SVX Engine cooling "Again & Again" - Page 79

Dessertrunner · #**1171** 08-19-2010, 12:18 AM

As regards the temp guages on the car these are the things that I beleive they tell me. Feel free to ask questions or put an alternative idea. This is base with out a thermostate.

A early test with thermstate showed that as revs went up the engine overheated on all temp guages even though the load (speed) was the same. This was found to be caused by a lack of coolant flow due to the pump losing prime. Removial of the thermostate and larger suction pipe fixed this issue on a road car.

If the radiator return coolant temp is low 70c but the head temps are right up I assume that the amount of coolant flowing throught the head is not enough. This can be checked by increasing revs and see if head temps drop.

If return coolant and head temps become simlar I would assume that the radiator is failing to do it job and needs further development. This has also occured when my radiator got blocked up with grass (driving around the farm) which reduced air flow.

So there it is this post deals strictly with what we learn from the temp guages on my engine. Also it provides postive feed back as to changes made as a result of the learning on the test bench.

Have a great day.
Tony

TomsSVX · #**1172** 08-19-2010, 04:59 AM

Let us know what you find Tony

Tom

TomsSVX · #**1173** 08-26-2010, 05:13 PM

I know this is a little late in the discussion but what the hell....

I think it would be good practice for anyone looking to worry about this cooling issue should have their first step to be replacing the head gaskets.... With the common failures nowadays, if they are not bad yet, they soon will be anyway... Get it done and then you can be sure it is not the issue

Tom

NeedForSpeed · #**1174** 08-26-2010, 05:41 PM

Quote:

Originally Posted by SilverSpear

Cool, you have winter in August over there?

They celebrate Christmas on the beach

Sorry for the slight hijack, couldn't resist

svxfiles · #**1175** 08-26-2010, 07:58 PM

Quote:

Originally Posted by NeedForSpeed

They celebrate Christmas on the beach

Sorry for the slight hijack, couldn't resist

Hot snow falls up!

cdigerlando · #**1176** 08-27-2010, 08:44 AM

I'm tuning in very late to this Thread, and have not read everything so I appologize in advance if anything that I cover has already been covered. I agree with Tom that Head gasket issues should be eliminated first. I'm sure you have done this. I'm also assuming you are running the aftermarket oversized radiator. Are you running water only? This may be a big issue for us. I have a buddy with a 600 HP STi who is also having overheating problems. I think a big part of this is vapor locking due to boiling, which is more likely with water than 50/50 coolant/water. While I agree that pure water has greater heat capacity, it does boil easier. I think this is my buddy's problem. I also ran into overheat problems with my SVX when running water only. But I also had a number of other problems including head gasket issue, and so did my buddy with his STi. Perhaps these were exaserbated by the use of water? I don't know for sure. He also had a dropped sleave, but this is sometimes caused by excessive heat, so they may have been feeding each other.

What type of coolant are you running? When you run with no thermostat, are you running nothing or a washer in its place?

This is all of great interest to me since I am planning on tuning a high HP sleaved SVX engine with turbocharger and engine management soon. I do not yet know what RPMs I will be running. I am also running a Air/oil cooler and an oversized radiator. I'm wondering if I should elimnate the thermostat.

Thanks

Chuck

NeedForSpeed · #**1177** 08-27-2010, 08:57 AM

Quote:

Originally Posted by cdigerlando

I'm tuning in very late to this Thread, and have not read everything so I appologize in advance if anything that I cover has already been covered. I agree with Tom that Head gasket issues should be eliminated first. I'm sure you have done this. I'm also assuming you are running the aftermarket oversized radiator. Are you running water only? This may be a big issue for us. I have a buddy with a 600 HP STi who is also having overheating problems. I think a big part of this is vapor locking due to boiling, which is more likely with water than 50/50 coolant/water. While I agree that pure water has greater heat capacity, it does boil easier. I think this is my buddy's problem. I also ran into overheat problems with my SVX when running water only. But I also had a number of other problems including head gasket issue, and so did my buddy with his STi. Perhaps these were exaserbated by the use of water? I don't know for sure. He also had a dropped sleave, but this is sometimes caused by excessive heat, so they may have been feeding each other.

What type of coolant are you running? When you run with no thermostat, are you running nothing or a washer in its place?

This is all of great interest to me since I am planning on tuning a high HP sleaved SVX engine with turbocharger and engine management soon. I do not yet know what RPMs I will be running. I am also running a Air/oil cooler and an oversized radiator. I'm wondering if I should elimnate the thermostat.

Thanks

Chuck

Chuck,

If this is all of great interest to you, you would do well to read the entire thread

,

especially before posting in this particular thread. You will be impressed with the research and development in this thread, IMO, one of the best and certainly most significant threads ever

Catch up fast.

cdigerlando · #**1178** 08-27-2010, 10:49 AM

Quote:

Originally Posted by NeedForSpeed

Chuck,

If this is all of great interest to you, you would do well to read the entire thread

,

especially before posting in this particular thread. You will be impressed with the research and development in this thread, IMO, one of the best and certainly most significant threads ever

Catch up fast.

Yes, I'm familiar with the forum and know that the discussions can be labored. I was very interested in some sort of summary conclusion, which I think I got in Desertrunner's last post, but I just wasn't sure regarding the radiator he is running or the condition or or when his head gaskets were replaced.

Dessertrunner · #**1179** 08-27-2010, 05:48 PM

Hi Chuck,
I would love to work with your mate with the STI as I feel confident that I can get it to cool.

As regards head gaskets I need to speak up and make the following point,
If you have a standard car and it suddenly starts to overhead and you haven't run it at high revs then most likly the head gasket is blown.
If you have decided to move the operational power and or revs up your head gasket will blow from lack of cooling and will go again.

The points you make about type of coolant and having a larger radiator are factors but will never fix the problem they only move the point at which the system will fail.

The main problem is that the pump loses prime and then the cooling system fails. During this process the coolant becomes airrated and the heat transer rates are shot. As Harvey pointed out at the start of this project when that happens the coolant boils at the inlet of the pump and its all over for your engine.

As I mentioned chuck I would kill to be able to help you mate with his cooling issue. I feel sure we have it beat provided people do the changes that need to be done.
Tony

Dessertrunner · #**1180** 08-28-2010, 05:54 AM

I have been trying to find time to post a bit of info to help people understand what we are trying to acheive in cooling our engines.

If the cooling system pumps coolant without any problems the pump can move the heat.
During the trial on my road car on a hot day at 3,000 rpm the return coolant from the radiator was at 80 C out of the engine at 100 C. We know that the engine is pumping 100 l per minute. So the amount of heat being removed is 20 by 100 by 3.9 btu (for evey 1litre at 1 C change). So in simple terms 7,800 Btu of heat was being removed per minute.
What we did then was move the revs up which resulted in the return coolant temp going up not down. Hope you are still with me at this point. If we consider this what happened? At 6,000 rpm the pump moves 200lpm so in theory the cooling system should have handled 15,600btu but in fact it handle less heat.

We should of realized straight away that the pump was losing capicity. If you follow me a bit further at revs of 8,000rpm the pump will do 266lpm if the return temp is 20c below discharge then its possiable to move 21,000 btu of heat.
As you can see the maths proves the point that the pump was losing prime.

Sorry for going on but I felt its worth understanding the maths behind the cooling.
Have a great day all.
Tony

Boxersix · #**1181** 08-29-2010, 05:08 PM

Tony, I'm not a BTU calculation whiz here myself so..can you double check my calcs on this

BTU required to boil one liter of water(~918grams) from a temp of 20c

I calculated it at about 226Kj per 100grams.

~1968740 BTU????

I'm just turning gears in my heads that's all

Dessertrunner · #**1182** 08-29-2010, 06:13 PM

Adam,
Do I understand you correct to say from 20C to boiling point. If so you need to keep in mind that to boil water at 100c liquid to 100c steam consumes a major amount of energy to change its state.
For example (sorry to change units) my factory freezes product and to move one tonne of water 1C uses 0.87 kw's of refrigiation but to move it from 0c liquid to 0c solid uses 67.63 Kw's.

With out doing the calc's my guess is your number is correct due to the boiling stage.
Tony

Boxersix · #**1183** 08-29-2010, 06:36 PM

Yeah I was factoring in for LH of vaporization too in that calc.

I'm just a curious cat at the moment and am interested in knowing how much heat energy one liter of water can pull from the engine before coming to a boil.

I'm really good with flow and loss coefficients, not so much with thermal dynamics.

Dessertrunner · #**1184** 08-29-2010, 07:55 PM

Best done in BTU, change 1 litre 1C (not boiling) needs 3.96 btu of energy.
I may not have been clear before but the point I am making is that cutting pump flow as was suggested won't transfer enough energy from the engine unless the radiator work really we like Steve's.

Adam what I want guys to understand is that cooling a engine is a big issue not fixed by one mod with out understanding the other effects.
Tony

teksvx · #**1185** 09-04-2010, 11:40 AM

Quote:

Originally Posted by Dessertrunner

We should of realized straight away that the pump was losing capicity. If you follow me a bit further at revs of 8,000rpm the pump will do 266lpm if the return temp is 20c below discharge then its possiable to move 21,000 btu of heat.

Have a great day all.
Tony

there is a part of the issus... it s the engine block thats restric the coolant flow. no meaning about how BIG is your water pump and hose. i wanna know the pressure at the outlet of the water pump and coolant return of the engine block. if you have more than 8 psi of differential pressure,your block causing restriction of coolant flow and causing "cavitation" ( bubble of vapor in coolant). That cavitation (bubble) also create an another issus, when this bubble explode they creating a shockwave that hurt all the coponent around creating pitting on metal and destroying engine head gasket material who aren t stiff enough