Why put the air intake over the exhaust manifold?

[Denzil68]

Hi,

Its an accepted fact that engines perform better with cold air intakes.

So why do a lot of older cars, such as the Ford Fiesta have air intakes with the feeds directly off the exhaust manifold?

Some older cars, Toyota 1000 for example even had a summer and winter setting allowing you to point the inlet at the manifold in winter time?

Ive never understood the point?

 

[timtheenchanter]

to warm the engine up quicker, and help cold starting.

they only run better with cold air once up to a good running temp.

the olsest is the manual type you mention, which needs swiching at the appropriate time of year, the newer version changes accress when the engine temp is up.

 

[Burnerman]

Only really necessary on carburetted engines - an exhaust take off used to be fundimental in preventing carburettor icing. This also used to be an issue on single point fuel injection, where the spray of fuel was present in the atmosphere.
Today, it may help the warm up time, as suggested.
John

 

[TicklyT]

Some engines were designed with part of the cooling system running through the inlet manifold to heat the induction charge.

Most induction systems drew in air that had already been pre-heated by the radiator anyway.

Production cars are designed with reliability in mind, sacrificing a little performance to achieve it.

Manufacturers could probably gain a bit of performance by doing away with all these bits and pieces, replacing them with an ex-works mechanic kept in the tool kit to adjust the carburettor fuel/air mixture constantly to compensate for changing atmospheric conditions.