Is the turbo heat-shield really necessary?
 

Just replaced the turbo inlet flange gasket and in re-assembly, noticed that the bolt which holds the bottom of the heat-shield is broken off. looks like the previous mechanic tried to remove it and twisted it off flush with the manifold.
Anyway, it appears that the bottom edge of the shield will interfere with movement of the switching actuator unless it's secured to the manifold.

So, if I'm going to reinstall this item, I'll need to drill and tap the manifold from underneath the car.

Question is, am I asking for heat trouble without this thing in place?

- k -

Not really.

It'll cause a bit more heat in the pass. compartment (slight at most) and cook you hoses and wires, again only slightly.
I've been running my 87 for about 5 years with out it and havent' noticed anything bad at all.

i havent been running miine without it for as long as ^^ but i have been for about 6 months. and so far havnt had any problem (knock on wood)

^I'll be the contrarian and say you should keep it. Do you really want to have cooked hoses and wires? Vacume leaks are a bad thing (petrified tubing), and petrified brittle wire insulation is a really bad thing especially considering the wiring your cooking is what talks to your ECU. There's a reason the Mazda put that shielding there.

I'm at the extream in that I'm running shielding despite I've ceramic coated everything. Over engineering is a good thing.

I've been leaning this way and you make a great point. My previous TII had petrified vacuum lines and it was a nightmare to troubleshoot.

Anyway, there is no way to drill that out while in the car, but I was able to bend the shield until it sits in place without bothering the switching actuator. Not ideal, but it should work.

thanks to all for opinion and experience.

- k -

I did re-wrap my wire harnes though.....

I really do want to re install mine, just too damn other things to do first.

they do help and its very simple why. the turbo is located sooo close to the lower intake manifold that even tho the shield may not do much it will lower intake tempatures by a fair bit. this being said you will not see any preformance from this but, it will help out the car. also it does keep your motor temp a few degrees cooler

If you have ever opened your hood after a hard run at night, you will see why the heat shield is there. The turbine housing will usually be glowing orange from the heat and as rx-7_obsessed stated it is extremely close to the LIM.

Do you really want that much radiant heat being exposed to the LIM? The gasket and water passage o-rings do not like heat and will become brittle. Increased IATs lead to knock, and knock leads to a rebuild.

My heatshield was not salvageable during the rebuild so I wrapped the manifold, put a blanket on the turbine housing, and wrapped the downpipe. PROBLEM SOLVED. Under the hood is now noticeably cooler :) Did it increase the performance? I can't really tell a difference, but I'm sure I've increased the durability/reliability.

Vince

Yes, the heat shield is necessary. In the case of the bottom shield, the engine mount will be baked without it and fail every few years. Now the annoyance of course is fixing up the shield, because in order to do this, you need to remove the turbo and manifold assembly.

the manifold shield also protects the lower turbo coolant hose from radiant heat. the turbo shield is absolutely necessary. giving all that radiant heat free reign in the engine bay is just asking for higher temps all around.

The heat shield on mine broke at the weld holding the bolt tabs to the shield. I definitely noticed a difference with that gone, everything on that side of the engine was hotter. I'll be replacing it while doing my rebuild. Like everyone has said, I don't like the idea of adding more heat to 20 yr old parts.

So what about engines with upgraded turbos and mani?

Any sort of heat management is a huge part of keeping a rotary reliable! I've got a heat blanket, and a lower intake manifold heat blanket. I've got heat shilding on all my wires that run close to my turbo area and I'm sure my motor and wires are happy campers for that.

Heat wrap everything.

I have two layers of heat wrap on my downpipe, two layers on my manifold, and a nice PTP turbo blanket on the turbine. At some point I'll be making a lower intake manifold shield and a frame rail shield (to deal with the brake and heater lines in that area).

It's easy to tell cars that are run without heat shields because all the underhood rubber turns rock hard. Just imagine what it does to the wiring harness which runs past the turbo.

Yeah completely forgot about that, heat wrap is your friend! As well as ceramic coating. I've got my lower and upper intake manifold ceramic coated as well as my hotside to the turbo and manifold. I'm changing to a fully divided manifold now and a different turbo so I'll either get these parts ceramic coated or just use a crap ton of heat wrap and of course the turbo blanket.

edit: at the risk of sounding like a noob... Woot 10,000 posts :)

as stated above you should heat wrap your turbo housing at the minimum also if you have a down pipe wraping that would be a good idea.....to sum it up my car did not have a heat sheild it was missing...when it rained the water would literaly boil and run off the hood after a sprinted drive....this no longer happens

The heat shields are not only there to reduce harmful underhood temps, also keep in mind that the energy that acts upon the turbine wheel is not solely from exhaust velocity, but also from heat energy (molecular acceleration) therefore the shields should help contain some of the heat at the turbine housing. Ever notice that extra lag on a cold engine vs a fully warmed one?

Make it look like you are cooking a chicken!!

Before running into this thread I had planned to simply bend some metal to fit and possibly insulate it similar to the OEM shield.

I'll do some research when time permits, but is exhaust wrap a good choice for a stock S5 turbo and RB downpipe? Seems like it would be easier to use but doesn't it trap water? Seems like the actual turbo would need to breath as it cools down. Wouldn't water condense between the wrap/blanket and turbo and then be trapped there? If there is condensation seems that a metal shield built around it would be better because it would allow the theoretical water to evaporate. Am I on track here or simply talking out of my ass?

I ordered a Turbo Blanket and Heat Wrap. Also going to try some heat reflective foil for the underside of the stock TMIC.
Going to post my results once everything arrives