Materials for heat management

[Alex Hodgkinson]

Last week I installed a dummy engine into my RX-7 in order to figure out where to route all of the pipework and wiring. Attention has now turned to figuring out how to manage the heat around the exhaust manifold/turbocharger/inlet area.





The manifold and turbo hot side will be running at 900-1100 degC, which is normal for a rotary engine.

The inlet manifold sits right above the exhaust manifold and next to the turbo downpipe.

What is most worrying is that the steering column runs about 40mm away from the hottest part of the exhaust manifold and it can't be moved any futher away!

The exhaust manifold has been ceramic coated, as will be the hot side of the turbo and the downpipe which should reduce temperatures by an unspecified amount. I was just given the option to do it when I ordered but does anybody know how effective it actually is?

I'm thinking of putting a sleeve of something which can insulate from heat around the steering column as well as making up a guard to reflect some heat away from it. For the inlet manifold I'll use something like gold reflective foil, or whatever seems to be up to the job as well as also making up a guard for that too. However flicking quickly through a well known demonic motorsport parts catalogue I couldn't see many wraps/coatings/tapes which are rated to that sort of temperature. Plenty which can withstand 1000deg for periods of time or radiant, but I'd really like something which can live with at least 500 deg of direct heat.

What sort of solutions do you use and can anybody point me in the direction for good products for this job?

[phoenix]

There are really three options available - reflect, insulate, convect. A combination of all strategies is probably best.

Although the exhaust is already ceramic coated you could add a insulating external wrap also.

Next, a polished stainless steel reflector would be the first barrier I would suggest as it will easily cope with the heat You could possibly use aluminium if it wasn't fitted too close to the exhaust manifold. Then, on the 'cool' side of the reflector, fix a layer of insulation - the blanket type material is what I use as it can be made into a self-contained 'pad' and then fastened to the reflector without relying on glue, which might not be a good idea at very high temperatures.

Components such as the steering column could be wrapped in the type of 'split' sleeving used to wrap cable/pipes etc.

It is probably better to get a cooling stream of air onto the components on the inlet side than to attempt to insulated them. We did this to the pipe from the intercooler to the plenum and the plenum itself and dropped the temperature of these alloy components by 25 degrees C - too the point where no heat could be added to the inlet charge by them running hotter than the air inside them.

Finding where the air flows in an engine bay is never easy, so some experimentation may be required to get this bit right.

[R59]

I agree with Phoenix. Though that doesn't look like a Chevy LS1/2/6/7 you've fitted there.....

[Notso Swift]

Rotories are heat pigs
Turbos are heat pigs
Turbo rotors are like wild boars!

I use this one of the Turbo blankets, be aware there is a huge range in quality, and exhaust wrap
I found the heat shield to be superflous
That said my car has the turbo mounted forward of the motor (east west 4WD), so I think I would have more natural air flow