding to the 1/10th inch material on my rad tank makes me damn nervous.