DIY Fiberglass intake/plenum.

[Robert McGhie]

Mikey B Sorensen wrote:
> 
> Well, there has been a lot of discussing of what materials to use when
> making a DIY intake/plenum.
> Now, I have some questions:
> 
> 1.  Will then fiberglass crack when it is torqued down on the block
> (V8)???, should one 'cast' in a 1/4 metal piece where the manifold is
> being torqued down to make it ridged???
> 
> 2. Will engine Oil and/or Coolant attack the fiberglass.  (some engines
> requires hot coolant through the manifold)
> 
> 3. Is it possible to paint fiber glass?? and with what???
> 
> 4. Will the fiberglass expand the same rate a cast engine block.. If not
> is there any specific gaskets to prevent leakage??  What I'm trying to
> say is.... IS IT A PROBLEM??.
> 
> 5. Lastly.. Which kind of resin + fiber mat should be used.. Brand &
> where to buy??.
> 
> Thanks in advance..
> Michael Sorensen
> 
I will attempt to answer some of these questions.

It is possible that the fiberglass laminate may crack if it is torqued
excessively. However, remember that most pleasure craft are made of
fiberglass and that engines and drives are bolted to these hulls without
breaking the laminate. A sleeve to limit the amount of compressive
forces on the laminate may be appropriate if you have a tendency to over
torque.

Many boats have fiberglass fuel tanks, so I doubt that oil or coolant
would be much of a problem. Exotic fuels such as nitromethane are an
exception.

Fiberglass boats are painted all the time. Any automotive finish should
be OK.

As far as expansion, I am unaware of the coefficient of thermal
expansion but it should be noted that cast iron and aluminum are quite a
bit different.

Most boats utilize polyester resin because of its lower cost. However, I
think the primary issue is temperature. If you read about the many
fiberglass aircraft, you will soon discover that the recommended color
is white. The reason being to limit the temperature because the
laminates loose their strength if the temperature gets to high. I
believe that this loss occurs somewhere around 275 to 300 degrees
Fahrenheit. Maybe someone with more knowledge would like to expand.

Robert