Exhaust Spinifex Fires

Submitted: Wednesday, Aug 26, 2009 at 15:30
ThreadID: 71801 Views:2887 Replies:7 FollowUps:8
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G'day all,

Would it be fair to say that an after market exhaust on my petrol 4.8 would be less prone to spinifex fires due to no heat shields being used like the factory systems.

I am looking at changing my original exhaust with a 3' stainless system which then just leaves the Catalytic convertor heat shield, so for this I'm thinking of wrapping with muffler bandage.
Has anyone done similar or is it a WOFTAM
Any thoughts on this appreciated

Cheers


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Reply By: Member - Gary J (NSW) - Wednesday, Aug 26, 2009 at 15:39

Wednesday, Aug 26, 2009 at 15:39
Ingo,
SOMEone's going to nail you regarding the 3 foot exhaust system. It's gunna take a LOT of muffler bandage!
AnswerID: 380558

Follow Up By: Member - Ingo57 (NSW) - Wednesday, Aug 26, 2009 at 16:25

Wednesday, Aug 26, 2009 at 16:25
hahaha Yes its already started......


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Follow Up By: Member - Timbo - Wednesday, Aug 26, 2009 at 18:52

Wednesday, Aug 26, 2009 at 18:52
Oh, I thought it was a 3 minute exhaust system...
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Reply By: Member - Allan B (QLD) - Wednesday, Aug 26, 2009 at 16:21

Wednesday, Aug 26, 2009 at 16:21
Hey Ingo,

Ya gunna need a helluva suspension lift to fit that 3 ft exhaust system.

But, Boy, what bragging rights!


Cheers
Allan

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AnswerID: 380560

Follow Up By: Member - Ingo57 (NSW) - Wednesday, Aug 26, 2009 at 16:39

Wednesday, Aug 26, 2009 at 16:39
go on kick a man while he's down why dont you...LMAO

Bragging rights, Imagine how many car alarms youd set off in the underground carparks with that sucker!

OK OK OK 3"



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Reply By: Gossy - Wednesday, Aug 26, 2009 at 16:44

Wednesday, Aug 26, 2009 at 16:44
A petrol bang is still a petrol bang. It will be hot :)

Unless you plan on covering the whole mufller pipe then the same risk is there (BTW the bandage does increase rust issues).

Cheers,
AnswerID: 380563

Follow Up By: Member - Ingo57 (NSW) - Wednesday, Aug 26, 2009 at 16:55

Wednesday, Aug 26, 2009 at 16:55
Agreed Gossy however I was under the opinion that its the the build up of resin from the spinifex which gets caught/jammed under the heatshield which causes the fire, not so much as the spinifex touching the exhaust.

Good point on the rust didnt think of that.


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Follow Up By: Member - MUZBRY(Vic) - Wednesday, Aug 26, 2009 at 22:21

Wednesday, Aug 26, 2009 at 22:21
Gday
No rust on a stainless system.I could be wrong, i was once before on 2.5.71
Murray
Muzbry
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Reply By: OzTroopy - Wednesday, Aug 26, 2009 at 17:43

Wednesday, Aug 26, 2009 at 17:43
The main heat offender is the govt required catalytic converter.

Making up a new catalytic converter heatshield that can be easily seperated for cleaning is my next project after the new exhaust goes on.

Till then I'll just keep the gloves handy as usual.
AnswerID: 380569

Reply By: Member - Mick O (VIC) - Wednesday, Aug 26, 2009 at 18:13

Wednesday, Aug 26, 2009 at 18:13
Ingo,

the fact that it is a Petrol unit increases the risk factor but then I'm sure you know that. I'd say that the exhaust system will make little difference, it's a matter of identifying just where the undergrowth gets caught up and dealing with that. Nothing substitutes for a regular check of the undercarriage and exhaust while you're on the track. That can be every 15 minutes depending on scrub type, thickness and just how much gets caught up underneath the vehicle. That and having a water based extinguishing system available as well (I use a 5 litre garden sprayer which sits ready for use in the rear wheel bag).

Cheers Mick
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trip would doubtless be attended with much hardship.''
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AnswerID: 380573

Follow Up By: Member - Ingo57 (NSW) - Thursday, Aug 27, 2009 at 14:09

Thursday, Aug 27, 2009 at 14:09
Mick

After lying under my car looking at the exhaust, the heat shield and cat seem to me like the two main offenders.
Agreed periodic checks and water sprayer is mandatory however would like to calm the nerves a bit when driving through the stuff, by the responses I guess my theory is a bit of a woftam and being paranoid about it is probably the best precaution.


Cheers


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Reply By: Robin Miller - Wednesday, Aug 26, 2009 at 21:47

Wednesday, Aug 26, 2009 at 21:47
Actually I thought it would go the other way INGO

The outer shield and its much lower heat radiation is a reason I have kept mine.

The aftermarket ones can be bad news , the radient heat emission is a killer , I even had one melt the inner of the coax aerial cable on my previous GQ.

The cable was inside the car but touching the firewall in front of the passenger seat.

The aftermarket Genie system I used also caused a lot more noise than the double walled system.

So I then wrapped it up it heatshield tape , this wasn't easy to do but I got there with lots of wire ties to hold it in place. (Its also expensive stuff)

Anyway , it then worked fine until a wet Simpson trip during which time salt laden mud got into the heatshield tape , it got baked in by the exhaist heat and pretty soon corroded out the headers and that was that.

If I was to get another I wopuld at least go for the enamelled version.
AnswerID: 380619

Follow Up By: Member - Ingo57 (NSW) - Thursday, Aug 27, 2009 at 14:01

Thursday, Aug 27, 2009 at 14:01
Robin,

My thoughts behind the heat shield is that the spinifex resin will build up on the edge of the heatshield and will continue to build up until the gap has been closed, then the resin has constant contact with a hot exhaust... after all the distance between the the heat shield and exhaust isn't much.

Was talking to a fella once that had a fire under his LC100 4.5 from spinifex, he was lucky enough to have his mate behind pick up on it and they extinguished the flames with water guns before to much damage was done.

His Inspection after the event when all was calm showed a build up of resin in 2 places.
one being the front flange of the cat converter and the other at the front edge of the exhaust heat shield.

My thoughts were If it is just brushing along the smooth exhaust this would be better than the grass hitting the edge or corners of tin and flanges creating/forcing more of a build up




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FollowupID: 648103

Follow Up By: Robin Miller - Thursday, Aug 27, 2009 at 20:09

Thursday, Aug 27, 2009 at 20:09
Hi Ingo

On my car the heatshield is finished off pretty well and there is little capacity for it to hold spinifex. The manual 4800 has a less complex cat convertor system and also does not have a down stream OXY sensor.

The main place it would gather I think is were the gearbox support member goes under the exhaust. A couple of breather hoses there would probably catch it.

Whereas a raw exhaust pipe can get hot enough to cause instant ignition at low speeds. On my previous Genie system you could even see it glow dull red on occasion.

Hence I reccomend that if you go down that path that its at least coated.





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FollowupID: 648142

Reply By: Rut Tearer - Thursday, Aug 27, 2009 at 11:18

Thursday, Aug 27, 2009 at 11:18
A better solution than muffler and exhaust bandages would be High Performance Coatings inside and out of both the exhaust and headers, this reduces heat dramatically and looks great as well.
AnswerID: 380686

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