Engine Cooling

[Hardingfv32]

This is a thread expanding on some of the things recently discussed in the Cylinder Head Temp thread.

My research indicates that the fin design of the stock VW engine is probably limited to the amount of heat rejection it can provide. Some kind of high pressure forced air blower is going to be required to get the cooling efficiency required for a 62 HP race engine... without also using an overly rich A/F mixture.

What I am getting at is that you can produce more HP using the ideal A/F ratio for max power. I am not sure you can accomplish this with the current fin design, certainly not without a significant increase in aero drag. A highly efficient oil cooling system is your only option to increase engine cooling.

Brian

[Daryl DeArman]

This is a thread expanding on some of the things recently discussed in the Cylinder Head Temp thread.

My research indicates that the fin design of the stock VW engine is probably limited to the amount of heat rejection it can provide. Some kind of high pressure forced air blower is going to be required to get the cooling efficiency required for a 62 HP race engine... without also using an overly rich A/F mixture.

What I am getting at is that you can produce more HP using the ideal A/F ratio for max power. I am not sure you can accomplish this with the current fin design, certainly not without a significant increase in aero drag. A highly efficient oil cooling system is your only option to increase engine cooling.

Brian

You have time and perhaps the desire. Why not fabricate some air scoops and tin that also act as heat sinks and give those a try?

Fabricate a test bench with old barrels and a head, an electric heat source that you can regulate and some CPU fans to supply air. Just measure temp change over time at given air speed and see what gains can be had without increasing and perhaps decreasing cross section/inlet size of scoops.

The class and the engine's been around for 45+ years without the use of the stock cooling fans, surely somebody experimented with heat sink type scoop/extractors at some point.

[S Lathrop]

As I mentioned on the previous discussion about cylinder head temperatures, I did have a cooling system on a Citation 84 FV that we removed the oil cooler because we could not get what we felt was proper oil temperatures with a stock VW oil cooler, too cold. The trick with that system was to use a duct system to extract the air from under the cylinder heads. I designed a FV in 1994 that the rear of the car was designed to maximize engine cooling and especially getting the maximum flow of air from under the cylinder heads.

Back in the air-cooled FSV days I ran exhaust temperature gauges (one for each cylinder). What we found was that getting that number exactly right was very critical. Too lean and we would loose a lot of speed on the long straights and too rich and we would stumble coming off the corners. The correct number was a bit cooler than what was considered optimum for HP but that was probably due to heat buildup in the heads from long time at full throttle. This was really critical on oval tracks where we spent a lot of time at full throttle. The FSVs did allow for jetting each cylinder and I frequently had slightly different jets for each cylinder.

If I was working on a FV today, I would start using EGT gauges and see what I was getting. We did do a fair amount of experimenting with jetting to get the performance we got.

[Hardingfv32]

1)

...surely somebody experimented with heat sink type scoop/extractors at some point.

I am a pretty creative fabricator but I have no idea what this might look like. Please expand.

2) One of my main objectives when designing a car is to stay within the SCCA minimum frontal area specification/illustration, with the exception of the rollbar and helmut placement. This creates some difficult packaging issue relative to the engine. That said I have developed cooling ducts that flow downward into the center of the heads. The inlet open is about 7-8 sq/in located at the driver shoulder height. The duct makes a 90 deg bend (4-5" radious) and expands into a roughly 70-80 sq/in opening on top of the cyl/head. This is my attempt to develop a diffuser that slows the flow and increases the pressure at the fins.

Excessively large inlets do not increase air flow through the fins. They only increase aero drag. It is my opinion that the inlet opening need not be any greater the area between the fins where the air flows. This assumes a well sealed duct system.

Brian

[Daryl DeArman]

1)

I am a pretty creative fabricator but I have no idea what this might look like. Please expand.

In the simplest terms imagine utilizing thin copper sheet to extend engine cooling fins into the cooling air intake. Select a material that conducts heat well that you are comfortable with in terms of fabrication, weight, and costs. Even one large fin that bisects the cooling fin is going to add minimal drag but will increase surface area of fins exposed to air flow substantially. How much heat it can draw out of the cylinder head is likely very dependent on how much surface area of the fin and the heat sink you can have in contact with each other.



If your cooling scoops were the same size and shape they are now, but rather than fiberglass were made of copper and physically touched as much of the cylinder head area as possible when they were mounted to the "tin". That copper would get much warmer than the fiberglass does, and all the air going across the surface of that copper duct would help cool the heads.

[Matt Clark]

thin copper sheet to extend engine cooling fins into the cooling air intake

I had thought about something like this a few years ago, but did not do anything beyond day dreaming.
I was picturing some copper or aluminum sheet metal or extrusion contraption that even used thermal paste (or possibly brazed) like when you seat a cooler on a CPU.
Since most FVs I had seen had scoops that cooled from the top-down, I was thinking maybe either leaving long sheets stick down into the air stream, or how to cool the back cylinders better with some of the cheap copper stick-on heatsinks.

[problemchild]

I generally found that improving on the basic engineering of Dr Porsche and his design team was not productive. Usually, manipulating the racing application to mimmick their original environment proved most effective. In this case, identifying the volume and speed of air required for the mass and area of the head/engine would seem appropriate, which I expect would align with the original VW system.

Since there are only two 6mm tapped bosses (14mm OD) that legally would allow cooling "ductwork" to be attached to, it is hard to believe that bolting heat sinks to these two tiny bosses, even if legal, would be impactful. Stretching the rules ...... you could bolt on custom valve covers that were acting as heat sinks. I know people that believe the bolt-on Empi valve covers lower oil temp. Totally abusing the rules, you could make exhaust gasket/heat sinks that clamped against the head before the exhaust.

Generally speaking, bolting on "heat sinks" would not be legal by our rule book. Neither would liquid cooling or refrigerated cooling or other hi-tech methods. The choices are: Fan shroud or "Forward facing air ducts may be installed for the purpose of delivering cooling air directly to the engine,cylinder heads, oil cooler, and/or carburetor."

From the GCR:
the focus remains the same: to provide a cost effective, highly competitive class that, through consistent and tightly controlled component and preparation rules, emphasizes driver ability rather than technological development of the car.
Formula Vee is a Restricted Class. Therefore, any allowable modifications, changes, or additions are as stated herein. There are no exceptions.
D. Allowed Modifications
9. Complete or partial removal of any cooling duct component. Removal of the fan and the fan housing. Fan belt origin is unrestricted. The use of a fan belt is optional.
18. Valve covers are unrestricted and may be bolted on
7: Body
K. Air ducting may be attached to the carburetor and/or the engine. Brake ducts are not permitted.
L. Forward facing air ducts may be installed for the purpose of delivering cooling air directly to the engine,cylinder heads, oil cooler, and/or carburetor. If these ducts are within the profile area defined in Section C.12, then the ducted air must make a 90 degree bend within the bodywork.
M. Air duct openings may be located within the cockpit area, and/or penetrate the firewall, provided the duct is baffled or the firewall is extended to prevent flame and debris from reaching the driver. Any shape may be used to form firewall extension. Any other firewall inlet shall also prohibit passage of flame and debris.

[Daryl DeArman]

I generally found that improving on the basic engineering of Dr Porsche and his design team was not productive.

. . . and this exercise may also prove to be unproductive. However, I bet Dr. Porsche never expected that ol' 40hp engine to produce 60+ HP at 6800 rpms through a little 28 PCI.

Since there are only two 6mm tapped bosses (14mm OD) that legally would allow cooling "ductwork" to be attached to

Says who? The GCR, specifically says that air ducting may be attached to the engine. Now, I hate the whole "If It Doesn't Say You Can, You Can't" argument because the GCR can't address everything down to allowing nitrogen in the tires, or amount of air pressure allowed. However, when the GCR says you can do something, you bloody well can.

Now, we can argue about how you can attach it, like maybe you can't modify any existing engine parts to allow attachment. What about interference fit like a channel extending over and down the fins, effectively encapsulating the fin(s)?

As to valve covers, they are "unrestricted". Why not make them the heat sinks with large integral fins, bolt-on with a large copper crush washer taking place of the more standard gasket (which is probably a pretty good insulator)?

[problemchild]

A cylinder head has a mass, an area, and a bunch of properties that determine how much heat it can transfer. That cylinder head does not know what year it is, what the application is, or what rpm is being used. Without cheating (introducing exterior heat sinks) you will not change that value. The challenge of the FV racer is to maximize your cooling efficiency, not to "Smokey Yunick" the rules and cheat.

The rule says ". Forward facing air ducts may be installed for the purpose of delivering cooling air directly to the engine,cylinder heads, oil cooler, and/or carburetor". The rule does not say you can bring ducted air to an external heat sink hammered into the fins on the head.

I agree that valve covers that provide extra cooling fit within the rules, and I used ones that I considered better cooling. They are, however, not using ducted air. They are in the direct airstream, and specifically allowed ....... probably because rulemakers were more interested in reliability than the potential for massive cooling gains. There are absolutely weight and aero compromises involved, even with the Empi covers that I used.

Has this class not learned it's lesson? People may hate the "If It Doesn't Say You Can, You Can't" argument but it just happens to be the rule, and the foundation of the class. People need to enjoy racing and stop with this rule-stretching nonsense..

[Daryl DeArman]

A cylinder head has a mass, an area, and a bunch of properties that determine how much heat it can transfer. That cylinder head does not know what year it is, what the application is, or what rpm is being used. Without cheating (introducing exterior heat sinks) you will not change that value. The challenge of the FV racer is to maximize your cooling efficiency, not to "Smokey Yunick" the rules and cheat.

Of course it doesn't know that stuff. What Dr. Porsche and his people knew is what the expected demands were on the cooling system and the conditions it was going to operate within. Very different than what FV folks are dealing with.

Doing something that the rules allow, just because others haven't done it the same way, doesn't make it cheating.

The rule says ". Forward facing air ducts may be installed for the purpose of delivering cooling air directly to the engine,cylinder heads, oil cooler, and/or carburetor". The rule does not say you can bring ducted air to an external heat sink hammered into the fins on the head.

So where does the the forward facing air duct terminate and where does the heat sink begin if the heat sink is integral to the air duct? Remember, the rule specifically allows the duct to be attached to the engine.

Has this class not learned it's lesson? People may hate the "If It Doesn't Say You Can, You Can't" argument but it just happens to be the rule, and the foundation of the class. People need to enjoy racing and stop with this rule-stretching nonsense..

Don't forget about the part that says if you can, then you bloody well can. Even if Greg Rice doesn't like it and believes it is rule-stretching nonsense that's bad for the class?

Where does the rulebook state that you may utilize any gas to pressurize your tires? Where does the book state that air pressure utilized in tires is open? Where does it say that you can run any ride height or alignment settings you wish? Clearly, there are many things that the book doesn't address yet are still understood as allowed. Do we want the book to grow larger and even more complex?