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

[rhodyguy]

I don’t think the exhaust systems have much in common. Comparing apples and oranges.

[wonkipop]

I don’t think the exhaust systems have much in common. Comparing apples and oranges.

will try and explain it to you.

if you were lucky (or unlucky in some ways (IMG:style_emoticons/default/biggrin.gif) ) to own a type 3 you would know or remember what i mean. if you took if for a long run where she got nice and hot and then pulled up and did not shut down straight away (as i always religously did - i would let it idle and cool itself down for at least 5 minutes) and then walked around the back and opened the tailgate to get something out (i had a variant) you would find your lower legs got scorched by a stream of very hot air getting feebly squirted out the back just under the muffler. its a vivid memory i have as i hauled my wetsuit out of the back.

thats what the warm air guides do on a standard old rear engine VW. they direct that air out the back and try and get it not to collect under the car when its sitting still.
and quite possibly also inject it out into a low pressure area that is right behind the car when its on the move.

they appear not to have wanted to do this with a 912. not entirely sure why but it might have had something to do with the proximity of the cooling fan inlet grille on the rear deck and the possibility of a loop forming when the car was sitting and running so maybe better to fire it straight down and have it disperse sideways.

when it comes to a 914 i think no matter what they did it was pooling under the car.
engine is too far back from the rear end. when i look at those warm air guides i see the engineers accepting letting it pool hot air under the trunk as the lesser of all evils.
and then installing an insulation pad to combat the heat build up.
but i don't see them ever coming up with a real answer in the end to getting rid of that heated cooling air. even with the guides they used.

i'm not saying the guides are useless or don't do something. i just see them as a half solution to a problem they never really cracked.

hope that makes sense. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/beerchug.gif)

what i have noticed with my 914, living in a hot joint like aus, is that in summer, with the heater dump valves openon top of everything else the car is pumping hot air like a freight train under the car, and if it is sitting still man does it get hot on the sides of the car. and i suspect in the rear trunk too though i rarely open the trunk to find out. but they have a real problem with heat dump no matter what you do. i never notice it in winter. body work never feels hot to the touch. i can't be sure the guides would make things any better. but curious to find out - if someone does have the guides and as going to do a compare and contrast as previous poster said he was thinking of doing.