FL5 Overheated on Track

[Vito.FL5]

Unfortunatelly, this thread has 28 pages and I don´t think we are going anywhere.

It’s been over 2 years since the FL5 came out and people are still ignoring the real problem.
What’s the point of doing a 3-pass radiator, if all it does is make the system worse?

You guys still don’t get how a cooling system works. I’m not an expert, but just stop for a moment and look at the engine bay.

OK, now that you did that, let’s recap what happens:

Water flows out of the head and splits into:

1. Radiator
2. Cabin Heater
3. Transmission Cooler
4. Turbocharger
5. Throttle Body
6. Coolant Reservoir
7. Engine Oil Cooler (this one goes a slightly different route but whatever)

All these are parallel circuits. The coolant chooses the path of least resistance. Only one of them — the radiator — actually removes heat. The rest just dump more heat into the coolant (Or at best, it does nothing — just bypasses the radiator, which is still a bad outcome.)

Now let’s look at the stock radiator: water enters from the top and exits from the bottom. That means all the tubes are available at once, minimal restriction, maximum flow. Fast flow means better “scrubbing action” inside the tubes, which improves heat transfer.

Now let’s say you go and cut the radiator into 3 parts and run them in series.

What happens?

You just tripled the restriction.
Coolant slows down.
Flow gets redirected to all the other paths (heater, turbo, etc.) because they’re now less restrictive than the radiator.

So now less coolant flows through the radiator, and more goes through circuits that add heat (or do nothing)
Sounds like a bad idea yet?

And yeah, maybe your ECT2 sensor reads 20°F cooler now. But that doesn’t mean you’re rejecting more heat. It means water is moving slower, heating up more inside the engine, and cooling down more inside the radiator — but the total heat transfer hasn’t improved, actually, slower flow reduces the radiator’s effectiveness.

There is an old article from NARSA, that shows how a given engine, producing a given amount of heat, and moving coolant at a given speed, will always show the SAME temperature drop between the radiator INLET and OUTLET, regardless of the size, design or efficiency of the radiator. The only thing that changes, is the AVERAGE core temperature. So if you see a big difference between ECT1 and ECT2 (and you believe you are subject to the laws of physics) the only option is that either the amount of heat produced by the engine, or the coolant flow dropped.

Now Instead of messing with how many times water passes through the same core, focus on the actual bottlenecks:

Improve airflow (fan, shroud, ducting)
Increase coolant flow rate trough the radiator (remove unnecessary parallel circuits is one option here, but there are others)
Optimize the radiator face area and core design (louvered fins, proper row count, etc.)

I didn´t get into the stupid headifold issue because this is something we can´t change yet, so I´m focusing in the cooling system here.

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[siwelnosaj]

Unfortunatelly, this thread has 28 pages and I don´t think we are going anywhere.

It’s been over 2 years since the FL5 came out and people are still ignoring the real problem.
What’s the point of doing a 3-pass radiator, if all it does is make the system worse?

You guys still don’t get how a cooling system works. I’m not an expert, but just stop for a moment and look at the engine bay.

OK, now that you did that, let’s recap what happens:

Water flows out of the head and splits into:

1. Radiator
2. Cabin Heater
3. Transmission Cooler
4. Turbocharger
5. Throttle Body
6. Coolant Reservoir
7. Engine Oil Cooler (this one goes a slightly different route but whatever)

All these are parallel circuits. The coolant chooses the path of least resistance. Only one of them — the radiator — actually removes heat. The rest just dump more heat into the coolant (Or at best, it does nothing — just bypasses the radiator, which is still a bad outcome.)

Now let’s look at the stock radiator: water enters from the top and exits from the bottom. That means all the tubes are available at once, minimal restriction, maximum flow. Fast flow means better “scrubbing action” inside the tubes, which improves heat transfer.

Now let’s say you go and cut the radiator into 3 parts and run them in series.

What happens?

You just tripled the restriction.
Coolant slows down.
Flow gets redirected to all the other paths (heater, turbo, etc.) because they’re now less restrictive than the radiator.

So now less coolant flows through the radiator, and more goes through circuits that add heat (or do nothing)
Sounds like a bad idea yet?

And yeah, maybe your ECT2 sensor reads 20°F cooler now. But that doesn’t mean you’re rejecting more heat. It means water is moving slower, heating up more inside the engine, and cooling down more inside the radiator — but the total heat transfer hasn’t improved, actually, slower flow reduces the radiator’s effectiveness.

There is an old article from NARSA, that shows how a given engine, producing a given amount of heat, and moving coolant at a given speed, will always show the SAME temperature drop between the radiator INLET and OUTLET, regardless of the size, design or efficiency of the radiator. The only thing that changes, is the AVERAGE core temperature. So if you see a big difference between ECT1 and ECT2 (and you believe you are subject to the laws of physics) the only option is that either the amount of heat produced by the engine, or the coolant flow dropped.

Now Instead of messing with how many times water passes through the same core, focus on the actual bottlenecks:

Improve airflow (fan, shroud, ducting)
Increase coolant flow rate trough the radiator (remove unnecessary parallel circuits is one option here, but there are others)
Optimize the radiator face area and core design (louvered fins, proper row count, etc.)

I didn´t get into the stupid headifold issue because this is something we can´t change yet, so I´m focusing in the cooling system here.

I respectfully disagree. I have had great results and so too have my customers.

I tracked the car successfully in 100° ambient temps. I have real results showing that my products are in fact working. Don't just take my word for it either, I have customers who have started using and testing and are having similar great results.

Multi pass radiators are not a new concept, they are just new to the FL5. Previously on my FK8 I ran a secondary unit that was a dual pass unit. I had great results with this set up over the course of years and a number of track events. I don't put much stock into ect2 temps; I care about ect1 temps first and foremost.

We have seen dramatic improvements, I can run in temps that others can not.

I agree that the parallel systems are an issue, but that's why I also have my dual oil cooler kit and the transmission cooler as a part of the whole cooling ecosystem. Also the cooling plate to help improve efficiency of the main radiator.

When PWR engineers ran the numbers they determined that the triple pass system has approximately 25% greater heat rejection compared to their single pass radiator which had been the gold standard to that point.

So again I respectfully disagree, we have made great progress and I would argue have solved the problem at this point.

 

[siwelnosaj]

I respectfully disagree. I have had great results and so too have my customers.

I tracked the car successfully in 100° ambient temps. I have real results showing that my products are in fact working. Don't just take my word for it either, I have customers who have started using and testing and are having similar great results.

Multi pass radiators are not a new concept, they are just new to the FL5. Previously on my FK8 I ran a secondary unit that was a dual pass unit. I had great results with this set up over the course of years and a number of track events. I don't put much stock into ect2 temps; I care about ect1 temps first and foremost.

We have seen dramatic improvements, I can run in temps that others can not.

I agree that the parallel systems are an issue, but that's why I also have my dual oil cooler kit and the transmission cooler as a part of the whole cooling ecosystem. Also the cooling plate to help improve efficiency of the main radiator.

When PWR engineers ran the numbers they determined that the triple pass system has approximately 25% greater heat rejection compared to their single pass radiator which had been the gold standard to that point.

So again I respectfully disagree, we have made great progress and I would argue have solved the problem at this point.

I would add that PWR does have quite the pedigree when it comes to cooling and they also believe in the direction we are going. Honda racing also is on board as they have gotten a unit to test and plan to get more pending their test results.

 

[HPT Cools]

Unfortunatelly, this thread has 28 pages and I don´t think we are going anywhere.

It’s been over 2 years since the FL5 came out and people are still ignoring the real problem.
What’s the point of doing a 3-pass radiator, if all it does is make the system worse?

You guys still don’t get how a cooling system works. I’m not an expert, but just stop for a moment and look at the engine bay.

OK, now that you did that, let’s recap what happens:

Water flows out of the head and splits into:

1. Radiator
2. Cabin Heater
3. Transmission Cooler
4. Turbocharger
5. Throttle Body
6. Coolant Reservoir
7. Engine Oil Cooler (this one goes a slightly different route but whatever)

All these are parallel circuits. The coolant chooses the path of least resistance. Only one of them — the radiator — actually removes heat. The rest just dump more heat into the coolant (Or at best, it does nothing — just bypasses the radiator, which is still a bad outcome.)

Now let’s look at the stock radiator: water enters from the top and exits from the bottom. That means all the tubes are available at once, minimal restriction, maximum flow. Fast flow means better “scrubbing action” inside the tubes, which improves heat transfer.

Now let’s say you go and cut the radiator into 3 parts and run them in series.

What happens?

You just tripled the restriction.
Coolant slows down.
Flow gets redirected to all the other paths (heater, turbo, etc.) because they’re now less restrictive than the radiator.

So now less coolant flows through the radiator, and more goes through circuits that add heat (or do nothing)
Sounds like a bad idea yet?

And yeah, maybe your ECT2 sensor reads 20°F cooler now. But that doesn’t mean you’re rejecting more heat. It means water is moving slower, heating up more inside the engine, and cooling down more inside the radiator — but the total heat transfer hasn’t improved, actually, slower flow reduces the radiator’s effectiveness.

There is an old article from NARSA, that shows how a given engine, producing a given amount of heat, and moving coolant at a given speed, will always show the SAME temperature drop between the radiator INLET and OUTLET, regardless of the size, design or efficiency of the radiator. The only thing that changes, is the AVERAGE core temperature. So if you see a big difference between ECT1 and ECT2 (and you believe you are subject to the laws of physics) the only option is that either the amount of heat produced by the engine, or the coolant flow dropped.

Now Instead of messing with how many times water passes through the same core, focus on the actual bottlenecks:

Improve airflow (fan, shroud, ducting)
Increase coolant flow rate trough the radiator (remove unnecessary parallel circuits is one option here, but there are others)
Optimize the radiator face area and core design (louvered fins, proper row count, etc.)

I didn´t get into the stupid headifold issue because this is something we can´t change yet, so I´m focusing in the cooling system here.

The key point is: "The coolant will choose the path of least resistance." In the single-pass flow channel structure, the coolant almost only flows in this area, and the heat exchange time is very short.

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