A quick drive at below freezing temperatures

[felixkk]

Took the C-V8 out for a quick drive today (just because)- bitter cold here in Zurich, -10C. The temperature gauge was normal when I went on the motorway... it then dropped steadily.

Did a quick stop for lunch- a bit worried about the fluids freezing. When I got back to the car after 10 minutes the temperature gauge had risen again back to the middle!

The oil pressure was also all over the place- high while on the motorway, lower than normal afterwards. The engine seemed to like the cold weather though, it responded well (but maybe it's because I've not driven the C-V8 for a while and am used to my everyday car). Toes and fingers numb when I got back! I took the office bicycle to the construction site this morning, and the brakes weren't working- they had clamped tight in the cold!

After lunch:

IMG_5376.jpg (106.46 KiB) Viewed 3253 times

A few miles later on the motorway:

IMG_5381.jpg (87.69 KiB) Viewed 3253 times

IMG_5375.jpg (249.34 KiB) Viewed 3253 times

[cannonball]

NICE RPM FOR THE SPEED FELIX,,

[felixkk]

NICE RPM FOR THE SPEED FELIX,,

the actual speed is about 10kmh less though...

[cannonball]

NICE RPM FOR THE SPEED FELIX,,

the actual speed is about 10kmh less though...

What so maybe 90mph = 3250 rpm,????

[felixkk]

NICE RPM FOR THE SPEED FELIX,,

the actual speed is about 10kmh less though...

What so maybe 90mph = 3250 rpm,????

I think more like 3500rpm. Please elaborate!

[cannonball]

What so maybe 90mph = 3250 rpm,????

I think more like 3500rpm. Please elaborate!

I am stating that the mtr is spinning quite low rpm for the given road speed most Jensen cars would be turning that rpm at circa 70 mph, so ITS A GOOD THING,,

[Chris_R]

What so maybe 90mph = 3250 rpm,????

I think more like 3500rpm. Please elaborate![/quote]

I am stating that the mtr is spinning quite low rpm for the given road speed most Jensen cars would be turning that rpm at circa 70 mph, so ITS A GOOD THING,,[/quote]
I got 3,000rpm for 81mph.

[felixkk]

Sorry, I was being a bit unspecific. I had to do a bit of (quick) reading:

Calculating speed from RPM

The formula relating road speed and engine rpm is

mph = (rpm * cir) / (gear * final * 88)

rpm = engine rpm
cir = tire circumference, in feet
gear = gear ratio of your car
final = final drive ratio of your car
88 = combines several conversion factors

"In general, a lower final drive ratio will lead to less torque at the wheels but a higher top speed. Meanwhile, a higher ratio will result in the opposite, i.e. more torque at the wheels but a lower top speed. Remember, this is done without any change to the power and torque of the engine. Since torque is what helps you accelerate, a higher final drive ratio will give you better acceleration. The catch is that your engine also needs to work harder, i.e. produce more revs, for a given speed, so the higher your final drive ratio the more fuel you’ll be using."
https://www.motorauthority.com/news/110 ... s-your-car" onclick="window.open(this.href);return false;

The fuel consumption is low (14.5l/100km or 19.5mpg on the motorway), and the rolling road results on HP and torque are a bit on the low side (I don't know what the top speed is, haven't managed that ). So is it correct to assume that one possibility could be that my car has a lower final drive? The engine was rebuilt in 2001, the transmission in 1982. Didn't find anything in the rather extensive file on any changes done though. Only one way to find out I guess...

https://www.joc.org.uk/forum/viewtopic. ... io#p190979" onclick="window.open(this.href);return false;

[kees]

Might be worth replacing the engine thermostat. Cold at high speed on the Autobahn? Not good!!
Kees Oudesluijs

[felixkk]

Might be worth replacing the engine thermostat. Cold at high speed on the Autobahn? Not good!!
Kees Oudesluijs

Or add a 541 flap on the front!

[kees]

Where is the temp. sensor situated, I presume in the cylinder head or at the hot end of the thermostat at least not at the radiator side?
Kees Oudesluijs

[Joerg]

Have driven my CV8 last week at similar temperature and the water temp needle stood exactly in the middle. The thermostat is definitely not working correctly.

[felixkk]

Have driven my CV8 last week at similar temperature and the water temp needle stood exactly in the middle. The thermostat is definitely not working correctly.

Then get it fixed Seriously though, I’m waiting to hear back from the man who knows my car better than I do...
The thermostat has always reacted as I would have expected it to, on a hot summer day on the motorway at 100mph or stuck in a traffic jam, and even on a bitter cold winters day. I wasn‘t expecting it to react so dramatically though. And what is going on with the oil pressure?

[kees]

If the engine is cold the oil pressure is high because of the higher viscosity of the oil at those temperatures.Why it is slightly lower afterwards I have no idea unless the temperature is than higher than normal.

Kees Oudesluijs

[slotcarone]

Have driven my CV8 last week at similar temperature and the water temp needle stood exactly in the middle. The thermostat is definitely not working correctly.

If your heat is working then the thermostat is fine. The cold weather will keep the temp gauge lower than usual.