SVX Engine cooling "Again & Again"

[Cam]

I understand that the head gasket could negate the effects of the fans, which is why I included that important little bit of information. The comment was more meant to show that it is possible to wire a switch in place. It does not have negative effects on the ECU, as far as I can tell.

This could be beneficial to all the racers out there that wish to have better control of their cooling set-ups. However, I expect most "racers" to have a decent understanding of their cars, and to make a mod like this seem ridiculously easy.

As for the problem at hand (cooling) I am absolutely not an expert. My coolant was contaminated (oil) and was boiling out and making the car run terribly. One interesting thing about my switch is it "back-charged" my system, and unstuck a relay (FAN RELAY). The relay is the reason I put the switch in to begin with. Ended up saving me 40 bucks for the damn thing. Good luck to everyone with their cooling issues. Try to get along.

Cam

[Trevor]

Originally Posted by svxistentialist

Diverse, diffuse, chaotic and difficult to decipher as this thread may be, it is still too valuable to the community to allow it to slide into petty interpersonal bickering.

Please observe the rules and keep on the technical topic, and away from personal rancour.

Thanks.

Joe

The facts:-

Shotgunslade placed himself in an embarrassing situation and made me his scapegoat.

He requested assistance with a problem whereby his radiator boiled after stopping from a run at high speed. A run at reduced speed before stopping prevented the problem. I made a continuing efforts to assist.

It was patently obvious, that a lack of airflow when stationery was the likely cause. He unwittingly demonstrated, that this simple fact was beyond him. His replies constitute a cover up.

[oab_au]

Originally Posted by Trevor

When this thread runs its course, I will list each fact which I have contributed. I have a very clear understanding developing, in regard to a somewhat unsavoury aspect perhaps not apparent at the moment.

I will save you time, and the readers the hunt. You can read all of your 179 posts here, where the technical information presented, can be searched for.
http://www.subaru-svx.net/forum/sear...earchid=629921

Harvey.

[Trevor]

Originally Posted by oab_au

I will save you time, and the readers the hunt. You can read all of your 179 posts here, where the technical information presented, can be searched for.
http://www.subaru-svx.net/forum/sear...earchid=629921

Harvey.

This is the second time you have posted in this fashion. Once again you waste space in a continuing effort to slander me.

[shotgunslade]

This is the second time you have posted in this fashion. Once again you waste space in a continuing effort to slander me

No slander needed, your demeanor is your own indictment.

The temperature spike commencing on the cool down lap where the car is still doing 70 mph in fourth gear is consistent with Tony's assessment that high rpm's cause cavitation in the pump, resulting in a vapor bind, and boiling inside the block. When the pump re-establishes flow at the lower rpm, very hot water is pushed past the sensor causing the spike. It seems that most of my coolant loss actually happens on the track, rather than in the pits or in pit lane, probably coincident with the loss of fluid flow and coincident boiling due to the vapor bind. The temperature sensor spiking at 70 mph in fourth gear is not consistent with ineffective fan actuation. Inadequate air flow would be characterized by a slow rise in coolant temperature, rather than a sudden spike. The question is, "how much pump modification is necessary to avoid this problem." The other question is, "Did my head gasket leak make the problem worse?" Neither question involves activation sequence for the fan.

This thread has been very instructive in seeking the source of this problem. I particularly want to thank Tony, Harvey and Tom for their thoughts, and their work. Thanks also to Bill, and, in absentia, Jack Laverty for insights and data.

Bill, are you sure your head gasket isn't blowing under high load? Aren't you still running a 4EAT. If, so, 3 AutoX runs with a TCU limited 6400 rpm seem insufficient to cause a boiling event (Except, maybe your fans aren't running. Hear tell that can cause all sorts of problems.)

[Trevor]

Originally Posted by shotgunslade

No slander needed, your demeanor is your own indictment.

If so, why did Harvey deliver slander? You have emphasised his stupidity.

[dynomatt]

I should also add, I don't have the AC condensor in my airflow...just the radiator.

Has anybody looked at the airflow of the fans? I vaguely recall an assessment that they're sufficient. There's no CFM of them quoted in the manual, so unable to compare to aftermarket alternatives.

I know Tony tested speed as one of his tests.

[Trevor]

Originally Posted by dynomatt

I should also add, I don't have the AC condensor in my airflow...just the radiator.

Has anybody looked at the airflow of the fans? I vaguely recall an assessment that they're sufficient. There's no CFM of them quoted in the manual, so unable to compare to aftermarket alternatives.

I know Tony tested speed as one of his tests.

Conclusions so far depend on a single unproven theory. This is a welcome and important point, particularly in respect of the AC condenser. In fact one which I had considered raising, in spite of continued opposition from a certain self indulgent quarter towards all I post.

Airflow and fan performance is certainly a factor to be considered. Furthermore it has been earlier suggested that at speed, the fans and shroud could constitute a hindrance to airflow.

[SVXRide]

Originally Posted by svxistentialist

Diverse, diffuse, chaotic and difficult to decipher as this thread may be, it is still too valuable to the community to allow it to slide into petty interpersonal bickering.

Please observe the rules and keep on the technical topic, and away from personal rancour.

Thanks.

Joe

Joe,
Thank you. Your polite warning will hopefully be fully understood by all involved in this thread.
-Bill

[SVXRide]

Originally Posted by shotgunslade

No slander needed, your demeanor is your own indictment.

The temperature spike commencing on the cool down lap where the car is still doing 70 mph in fourth gear is consistent with Tony's assessment that high rpm's cause cavitation in the pump, resulting in a vapor bind, and boiling inside the block. When the pump re-establishes flow at the lower rpm, very hot water is pushed past the sensor causing the spike. It seems that most of my coolant loss actually happens on the track, rather than in the pits or in pit lane, probably coincident with the loss of fluid flow and coincident boiling due to the vapor bind. The temperature sensor spiking at 70 mph in fourth gear is not consistent with ineffective fan actuation. Inadequate air flow would be characterized by a slow rise in coolant temperature, rather than a sudden spike. The question is, "how much pump modification is necessary to avoid this problem." The other question is, "Did my head gasket leak make the problem worse?" Neither question involves activation sequence for the fan.

This thread has been very instructive in seeking the source of this problem. I particularly want to thank Tony, Harvey and Tom for their thoughts, and their work. Thanks also to Bill, and, in absentia, Jack Laverty for insights and data.

Bill, are you sure your head gasket isn't blowing under high load? Aren't you still running a 4EAT. If, so, 3 AutoX runs with a TCU limited 6400 rpm seem insufficient to cause a boiling event (Except, maybe your fans aren't running. Hear tell that can cause all sorts of problems.)

Dan,
HG "issues" could well be an issue when RacerX experienced it's "burping overflow tank" issues. Yes, the car did have a 4HEAT at that time along with a stock radiator. What I can say for certain is that the car only drenched the driver's side wheel well during autoX events. It never exhibited this behavior at any other time (yes, it has been driven in a spirited manner outside the autoX course). As you know, RacerX is now a very different car - 5 spd and a 100k engine with custom intake and exhaust cams. I'm slowly proceeding with my winter project - PWR radiator, oil cooler, custom "scorpion" intake, wide band AFR gauge, + couple other things, so we'll see how things go this year.
I'm extremely tempted to add a modified crossover pipe (yeah, I have a few extra stock ones lying around) and an inline 'stat to the mix. I'm starting to wonder 1. what just removing the 'stat from the water pump would do, and 2. what removing the 'stat and enlarging the pump inlet to an ID of 40mm might do. I would love to land on a solution that doesn't require hacking up the PWR.
-Bill

[SVXRide]

Originally Posted by Dessertrunner

Bill Yes

Adam does your flow molding program enable calc's to be done when the liquid is in vacum?
Tony

Tony,

A large favor to ask of you, recognizing that you've done so much already on this topic. Could you please run your test stand set up with 1. a stock SVX radiator, stock water pump inlet, and no 'stat installed and 2. a stock SVX radiator, modified water pump inlet, and no 'stat installed? I realize the second configuration might be a little challenging, hose-wise, but I'm hoping the clear tubing you're using will have enough stretch to it to fit over the modified pump inlet (figuring you'll have a piece with a standard ID of 33 mm to fit the radiator's outlet).

Thanks.

-Bill

[Dessertrunner]

Bill can't run Stock SVX radiator as the only one I got is in the wifes car (I want to stay married). Can tell you that the air flow and cooling on a stock SVX radiator is so bad that when I was doing the airflow test on my wifes car it was bad and I over heated the engine just having one fan disconnected.

A test I did do was standard PWR and standard everything else except no thermo in the housing as they are a pain to force open. The whole setup failed badly, system was full of air. When I changed just the pump inlet only and left the radiator standard there was a major improvment hard to give a % to but my guess was 3 times better. When I changes to the the new PWR with 42ID outlet I noticed a further improvment but at 5,000 rpm some air was forming in the system. That is why I wanted to change to centre feed.

I would suggested that you just change the cover to a bigger size 42ID and see how that goes with a top thermostate. Also I think Toms idea of blocking one of the return pipes will help as well.

I hope this will help you decide what next.
Tony

[Trevor]

I make a statement directly in the interests those affected, regardless of how this may affect my popularity. Hate my guts, I don’t give a damn.

I am not concerned in respect of those who find clear adult language or simple facts beyond them. Like whys, that a clique exists and protects Harvey against logical argument.

As I have previously explained, the theory presented by Harvey involving boiling of the coolant at the pump inlet, is wrong. If cavitation/slip is occurring, this will not be due to this farcical and improbable theory, which is confined to localised boiling, due to a drop in coolant pressure.

An explanation in this regard, can be presented on the basis of figures relative to the output curve for a typical centrifugal pump. However in this instance, current posts indicate that simple everyday principals and terms are preferable.

The exact problem covered by this thread, directly relates to engine RPM and therefore pump RPM, exceeding a certain speed. The speed is that which the engine manufactures will have had in mind when designing the cooling system. In other words, optimum cooling pump speed is being exceeded.

It is significant that at this optimum point, engine power will be on the increase, as will heat output and the need for increased cooling.

The resistance within the cooling circuit has a throttling effect, which restricts coolant flow in the same way as a faucet/tap can restrict the flow from a pressurised water supply. However the resistance is fixed and is not variable.

The pump exerts pressure against a fixed resistance. As pump speed increases and flow increases, a certain a point will be reached, when due to a fixed restriction/resistance/head, the impeller can no longer increase the flow. The impeller will then ‘slip’ through the coolant rather than move it. The pump will stall or cavitate and there will be no further increase in the rate of flow. The pump is operating beyond its designed parameters.

Many will understand that the propellor fitted to a particular outboard motor has a certain size and pitch, so that the motor can reach maximum RPM and provide maximum boat speed. The operation of a centrifugal pump is not exactly the same as a marine propellor, but the same situation applies.

If the motor is fitted to a boat which is too large, or presents too much resistance for that particular motor when running at full power and RPM, the propeller can stall or cavitate, that is slip/skid through the water, rather than increase the speed of the boat. If the motor is tuned for racing and engine speed and propellor speed is increased, a different propellor must be fitted in order to prevent this problem.

When running in excess of optimum RPM the SVX cooling pump is likely to cavitate/stall, but not as a result of an illogical issue involving localised boiling. There is no indication that the extreme and improbable situation as described Harvey, is occurring or is in any way involved in the problem covered by this thread.

(N.B. The issue involved within this post, has nothing to do with, or in any way relates to, my earlier suggestion regarding the possible modification of the pump impeller.)

[Dessertrunner]

Trevor,
You got it wrong again, if a pressure restriction causes a pump to "Slip" as you called it due to the fact that the upstream pressure is to much. Caviation WON"T happen it only occurs when the pressure upstream is decreased.
You also totaly ignored the suction on a pump, according to you we could feed a SVX pump through a drinking straw which we all know would be stupid.
Tony

[svxistentialist]

I like the sound of this theory Trevor and I have a couple of questions, direct questions.

You are as I see it directly challenging Harvey's hypothesis that when the pump impellor has no fluid returning, or not returning quick enough, a negative pressure is caused locally. This negative pressure can/could possibly reduce the pressure[locally] of the coolant round the pump area to a level where localised boiling occurs.

This boiling could create gas and have the pump impellor spinning in air and introduce gas into the coolant. In theory.

1) Does your theory above hold that there is no local boiling because the reduced pressures don't get to a low enough figure?

2) Are you maintaining that the impellor is spinning in coolant/fluid, but unable to push sufficient fluid through the system because of resistance?

3) If yes to above, could this churning of the fluid introduce gas into the system even though you maintain boiling is not happening?

4) If your theory pivots on there being no boiling near the pump, how would you go about proving that? Measuring it in what way?

Joe