Dieselboy getting his goal with his heavy SUV!

[renault_megane_dci]

In my personnal experience every time you turn AC on, the fan comes on.

And if you use defrost, AC is activated (cause it dries the air)


I can't remember what you did about using hotter air ?
In the summer where outside temp is way hotter, my car uses much less fuel even compared to winter with long enough trip to have everything at working temperature.
My assumption is that hotter air acts like engine downsizing.

Did you use any fancy oil additives in the gearbox and axles ?

Would you consider removing the shaft to the FWD axle (if it's a 4WD) ?

Did you remove your roof rack and antenna ?


Really, since we can't really do aeromods in europe, I fear your targets look very hard to achieve unless sticking to longer slow trips and using another more suited vehicle for usual locomotion.

[TimV]

The AC has its own 2 electrical fans. The fan i aim speaking of is the fan behind the radiator that sucks air trough it.

I did no mods to get hotter air, you want colder air, the colder the better in a diesel.

I was planning to change the oil in the gearbox and differential, but didnt do that already.

This is an 2 (rear) wheel drive version. So no spinning parts to the front wheels.

Roof racks and antenna are still on, cause i like the looks of it

The only big mods i have planned to do are: belly pan (and remove it for yearly car inspection), side skirts, rear tire spats and active grill shutters (for the lower grill opening).

i aim closing this year off at 5,9l/100km (the car is rated at 8,1l/100km combined)

The reasen why diesels use more fuel in winter is following:
-lower energy winterdiesel
-colder air means longer heat up time of all components (engine, transmission, differential, tires, ...) so longer more losses
-thicker air means higher drag and CD.

[renault_megane_dci]

I am in automotive business since 2001.
I joined this site 2009.

Seeing current passion for this thread, In only wonder why you use that tone with me.

On a Renault (I work for them in engineering before you ask) request for AC automatically set a timed run of the cooling fan. (Obviously the heater fan is on indeed). That is a fact.
I assumed it was the same on most vehicles, including yours.

As for temperature, I stated my opinion comparing long enough run when it's colder for the car to still be at operating temperature.
I know what is required for power : colder air.
My point is since we have plenty of power in our diesel cars, maybe hotter air acts like downsizing power.
The proper way to make use of more power being through taller diff ratio. Since this is not the most economical mod, then downsizing the power is IN MY OPINION a nice way to achieve the target of using less fuel.
There is a direct link between your engine RPM and speed so the idea is to use the least fuel for a given RPM. The tuning you had done is to increase the amount of air at each rpm but I don't know if the ECU has been tweaked to deliver less fuel proportionaly to the amount of air (there is an air sensor by the way ...).
So I know there are various reason why overall FE drops in winter but I believe a reasonnably hot air pick up should help and not only for warm up.

[cRiPpLe_rOoStEr]

Hot air in a Diesel is only helpful during a cold start and while the engine is still reaching its operating temperature.

[TimV]

Today the car went in for a verry big make over.

What is done to the car?
- new engine oil
- new oil filter
- new air filter
- new polfilter for the heating/cooling of the cabin
- new transmission oil lowest reccommended
- new rear drive axle oil (differential) lowest reccommended
- new thermostat ( i was feeling that it didnt fully closed during engine warm up)

The dieselfilter is still good for another 30 000km.
Thats the benefit of ecomodder. Using less fuel. Keeps the filters cleen for longer

And this is a bummer. The carguy checked the tire pressure....
Lowered it from 3bar (rear and 3,2 bar front. Max sidewall is 3 bar. 44psi) to 2 bar... (29psi)...

So back to the station to air up the tires

Ive also got my yearly bonus in. Witch is 100€ close to a new turbo fitted. So after winter is ended. There is going to be a new turbo for this car. The current one is whining verry hard... VNT are not stuck. Only play at the shafts. So its going to be rebuild

I keep you updated if the coolant is faster at operating temperature or not...

[user removed]

Lots of times the shaft play allows the vanes to contact the side of the housing, where clearance needs to be minimum and shaft wobble is a killer. Make sure the supply and return oil lines are not clogged with carbon.

regards
mech

[TimV]

Thanks for the tip!

[TimV]

The first thing i noticed while i left the garage. Whas the crappy handling with the lowerd tirepressurre. So the first gasstation i find on my way home. I aired up my tires.

Rear tires to 3 bar (=43,5psi. 44= max sidewal) and the front tires to 3,2 bar (=46psi).

While i left the gasstation. I was happy with the new thermostat. It looked like the engine warmed up faster. And bonus!!!

Stock thermostat was a 85degrees Celcius one (=185 Fahrenheit). The new thermostat is an 90degrees Celcius one (194 Fahrenheit).

Transmission shifts slitly better, or i imagine that.
And coasting is better with the new oils. Or again, maybe imagination.
Transmission oil was still ok. But needed replacement in the near future. Differential oil was garbage. That was needed to be replace like 60 000km ago (37 250 miles).

Next job is to rebuild and upgrade the turbo.
Going from the stock 270degrees oil bearing to an 360degrees oil bearing. And hopefully the compressorwheel 1 size bigger. Turbine wheel should stay the same.

[TimV]

In wintertime I alsmost always need to run my lights, so i want to lower my powerdraw.

So replacing the lights that are on the most with some led lights might be an option.

This is also to lower the strain on the alternator while the electric heaters are running.

=> What lights cant i change?

- Blinkers (because otherwise it blinks way to fast )
- The front head lights (low beams). Why?, those need to have a verry specific light patern, so this needs to stay stock for annual car inspection, and for the cops :P
- High beams (also needs to have a specific light patern).

=> What lights can i change?

- parking lights
- front fog lights
- rear fog lights
- tail lights
- license plate lights
- brake lights
- 3th brake lights
- reverse lights

=> So witch lights are effective to change?
(replacing a light that is on only for like 1 hour every year isnt worth the investment)

- Front parking lights (is always on, even with the low beams)
- 3th brake light (is same lamp fitting as the parking lichts, so buying a big package of lights is the way to go)

=> What lights arent you shure about?

- Ive got 2 tail lights (only function as a tail light) I can change those (but the 2 other tail lights have the function of a tail light AND brake light)
Could it harm if i change the dual function of those 2 to ONLY brake light?

- I might change the front fog lights (I can turn those separate on, so the rear doesnt need to be on to activate the front)
So i might change the front fog lichts to led, and set only the parking light on and the fog lights, so no low beams. (or high beams)

- I might change the reverse lights for more light, but it is alread bright enough, i do need to reverse every day twice. Into a parking spot at work and on to the driveway to the garage behind the house.

- Dashboard and instrumentboard lights, but i have absolutely no idea how to replace those...

[oldtamiyaphile]

Originally Posted by TimV

=> What lights cant i change?

- Blinkers (because otherwise it blinks way to fast )

You can use a solid state flasher relay to fix this.