SVX Engine cooling "Again & Again"

[Dessertrunner]

You two guys have it all figured out so you cool the engine, you both haven't got a bloody clue.
Tony

[shotgunslade]

I think the inlet condition of the pump is critical. Best design would have a straight pipe for 10 diameters at the pump inlet. We can't achieve this, however. I think the important part of Tony's design is the 42mm ID inlet to the pump, and the absence of the thermostat. This lowers velocity and turbulence at the pump inlet. I think a similar benefit could be achieved if there were an expansion immediately at the radiator outlet connecting to a 45mm hose. The expansion should be as far away from the pump inlet as possible to allow the flow to stabilize before entering the pump. The expansion would probably have to be pipe instead of hose to prevent collapse.

[JONES OFF ROAD]

Originally Posted by TomsSVX

Im with trevor here, whatever enters the radiator at 1.5" OD can and should exit at the same diameter... Rather than just trying to make a bigger opening to come out of the radiator would it not be just as plausible to have a custom hose made to expand from 1.5 out of the the 1.75 require inlet to the pump?

Are you using a thermostat???????????

Tom

The above is correct, but..................what happens when the water does not ENTER the radiator because the WATERPUMP stops pumping??

The custom hose to a larger pump inlet may work, just needs someone to try it!

[Cam]

All I know is if someone could make another modified xover pipe an inlet like tony has I would be very interested in purchasing both to try on my car with the stock radiator.

[Trevor]

Originally Posted by Dessertrunner

Subaru fell for the same trap as Trevor, they beleived that a closed loop system ment that some of the pressure would turn up at the pump inlet. This is fundemtally incorrect.

TONY, what I have actually advised is correct but you have misunderstood. But I think I can understand what you are driving at, or towards, see last paragraph.

If I take the outlet from the pump and infeed it into the inlet unless there is a restriction in the system there will be no pressure on the outlet of the pump and unless there is a restriction close to the inlet there will be no vacum.

A connection can not in practice be made, pump outlet/inlet, without there being some, even if slight, restriction. The pump must overcome this restriction, in order to move the liquid and pressure must result and energy be consumed.

Any restriction, no matter how limited, must result in reduced pressure at the pump inlet, as compared with the outlet. The use of the term vacuum is not correct, and leads towards confusion at the very least. Suction is a more useful way of describing a possible condition at the pump inlet.

The water loops for the minium pumping energy.
On the other hand if I either block off the suction or the outlet the whole pressure?vacum numbers changes. It would be possiable to restrict the suction so as the pump is pumping vacum but the outlet is reading zero pressure.

The energy require to "loop" the water is directly related to the total restriction within the loop. Maximum flow will take place in parts of the loop having the least resistance, particularly where parallel passages exist.

The pump can not "pump vacuum". It would be possible to block the inlet so that there is zero output. Or is it meant that the pump can not prime and deliver, if no liquid is available at the inlet? Again see last paragraph.

The way it works is the restriction in the system can be large enough to increase pressure but still small enough to not cuase a problem on the suction. If the restriction gets to great the suction goes up till the pump drops off which then gives the impression that the pressure is not a problem. Tony

Agreed, but let us put it this way. ---- Any form of restriction will result in pressure within the system. Each item of restriction will throttle the flow and cause an increase in pressure behind that point. A high level of restriction, will mean that a given rate of flow from the pump outlet, can exceed that available at the input. Therefore at that point suction could exist, but not a vacuum. "The pump drops off" or can stall, as I have many times explained.

We are both sorry about the long explanation.

[Trevor]

Originally Posted by TomsSVX

Im with trevor here, whatever enters the radiator at 1.5" OD can and should exit at the same diameter... Rather than just trying to make a bigger opening to come out of the radiator would it not be just as plausible to have a custom hose made to expand from 1.5 out of the the 1.75 require inlet to the pump?

Are you using a thermostat???????????

Tom

Tom,

The pressure will be throttled at the radiator outlet point and can not be restored by a simple increase in the following passage.

But there again, the alteration in the size of the actual pump housing could be affecting impeller operation for better or worse. This could be the crux of the modification, rather than inlet cross section. Nothing has been confirmed in regard to what is actually taking place.

[Trevor]

Originally Posted by Dessertrunner

You two guys have it all figured out so you cool the engine, you both haven't got a bloody clue.
Tony

Tony,

Not nice, please keep your shirt on and answer the valid quereies within post #869. Be sure that the queries do not constitute negative criticism, as you appear to have concluded. Your reply is important will advance your cause.

Sincerely, Trevor.

[SVXRide]

Originally Posted by Dessertrunner

Bill,
Not sure what will happen when we run the state but will do a trail and its yes to the rest of the questions.
I am looking at the final cover design I think it will be a lot simpler but yes we could see what we can do.

Okay redid the test at 30c air temp.
6th gear 58 radiator return 72 engine
4th 62 78
3rd 70 88

I think its fair to say the proof is in the numbers, there was no change of the engine overheating. The improvment to the cooling is mind blowing.
Tony

Tony,
Thanks for the response! You must be walking on air (okay, how about non-boiling coolant?).
Can't wait to see how adding the 'stat back into the system affects things. I'm guessing that the final solution might just involve putting an in-line 'stat in the return line to the radiator like YT is looking to do with Dan's engine.
Cheers.
-Bill

[SilverSpear]

Originally Posted by TomsSVX

Are you using a thermostat???????????

Tom

Originally Posted by SVXRide

Can't wait to see how adding the 'stat back into the system affects things. I'm guessing that the final solution might just involve putting an in-line 'stat in the return line to the radiator like YT is looking to do with Dan's engine.
Cheers.
-Bill

Didn't know that your system runs without a thermostat Tony.
Again your achievement deserves a lot of credit in the EG33 cooling nightmare, I think this is the reason the Purple boosted WRX with the SVX engine failed a few years ago (check the E33 thread in turbo mods).

But the lack of thermostat might be a problem for those who live in very cold areas. I would suggest you put an inline one, drive in a hot sunny day, high revs, uphills and test further that modification that you've done.

Again kudos for you my friend!

[Dessertrunner]

Trevor,
You seem to selective find the bits of posts you want and not the important part.
At the start I said the intake on the inside of the thermo cover was 29mm ID on the other part of that cover the ID is 33mm. Through this size pipe you are trying to suck upwards of 250 litre per minute. You and Tom seem to think suction and pressure have the same flow rates but they don't.
Currently the top pipe on the engine is 33mm ID and it is operating in pressure. On the inlet of the pump it is in vacum and if I want to acheive the same flow rate as the top pipe I will need it to be nearly 45 ID.
In one of the tests I did I had 5psi (I beleive that at 7Krpm it would be higher)pressure at the radiator cap which is top tank pressure. If I can move the restriction on the suction back up the system into the radiator as far as possiable I will get the benfit of this 5 psi on the suction (which will become zero pressure).

By the way,
The internal of a thermo cover is 29mm --- or 660 sq mm
A Standard Subaru radiator in & out pipe is 32mm ID --- or 803 sq mm
A PWR standard is 35 ID --- or 961 sq mm
A modified PWR like I have is 42 ID ----- or 1,384 sq mm

As can be seen from the numbers the new PWR outlet pipe means that the whole suction is 2 times bigger then the standard in surface area if I add to that the saving in friction my guess is that the flow rate is now 2.5 times greater then the standard.

And this post is all in ID in case you missed that.
Tony

[TomsSVX]

Originally Posted by JONES OFF ROAD

The above is correct, but..................what happens when the water does not ENTER the radiator because the WATERPUMP stops pumping??

The custom hose to a larger pump inlet may work, just needs someone to try it!

Listen, I have one issue with the idea that the pump is becoming air bound and please hear me out... If this was the case, we would see a shear drop off of pressure on the outlet of the pump.

Further more, the cover to the pump causing a restriction on the suction side becomes an issue as well... If you run an electric pump which you have, the cover should be on the pressure side of the things. With this in mind, you were still having issues were you not?

It is these reasons that I seek further investigation before I go ripping apart the lower tank of Dan's radiator before more testing of the new water manifold I had made... It is not that I don't believe you or Tony and definitely not that I do not appreciate the hard work with what you have done to test your theories... But there needs to be explanations for all of this that make total sense

Tom

[Trevor]

Originally Posted by TomsSVX

Listen, I have one issue with the idea that the pump is becoming air bound and please hear me out... If this was the case, we would see a shear drop off of pressure on the outlet of the pump. --------.Tom

Tom,

I think the suggestion is that if the water pump stops pumping, flow will cease. Rather than that the pump is or could lose priming. There can surely be no justification or reason for suggesting that a large pocket of air could develop.

[Dessertrunner]

Tom,
I understand your point and see were you are coming from. When Steve used the electric water pump it was a Craig and only a supposed 110l per min. Given the pressure it had to deal with there is no way it was pump 110litres.
I think I worked out that Jacks pump has a simlar capiciaty to the standard pump at 5,000 rpm and that would explain why at higher revs it can't cool the car, its a straight coolant/flow rate issue.
I would suggest you do all the things you are thinking of doing then just change the pump thermo cover to a larger pipe with a inline reducer to the radiator. You will see a big difference at high revs just by doing that. Cutting the radiator is not the biggest issue its the cover thats the killer.

Trevour if you don't beleive that the centrifical pump can loss prime due to a restricted suction then you must beleive in the tooth fairy so i can't help you.
Tony

[SVXRide]

Tony,

I call dibs on the second 'stat cover that comes off of your production line
I take it you'll machine them for a standard o-ring in place of the 'stat/o-ring combo that the stock cover supports?

Cheers,
Bill

[shotgunslade]

Tony:

Put me in line right after Bill.

Dan