Lower heat shield question Options

[technicalninja]

I've got the beginnings of a performance T4.
I bought a decent 73 2.0 core complete from 914Sixer.
I got a set of 1.8 SSI aftermarket heat exchangers from another member that are also pretty nice.

What I am missing is the bottom tins that go between the heat exchangers and the engine case.

Anytime folks put dedicated headers on a T4 these are left off...

How important are they?

I'm thinking "not much" but I would like insight from others.

Thanks

Rick

[technicalninja]

Awesome replies!

Already altered my thought process...

One I had from the start involves operation at speed.

Because the tins create a reverse cavity to the direction of airflow, at speed...
The airflow under the car should create a low-pressure area at the rear exit of the lower tins and actually increase airflow through the cooling system.

The fact that the tins should ALSO be thought of as bracing for the stupid long exhaust system is just GRAVY that I flat assed over-looked...
These attach to the outer shells. Might rattle like a bitch without them.

This is a street car so being able to handle heat directly under the engine WILL be important. "Mc Donalds drive through test" will be one of its targets.

Sure, it probably will not be a huge difference and I should be able to put the car through it's preliminary resurrection but I'm leaning "requirement" now and maybe "improving" as well.

Hey Wonki, your post regarding vapor lock with the T4 in another thread started a whole new line of thinking for me...
Has anyone tried "after-cooling" with a timed fan to improve heat soak issues with the 914?
Seems stupid simple to me. It would need to feed the magnesium housing.
Lots of stuff used aftercooling systems which actually tended to work quite well...
You need just enough air to overcome "stagnate" to vastly improve cooling after shut down.

Thanks for the replies again!