View Single Post
      10-29-2012, 12:40 PM   #38
Jon D
Brigadier General
Jon D's Avatar
Scotland
220
Rep
3,016
Posts

Drives: 2022 840d
Join Date: Sep 2009
Location: Scotland

iTrader: (0)

Quote:
Originally Posted by HighlandPete View Post
Thinking about this a bit more, it is difficult to compare results, as we all have varied conditions, add in the fact that different engines have various coolant and engine oil capacities. Plus the diesel models have the PTC electric heater assisting cabin heating. Petrol models don't, so we certainly don't have a level playing field, even to compare engine types or sizes.

From data, I see a 520d has a 5.2-litre sump capacity, the 535i has 6.5-litres, the 530d 7.2-litres, so there is quite a large difference in heat absorption, due to that alone.

Another factor is the mpg (or for time, litres/hr) we are achieving during warm up. That will have a major influence, as after all, it is waste heat that we are using to warm up.

HighlandPete
Interesting thread; I haven't had a petrol engined car in a cold climate for over 12 years and I'm still getting used to my 640i, which I've only had for a few weeks. So, bearing this discussion in mind, I decided to monitor my car's heater warm-up time today. It was 4.5° outside, yet within less that two miles from home, I was amazed to find the vents blowing warm air; if you add on the time taken to get out of the garage, the engine would have been running for no more than 5 minutes. Obviously there was no movement on the oil temp gauge at this stage, but the coolant temp must rise remarkably quickly in order to impart heat so soon.
Along with many other automotive technical technical advances, the radiator slats obviously play a significant part in this improved efficiency.
Appreciate 0