Thread: Correct installation of headers/extractors?

This story has a happy ending.

On Dave's suggestion I took it to a certain exhaust specialist next door to Jaycar in Thomastown. They replaced the dodgy joint with flanges and put in new custom-bent pipes downstream of the extractors, plus a new muffler (the old one was beginning to deteriorate and it wasn't optimised to match the extractors). They did a great job. It's louder than the old set-up. For better or worse it sounds a bit more like a V8 now.

What's really pleasing is the power boost and the smoother responsiveness of the engine from the combination of the off-the-shelf Redback extractors and the new exhaust system. The extractors by themselves were a mild improvement, but together with the matched exhaust it's a quite substantial improvement. I took it for a test drive with my brother, who has a late-model Defender and drove my Series 3 before and after the changes. He was impressed: it climbed a steep hill in high ratio second that it could only manage before in high ratio first, and that was without an adult passenger, a child and a dog on board.

I told the exhaust shop I wanted the sweet spot between too restrictive (too much 'bad' back pressure) and too free (not enough 'good' back pressure, if I understand it correctly). They said 2.25 inch diameter tubes were optimal: any bigger might kill low-end torque. They also advised against a hot dog style muffler (too free) and recommended a baffled muffler, which is freer than the one it replaced yet still provides the necessary back pressure. I went with their advice.
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As for the more grunty engine note, especially on acceleration, I don't mind it but as a family touring vehicle I'll have to do a bit of sound deadening down the track.

Originally Posted by whitehillbilly64

'Roof silicone wont hold'
Experience, or Theory ????
But I agree, the work should have been done correctly.

whitehillbilly

Both, the temperature ratings are on the packaging.

if you use a low temp sealant it can burn through you get a path for the hot gasses and then you have an exhaust leak.

Roof sealant also wont withstand some of the coolants so while, (in theory) you should be able to use it as a waterpump or core plug sealant... its not typically rated for heat, chemical pressure and component creep all at the same time.