Cobwebs

[Forumadmin]

Today I took the SA to a Car Club meet in Rickmansworth in the morning , followed by a drive with the hood down ( sunny but gale force wind) to Sarratt pub for lamb roast. Certainly blew the cobwebs out of Josephine.
Yesterday went to Warco for their machinery open day. Main purchase was a vertical and horizontal rotary table for my milling machine.

[Keith Clements]

I needed to keep the revs down on the way to Lowestoft on Saturday to a friend's 50th wedding anniversary. With air temps over 30 and track temp a lot higher Josephine suffered in much the same way as the Mercedes F1 with 30 radiators. The heater was switched on to add a bit more cooling as there was no mechanical fan on the rad just an electric one. No water was used at all. What I did notice by studying my 5 temperature gauges is that once the oil temp goes above 110c you need to slow down as then head and header tank temps start to climb. Perhaps fitting a fan on the oil cooler rad is the next step if we have more days like that. As soon as we were close to the coast and the air temp went down a couple of degrees there was no cooling issue.

Trevor never did turn up!

[Keith Clements]

Drummond said the pump fitted has a higher capacity than standard and also said that he limited the capacity because if there is too much flow the water does not get time to cool.

Now there is a thought. Could it be that the higher revs gives too much flow?
Is this counter intuitive?
The reason I was using higher revs is that the overgrown track to the garage dislodged the overdrive connection and I was not going to fix in my party clothes.

The head temps and header tank temp were usually the same suggesting that flow was good. At persistent high revs, that is 10 miles at 3500rpm, oil temp climbed above 110
Below 3000 rpm oil temp on gallery input stayed below 110 C.

[BarryCambs]

At first glance, it does seem counter intuitive a higher capacity pump would cause problems, but maybe you're right and there just isn't time to dissipate the heat if the flow through the rad is too great. While clearly a very different car, so long as you are moving to get some air flow, the long two copes without any issue in temperatures up to 30. I can only assume that with the thermo siphon cooling, the water is pretty much trickling through the radiator so presumable dissipates nearly all heat. If anything, it seems over cooled.

If a temperature gauge could be fitted easily to the bottom of the rad, I guess you could measure the heat loss between there and the header tank at different revs, though that would require a nice long straight or a rolling road!

[Keith Clements]

I have 5 temp sensors on the engine .... the standard oil sump and water header tank plus oil temp after oil cooler and one in each head water jacket. Having experienced my Jup and the Javelin with many different engines and radiators, my conclusion is that Gerald Palmer was correct when he said he was not happy with the cooling. Air flow through the rad does suffer from being warmed by the engine and exhaust prior to going through the rad, plus its flow is restricted by any gubbins in front of the rad. Also I think there is a problem at about 60 mph with air flow as the engine heat output rises more quickly than the increase in flow of air. No doubt wind tunnel testing could prove this.
The Jup immediately cooled down when stuck in traffic at roundabouts which is contrary to most people's expectations, but then it has a high capacity electric fan not dependent on engine speed. If the mechanical fan was fitted there may not have not been an issue at the higher revs., but I suspect there might have been. I could replace the fan if the situation persists.
Note my oil cooler is fitted on the bulk head above the gearbox and probably also suffers from warm air going over it, but it is more protected there.

[Srenner]

In most cars, fans become an obstacle above 20-25 mph. Think of all the things manufacturers tried to not lose horsepower and keep motors cool.

Having a puller fan on the backside of the rad helps entrain the air flow through the rad. I have added several air deflectors such that the air has to pass through the rad.

Having said that, each of the cars I have restored has different warm-up characteristics and differ in how easily they shed heat. Generally, a well cleaned block and a serviced radiator will result in a fairly good cooling system. My racer needed the alloy rad and one of those aids immensely for the street car.