SVX Engine cooling "Again & Again"

[Dessertrunner]

Originally Posted by bazza

Well after 3 days of track work I think the water cavitation issue unfortunately remains, doh! I was running the following:
* Radiator as big as a house
* 2" inlet to the water pump
* No thermostat, so no restriction coming into the pump
* Coolant temps around 70-75'C, never got hot once

The issue was an air pocket would form in the system after 5+ laps and it was collecting above pump side in the radiator and pushing water out of the system into the overflow. It then wasn't sucking it back in.

For comparison sake my mates had:
* EJ206
* EJ205
* EJ257

None had the air pocket being formed and I know that the 4 cylinder Subaru's NEVER have an issue with the overflow not sucking water back in. You can actually hear them suck it all back as the engine cools down in the pits whilst idling.

This is so annoying as I had to purge the system between sessions that I seriously considered binning my EG33 and going back to the trusty EJ257's because they NEVER have this issue, dammit. However the torque, power and driveability of the turbo EG33 cannot be argued with - it's unbelievably good so I'll persist.

So for my solution, I'm considering putting the radiator in the boot, adding my electric water pump to the outlet and seeing what happens. Bob has already said on Jack's setup they saw and improvement and with my own testing putting a little pump before a big pump I've seen improvements even though it sounds like it wouldn't. The radiator in the boot for my setup is simply so I can run a FMIC and reduce some of the weight my fatty car now has - 1256 kg.

I'm also going to put an air bleed to the header tank so the air can escape from the radiator. I'm also going to add a tee piece with a "tap" so I can easily drain the system of air if required.

I'll update when it's all working.

Your soluation has not one sound basis for going down that path. When you posted the images of your system last time my guess is you had 16 hose clamps and a heap of fittings. Bazza you keep giving everyone grief about how they just do things with out a sensiable or science based approach, now you come up with this strange soluation. You need to take a chill pill and look at the problem with logic.

- If air gets in the system then one of your hoses could be leaking on the suction side?
- The coolant is not getting sucked back because there is no heat in your engine to enable a pressure drop as it cools?
- Is the radiator a crossflow, if so which side of the radiator is the cap?
- Were is the overflow pipe connected?

We need to work through these things before you move the radiator to the back. Also I am not convinced that running the cooling system with out the thermostate was a smart idea.
Tony

[teamilluminata]

Originally Posted by SVXRide

That would be great! I've got a spare stat cover I could send you to replace your cover. Can you PM me your email addy and the address I should ship the cover to?

Thanks.

Bill

Probably best if you contact Ryan direct : http://www.thompsonracingfabrication.com/

[SVXRide]

Originally Posted by teamilluminata

Probably best if you contact Ryan direct : http://www.thompsonracingfabrication.com/

Thanks! Will do!
Bill

[Dessertrunner]

Thinking over your problem Bazza, maybe the easiest thing todo is drop you timing belt off and we will hang 3 phase electric motor under the engine and belt drive the water pump. If we do it with a VSD we can run it upto 7k and find out what is causing the problem in your system.
Given that your not generating any heat my guess is we will find the soluation pretty quick.

Tony

[Dessertrunner]

Originally Posted by bazza

Bazza,
How simlar to this is your current system design?

[Dessertrunner]

I have been considering a issue that always come up and that is the idea of running with out the thermostate in the system.
I need to put on record that this is not a good idea at all. If the thermostate is to be mounted in the suction side it maybe the only choice but the system will give issues.

My reason for saying this is that Caviation is a volume/flow issue, in other words as you speed the engine up the pump can pump more coolant and as such it wants more supply from the inlet side. If there is no restriction on the up side of the pump and you take the revs up the pump will need more flow. The way around this is to have the thermstate on the outlet of the block so it will limit the amount of coolant that can be pumped due to the pressure increase limiting flow.

In short don't run without thermostate,
Thermostate must be at the top of motor, Suggest it needs to be in a welded housing such as I now use.

Tony

[Dessertrunner]

Yes I am alive, have been flat at work also had a overheating issue with my wifes SVX. For a while I figured it was a head gasket but it turned out to be the little bypass hose under the manifold that returned coolant to the pump.

So I ripped the manifold off fixed the hose and----------

installed the modified top pipe thermosate holder with a 170F (77C) thermostate. The car was driven around all day with air temp at 37C and when it got home I checked the car everything was perfect. Not a drop of coolant was lost and the overflow tank never changed its level. The difference to the cars bonnet temp is unbelievable you can even touch the top of the motor (for a short time) and not get burnt. In the past all our SVX on hots day when you stop, make bubbling noise in the overflow tank. Now that never happens.
As they say once tried I will never go back.


My car also has the thermostate on the top pipe and as a result of experimants over the last 3 weeks I have come to the following conclusion.

- In a past thread Bazza mentioned that the restriction from the block on the SVX was less then the restriction on the 4 cyclinder Subaru engines.

- He also mentioned why is it the STI's don't have the over heating problem.

- Last track day Bazza had issues with build up of air in the system.

- Bazza did not run a thermosate last runs.

- Today driving my car around the engine temp was around 80 to 85C with a 77C thermostate and the fans never turned on when the car was moving. Important and worth noting is that for the thermostate to be full open coolant has to be at 89C, so the system had capiciaty up its seleve.


What does all this mean well I feel sure that you can't run with out a thermostate. I had beleived in the past that the blocks have a lot of restrictions but when we change to a bigger radiator etc we reduce the pressure restriction in the system. Then at higher revs the pump can pump more coolant. In Bazza's case he has a massive radiator with no restriction so the pump can pump hard in addiation he didn't have a thermostate in the system so the pump was demanding more coolant.

The point I am making is we need to be carful no restriction will cause caviation and as a result build up air in the system exactly as happened to Bazza. In discussions he made a point that we need to set up a engine and hammer the hell out of for 5 hours and see if it builds up air.

Anyway I am 100% convinced that we need to run the thermostate in the top pipe and a small one to restricte flow.

Tony

[SVXRide]

Tony,

Anyway I am 100% convinced that we need to run the thermostate in the top pipe and a small one to restricte flow.



I get the thermostat comment. Is the "...a small one.." intended to mean of the same ID as the stock pipe/thermostat?

Had you already modified the stock thermostat housing?

Cheers

Bill

[Tapani]

Just a thought.... what if you decrease the pump speed by, let's say, 20%? To prevent cavitation at high revs.

If this helps you may look into redesigning the impeller.

Tapani

[Dessertrunner]

I had been of the opinion on the block side that less restriction would be better but thats not the case. What I ment about the thermostate was that I had been on the same page as Bazza in that I should put the standard Subaru one up top as it will have more flow. Now I think I just need to stick with the current unit I am using. Also I don't think its worth changing the top pipe on the radiator.

Yes we could reduce the pump flow such as drill it like Trevour use to go on about but I figure its just about getting the balance right. Should be pretty simple.

Tony

[subarvair]

I am using a eg33 in a project and want to use an enlarged thermostat housing with the inline thermostat built into the return pipe. Is anybody building an enlarged thermostat housing. It needs to fit 2" id hose.
My eg33 is running pretty good on a Megasquirt 3 but have a lot of tuning to do.
Thanks
Mike

[Dessertrunner]

I think the airflow through the engine bay is bad.
See results.
Tony

[Dessertrunner]

Hi Mike,
Most guys build there own new thermostate cover for the water pump. As for the new thermos holder up top it depends if you want to weld it or not.
Tony

[teamilluminata]

Originally Posted by subarvair

I am using a eg33 in a project and want to use an enlarged thermostat housing with the inline thermostat built into the return pipe. Is anybody building an enlarged thermostat housing. It needs to fit 2" id hose.
My eg33 is running pretty good on a Megasquirt 3 but have a lot of tuning to do.
Thanks
Mike

Thompson Racing Fabrication built mine.

[SilverSpear]

Originally Posted by teamilluminata

Thompson Racing Fabrication built mine.

??? $$$ ???