18 replies to this topic

[davelh]

Hi Guys,

 

Getting to the real pointy end of things, and needing to get an exhaust.

I am torn!

Not sure if I should go single or twin, and not sure on what size.

I would like it to go over the 9" into a conventional tailpipe(s).

I obviously want to hear the exhaust, but don't want to be a magnet for defects.

I am running Pacemaker VN headers.

What are my options?

 

Cheers,

Dave

[Bigfella237]

I don't think there are any "off the shelf" options, if that's what you're asking. Especially having a diff conversion.

 

If it were me I'd go twin for sure, probably twin 2½" if you're running anything but a standard donk, but it will take someone who knows their stuff to get 2½" tailpipes over a 9" without them hitting on anything.

 

I'm not in Addy but hopefully someone down that way can recommend a decent exhaust shop?

[davelh]

Cheers big fella. Not looking for anything off the shelf, more what I should be looking at getting made. Appreciate the input! I am definitely leaning towards twin, but everyone keeps telling me I should go with single.

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[Bigfella237]

If we were talking about an early Commodore I might lean toward a big single system but a Torana doesn't quite look right with only one pipe coming out the back!

 

As far as volume is concerned, a single 3" pipe is around 116cc's per inch of length (yeah I know I'm mixing inches and metrics, sorry).

 

Whereas a twin 2" system is 103cc's per inch.

 

A twin 2¼" system is 130cc's per inch.

 

And a twin 2½" system is just over 160cc's per inch.

 

So the big single system (which almost certainly wouldn't go over a 9" diff anyway) ain't looking quite so good now!

[gtrboyy]

What engine/trans/diff specs?

 

Mild motor 2 1/2 will suit most setups...if it's a grunter need to be be more careful as don't want it restrictive yet won't want drone in cabin & too loud to enjoy.

[davelh]

355, vn Heads, crane 284 cam, harrop dual plane, holley 650 dp, 9.5 comp, 3000 stall turbo 350 with 3.5 9"

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[gtrboyy]

Pacies with outlet pipe changed from 2 1/4 to 2 1/2 if it hasn't been already...adds torque most engines.

 

Twin 2 1/2 pipes will be fine to 2 mufflers at diff...can go 3" single with resonator/muffler if one fits to sound nicer no drone but twin pipes out back always look cooler.

 

Haven't had an lh/x in decades but lc gtr & early commodores usually end up going under diff plus rear resonator to kill exhaust drone.

 

Tailpipes to extend past bar as have had rear bars resonate off just idle,very annoying especially when sound so nice outside yet give you headache inside after short drive.

[claysummers]

Aldinga exhaust and radiators did mine. Fair price and I’m happy with it. The new proprietor Scotty had to call in old Martin the guru out of retirement though.


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[davelh]

Aldinga exhaust and radiators did mine. Fair price and I’m happy with it. The new proprietor Scotty had to call in old Martin the guru out of retirement though.


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Long way from my house! Probably going to go to everlast as they are close.

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[claysummers]

Yes that is what I did. $50 cash tilt tray.


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[rexy]

Plenty have fitted twin 2 and a half inch systems over 9 inch diffs. The occasional legend has managed to fit twin 3 inch pipes.

The old off the shelf available left and right tailpipes in 2.5 inch fit fine over the 9 inch in my old LX. They were available on eBay a while ago but dunno about now.

 

Flow in tubes is very complicated! Cross section area is only part of the equation.

 

Single systems look wrong in my opinion. Unless it’s going out a side pipe

[Heath]

I wouldn't consider a single system unless it's a side pipe. Idealistically not right for me, even though they are of course a much better weight-to-cross-sectional-area ratio.

 

I went twin 2.5" in stainless. Two magnaflows and I made mine pretty complicated with an expansion-chamber (and balance pipe in one). Seems to be sounding alright but haven't really opened the taps properly yet.

[Bigfella237]

Which reminds me... a stainless system will have a different sound to a mild steel one, stainless seems to resonate more of a crisp crackle whereas steel pipe seems to absorb some of the higher notes.

 

And of course every muffler will sound different as well. If your exhaust guy is obliging you could ask him to try a few different mufflers just to see if you like the sound of one brand or type better than the others.

[davelh]

Cheers Heath. I was thinking of staying with mild steel, not a huge fan of stainless exhausts.

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[Heath]

Which reminds me... a stainless system will have a different sound to a mild steel one, stainless seems to resonate more of a crisp crackle whereas steel pipe seems to absorb some of the higher notes.

Agreed.

And the best Holden V8 that I have heard had a mild steel exhaust.

But if your motor sounds good, stainless will still sound pretty excellent. For me it was driven by aesthetics. Trying to make an exhaust that looked really hot. And I don't regret doing it.

[gtrboyy]

Stainless sound different at first but then after few heat cycles etc they seem to settle down more lecss crackle etc & start sounding decent atleast seemed that way with 2 ls powered utes I had.

 

Reckon mild steel sounds better with thicker walled tubing & good mufflers.

[Cook]

Hi Davelh.  I have a similar setup to you and running 2 1/2" stainless over 9" diff.  It was very restrictive but had a good exhaust guy do the job.  Each to their own but I had the end turned down slightly.  You can just see it in the pic.  I love the sound. Cheers Ron

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[Cook]

Sorry should have mentioned it is a twin system.

[davelh]

Thanks cook! Thinking I will ho for the twin 2.5 inch.

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