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

[914werke]

so long as you have good sealing around the engine bay tin apron the lower guides are not in my opinion necessary.

others will say they are.

Including VW/Porsche engineers. (IMG:style_emoticons/default/happy11.gif)

[wonkipop]

so long as you have good sealing around the engine bay tin apron the lower guides are not in my opinion necessary.

others will say they are.

Including VW/Porsche engineers. (IMG:style_emoticons/default/happy11.gif)

don't disagree. but its the why of the engineers putting the guides in that might be of interest.

i know what you are saying.

what i observe is that sitting still idling the flanks of my car get very hot.
that exhausted cooling air goes straight down without the guides.
and then tends to collect in the zones around the edge of the engine.
like where the fuel pump is.
the tops of the rear wheel wells and the trunk floor.

back in the 90s i recall doing a comparison with a mate of mine who had a 73 2.0 with the guides. i was curious about it then and thought i should get hold of some guides.
the difference we found was his trunk floor got hotter than mine. the tops of the rear wheel wells and fenders got about as hot. and the flanks on the side of the car did not get as hot.

the guides do something. don't disagree. they guide the air to an area the original engineers thought was less negative to the fuel line and pump.
but they don't guide the air out from under the car. it still pools in a big heated bubble under the trunk.

the guides are an adaption of an element that definitely did do something on rear engined VWs. on a standard VW they guide the air right out from under the car completely. its a little bit of a different problem in the same engine in the mid mount location. and if you ask me the same engineers never really cracked it.

the heated air pooling under the car only happens when you have the car sitting still in traffic. its not a problem when the car is moving.