SVX Engine cooling "Again & Again"

[svxistentialist]

Tony, I think in fairness to Trevor's reservations about the system and circuit being non standard when tested at atmospheric it should be remembered that the reason for pressurising the system is because water [and in this case coolant] has a different boiling point when under pressure.

As your test rig was running normally [as I understand it] at atmospheric and without a head then said rig could not realistically emulate high temperature conditions in the engine under normal load and operating conditions. Local conditions near the pump could cause localised boiling when running at a lower than normal pressure.

The changes you have made to your test system have allowed improvements to the flow path without positively proving that this will also work the same when under radiator tank pressure.

I for one accept that your trial and error method works, and I would be following the same path if I was planning to race or boost an EG33 to serious horsepower.

Using a larger outlet from the lower radiator tank is a given improvement as I see it, but I'm less convinced the outlet needs to be in the centre. Also I would expect your modification [assuming it works, as I do] to improve when operating under a head, compared to circulating at atmospheric.

And for that reason as you are now saying you did pressurise at one point and it made no difference, I am now suggesting that Trevor should accept your modification as being proven.

Trevor?

If you feel more needs to be proven here, please provide a detailed methodology in line with current thinking so that proof can be tested and accepted.

Joe

[Trevor]

Originally Posted by Dessertrunner

Wow Trevor you are right on cue, I DID PRESSURISE the system at one point and it made no difference.
You have not come up with one crediable reason why the system needs to be pressurised just that it seems like a "bloody good idea". Happy for you to provide a sicentific paper or simlar to back up your statements.
If it is to prevent air getting into the system its not needed.

Happy to debate the issue till the crows come home.
Tony

Tony,

The evidence recorded within this thread, confirms that at no point did you pressurise your test systems to an extent, even approaching that applicable in respect of an actual operating SVX cooling system. This is a fact beyond debate.

[Dessertrunner]

Joe I hear you and understand were you are coming from and may not explain myself properly but the over pressure does not change the pumps point at which it cavitates as this is related to suction. I think the belief is that an over pressure of 10 psi will mean more pressure on the suction. This is not correct as its a closed system and any over pressure applies to both side of the circut which then mean no difference.
The best way to explain it is, if I am driving my car at 100 kph and I have a fly inside the car fly around is he flying at 100 kph. The answer is no its all relative the fly is only flying at the incar speed. The pump circut won't change interms of caviation based on over pressure.
The point at which the engine boils will change based on over pressure but thats it the pumps performance won't improve due to over pressure.

One thing I don't get Joe is so many people doubt the soluation or question if its right and most don't have any solid fact to back it up. Would like to understand that better is it that as usual am i not explaining it properly or what?
Tony

[Dessertrunner]

Trevor what purpose does an over pressure acheive. You keep saying it needs it but don't have one single reason to justify it. With out justisfication it is "Blue Sky" stuff.
Tony

[Trevor]

Originally Posted by svxistentialist

Trevor?

If you feel more needs to be proven here, please provide a detailed methodology in line with current thinking so that proof can be tested and accepted.

Joe

Joe,

Yes I do feel that more needs to be proven here, i.e. a method of preventing an SVX engine from overheating when engine RPM constantly exceed the designers expectations. To date nothing has been proven.

As for complying with your request for "detailed methodology", surely the simple statement that the proof of the pudding is in the eating, is sufficient and the requirement obvious. However in line with what is so well illustrated within this thread, I will detail for those stupid.

A car previously having the applicable fault, must be tested within the same environment, without any subsequent modification other than that to be proven and with the exact same conditions applied.

Each test must involve only one modification, so that proof is confined and exact. In the event that several modifications are required in order to provide maximum effect, each must be proven separately.

[Dessertrunner]

Trevor you still haven't said what the purpose of the over pressure is, just raving on again with out fact or reason.
Solution to problems are found by breaking problems down into there smallest part not by increasing the complexity of the problem.
Tony

[Trevor]

Originally Posted by Dessertrunner

Trevor what purpose does an over pressure acheive. You keep saying it needs it but don't have one single reason to justify it. With out justisfication it is "Blue Sky" stuff.
Tony

Tony,

I have not suggested "an over pressure" test. I have stated that pressure should be present close to that which is normal.

No test can be valid or even worthwhile, unless the what is being tested is closely, if not exactly, simulated. Your set up does not provide conditions even close to reality.

You argue against what is fact. Blue skys are the stuff of fiction.

[Dessertrunner]

Here is the unit used to pressurize the radiator when I did the test. It is a radiator pressure tester and have the added advantage that it can let me try higher pressures then the engine normally operates at.
Tony

[Trevor]

Originally Posted by Dessertrunner

Here is the unit used to pressurize the radiator when I did the test. It is a radiator pressure tester and have the added advantage that it can let me try higher pressures then the engine normally operates at.
Tony

Tony,

After reviewing your posts covering the testing you are now using as evidence, I can find no evidence that you used such a device or an any way applied significant pressure.

[Trevor]

Originally Posted by Dessertrunner

Joe I hear you and understand were you are coming from and may not explain myself properly but the over pressure does not change the pumps point at which it cavitates as this is related to suction. I think the belief is that an over pressure of 10 psi will mean more pressure on the suction. This is not correct as its a closed system and any over pressure applies to both side of the circut which then mean no difference.
The best way to explain it is, if I am driving my car at 100 kph and I have a fly inside the car fly around is he flying at 100 kph. The answer is no its all relative the fly is only flying at the incar speed. The pump circut won't change interms of caviation based on over pressure.
The point at which the engine boils will change based on over pressure but thats it the pumps performance won't improve due to over pressure.

One thing I don't get Joe is so many people doubt the soluation or question if its right and most don't have any solid fact to back it up. Would like to understand that better is it that as usual am i not explaining it properly or what?
Tony

Tony,

Joe is confused, but all along I have understood exactly what you have in mind.

Your theory is that the original pressure delivered by the pump, becomes depleted by resistance within the circuit, to the extent that no pressure reaches the pump inlet. Therefore that at this point the pump is as it were, “is gasping for fluid”, resulting in a space within the fluid flow and suction at that point.

What you must explain is how increasing the pump inlet pipe can correct the suggested situation.

[Ironhydroxide]

OK, I have surfaced once before in the whole scheme of things, but now that i feel that there is more to say here than is being said, as there has been a lot of Bashing going on recently. I wouldn't be surprised if I get flack for this, but i am doing it anyway.

I totally agree with Dessertrunner. There may be more things that are causing the Cooling Problem, but one large one is the restrictions the pump has (ie. flow, max RPM, etc.) and one of these restrictions is the volume of liquid able to be pulled through the T-Stat cover.

Just to put it in perspective to those who think that if a pump can push (displace) a certain amount of water through a certain size pipe, it should be able to suck the same amount through the same size pipe. Try Sucking through a straw as hard as you can till your lungs are full. Then try blowing that same amount of air out through the straw. It is (for one) easier to blow air out of the straw than to suck it into the straw.

Here are some links that i feel should be read in context of this topic. (even for those who think they already know it all, it may be a good refresher) *Cough trevor

http://en.wikipedia.org/wiki/Pump
http://en.wikipedia.org/wiki/Cavitation

now it is back to watching intently until I again feel that my comments may be of some actual use to the many other readers here who don't post just cause they feel the testing should be commanded by them. (but those who do don't seemingly suggest many different or constructive tests other than slowing the pump down, or drilling the vanes)

[Dessertrunner]

Trevor,
I know it sounds strange but in a closed loop system it is impossiable to supply postive pressure to the suction of the pump no matter how big the pipe between the two. As strange as its sound it took me a lot of head scratching to get my mind around it but it is a fact and I have confirmed it to be true.
If the pump is with out restriction then the coolant turns up at the pump inlet and any pressure the pump inlet would have been supplied with will be lost by the pump pumping faster. The pump will just pump more which will cause any pressure gains to be lost. It makes sense because at some point the coolant flow and pump revs balance.

In answer to the difference between pressure restriction and vacum restrictions. I will take a side step and give an example. One of my irrigation pump sites has 3 by 70litre per sec pumps and on the up stream side I have 4 pivot irrigators. Hang in there I am getting to the point.
If I open the valves to two irrigator which need 140l per sec and I only turn 1 pump on the cavition is so bad you near go deaf. Once I turn on the second pump the noise and problem goes away.
Problem was system up stream wants and could handle 140lper sec but as I only had 1 pump running the suction on that pump could only supply around 70lper sec. Because there was no up stream pressure the pump wanted to pump 140lpsec and tried. Now if I close the valve on the pump half way I have created a restriciton and even though I have one pump running the pressure restriction is enough to reduce flow on the pump back to 70lp Sec noise now goes away.

The answer to your question is the suction and outlet need to be in balance even or possiably more so in a closed system. The challange we have and will face is finding the balance. Tom and I have changed to the top pipes as did Subaru this then lets the coolant around faster (more flow per minute) as in my example now the cavitation happens at a lower revs.
Your suggestion to drill the impeller does fix the problem because it reduces the pumps pumping rate per min which inturn means that the suction has to do less work and is less affected by the restriction. The only problem with this is that in our engine we need evey litre of coolant we can get around the system.

I have one further example. If you sit in a bath and you want the water to mix or circulate so the temp is the same at both ends you pull you hand along and the water follows. It goes around the side of the bath and back to your hand at which time you pull it again. If you to restrict it on the down stream side of your hand a vacum pocket would form. If you were to block the up stream of your had it would not form because it can't get away from your hand (the pump)

Long answer but in short if we decrease the upstream pressure from the pump but don't improve the suction we are more likly to boil our engines because we have taken the two further out of balance

[Dessertrunner]

Ironhydroxide, thank you thank you I am feeling like I am a lone voice in the woods. Feel free to jump in when every.
Tony

[oab_au]

I think that the testing that Tony and Jones have done, has shown that the main problem that has affected Steve and Dan has been found, and rectified. The results are pretty conclusive.

The clue came with Tony’s pressure testing on his own car. The graph that he produced (post #299) showed that the pressure at the thermostat housing, fell as the rpm went up. That showed the possibility, that because of the temp of the water, and the negative pressure, at the thermostat housing, the coolant could boil.

As John (SVX Commuter) says, and I respect that John has been with pumps long enough to have found all the problems. The boiling starts to build steam or vapour at the centre of the impeller, to implead the flow. This then reduces the flow of coolant through the engine. The engine starts to heat up, and the coolant entering the pump, increases in temperature, so it will boil earlier at the same negative pressure. This is a compounding effect, the more vapour entering the pump, will further reduce the flow through the engine to the result, of the coolant in the block boiling.

The vapour is the result of temp and pressure, and does not leave the pump.. As the vapour rises up the impeller vanes, the pressure increases and the vapour condenses back to water. The pressure in the engine block will remain high, even though the flow is reducing.

The testing that Tony has done with the test rig has shown that when the inlet to the pump is increased, the negative pressure at the pump is reduced, and Steve has proven the theory with an excellent result in the buggy. This is the best testing we could have wished for. Racing in very high temps, and sustained high rpms, the only difference to Dan’s car (besides the car) was a different radiator.

With what we have learned, if Tom uses the modified thermostat housing, Dan will have the same results as Steve. The modified top pipes should be retained to ensure, that with the increased flow that the thermostat mod will allow, there will be even flow through the two sides.


Harvey.

[Dessertrunner]

Well put Harvey. Have a great day.
Tony