58 replies to this topic

[New Britain]

Apologies if this is a pathetically dumb question, but my searches here and elsewhere have gone for naught.

Now that ACO have made it mandatory for LM, some new racing cars have air conditioning as an OEM option.
Is anyone aware of an after-market system that can be retro-fitted to a racing car, or is this something that one has to develop for oneself from scratch?

Cheers.

[desmo]

I'd look at the regs to see the wording. A hole in the bodywork with damp rag stuffed in might meet the requirement.

[cheapracer]

small rotary compressor run only on overun/braking would be sufficient and make no difference to lap times.

[primer]

Instead of cooling the cabin, it might be better to try and keep the driver's head cool with air cooled helmet. I believe Richard Burns tried one such setup in rallying.

[Greg Locock]

watercooled seats, watercooled suits, and air cooling versions of each have been tried. Peltier effect heating and cooling is the best bet, not too sure if they are commercially available yet.

[gruntguru]

small rotary compressor run only on overun/braking would be sufficient and make no difference to lap times.

Could actually run it anytime throttle is less than 90% if needed. Would probably allow a smaller compressor to be used.

Edited by gruntguru, 03 May 2010 - 03:51.

[Fat Boy]

Small air conditioning units for the helmet are very common in anything that has a closed cockpit.

[cheapracer]

Which reminds me of how shocked Peter Brock was when Alan Moffat came to the Holden team and demanded power steering; "but we will lose power" - AM "yeah but you will go faster for longer".

They went faster for longer.

Older V8 Supercars.

[desmo]

Is the idea to improve overall performance of the entry by maximizing the driver's contribution or simply to meet the letter of a rule mandating an AC system?

[SteveCanyon]

So just how much power does a small compressor absorb? Can't be more than 5hp or so ...?
Fair enough there's additional losses involved in spinning-up the compressor as it cuts-in & accelerates with the engine and also the extra mass of all the gear, and the extra aerodynamic drag from the radiator.

[gruntguru]

So just how much power does a small compressor absorb? Can't be more than 5hp or so ...?
Fair enough there's additional losses involved in spinning-up the compressor as it cuts-in & accelerates with the engine and also the extra mass of all the gear, and the extra aerodynamic drag from the radiator.

As a rough rule of thumb, the compressor will use about half as much power as the cooling performed. So 5kW compressor = about 10kW cooling. I did some calcs once on using AC to cool the engine air intake in hot and/or humid climates. I don't remember the exact numbers but in most cases the extra power created was more than double the compressor drag and of course you still have the option of switching the compressor off above 90% or 95% throttle! The rules do not permit such trickery in most categories.

[Grumbles]

Airconditioning doesn't necessarily reduce available engine power..

[SteveCanyon]

As a rough rule of thumb, the compressor will use about half as much power as the cooling performed. So 5kW compressor = about 10kW cooling. I did some calcs once on using AC to cool the engine air intake in hot and/or humid climates. I don't remember the exact numbers but in most cases the extra power created was more than double the compressor drag and of course you still have the option of switching the compressor off above 90% or 95% throttle! The rules do not permit such trickery in most categories.

Most interesting, thanks!
FWIW one thing I wanted to try for the very Aussie knuckle-dragging SummerNats in Canberra, for the dyno competition was to do what the Germans did in WW2 with the Dornier 217P high-altitude bomber - they were a conventional looking bomber but had three engines; the third engine was buried in the fuselage and all it did was drive a very large supercharger, which fed that engine and the other two on the wings.
I figured that I could put something like a 100hp two-stroke outboard engine in the boot of the car to drive a big blower, and have a big intercooler as well. Since the main engine would have no parasitic drag from the blower it should make pretty good numbers .....
.... but I reckoned I'd only get away with it the once then it'd be banned.

[Tony Matthews]

.... but I reckoned I'd only get away with it the once then it'd be banned.

Could sound pretty cool, too!

[McGuire]

We tend to visualize great hulking Frigidaire C60 setups but actually, these entire systems weigh <20 kg using OE shelf components. Power less is negligible, couple of hp. Essentially, the regs forbid interior temps >32 degrees C in closed cars. ACO was allowing a .3 percent air restrictor adjustment for closed cars as compensation but I believe that has since been eliminated.

[Ross Stonefeld]

32C? Are you sure it's not higher? Ambient would be warmer than that in France in June no?

[McGuire]

32C? Are you sure it's not higher? Ambient would be warmer than that in France in June no?

I believe the reg also specifies "...or 10 degrees higher than ambient temperature."

[Lee Nicolle]

Biggest problem it would appear is weight over the engine end of the car upsetting the balance. Plus the centrifigal mass of pulleys and belts. And the attendant problem of trying to keep them all on when you turn the engine hard. That happens on roadcars, give the engine a rev and have belts slipping or flipping off, that on factory manufactured units at 6000 rpm. Have seen high rpm small engines do it on standard engines.
Power steer seems to cause less problems provided you slow it right down though you normally end up with notchy steering at low rpm though personally I hate powersteer on race cars as you lose the sensitivity from the wheels.
Plus with all these luxury accesorys you ahve to find somewhere to mount it on the engine or transaxle.
Ofcourse full automatic is next!!

[New Britain]

I'm much obliged to everyone for your comments.

The situation is that car is 997 Cup car competing in 4/6 hr races. There is no formal requirement for A/C. The racing (for me and my teammates) is just for fun; I'd rather be semi-comfortable even if it costs in lap time. As has been said above, it is possible (indeed, I think quite probable) that cumulative times would actually go down if the middle-aged guys such as I who are driving are not wilting by the midpoint of a stint.
The helmet cooling system that I have seen, in NASCAR, looks like it would be awkward to swap during driver changes. Also, we use open-face helmets, with which I presume the helmet cooling system would be less effective. I would be happy to be corrected on either of these points.
My technical knowledge in racing is roughly limited to being able to tie the laces of my boots (most of the time). It does seem that there is a lot of space inside the car, and therefore it is inherently very inefficient to try to keep the entire interior cool, when the only thing that needs to be cool is the driver who takes up a fraction of the overall volume.
Although the engine and 'box in Porsches are behind the driver, the radiators are in the front. It seems to be a feature of the air flow in these cars that the heat coming off the radiators and front brakes flows very neatly into the interior. A while ago a medic had occasion to check the interior temp of one of these cars shortly after it had stopped mid-race. I was told that the reading was high 50s.

My hope was that, with so many outfits and entrepreneurs offering products for every conceivable facet of motor sport, one of them would have developed a racing-specific A/C system, which could be adapted to different cars.
On the other hand, perhaps this sort of thing must be integral to the car (I know that Porsche offered A/C in the '09 RSR, but it appeared to entail a number of elements specific to the car), and we would be better off focusing on cooling the driver, rather than on cooling the space.

Cheers.

[MatsNorway]

I'm much obliged to everyone for your comments.

The situation is that car is 997 Cup car competing in 4/6 hr races. There is no formal requirement for A/C. The racing (for me and my teammates) is just for fun; I'd rather be semi-comfortable even if it costs in lap time. As has been said above, it is possible (indeed, I think quite probable) that cumulative times would actually go down if the middle-aged guys such as I who are driving are not wilting by the midpoint of a stint.
The helmet cooling system that I have seen, in NASCAR, looks like it would be awkward to swap during driver changes. Also, we use open-face helmets, with which I presume the helmet cooling system would be less effective. I would be happy to be corrected on either of these points.
My technical knowledge in racing is roughly limited to being able to tie the laces of my boots (most of the time). It does seem that there is a lot of space inside the car, and therefore it is inherently very inefficient to try to keep the entire interior cool, when the only thing that needs to be cool is the driver who takes up a fraction of the overall volume.
Although the engine and 'box in Porsches are behind the driver, the radiators are in the front. It seems to be a feature of the air flow in these cars that the heat coming off the radiators and front brakes flows very neatly into the interior. A while ago a medic had occasion to check the interior temp of one of these cars shortly after it had stopped mid-race. I was told that the reading was high 50s.

My hope was that, with so many outfits and entrepreneurs offering products for every conceivable facet of motor sport, one of them would have developed a racing-specific A/C system, which could be adapted to different cars.
On the other hand, perhaps this sort of thing must be integral to the car (I know that Porsche offered A/C in the '09 RSR, but it appeared to entail a number of elements specific to the car), and we would be better off focusing on cooling the driver, rather than on cooling the space.

Cheers.

Unless its outlawed you can do like the BMW M3 ALMS car do to save cool air.

They have a big lexan plate behind the rear seats so they don`t have to cool the rear seats and trunk. they also got heat insulation here and there.

[cheapracer]

My technical knowledge in racing is roughly limited to being able to tie the laces of my boots (most of the time).

Welcome to the team, I'm sure you'll fit in right away!

[primer]

Why is the fuel not used to cool the driver. You could have a closed loop heat exchange system where a fluid (water) circulates in certain parts of the racing suit and helmet to keep the driver cool, and this in turn dumps heat into the fuel. Put the exchanger inside the fuel tank itself. Some sensors and very little computing power would be required to control the flow rate of water so that the driver does not become uncomfortably cold.

Before a session you could fill up the car with really cold fuel, and the only issue would be to isolate the tank as much as possible so that it picks the least amount of heat from engine and ambient. For sure this will not provide as consistent cooling as an air conditioner but for racing application it should be good enough. It would also be very light, reliable and idiot proof. Seems almost too easy, shirley someone must have used it sometime in racing history.

[MatsNorway]

Why is the fuel not used to cool the driver. You could have a closed loop heat exchange system where a fluid (water) circulates in certain parts of the racing suit and helmet to keep the driver cool, and this in turn dumps heat into the fuel. Put the exchanger inside the fuel tank itself. Some sensors and very little computing power would be required to control the flow rate of water so that the driver does not become uncomfortably cold.

Before a session you could fill up the car with really cold fuel, and the only issue would be to isolate the tank as much as possible so that it picks the least amount of heat from engine and ambient. For sure this will not provide as consistent cooling as an air conditioner but for racing application it should be good enough. It would also be very light, reliable and idiot proof. Seems almost too easy, shirley someone must have used it sometime in racing history.

Sounds like fire hazard to me.

[CSquared]

I believe the reg also specifies "...or 10 degrees higher than ambient temperature."

How do they measure that when they're using one of those methods to directly cool the driver/helmet?

[J. Edlund]

What the regulations says:

14.1.9 – Temperature inside the cockpit (Closed cars):
An effective ventilation and/or air conditioning system must:
• Maintain the temperature around the driver when the car
is in motion :
1. at 32°C maximum when the external temperature (*)
is less than or equal to 32°C,
2. at a temperature less than or equal to external
temperature (*) if it is above 32°C;
• Get the temperature back down to the value defined
above (case 1 or 2) in 8 minutes maximum after a car
stop.
• Be described on the homologation form and approved by
the ACO ;
A temperature sensor can be fitted inside the cockpit by the
organiser at level of driver’s helmet to the centreline of the car.
The sensor must be shielded from direct draught (to the
Scrutineers’ assessment).
A driver suit with improved breathability and complying with FIA
8856-2000 specifications is strongly recommended.
If the temperature around the driver exceeds the value defined
above (case 1 or 2), or if the sensor is disconnected, the car will
be stopped until the problem is solved.
A driver, who shows at the end of a stint important signs of
tiredness, can be examined by the doctor of the organisation. If
it is due to heat stress, the driver will not be allowed to
participate again in the race.

(*) The external temperature will be measured in the shade and out
of the wind. This temperature will be displayed near the pit lane.


Some data for AC compressors can be found here:
http://www.sanden.com/

[zac510]

When I was at LM24 last year we had the Flying Lizards team in our camp area doing a talk and someone asked about the air conditioning on the car. They said there are some fancy control strategies involved in making sure that the compressor clutch doesn't kickin mid-corner or at an inopportune time all while not costing them any more horsepower than they need to sacrifice to be legal.

But they're pushing the limit for 24 hours, maybe in your race just having the compressor on at all times will not be a major issue.

[GreenMachine]

Does this mean these cars run with windows closed? I imagine that LMP1 Le Mans cars do, but others?

If the window is open, how do you keep the cool air in?

[Lee Nicolle]

Paul morris of Paul Morris Racing in V8 Supercars had a AC fitted to his car for Adelaide. From memory it was a box inside the car and possibly electrically driven, not engine driven. Though it did not seem to be there for long though Adelaide is a concrete tunnel not a racetrack and no surrounding breeze moves the air.
He is in Queensland australia.

[New Britain]

But they're pushing the limit for 24 hours, maybe in your race just having the compressor on at all times will not be a major issue.

No issue at all.

[New Britain]

Does this mean these cars run with windows closed? I imagine that LMP1 Le Mans cars do, but others?

If the window is open, how do you keep the cool air in?

The norm is full fixed plastic windows. Occasionally someone might put a slider in, but that usually does not work well because of boundary layer of dead air in windscreen wake.

[CSquared]

What the regulations says:

14.1.9 – Temperature inside the cockpit (Closed cars):
An effective ventilation and/or air conditioning system must:
• Maintain the temperature around the driver when the car
is in motion :
1. at 32°C maximum when the external temperature (*)
is less than or equal to 32°C,
2. at a temperature less than or equal to external
temperature (*) if it is above 32°C;
• Get the temperature back down to the value defined
above (case 1 or 2) in 8 minutes maximum after a car
stop.
• Be described on the homologation form and approved by
the ACO ;
A temperature sensor can be fitted inside the cockpit by the
organiser at level of driver’s helmet to the centreline of the car.
The sensor must be shielded from direct draught (to the
Scrutineers’ assessment).
A driver suit with improved breathability and complying with FIA
8856-2000 specifications is strongly recommended.
If the temperature around the driver exceeds the value defined
above (case 1 or 2), or if the sensor is disconnected, the car will
be stopped until the problem is solved.
A driver, who shows at the end of a stint important signs of
tiredness, can be examined by the doctor of the organisation. If
it is due to heat stress, the driver will not be allowed to
participate again in the race.

(*) The external temperature will be measured in the shade and out
of the wind. This temperature will be displayed near the pit lane.


Some data for AC compressors can be found here:
http://www.sanden.com/

So it sounds like the direct helmet, seat, or suit cooling methods are not, by themselves, enough to meet the regulations.

[NTSOS]

The GT1/GT2 C6.R Covettes all use production based AC systems with modified ducting.

[cheapracer]

The GT1/GT2 C6.R Covettes all use production based AC systems with modified ducting.

Yeah Grunt is right, all you would need is a brake light switch/microswitch on the accelerator so near full throttle it switches off for full force on straights.

On the subject, my Mazda ^ has AC and AC Eco positions (economical I presume), whats the go there.

Yeeah, yeah I never read the manual

[threep]

A friend competes in a classic closed cockpit formula and heat in the cockpit is a huge problem. Apart from hydrating properly in the hours us to a race and some customised ducting to direct external air to his body, there's not much else which can be done easily. There are one or two competitors which use cool suits like this....



but "13 quart ice chests" weigh a fair bit so you'd have to weigh up the loss in human performance after a certain period of time compared to the weight (& cost) of such systems.

You would need a well sealed cockpit to make air-con effective otherwise you might just be pumping expensively gained cool air (expensive as in mass, drag and electrical load) into the environment.

[SteveCanyon]

Yeah Grunt is right, all you would need is a brake light switch/microswitch on the accelerator so near full throttle it switches off for full force on straights.

On the subject, my Mazda ^ has AC and AC Eco positions (economical I presume), whats the go there.

Yeeah, yeah I never read the manual

It'd need some testing but how would simply spinning the compressor much slower go? I mean a good system works really well at a 700rpm idle, so there's no real need to spin it at 8,000rpm+.

As for the AC and AC ECO thing, on the Pajero we have it's to use different temperature settings on the thermostat; the economy setting has it set a little higher. I guess yours would be the same.

[McGuire]

Is anyone aware of an after-market system that can be retro-fitted to a racing car, or is this something that one has to develop for oneself from scratch?

Not as yet, and right there is a great opportunity for someone -- be the first into the market with a well-engineered third-party A/C unit for race cars. When you are first, you are #1 go-to supplier in the market until someone knocks you off. The demand is there: ACO/ALMS and the other series that pile on after them....and all those gentleman racers getting older all the time. Track day cars, quasi-vintage racing, etc and so forth.

Wouldn't take much, either. Outsource a suitable compressor and condenser, engineer a simple cabin box to house the evaporator and fan motor, sort out an elementary thermostatic control; develop compressor mount/drives for the half-dozen or so most popular engines as you go. (A bunch of the parts could be cribbed from the aftermarket A/C industry.) One of you kids needs to get on this and make a pile of $$$.

[Ross Stonefeld]

You got the idea, we got enough tech junkies here, I know a bit about marketing or at least a good PR scam...

[Tony Matthews]

You got the idea, we got enough tech junkies here, I know a bit about marketing or at least a good PR scam...

You'll need some drawings...

[Canuck]

and some modelling...

[New Britain]

A friend competes in a classic closed cockpit formula and heat in the cockpit is a huge problem. Apart from hydrating properly in the hours us to a race and some customised ducting to direct external air to his body, there's not much else which can be done easily. There are one or two competitors which use cool suits like this....



but "13 quart ice chests" weigh a fair bit so you'd have to weigh up the loss in human performance after a certain period of time compared to the weight (& cost) of such systems.

You would need a well sealed cockpit to make air-con effective otherwise you might just be pumping expensively gained cool air (expensive as in mass, drag and electrical load) into the environment.

Another way to cool the body alone:

[Tony Matthews]

and some modelling...

How about Elle Macpherson?

[benrapp]

Surely a 997 Cup can be rigged with a production Porsche a/c system? It's a factory option on the GT3 on which the car is based.

I've got a monster fan motor in the front of my 964 Cup which pumps ambient air through the defroster vents and a pipe aimed at my face. It maximises the effectiveness of my highly advanced evaporative cooling system.

Now that I've road-registered the car, I have to say I am also suddenly very interested in retrofitting a/c...

[New Britain]

Surely a 997 Cup can be rigged with a production Porsche a/c system? It's a factory option on the GT3 on which the car is based.

I've got a monster fan motor in the front of my 964 Cup which pumps ambient air through the defroster vents and a pipe aimed at my face. It maximises the effectiveness of my highly advanced evaporative cooling system.

Now that I've road-registered the car, I have to say I am also suddenly very interested in retrofitting a/c...

I believe that the racing car's airbox gets in the way of where the compressor is mounted in the road car.

[SteveCanyon]

FWIW I've seen electrically-driven compressors, they can be fitted anywhere, so they don't have to be in-line with the engine pulleys.
Dang, I can't find the information on it sorry.

[Greg Locock]

FWIW I've seen electrically-driven compressors, they can be fitted anywhere, so they don't have to be in-line with the engine pulleys.

Go and get a beer from your fridge. That might inspire you. I bet a Prius uses one, but that's probably too powerful for a race car. If there is a market for a high efficiency low output electric a/c system then one of my friends would be delighted to set up a production line (or at least design it so Cheapy can make it).

But, seriously for a race car I'd give up on a cabin based system and concentrate on cold seats and cold suits. Cold seats/cold air feed to helmets are brilliant. I'm serious, we'd like to get into this stuff. Cold suits are probably better than cold seats, but they are more likely to be water than air based. Obviously if your rules specify a cabin temp, then you either get the rules changed or suck up the inefficiency.

[SteveCanyon]

Go and get a beer from your fridge. That might inspire you. I bet a Prius uses one, but that's probably too powerful for a race car.

Yes, I was talking about a car-based electrical compressor and not a 240v fridge one.
I think you're right about the Prius using an electric one as well.

[cheapracer]

I think you're right about the Prius using an electric one as well.

Which may well be made here.

Sample here ....
http://www.alibaba.c...or_Vehicle.html

[mariner]

Cheapracer, I just love the alibaba site, spent some time just surfing it. Maybe 10 ATV's to sort my 2010 christmas list!

[Villes Gilleneuve]

watercooled seats, watercooled suits, and air cooling versions of each have been tried. Peltier effect heating and cooling is the best bet, not too sure if they are commercially available yet.

for the last 20 years.

[Greg Locock]

for the last 20 years.

Peltier effect in seats have been commercially available for 20 years? Cite please.