Hi Jay,
I did as you suggested.
I did not decreased the amound of block, but slided the extra piece of plastic more to one side on the grille (exterior block part). So the airflow comes straight onto the radiator now by a small square hole. See pic:
Result so far:
- For daily commute perfect with 6 to 8?C outside temps (30 to 40 minutes one way mixed roads).
- Had to drive one hour 100% highway: not good, heat keeps on building up and that makes me nervous (94?C engine block and 92 at radiator).
- Oil temps go over 90?C on highway (normal value I think and I never measured before on highway the temps).
- Fuel consumption stayed at 5,6 l/100km, but that's normal as the tank is almost empty now and changing this will be quite impossible. Think it's a good value for winter time.
So when I returned home for another 1 hour highway after only 10 minutes rest for car (still hot !) I removed the extra external block and saw as I expected an enourmous temp drop at radiator side (as if there's no block at all, while I'm still having 60% blocked).
For the moment I will keep the 90% block slided to one side so radiator has cooling. I will prepare an extra second external block to see what fits for longer rides (highway or > 45min trips).
I will keep you informed of further results.
Right now my first impression is possitive as my fuel consumption doesn't increase in winter (1 to 8?C outside).