Radiator Differences

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Way2go
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Re: Radiator Differences

Post by Way2go »

I think the finer points of this are a bit irrelevant for the BX. My BX has the larger radiator because it is an air-con car with a potential greater load on the engine. However the air-con is not currently used due to low gas so the compressor clutch is not engaged. In normal use it will quickly attain & maintain its temperature of 90deg within a few miles. In ambient temperatures below or around zero it will take 5-6 miles to get to 90deg.

What is truly excellent design though is that the heater warms up after starting and not delaying until the thermostat opens. When the gauge reaches just before 90deg though you do feel a leap in heater output as a result of the opening thermostat. :D BX heaters for the win! =D>
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Dollywobbler
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Re: Radiator Differences

Post by Dollywobbler »

I don't see how that differs from most cars to be honest. Heaters usually bypass the thermostat.
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Re: Radiator Differences

Post by Vanny »

Way2go wrote:My BX has the larger radiator because it is an air-con car with a potential greater load on the engine.
AC equipped cars normally have a condenser doing a fantastic job of heating up the radiator AND blocking air flow (ram pressure is greater on an AC equipped car). Running compressor load, even on a system as old as a BX is equivalent to driving up a mild incline. Peak compressor load can be a little higher, but still a fraction of the peak engine output.

At the end of the day, in the real world of the car getting from A to B, you're better off with a slight over cooling than an under cooling.

If i'm doing serious work on a vehicle with an unknown history, i will normally flush the rad regardless of external appearance. It's amazing what you can find. Half blocked radiators are not much use to an engine!
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Re: Radiator Differences

Post by Vanny »

Dollywobbler wrote:I don't see how that differs from most cars to be honest.

Have you not been in a modern car?

They take days often weeks to produce any heat (well it feels like that long if your sat on a leather seat in a car that's mostly frozen!). Probably more to do with engine efficiency than a poor cabin heating system design, but i love jumping in the valver knowing that before i get to the end of the road i'll be toasty and warm.
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Re: Radiator Differences

Post by Kitch »

mat_fenwick wrote:True, but we're not talking about a massive increase in size - there's going to be some thermal shock regardless - this would be no worse than what a 1.9D would see with its standard radiator. Maybe if the new one was double the capacity it'd be an issue long term, but I don't think it would be significant in this case.

As an aside, if you guys are building a high performance car with a massive cooling system capacity, do you do stuff like drilling bypass holes in the thermostat? I guess that would help, especially on a fragile tuned lump.
Didn't see that reply.....on the K-series I tend to drop a small bypass hole in the stat body, as thermal shock is one of the issues that kills head gaskets on them.

I was only reading up on this thread to see what the outcome was, as the XU petrol rad is much cheaper than the XUD one and the estate's radiator didn't pass the stopleak test today #-o
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Re: Radiator Differences

Post by citsncycles »

Well it looked identical to the one we took out, and also looks the same (from memory) as the one in Timex, although as that's not the original it's no guarantee!
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