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datatrain · Posted: Tue Jan 20, 2009 5:59 am Post subject: Wrapping exhaust manifold pipe

Obviously I have too much time on my hands...

Is there any advantage to putting heat insulating material around the pipe from the manifold to the catalytic. Other than protecting the plug wires from high heat ? I seem to recall quite a few years ago there was panel of material glued to the body near the manifold.

Will it overheat the cat if I do ?

I'm guessing the best material would be asbestos but it's probably no longer for sale. I'm not sure fibreglass could take the high temps.
Thnx
DAve
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

924RACR · Posted: Tue Jan 20, 2009 6:07 am Post subject:

I'd be very concerned about the higher operating temp of the pipes killing them. BTDT with my last header.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Hot exhaust gas flows quicker, which is why folks like to keep heat in the exhaust piping through wrapping, thermal coating etc. Keeping heat in is very important in a turbo motor as it can help lower the spool-up time. Can also play an important role in an NA motor to help scavenge during the exhuast cycle of the engine.

However, if you wrap your header or any exhaust pipes close to the engine, be very, very wary of oil leaks. Even a slow drip can soak exhaust wrap over time. Heat + oily cloth = BBQ.
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1987 951 - M193 Version for Japan

Rich H · Posted: Tue Jan 20, 2009 8:50 am Post subject:

If you like not itching then I would give it a miss...BTDT
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Ceramic coating is the way to go IMO.
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erstwhile owner of just about every 924 variant ever made

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

I've been told the exhaust will corrode way faster when it's wrapped in material... didn't get any explanation though...
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

Rich H · Posted: Wed Jan 21, 2009 7:57 am Post subject:

A bigger problem as has been mentionned is the heat, the manifold stays hotter and for longer than it normally would which can mean cracking. Also remember that heat that could not escape is now being shunted further down the system so more of the exhaust gets hotter too.
_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

pocketscience · Posted: Wed Jan 21, 2009 7:59 am Post subject:

924RACR · Posted: Wed Jan 21, 2009 10:58 pm Post subject:

My racecar saw the wet maybe once or twice with the last header (which was wrapped and failed within 2 yrs). It was the excessive heat buildup that killed it; pipes split, and the metal was scaling away, not corroded.

The manufacturer explicitly recommends against wrapping, BTW.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Rich H · Posted: Wed Jan 21, 2009 11:02 pm Post subject:

In short, don't do it...

_________________
1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

datatrain · Posted: Thu Jan 22, 2009 8:16 am Post subject:

You guys all convinced me it's a bad idea.
Thnx
_________________
'78 924 NA with Collector plate
33 year old car, with me for 21 yrs
Mint '92 318i BMW
Near mint '98 Buick LeSabre
VE7HFR

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

well... you wrap the pipes because you want a higher temperature in the exhaust, but that same thing will kill your manifold..

easy choice

I've got a manifold in which the barrier between the 2 banks has vanished... I guess it's a combination of a lean mixture and wrong ignition timing.
_________________
"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment