2. THE COOLING
The new aluminium radiator fitted last year before winter is working SO well that I can't get the engine hot enough. With the old radiator, I had to drill out my 160F thermostat to make it cool sufficiently in stop/start traffic, with both electric fans on too.
Swiss cheese anyone!?
But now, I can barely get the temps to reach 50°C! This is a problem, because I suspect the oil is simply not getting hot enough to boil off moisture / sulphur or reach it's correct operating temp. So I swapped out the Swiss cheese for a new thermostat and all is good with the world again.
I had to make a new bracket for the fans to mount within 5mm of the rad fins as I wasn’t going to hang them off the matrix and there was no other elegant way to achieve this. I have to say, I’m super pleased with the outcome. The fans blowing at 100% duty cycle actually spin the mechanical fan on the other side of the rad. So the airflow is clearly great.
Being a total geek, I hooked up temp sensors and a gauge – one sensor on the oil filter housing, the other inside the radiator cap. I fast idled the car for some time inside the garage to get it up to temp. This typically heats the garage up to over 30°C. The analogue temp gauge in the car proved to be very accurate – so that gives me good confidence in trusting it. Although I did sport a Carbon Monoxide headache afterwards as the wind was blowing some of the exhaust back into the garage
This is what 90°C looks like:
But the best bit was, turning the fans on, pulled it down from 90C to 72C in 5 mins. Down to 79 in 2 mins. This bodes well for queueing to get into Goodwood or other show on hot summer days.
Most notably, the engine is BEYOND happy! I no longer get the embarrassing kangarooing out of fuel stops for the first ¼ of a mile due to vapour lock / “percolated fuel inside the fuel lines” – I’m sure you’ve all been there
After a proper thrash, I can blip to 4K rpm and turn off the ignition without a trace of running on.
I also did a brief test of under-bonnet temps by letting her fast idle at 1.5K rpm out of the garage for 5 mins. They peaked at 60C. I had a sensor right next to the rear carb mouth and one at about valve cover gasket height on the other side. 3 observations:
1. The home-made Heatshield is doing a great job as temps are near identical on both sides. Having said that, the temp on the manifold side did rise more quickly.
2. When engine was turned off, they started rising sharply. But given that I have a timer on my electric fans which lets them go on for 5 mins after the engine is off, I turned them on to see their effect. The under-hood temps started to fall almost immediately and by 10°C in about 4 mins. So the airflow really does help reduce heat soak.
3. Given what Mr Vizzard tells us about every 11°C drop in intake air temp equates to 2% more torque, it makes for 4% extra torque. When I did this test there was a 44 degree delta between the air at the front of the rad and the engine bay temps by the carb mouth. I’ve been planning to do this while moving at different speeds but the car wasn’t right. Now that it is, watch this space.
