Remove Aircon ????

[mrvol]

Hello ,

I m a Cerbera 4,5 Owner from germany.. and I think about to remove my Aircon, because of the wheight of the Car

What do you think.. Does it cost me some Power because i dont will have the Fuel Cooling anymore .. does anybody have some experiences with removing the aircon..

thanks for your help..

Sorry for all the errors :-D

regards Volker

[LukeSi]

First time I've seen someone want to remove the aircon from their tiv. Can't imagine it would cause too many issues. No small job though I believe, and you might regret it.

[mrvol]

I hate Airconditions :-D.. If you need cold Air open the window .. :-D... I made a full restauration of my cerb 4 years ago.. the conensator and the dryer are new.. i think all about the Aircon wheights maybe 8-10 kilogramm.... So would be nice to reduce that wheight...

I love lightwheight cars.. even my wheelnuts are out of Aluminium... :-D

The only think I dont realy know is what is about the fuel cooling ??

[LukeSi]

mrvol said:

I hate Airconditions :-D.. If you need cold Air open the window .. :-D... I made a full restauration of my cerb 4 years ago.. the conensator and the dryer are new.. i think all about the Aircon wheights maybe 8-10 kilogramm.... So would be nice to reduce that wheight...

I love lightwheight cars.. even my wheelnuts are out of Aluminium... :-D

The only think I dont realy know is what is about the fuel cooling ??

Don't worry as far as I know aircon is only used to cool the passenger compartment. I would be interested to see pictures of your car. Quite honestly though I don't think removing it would make a noticeable difference.

[Tanguero]

The fuel cooler is in front of the engine clipped to a chassis cross member. However bear in mind that it doesn't do anything when the aircon is switched off. Also you don't have any parasitic drag when the aircon is not on. Is the few kilos of the pump, condenser etc really going to make much difference?

[Mr Cerbera]

Don't forget all those grammes of plastic ducting and airballs that can be saved as well !

[G9RGE]

I removed my aircon last year for a number of reasons, I always have the windows down and never use it. It worked but was never amazing, removing the aircon rad would provide better cooling to the rad, and then the weight.
I have had no problems since, I did notice that my engine water temp was a lot lower but I did give It a flush and fresh coolant at the time. I guess there are also weight gains, condenser, compressor and rad.

[Superjuiced]

air con has been removed from my 4.5. it never had it in there since ive had itI think the guy who owned it last took it out when he was either in the strip or gettin it rolling rd. can't say what the difference is but no problems with it out. I have a load of new heat shielding around the cockpit so it doesn't cook me like some of the others, also no cats helps. I still have it so could drop it back on if needs be but I prefer to open a window and smell the air!!

[mickydoo]

Hey chaps. Is this not basic physics?

If the aircon is on, the Cerbera fuel cooler pipe will provide cooler fuel that will be denser and therefore more energy per ml injected. It also will impart a cooling effect to the airmix, and therefore one would expect marginally increased power. It will also reduce the impact of a warm engine & warm fuel pipes on the fuel/air mix.

This is definitely a benefit in countries that are warmer in the summer, although less so when much cooler in the winter.

The question is does the aircon actually cause any significant degredation to performance in the first case, and therefore is the net difference increased by the cooler fuel? The weight, assuming its in the 8-10kg range, is <1% of the car's weight, so if removing it causes a loss of performance >=1%, then it's a waste of time (or thereabouts - I'm sure the maths is more complex than that, but for simplicities sake, and calculating BHP/tonne, it works for me!)

Also if the ECU is mapped for "cool" fuel, then it will run lean if the aircon is either off, or removed, once the engine has warmed, or the ambient temperature is naturally high. The opposite is true if the ECU is expecting naturally "warm" fuel. i.e. a remap might be necessary if you remove the aircon.

And I don't know much about cars.....

[Tacchino]

Has anyone ever managed to find out how much cooler the fuel actually is when it gets to the fuel rail?
Surely that would help finding the answer.

Also, does the Cerbera injection system run on the same principle as many other cars in that the fuel pressure rail holds fuel at a specific pressure but fuel flow is continuous with the excess being returned to the tank?
If so, wouldn't this mean that to benefit from the cooler fuel you would need to be flat out for some time to ensure that only cool fuel was in the rail!

And I know even less about cars (that's Bournemouth for you!)

[mickydoo]

...indeed.......but we do know plenty about bikini-clad hotties.....

[mrvol]

Hello again..

Today i started a small calculation:

boundary conditions
____________________________________

RON 98 = 14,7 AFR = Lambda 1
11,76 AFR = Lambda 0,8

density Ron 98 (dR98) = 740 kg/m³ (liquid)
density Air (Teta= 30 °C) = 1,164 kg/m³
spec. Heat cap. RON 98 (cpRon98) ~ 2,1 kJ/kg*K (Teta = const.)
spec. Heat cap. Air (cpAir) ~ 1,005 kJ/kg*K (Teta = const.)

VStroke ~ 4500 cm³ ~ 0,0045 m³
Vstrok ~ 560 cm³~ 0,00056 m³
_____________________________

For enginespeed = opt > Airmax=1,1 (This means for maximal Cylinderfillig with resonance charge + 10% this is free chosen from me an a Value from good Air inlets from Honda)

= Vstrokemax = 616 cm³
>MAirmax = Vstrokemax * density Air = 0,000714 kg = 0,714 g AIR


= for max Throttle and Lambda 0,8
> MRon98= MAirmax / AFR (Lambda 0,8) = 0,714 g / 11,76 = 0,061 g RON 98

dURon98 = dUAir with (dU = dQ + dW ) - dW = 0 because there is now mechanical work and dQ = M * cp *dT
dQron98 = dQAir
MRon98 * cpRon98 * (T2Ron98 - T1Ron98) = MAir * cpAir * dTAir

> (MRon98 * cpRon98 * (T2Ron98 - T1Ron98)/ (MAir * cpAir)= dTAir

If the Fuel is cooled from 70°C to 20°C you will receive a lower Air Temp of 9 K !!!


This means a better filling !!

The Mairmax increases from 0,714g/cycle to 0,741

> + 3,78 % more Air.. for 95 hp/liter means this the Cerbera would have only 411 hp to 427 hp instead..

Fuel cooling increases the Power of our TVR´s for about + 12 -18 hp...

(Depends on how warm is the Air at the Inlet and what is about the Mapping - firing Angel and so on..!!


Now the Question:

How much Power does the Aircon needs ... I will fin it out.. I estimate ca. 3-4 kW Full Enginespeed

12 hp means ~ 9 kW...

and plus the Aircon wheights all 25 kg that means a Power/wheight ratio plus of 2,1 % is equal to + 8 Hp (5,9 kW)

So Wheightratio plus is 5,9 kW and 3 kW Aircompressor = 8,9kW... ~ 9 kW Fuelcooling

So i Think it doesn´t matter on the Power.. But its Better for the engine Running because of some lower Exhaust Temperature.. (a little bit but not so important i think.. Most important is the evaporating of gasoline in the rail if the gasoline is to hot. And for the ECU.

Does the Cererba ECU´s uses Lambda MAP in full Throttle ?? If not if they use a static Map we all need the Aircon !!!

regards from germany

[Tanguero]

The fuel cooler is on the return side of the fuel line - it cools the fuel before it goes back into the tank, not before it gets to the engine. Obviously this will result in cooler fuel at the engine eventually but not as much or as directly as if it was before the fuel rail.

Not quite sure how you would go about calculating in the thermal mass of the fuel tank as a function of time as fuel was used.

[purpleliability]

You could always fit an air to air fuel cooler in the circuit as well, this could run between the tank and the fuel rail so the fuel to the rail and from the rail is cooled...

[mrvol]

The Calculation is between no Fuel cooling and with Fuel cooling... Doesnt matter if its in the return or the feed part..

The Fuel cooling is a hole process over the time an holds the fuel temp down at 20 °C instead of pumping the Fuel (if you have low Fuel level) up to 70 °C or 80 °C.

I hardly think about an Air to Air soulution.. Problem is .. it does not work if you have slow city cruises. I will calculated some Diesl Fuel coolers from actuall BMW or Mercedes. They have coolers at the Bottum of the car.

There is a high velocity of the Air that is good for heat transfer.. maybe i use somthing like a laval nozzle to increase the velocity ..

I´m afraid that the Airspeed next to the engine were the original cooler is is very slow because it banks up in Front of the engine !!

I will try do a Simulation for it !..

regards Volker

[a1rak]

[quote=Tanguero]The fuel cooler is on the return side of the fuel line - it cools the fuel before it goes back into the tank, not before it gets to the engine. Obviously this will result in cooler fuel at the engine eventually but not as much or as directly as if it was before the fuel rail.

Is that correct?, I thought the fuel came from the tank over the top of the engine into the cooler back up to the fuel rail then out of the fuel rail back to the tank. Thats how my 4.5 was plumbed in when I got it.

I really dont think this cooler does F.A. it only works when the aircon is on, its a tiny little heat exchanger and if it accounts for 18bhp i will drop my pants and suck my own bratwaurst or what ever Germany for sausage is.

[Tanguero]

On my 4.2 the cooler is definitely on the return side. This does not mean that is how it left the factory though!

I would be astonished it the fuel cooler does enough to remover the extra heat that has been picked up by the fuel in the fuel rail, which is what it is there for.

[mrvol]

a1rak said:

its a tiny little heat exchanger and if it accounts for 18bhp i will drop my pants and suck my own bratwaurst or what ever Germany for sausage is.

:-) ha ha ...be careful with your wishes !!!!

And yes.. the exchanger is little, but the Temperture difference is very high i think.. The cooling fluid maybe has 10°C or so.. so for this yo does not need much Face..

And yes Bratwurst is right.. you can also say Würstchen !!