Originally posted by DemonSVT:
I think a "small" phenolic spacer between the LIM and UIM would be beneficial for one reason. Heat barrier.

Also if you incorporated a way to precisely mate to UIM and LIM together it would almost be a "must buy" for every Duratec user.


As for making it a "large" spacer. Hood clearance is already at a premium (I.E. no room) and you also would be lengthening both primary and secondary runner (lower, smaller powerband) if it were not.



Let's not forget that the o-ring style gaskets with the plastic spacer that 'already' comes with the intake qualifies as a heat barrier.

However I have to cast doubt on the benefits of just a spacer. The trouble with heat is that it warms up everything around it through convection, conduction and radiation. The spacer only works with conduction and then it only slows the rate of heat conduction it doesn't stop it.
This really is the answer to why it is a waste of time....the temperature in the lower intake would have to have rapid and large changes, and I really do mean very large and very rapid changes in very short time periods for this to be somewhat effective.

When the engine is 'warmed-up' all the components are running at operating temperature which means for the most part they are equal in temperature OR they are running at a steady-state of heat exchange as per the coolant flowing through the heads and block pulling heat out of the cylinders.
By this time the intake is already equalized to a certain temperature. A phenolic spacer will not lower the ultimate temperature of the manifolds! They will all be the same temperature, plastic or aluminum. If there were sudden spikes of temperature in the lower intake manifold of say....100 degrees or more within 1-2 seconds then I'd say OK, put in a better spacer. But that doesn't happen, especially in a liquid cooled motor.

Also, if it comes to it, you would put the same theories to work in reduction of heat flow that you do in the building of a simple Thermos.
Low thermal conductivity and VERY LOW surface area between the parts that make contact.
The small suface area of contact does more to limit heat flow than making it of pure styrofoam; hence why my all stainless steel vacuum thermos keeps liquid hot all day even though it isn't made of plastics!!!!

*******Demon this isn't pointed at you but for anyone who cares to read it.

One other thing, having plastic intakes does nothing for keeping the heat down. They do have a lower thermal conductivity so they should reduce the overall amount of heat that is transferred to the incoming air stream. It is less of an issue the faster the air speed is so at higher rpm it will be less beneficial.

Again, there is a big difference between thermal conductivity and the actual temperature of the objects in question. Bottom line is a spacer between the intakes will not do much if at all. A spacer between the heads and the lower intake will still do little more than the existing plastic gasket already does.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black