radiator

[JAINIL]

should i use water-cooled radiators or oil-cooled radiators for fsae competition... and which has more cooling rate under indentica other conditions ?

[JAINIL]

should i use water-cooled radiators or oil-cooled radiators for fsae competition... and which has more cooling rate under indentica other conditions ?

[PatClarke]

Jainil,

If you have to ask a question like that, I suggest you probably could run just as successfully with no radiator at all!

Please do some research before asking dumb questions. There is a mountain of information on this site and several more mountains on the internet in general....and you could try your University library...They might have something.

Pat

[Rex Chan]

Even though I don't really understand the question (maybe the original poster is equally confused?), I'm going to reply with what I know, and ask some questions for other, more experienced engine people.

We use water to cool our engine: water flows through the water jacket around the cylinders, then heat is transferred to the air by a water-air heat exchanger (radiator).

We use oil to lubricate and cool our engine. On a CBR600RR, there is an oil cooler attached to the engine block, through which hot oil passes (before it gets to the main galleries). Water from the coolant system also flows through this oil cooler, making it an oil-to-water heat exchanger. I think on the stock bike, this is supposed to heat both fluids up faster when the engine is cold, and maintain oil temps once everything is nice and hot.

Since we run a dry sump system, oil is pumped into an oil tank, before it feeds the pressure oil pump. This tank sits open to air, and therefore transfers some (don't know how much) heat away from the oil. We also could place an oil-air cooler in the scavenged oil lines, but have not done so because oil temps seem under control (no higher than 115C after long (enduro-style) runs on warm days).

One question for teams that use the stock oil cooler from the bike: how do you manage/control the amount of water reaching the oil cooler? We use a Y-piece to split the water out of the radiator, which is how I understand it works on a stock bike. However, this seems to rely a lot on the geometry of the actual part, and should vary dramatically if you make your own parts.

We use electric water pumps on the car and on the dyno. While water & oil temps are fine on the car, the oil temps routinely rise without stopping on the dyno, unless load/RPMs are reduced while the oil cools down. A contributing factor is that we run a water-water heat exchanger in the dyno (engine coolant on one side; building cooling tower water on the other), which is VERY effective. This means we have to slow the flow of engine water, to prevent undercooling of the engine water. Since the engine water also removes heat from the oil, the slower flow may not be enough to keep oil temps stable under continuous, high engine load.

[Nicky]

@Rex: We run a fairly large radiator and hence keeping the engine temperatures under control is controlled by the switching the fan on or off. At a medium load the engine heats up by 0.1^deg/sec while with the fan on it cools by 0.2^deg/sec. Since this is controlled by our ECU, we have the coolant temperature under control and the graph is a sinusoidal one with a peak at 88^c and a min at 85^c. I reckon the oil temperature wouldn't cross 95^c in our case with such low coolant temperatures.

From where my understanding goes, a dry sump keeps the oil temperature atleast 10-15^c cooler than a wet sump one. Reason being that the oil doesn't stay in the engine long enough to heat up. Do you still find the need to use a separate oil cooler?

[Rex Chan]

Re: Nicky - during pre-FSAE-A comp testing, I got engine water temps stabilising at 89-92C (ON/OFF temps for electric thermo fan), but the oil temps would stabilise much higher (115C was about the max sustained OilTemp, measured in the bottom of the dry sump oil tank). The temp profiles were different for each fluid: water would heat up faster and reach operating temp (85C - up to 85C we only use electric water pump, fan kicks in at 92C) earlier. Oil temps rose slower, but would eventually get to a higher overall temp.

I'm not sure I buy the less time in engine = cooler. The heat transferred to the oil will be same in each case, but the different fluid flows will affect heat transfer from the oil to water/air/etc. With the wet sump, oil has sump pan to transfer heat to air. With dry sump, there is the oil tank, so cooling will depend on tank location. Both have the stock oil-water cooler. We use this cooler, not a separate, extra one.

[Adambomb]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JAINIL:
should i use water-cooled radiators or oil-cooled radiators for fsae competition... and which has more cooling rate under indentica other conditions ? </div></BLOCKQUOTE>

Too old skool for me. All the cool kids these days are running fuel-cooled. Then you don't need a fuel tank! You also know when you are out of fuel because the engine is overheating.

[murpia]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by donal:
Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics. The radiator is always a source of heat to its environment, although this may be for either the purpose of heating this environment, or for cooling the fluid or coolant supplied to it, as for engine cooling.
The heating radiator was invented by Franz San Galli, a Polish-born Russian businessman living in St. Petersburg, between 1855–1857 </div></BLOCKQUOTE>
How do we program the spam-bots to reply to all the dumb new threads immediately?

Regards, Ian