11:1 CR Race/Street Engine build

[subbieatnz]

Originally Posted by TomsSVX

As I have tried to explain before many times and so have others, the overheating is not due to an insufficient radiator. When the needle is in the red, the coolant comming out of the radiator is still at ideal temp. It is a restriction/stagnation in the engine's cooling system. That is why I will be keeping the stock flow path and merely adding new ports to the cylinder heads for aux cold water inputs to keep the water from boiling and causing the spikes in water temp.

Tom

So when can we see some pics of this engine build

[Dessertrunner]

Tom
If you remember I have temp guages on the out put of the engine and on the water returning to the engine from the radiator. Under high revs/high loads the radiator water is only 5 C under the inlet temp. On a hot day the system melts down. I have raced the car, driven in the dessert on 40c days and I can assure you the current radiator won't cool the engine due to the low flow rate. I have been monitoring the temps for 150,000. I do agree with your suggestion to improve flow and add more water as you have talked about. It also seems that if you are going to race the car the AC evaporator infront of the radiator has to go to improve airflow.
We need to solve the problem so we all don't waste the money we spend on rebuilds.
Tony

[shotgunslade]

We need to think about this issue in terms of the fluid mechanics of the system. We essentially have a heat source (the engine) and a heat sink (the radiator) connected by a variable flow fluid link. Flow through this link will vary with engine speed. The water pump is a centrifugal pump and its output varies with engine speed. So, the faster the engine goes, the more heat it generates and the more water flows through the system. The bulk temperature differential across the engine likely will increase with engine speed , because the increase in water flow doesn't keep up with the increase in heat generation as the engine speeds up.

The radiator on the other hand, is a different animal. The amount of heat it can reject is a primarily a function of 3 variables: heat transfer surface area between coolant tubes and the airflow, airflow through the radiator and the average tremperature differential between the incoming air and the incoming water. As the flow rate of the water increases, assuming that the airflow rate stays constant and the incoming air temperature stays the same, the temperature differential between the incoming water and the leaving water will drop. That is because the heat rejection from the radiator remains relatively constant and the mass flow rate of coolant water increases. Ergo, the temperature drop of the water through the radiator is less. Just as much heat was rejected, but it was rejected by a greater mass of water.

So what does this have to do with our discussion. Just this: The statement that the water isn't staying in the radiator long enough to lose heat is nonsensical. Heat rejection from the radiator is not influenced much at all by the water flow rate through the heat exchanger, it is much more influenced by the air flow rate. Lowering the water flow rate will increase the average temperature of the radiator surface, because the leaving temperature will rise, but this is not a big effect. Lets look at some numbers.


Flow rate = X. Incoming radiator water temperature 90 Deg C - Leaving water temperature 100 DegC. Air temperature 40 DegC. Average temperature differential 55 DegC.

Flow Rate = 2X Incoming radiator water temperature 90 DegC - Leaving water temperature 95 DegC (twice the flow rate, same heat gain across the engine- half the temperature rise) Air temperature 40 DegC. Average temperature differential 52.5 F DegC.

Not that different.

The analysis to determine radiator size has to look at the heat generated by the engine at full output and look at the heat loss through the radiator to the incoming air at approximately 95 DegC average coolant temperature. Coolant temperature rise across the engine can then be calculated based upon the coolant mass flow rate, engine heat generation and the specific heat of the coolant.

The most important characteristic of the radiator is the area of heat transfer surface between air and water. What big radiators give you is more heat transfer surface. It isn't about water velocity through the radiator tubes. If anything, slower water velocity through the tubes inhibits heat transfer, as the laminar boundary layer at the tube wall will be thicker, and thus heat transfer between the bulk of the coolant and the radiator tube wall will be inhibited.

Short answer is: If your radiator is correctly sized (area of heat transfer surface between water tubes and air flow) to reject the heat that your engine is generating at peak output given a design incoming air temperature, you cannot pump too much water through the engine. Assuming that local flow conditions do not cause cavitation, flowing more water is always better.

[SomethingElse]

Are you going to run an oil cooler? If so where are you going to tap into? possibly an oil filter adapter type?

[SilverSpear]

You need a different front bumper, something "more" open for better cooling. Look at my front bumper and try to imagine the potentials behind it... I can imagine right now two small motorcycle rads for example mounted inline (behind the projectors area) along with an electric pump, a switch button...

[shotgunslade]

Yes, an oil cooler

[Dessertrunner]

I agree with what is being said that you can't have enough coolent flow rate, the more you can get the better. The SVX engine has half of the B6 flow rate and also it has 2 return pipe to the radiator as opposed to our 1. The return pipe issue supports Tom arguement about a restriction.
It takes time for coolent to lose heat, it doesn't happen instanently. If you can't increase flow then the only way to improve cooling is to increase time in the radiator so the return temps come down lower.
In answer to the other question asked the guy is using a standard engine except for extractor, Motec ECU which he has set for sequential firing. He is getting 180whp. Claims the sequential firing gave him 6whp more. There are 2 SVX engine on drag strips over here with twin turbo's and one has had a special steel crank made for it. My guess he is the only guy in the world with an SVX engine with a steel crank.
Will let you know what happen with the cooling.

[SilverSpear]

Originally Posted by Dessertrunner

I agree with what is being said that you can't have enough coolent flow rate, the more you can get the better. The SVX engine has half of the B6 flow rate and also it has 2 return pipe to the radiator as opposed to our 1. The return pipe issue supports Tom arguement about a restriction.
It takes time for coolent to lose heat, it doesn't happen instanently. If you can't increase flow then the only way to improve cooling is to increase time in the radiator so the return temps come down lower.
In answer to the other question asked the guy is using a standard engine except for extractor, Motec ECU which he has set for sequential firing. He is getting 180whp. Claims the sequential firing gave him 6whp more. There are 2 SVX engine on drag strips over here with twin turbo's and one has had a special steel crank made for it. My guess he is the only guy in the world with an SVX engine with a steel crank.
Will let you know what happen with the cooling.

Hmm.. Can you ask around for more info concerning that steel crankshaft?

[Dessertrunner]

Okay will see if I can find out details for you. What info do you need?

[SilverSpear]

Originally Posted by Dessertrunner

Okay will see if I can find out details for you. What info do you need?

Well Tony, this is not info just for me, but for the entire community over here. The more we know who manufactures what for these cars, the more it can help source for future projects (once seemed almost impossible to achieve).

I think what interests people is who manufactures that crank and under what specs...

Thanks in advance..

[TomsSVX]

Originally Posted by Dessertrunner

I agree with what is being said that you can't have enough coolent flow rate, the more you can get the better. The SVX engine has half of the B6 flow rate and also it has 2 return pipe to the radiator as opposed to our 1. The return pipe issue supports Tom arguement about a restriction.
It takes time for coolent to lose heat, it doesn't happen instanently. If you can't increase flow then the only way to improve cooling is to increase time in the radiator so the return temps come down lower.
In answer to the other question asked the guy is using a standard engine except for extractor, Motec ECU which he has set for sequential firing. He is getting 180whp. Claims the sequential firing gave him 6whp more. There are 2 SVX engine on drag strips over here with twin turbo's and one has had a special steel crank made for it. My guess he is the only guy in the world with an SVX engine with a steel crank.
Will let you know what happen with the cooling.

Tony, the PWR radiator is sized very well for a modified EG33 yet it cannot break the heat of a stock engine? I don't think the issue is with radiator capacity but how the fluid is moved.

When I talk about increasing flow, I do not mention increasing velocity for a reason. I will be working with Shotgunslade on the new engine with water pump flow rates and our sucess/failure rates at different flow rates but when I talk about flow now it is the flow withing the block. After sitting down with an open block and heads in front of me it came pretty quickly that there are a couple spots in the cooling system that have the chance to allow water to sit and stagnate. I believe it is within these sections of the engine that the water is allowed to boil. This will drop the overall system pressure allowing the water to vaporize and cause the entire system to become less efficient due to the lack of suitable pressurized water.

So more or less it is all about finding the root cause rather than trying to find bandaid after bandaid. The work done by RallyBob and Jack on their EG33 has already been a huge help and knocked a couple plausible items off the list. Right now the X-over from block half to block half is going to be looked at along with the stagnation issue that I believe is the major contributor of the issue.

This issue we see now may/may not be the entire reason the engine was tuned down from the factory. They may have had it worked for a lot more top end power but ran out of time/money to fix the problems with the block/cylinder heads. Hence the low redline and beefier low end torque curve. After that they just used a low final drive rate to level everything out and get it on the market. We have found the engine can run for days within the stock confines at 5500 rpm without overheating or giving any signs of issues but beyond that we start running into problems and maybe Subaru did the same thing and took the easy way out of making everything else work for the engine under those conditions... It is simply an idea and I am more than likely days off on this but still plausible

Tom

[Dessertrunner]

Okay got the guys phone number with the steel crank, word is he sells them. Also forgot to mention that the guy with the buggy is having trouble with the cam angle sensor on the cam pulley giving a bad signal at 6K, it stopped the buggy getting maxium power.
On cooling we need to all get our heads together to sort this out so I am interested to see how you go Tom.
Tony

[TomsSVX]

Originally Posted by Dessertrunner

Okay got the guys phone number with the steel crank, word is he sells them. Also forgot to mention that the guy with the buggy is having trouble with the cam angle sensor on the cam pulley giving a bad signal at 6K, it stopped the buggy getting maxium power.
On cooling we need to all get our heads together to sort this out so I am interested to see how you go Tom.
Tony

Good thing I can use the Cam angle sensor out of whatever car I want with the Hydra. But it is likely that the wiring on that engine may have had it and the shielding has gone. Or the wire is broken and has some high resistance which cannot carry a tune at 6k+rpm as the EG33RS and other EG33's turning high RPMs have not had contamination issues with CAS signals

Tom

[Dessertrunner]

Tom he felt the problem was from heat as his extractors were about 3" away. When the engine was cold it reved out when it got hot it broke up.

[TomsSVX]

Could be. but all things considered, if the wiring was good it should not be effected like that. if it is, its about time he shielded things from that kind of heat

Tom