I have used quite a few aluminum heads on several different engines and I
will tell you that iron heads will make just as much HP as aluminum, all
other factors being the same, They will save about 40 lbs in weight, but
they will also cost you fuel economy. Iron head motors reach their peak
efficiency around 195 degrees F, where aluminum heads require 215 degrees
optimum water temp for max efficiency. These facts I have deterimed
personally on an engine dyno. This is not second hand data. These
unadvertized facts are due to the difference in heat rejection between iron
and aluminum, hence the difference in water temperature for max efficiency.
Normally this has little meaning, but at the cost of fuel today, should be
consifered. Of course the weight savings of aluminum mitigates the vaue of
the difference slightly, but as fuel cost climbs, this efficiency difference
should now be considered.
That's the sort of info I was looking for.
I'm still getting some oil leakage into my cylinders and was thinking
I may need to replace the valve stem seals and figured I would look
at my options. If I was racing then I may go with the aluminum heads
but if there is really no difference then why spend the money.
I'm also thinking that while I'm having the work done....to replace the
rocker arms with either Viper rockers or some aftermarket roller rocker.
I know it has been done but I've yet to see what the result was from
anyone that has done this.
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