10 replies to this topic

[chr1s]

Whilst going through an old 1979 edition of Motorsport I came across a piece about Formula one radiator design and the following paragraph jumped out at me:-   Patrick Head replaced the oil radiator with an enclosed and sealed heat exchanger in which the oil and water pipes dissipated their heat and distributed the surplus to each other, the water radiator being the controlling element...

 

This is something I'd never heard of before, and if i'm honest, don't really understand!  I wonder if any of the more technically minded on here can elaborate?

[PJGD]

Most cars at that time would have used an oil-to-air heat exchanger or radiator for which an opening in the bodywork would be required to access ram air.  The system being described in the MS article would be an oil-to-water heat exchanger wherein the water will be engine coolant.  This is very common in current cars and trucks today, and clearly the heat can go in either direction depending on the temperature difference between the two fluids while observing the second law of thermodynamics (Flanders & Swan can explain that).  The optimum operating temperature for both coolant and oil are essentially the same so why not use a single radiator and a single temperature controlling thermostat.  This way the oil heats up quickly resulting in low hydrodynamic drag, and temperature control is probably closer than would be obtained with the oil-to-air radiator.  Many companies make liquid-to-liquid heat exchangers.

[Porsche718]

If you think about it, cooling systems have a thermostat that restricts flow into the radiator when required. This keeps the engine at a constant and optimum operating temperature. Engine oil temperature also requires an optimum temp. An oil-to-air oil cooler may vary operating temperatures greatly depending on atmospheric conditions.

 

Having the oil temp effectively controlled by the coolant temp would keep the operating temp more constant. With the specialised oil requirements of Formula 1 engine (even back in 1979) this would greatly increase engine life.

 

I'm sure Cosworth would have given customers the optimum oil temperatures they required the DFV to run at for longest life and best performance.

 

PJGD quote: "The optimum operating temperature for both coolant and oil are essentially the same so why not use a single radiator and a single temperature controlling thermostat."

 

This is generally correct. But I have predominately been involved in open wheeler racing and have often seen cars with "hot zones" and "cool zones" within the engine bay. Effectively keeping lower engine area (crankcase, dry sump and ancillaries) running at a hotter temp then the "cool zone" (head, intakes, coolant pipes etc). 

 

These zones would be in the form of tightly fitting aluminium or carbon fibre panels that would not allow leakage ie: hot air into the cool zone or cool air into the hot zone. 

 

It is a fascinating part of modern race car design.

Edited by Porsche718, 30 January 2023 - 05:25.

[GreenMachine]

Traditionally race cars have oil coolers and separate coolers for the engine coolant.  Combine them, and you will need additional cooling for the engine coolant - you get nothing for nothing.

 

As a user of a heat exchanger in my racing sports car, the biggest single benefit was the ability to transfer engine heat into the oil, bringing the oil up to temperature far more rapidly than simply running the engine and letting the oil build up temperature 'naturally' - especially on a car trailered for 100kms or so in temperatures around 0*c!  Otherwise, for the first event of the day warming up in the paddock, the marshalling area and the warmup lap was insufficient to get to my specified minimum temperature of 80*c, where I could use full revs.  Once there (80c) and the full 8k rpm employed, it quickly reached 125*c which it was able to maintain by transferring the excess heat into the coolant, thence via the radiator, to the atmosphere.

 

The trick is to be aware that for an ICE using a heat exchanger this way increases the demand on the radiator, and then ensuring it has the capacity to handle it.

 

I am not so sure that for a race engine, tuned to within an inch of its life, optimum oil and coolant temperatures are the same - especially a turbo engine.  Engine coolant temperature is quite critical, generally within a narrow band.  Oil temperature is generally more tolerant of a wider temperature band, but within limits.  For my race engine they were 90-105*c coolant, 80-130*c oil.  I'd be interested to know what a DFV wanted for best performance/longevity.  Even more so for a modern Honda or Merc, but while we mere mortals could probably take something from the DFV specs, I doubt the relevance of today's F1 clockworks ...

[chr1s]

Thank you all for your answers, as regards the DFV's operating temperature , the same article mentions that after winning the Austrian Grand prix, Jones said to Head that  "The car was perfect. Oil pressure never wavered and oil and water temperatures sat at 90 degrees C throughout..."

[PJGD]

90°C is about what I would expect in this situation.  If you know the controlled temperature you will be running at, you would normally select the viscosity of the oil to give you the lowest hydrodynamic drag at that temperature while still retaining adequate lubrication rather than selecting an oil on some other basis and then trying to control the temperature to suit it.

[chr1s]

Apologies for bumping my own thread, but I've just read in a later Motorsport magazine that the heat exchanger was dropped in 1980,  as the B spec FW07 had the entire underside of the engine paneled in and as a result the oil and water temperatures were too high, so a conventional oil radiator was used which was mounted in the left hand side pod. 

[petere]

Apologies for bumping my own thread, but I've just read in a later Motorsport magazine that the heat exchanger was dropped in 1980,  as the B spec FW07 had the entire underside of the engine paneled in and as a result the oil and water temperatures were too high, so a conventional oil radiator was used which was mounted in the left hand side pod. 

 My recollection is that initially FW07, and a few other DFV powered cars were using standard VW Golf water radiators in both pods, with a standard oil cooler matrix inside a welded jacket that passed coolant accross the face, nothing too sophistocated. When it revereted to  a conventional system it switched to asingle Citroen CX (diesel??) water rad and a large (44  row ?) oil cooler.  When we were running BMW turbo's a couple of years later we were running with conventional face cooled water and oil radiators, no heat exchangers.

[chr1s]

The same article did mention that the original 1979 set up, with the sealed heat exchanger, had a brass radiator instead of aluminium as apparently this helped it  run a bit cooler. 

[DogEarred]

Thanks to advances in CFD analysis, cooling can be controlled much better these days.

 

Engine oil & water optimal running temperatures differ as well as gearbox oil temperature.

 

CFD can analyse the conditions & predict exchanger core dimensions. It can also take into consideration & predict temperatures in the various sealed off areas of the engine bay, as Porsche718 states.

 

We can have multi function exchangers that cool both engine & gearbox oils or hydraulic fluids.

Methods of construction can now create weird & wonderful shapes to aid packaging.

 

And water & oil preheating allows drivers to safely go just about flat out on the first/warm up lap.

 

Companies such as PWR also produce Micro Matrix heat exchangers - compact micro tubes, making for lighter & more efficient cooling - at a price of course!

 

Times have changed!

 

And to quote Carl Fogarty at the opening of his brand new Superbike factory after receiving Petronas sponsorship - "Shows you what you can do with a shitload of money."

[petere]

The same article did mention that the original 1979 set up, with the sealed heat exchanger, had a brass radiator instead of aluminium as apparently this helped it  run a bit cooler. 

Yes, in some later 1979 shots (not modern historics) the water rads are definately not Golf so that makes sense. Howver, in some of the earlier ones, and also the cars that went to RAM racing they do look like Golf units.