If you made two engines identical - apart from one having ally block and
head while the other cast iron - which would warm up fastest after a cold
start?

--
*I started out with nothing, and I still have most of it*

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
If you made two engines identical - apart from one having ally block and
head while the other cast iron - which would warm up fastest after a cold
start?

Air or water coooled?
Aluminium is a better conductor of heat, so presumably the coolant used
for the ally block would would warm up quicker. But if they were
air-cooled engines, heat would be lost quicker to the air from the ally
block.

http://www.engineeringtoolbox.com/th...als-d_858.html

In article ,
Willy Eckerslyke wrote:
Dave Plowman (News) wrote:
If you made two engines identical - apart from one having ally block
and head while the other cast iron - which would warm up fastest after
a cold start?

Air or water coooled?
Aluminium is a better conductor of heat, so presumably the coolant used
for the ally block would would warm up quicker. But if they were
air-cooled engines, heat would be lost quicker to the air from the ally
block.

http://www.engineeringtoolbox.com/th...als-d_858.html

Water cooled. My experience of ally engines says they are slower to warm
up. Of course newer ones will have a much lower water content than older
designs and many newer designs use some if not all ally. Hence the
theoretical question.

--
*A conscience is what hurts when all your other parts feel so good *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:

If you made two engines identical - apart from one having ally block
and head while the other cast iron - which would warm up fastest after
a cold start?

Aluminium is a better conductor of heat, so presumably the coolant used
for the ally block would would warm up quicker. But if they were
air-cooled engines, heat would be lost quicker to the air from the ally
block.

http://www.engineeringtoolbox.com/th...als-d_858.html

Water cooled. My experience of ally engines says they are slower to warm
up. Of course newer ones will have a much lower water content than older
designs and many newer designs use some if not all ally. Hence the
theoretical question.

I suppose there could still be a large degree of air cooling going on,
even with a water cooled engine. So even if heat is conducted quicker
into the coolant, this is balanced by more heat being lost to the air.
Or something...

On Wed, 03 Feb 2010 11:28:14 -0000, Willy Eckerslyke
wrote:

Dave Plowman (News) wrote:

If you made two engines identical - apart from one having ally block
and head while the other cast iron - which would warm up fastest after
a cold start?

Aluminium is a better conductor of heat, so presumably the coolant
used for the ally block would would warm up quicker. But if they were
air-cooled engines, heat would be lost quicker to the air from the
ally block.

http://www.engineeringtoolbox.com/th...als-d_858.html
Water cooled. My experience of ally engines says they are slower to
warm
up. Of course newer ones will have a much lower water content than older
designs and many newer designs use some if not all ally. Hence the
theoretical question.

I suppose there could still be a large degree of air cooling going on,
even with a water cooled engine. So even if heat is conducted quicker
into the coolant, this is balanced by more heat being lost to the air.
Or something...

Thermall Capacity of iron's .46 KJ/kg, thermal capacity of aluminium is
..91, but engine blocks tend to be similar volumes rather than weights and
allys a1/3 of the density. But given ally's 3 times as conductive I
suspect the whole engine warms up evenly, in a cast iron engine the
coolants heated in the head faster than the block warms up.

--
Duncan Wood

On Wed, 03 Feb 2010 11:28:14 +0000, Willy Eckerslyke
wrote:

Dave Plowman (News) wrote:

If you made two engines identical - apart from one having ally block
and head while the other cast iron - which would warm up fastest after
a cold start?

Aluminium is a better conductor of heat, so presumably the coolant used
for the ally block would would warm up quicker. But if they were
air-cooled engines, heat would be lost quicker to the air from the ally
block.

http://www.engineeringtoolbox.com/th...als-d_858.html

Water cooled. My experience of ally engines says they are slower to warm
up. Of course newer ones will have a much lower water content than older
designs and many newer designs use some if not all ally. Hence the
theoretical question.

I suppose there could still be a large degree of air cooling going on,
even with a water cooled engine. So even if heat is conducted quicker
into the coolant, this is balanced by more heat being lost to the air.
Or something...

The RV8 in the _back_ of my camper (not much air cooling there) is very
slow to warm up; that's an ally engine.
--
asahartz woz ere

In article ,
asahartz wrote:
The RV8 in the _back_ of my camper (not much air cooling there) is very
slow to warm up; that's an ally engine.

Yes they are. But of course it's an old design with large water capacity.

--
*Those who get too big for their britches will be exposed in the end*

Dave Plowman London SW
To e-mail, change noise into sound.

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Duncan Wood"
saying something like:

Thermall Capacity of iron's .46 KJ/kg, thermal capacity of aluminium is
.91, but engine blocks tend to be similar volumes rather than weights and
allys a1/3 of the density. But given ally's 3 times as conductive I
suspect the whole engine warms up evenly,

Which is right, ime. Ally heads and blocks distribute heat better and
alleviate hot spots. As which actually warms up quicker overall, I've
known both of equivalent sizes to warm up at pretty much the same rate,
but it's all down to age of the design and the cleverness involved. For
decades now, thin-wall CI blocks have been taken for granted and they
tend to warm up a bit quicker than traditionally thick castings. Overall
though, I'd say ally warms up quicker overall (ie, the heater works more
quickly), but CI warms up the combustion chamber quicker - and that's
just down to the conduction factor.