Blanking Off The Radiator

[Opifex]

Hi CO2SLAVE

I must admit I like your logic and had been thinking along similar lines myself, but as the experts here all seem to think it's a good idea I decided to give it a go.

In January I was getting disastrously low mpg mileage due, I think, to low temperatures in the UK and only short journeys. After blanking the bottom radiator I didn't notice any dramatic improvement. Last weekend with the blanking still in place I drove from Calais to Provence and got the lowest mpg I ever had on this trip. Temperatures were around 3^o the whole way and there was a strong headwind for the first 300 miles but, on the other hand, the speed was about 5mph lower than I usually do.

So, my conclusion is that I haven't seen any improvement due to radiator blanking, but I'll leave it on and see what the effect is over the next few weeks. Maybe it's only effective in stop-start conditions. On the plus side, it costs next to nothing to try it and didn't cause any overheating on the long motorway journey.

[valmiki]

That's right Opfex, it's in stop-start that I've noticed the most difference.

With a short commute as mine (8 miles each way) as soon as I hit the city roads the traffic becomes slow. What I was noticing was that the engine would stay on to heat up, then the hybrid would kick in, I'd crawl for while under Battery power, then as the engine cooled down (because of the forward movement under Battery and general weather conditions), it would start up again to warm the engine.

Blocking the radiators has meant that the time taken for the engine too cool down enough to restart the engine has increased. The insulation keeps the engine warmer, for longer, when going forward.

With my Scangauge, I can also tell what temp. the engine has to be so that it will switch to Battery power under stop-start conditions. eg. if no heating is on, once the engine hits about 40C it will allow battery-only power, if the heating's on the the engine has to get to 50C. Pretty useful device but I know many people don't have them. It comes in useful as I can judge when to put the heating on without the engine coming on (ie. above 50C) and once it goes below, I switch the heating off. Sad I know, but it's something to do while listening to Radio4 on the drivein to work! Lol.

[GreenJuice]

That's right Opfex, it's in stop-start that I've noticed the most difference.

Scangauge: Pretty useful device but I know many people don't have them. It comes in useful as I can judge when to put the heating on without the engine coming on (ie. above 50C) and once it goes below, I switch the heating off.

I have the same experience and do exactly the same. Stop-start in urban traffic and you can really see how quickly the engine block loses heat. Even when ambient temperatures are around 15-18C, I can do a full commute without the coolant temperatures ever reaching the preferred operating temperature (at what is known as stage 3); using Scangauge to guide me on the various ways to keep the ICE off, like the one above.

[Opifex]

Blanking update.

I did a 25 mile each way trip at the weekend with the outside temperature around 11^o and got an indicated 68mpg overall. After the appalling returns I've been getting for the last two months I was delighted. Speed was around 50mph and the journey was over very undulating terrain and included a few villages to negotiate.

I think on this journey the blanking was probably helping because the engine was regularly switching off on the downhill stretches and through the villages and wasn't being cooled by the natural air flow.

[MLW2233]

That's interesting. I did a 140 mile round trip at a steady 55-65 at the weekend and got 67 mpg. A better figure than for some time. I've blanked off the top two strips (Gen 2) and left about 3 inches open at either end. Car ran very well. There seems to be enough air going through, probably from the bottom as well. Also of course one is taking heat off the engine via the car heater.

[Opifex]

I thought an update may help anyone who has blanked the radiator and is worrying about overheating now that Spring is showing signs of arriving soon.

I've still got the top radiator clear and bottom radiator completely blanked and was a bit worried last week when I did the trip from Provence to the UK. Result was that there was no problem at all running all day at 80mph with outside temperature around 12^o.