Ideal ambient temperature

[Oversize]

With all the driving I've been doing lately I've discovered that Deep Blue runs best with an ambient temperature around 19deg c. Higher or lower and the difference is quite noticeable.... I'd imagine it would vary depending on the vehicle and induction system. Any thoughts, or experiences??

 

[SEL_69L]

The 6.9 would have to be a cold climate car. The whole of the w116 range, irrespective of the engine capacity, has the same radiator frontal area. My car seems to be happy enough, to run with an engine temperature of 90 - 95 degrees.

The 6.9 would have to be the most nose heavy of the range, with that large chunk of cast iron, in the form of an engine, over the front wheels. Probably helps to explain why the hydraulic suspension was installed.

 

[BenzBoy]

With all the driving I've been doing lately I've discovered that Deep Blue runs best with an ambient temperature around 19deg c. Higher or lower and the difference is quite noticeable.... I'd imagine it would vary depending on the vehicle and induction system. Any thoughts, or experiences??

Cooler air is denser giving a better oxygen to carbon ratio during firing. However, it's not as simple as that because then you have to aco#### for how much the ambient air temperature is raised when the air is drawn through a hot engine bay and into the intake manifold. Then you have to account for the temperature of the engine itslef and the impact it has on air density. Thus you need to be a scientist with a lab on hand to determine all the variables and come up with an equation that will give the best operation at x degrees ambient temperature. I have watched it done and I got lost with all the infra-red sensors and gas analysers that were used.
I'm going to take a guess here and say that Benz worked it all out matermatically for a car to run well in either a European summer or winter - and 19 degress Celcius is pretty close to the average ambient temperature!!
In other words, I think you are correct.
You should get the higherst miles per hour on a calm night of between 15 and 20 degrees C with low humidity and high air pressure greater than 1010 kpa. Now where did I read that last bit? Memory... memory... I just had a phone call asking for the correct angles to re-spoke a Phantom 20" wheel and I could remember that...
On the other hand - I could be dead wrong!
You need to get onto the ABC website and hunt down Dr Karl's website and send him an email - he will answer and get it right.
Regards,
Brian

 

[Oversize]

I think the 6.9 and other early models would definitely benefit from a cold air intake (especially in Australia) and MB herself demonstrated the value of such by installing them from the W126.

The radiator area is an interesting one. Aussie 6.9s had a larger radiator and thermofan, but no engine oil cooler. In addition, they had the external transmission pump. Euros with the higher compression had engine oil coolers. The Aussie 450s also had engine oil coolers and I'm wondering if their radiators were exactly the same as the Euro 6.9s.... Or did they have the same LxW, but with a thicker core?

I'll have to check other things like external transmission, power steering and suspension coolers as well... Some of these were just plumbed solid pipes out the front, just below the thermofan.