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Exhaust making help


cute wee gem

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I've started buying all the bits to make an exhaust on the Gemini. But not 100% sure how I want to do it. Here's a sketch.

exhaust.png

What are your thoughts on flexi and muffler placement, and what type/brands of muffler/s I should use? Should I just have one flexi joint after the dump and WG or one for each?

I'd prefer to just have one muffler at the very back, as there is bugger all room under the car due to lowness, so a glass pack/coby type would be the only option if I must have one in the center, but I can fit something larger at the rear. Would it be illegally loud with no mufflers at all?

I'd also rather not be able to see a massive muffler at the back, and just have a 2.5" pipe dumping under the valance

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My crown is rolling without a flex, which is probably why it keeps cracking. They aren't essential, but are a good idea for low cars as your exhaust will still probably hit on judderbars etc.

Mufflers closer to the engine have a better effect and will reduce the higher pitched 'bark' kinda sounds that lots of shitty 4cyl ricers have with their fartcannons right at the back.

As for type etc, I dunno.

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If yoou could get a flexi resonator? then thats two problems solved in one and would save you some coin as you could run it just by passenger footwell and eliminate both ya first red and your two blues from pic.

Turbo cars usually have a quieter system but can get tractor sounding. If your Gem is like my Chevette then the cutout for the rear muff is right at the back and kinda short but wide? I think Im gonna cut mine out a bit longer so ya cant see muff as easy from rear as you say.

Im looking at building chevette system atm also but have just decided to pay instead as it was only going to be $150 more to have someone build it for me. I priced up a 2" system from Steel & Tube trade price if you wanna know pricing, I assume youll be running larger than 2" though.

Is your exhaust start on drivers or passengers?

Gaz

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Exhaust starts on the passenger side, exits on drivers. I'd be keen to hear what yours has cost, I never bothered to price one up personally as I like making stuff :D

flexi 2.5" = 50

WG flexi = free

Flanges = free

3m 2.5" tube = 100

2.5" mandrel bend "combo" = 115

209886489_full.jpg

Only thing I haven't got are hangers and a muffler/s, as I'm not sure what to use yet.

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My crown is rolling without a flex, which is probably why it keeps cracking. They aren't essential, but are a good idea for low cars as your exhaust will still probably hit on judderbars etc.

Mufflers closer to the engine have a better effect and will reduce the higher pitched 'bark' kinda sounds that lots of shitty 4cyl ricers have with their fartcannons right at the back.

As for type etc, I dunno.

Had the same problem with the Gem's old exhaust, it cracked the extractors a few times from cunty driveways so decided I'd try a flexi this time. I might jump under it today and see if I can fit a muff up front somewhere, I think a coby would be the only option though.

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gemini has a raised piece of floor under passenger seat for muffler placement,

i'd put it there, a flowmaster or something similar would be the best bet as they are availible in similar size to that cut away in the floor, then crossover behind the handbrake assembly and up over the diff using factory hangers.

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^^ its a pretty small cutout though isnt it, my Chevette is anyways?

My system also runs from passengers. Going to crossover on 45° basically at gbox tailshaft (was thinking to try fit a bullet type resonatoor in on the angle). Crossover should be complete before handbrak cables. Then running back over the diff and out as normal.

Where is your fuel line crossing over? Mines going over at the gbox xmember.

Will confirm prices I wrote down tomorrow as can only remember off top of head.

5m of 2"x1.6mm = $60

2" mandral donut = $55

Flanges = $10

All +GST

Gaz

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how quiet do you want it?

ive built several exhausts, having the most effective muffler at the end of the exhaust gives it the 'smoothest' sound, having a long unmuffled tailpipe makes it 'cackly'

stainless dumpy mufflers or your typical cannon mufflers are shit, unless its a flash high end japanese brand.

having a turbo helps shut it up a lot, and 2.5" instead of 3" will also be good for not being stupidly noisy.

if you want it reasonably quiet, a coby in the middle and a super-turbo style triple pass muffler at the back would be my suggestion

my car has a 3" system with a big ish stainless packed straight thru muffler under the rear seat, then a long coby just before the bumper, and thats reasonably quiet for what it is

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if you want it reasonably quiet, a coby in the middle and a super-turbo style triple pass muffler at the back would be my suggestion

my car has a 3" system with a big ish stainless packed straight thru muffler under the rear seat, then a long coby just before the bumper, and thats reasonably quiet for what it is

This is good to hear, I imagine your car would make a fair bit more noise than mine too. If I try a single muff first, would a stainless packed job be better than a coby?

I don't want it factory quiet, but I don't want it to be too loud inside the car either. I think it'll just end up trial and error

I can't really remember exactly where the fuel lines cross, Gaz. IIRC it's at the gearbox crossmember like yours

deff roll a WG flexi also

Will do!

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i dont know wether stainless is better from a noise reduction view but it would last longer. the bigger the better though- the larger the muffler,( body size not pipe diameter) the more packing it has and the better it can absorb the noise.

i tested mine when i replaced the muffler, it had a flowmaster 50 series on it which turned out to be too restrictive, the stainless one is oval, 3''perf tube inside, with just a kink in it, you can see right thru it. it was exactly the same with both mufflers.

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Just had the exhaust done on my Gemini. 2 1/2 inch mandrel bent system. Has a 14" bullet style muffler at the front (the biggest i could comfortable fit in the cutout under the drivers seat) and a large flat oval triple pass muffler on the rear. Only problem is the rear cutout isn't very tall and i can see most of the muffler from the rear. Doesn't look right. Im most likely going to cut the floor and raise it up to get the muffler sitting right. Im hoping it wont sound too loud. Thinking back i probably should of done it in 2" instead of 2 1/2.

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Does anyone agree that stainless muffs sound differant or am I dreaming? I had one in the Cortina and could swear it was kinda tiny sounding, oh wait, was that the pinto?

lol

Gaz

stainless is hard and nasty and pretty and shiny and in theory reflects more of the higher frequency's that mild absorbs/dulls

hence why alloy muffs are most effective

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