Johnny G Pipe

Mine are largely rusted out, especially on the cat side. Car seems fine:

Do they:
1.Protect surrounding components from engine heat?
2.Prevent cabin from getting too hot? My cabin gets hotter than my other cars in summer, but surely that's down to the big motor and oil lines mainly?
3.Optimise air flow to cool the engine? (doubt this one)
4.Protect the plugs/ other engine bits from road crud?

Indycam

Ola Johnny G Pipe
Some heat shields keep the heated cooling air from being pulled back into the cooling fan .
Keep the dirty / wet air from under the car from being pulled into the engine compartment .
Keep the cat from cooking the wires , valve cover ...

Cupcar

Quoting the Porsche literature on the subject from the introductory literature for the Carrera 4 in 1989.

Next to a photo of the engine paneling it says:

"Engine Paneling

Engine paneling is new. The underside of the car is paneled in plastic in order to reduce the reflection of noise."

So they are not "heat shields", they are "noise shields"

springer3

That may be true of the under tray panels. The heat shields near the exhaust manifolds protect the engine's cooler components from the heat radiated from the red-hot exhaust. You can buy relatively inexpensive radiant barrier heat shields from Pep Boys and other parts houses. I keep my heat shields in good repair. Heat kills!

Dunasso

1) Under trays - Plastic protective guard

2) Heat shielding - Stainless exhaust shielding

3) And cooling tin - metal schrouding of engine compartment

These three things have very different objectives.

1) The under trays, reduce rebound sound and air turbulance under the car. They also protect the engine and covered parts from road debree. "Some throw it out, but I feel its purpose is justified"

2) The heat shielding stops radiant exhaust heat from overheating other engine and body parts that may otherwise deteriorate or even possibly catch fire due to the excessive heat produced by the exhaust. "Important, do not discard"

3) The cooling tin, Keeps the hot air that is blown down from the cylinders and cylinder heads from being recirculated back though the cooling fan. This ensures a consistant application of cool air to these vital components. "Do not discard this is important stuff and so is the engine bay gasket"

Duncan

Johnny G Pipe

Thanks for setting me straight! I was mainly referring to the shield between the cat and the engine. I see now that too much heat from the cat section is probably getting into this space, and will over time shorten the life of the wires and seals and stuff on that side - even though engine oil temperature is maintained at normal levels overall. Is that right?

I remember being told that missing shielding allows salt and dirt onto your plug leads etc., and I can see how that would happen too.

I'm interested in looking into replacing this section with proprietary heat shielding - looks pretty easy to do without dismantling anything. I'll do some research for a UK source - the Porsche parts are eyewatering, from what I remember - 600 quid for the full set, or something like that..

Graham L

when i had my recent rebuild i ended up paying around £600 for the full set.