Consensus on home hacked up downpipe

[Andy_Mac]

Wanting to try up the boost on my setup to get a bit more power. Problem is for the JDM Legacy's catted downpipes come in at well north of $1500. So wondering how povo I can go and still be worthwhile.

Would it be beneficial to cut open the wastegate side of the original downpipe, open up the flange hole as wide as possible and merge it into the main section?

Suppose doing work like that has the potential to mildly warp the flange so may need to be resurfaced afterwards?

Also would keeping the stock cat/cats diminish any gains this may have

[boon]

The turbine volute on a Legacy turbo is TINY. It's like the size of the wastegate port. A little bit of porting and pipe changes aren't going to make a difference that's worth the effort.

As long as there's a factory cat there the whole DP is a choke point, if you want a povo way of making it a whole lot better cut the cat out and replace it with pipe. If you want it to still look normal, put the bulgey heatshield back on when you're done.

[Marky]

^^ What he said

Cut the cat out of it and you'll get some junkyard gains for next to no cost

Can either cut the pipe and use a bashing pole to hollow it, then weld the pipe back on

Or make a flap in the side of it and again, get out the bashing pole and weld back closed

This is assuming you have a bashing pole as part of your toolbox, it's filed in mine next to the cable ties and knead-it

I encourage this sort of carry on wholeheartedly and most mechanics would do it for a box if you ask nice

[Andy_Mac]

Might just give that a shot then. Given up on the idea of saving up for a real one, many many things i would rather spend 1500 on.

So having the wastegate bleeding straight up against a flat plate won't be all that detrimental in this case since there isn't all that much flow anyway?

I'm sure my massive breaker bar used for snapping bench vice's will do the trick of smashing up a cat.

[lachlan]

I cut along the edge of each end ans along one side . Fold it open and jus pick the pieces out . Weld it back up . Take the pieces to the scrappy . Get a minimum 20 dollars . And dont have to smash up and clean up and breathe that crap in .

[Andy_Mac]

Do you really get that much for cat innards? I thought they were some sort of ceramic material?

[Rosssub]

Have you got an aftermarket boost controller? Or will you get a tune? Or fit a slightly bigger restrictor pill in the WG hose?

De-catting my primary DP when TT made it boost spike to over 20psi.

[Andy_Mac]

Thinking about gettig a retune done. Just feels like it needs a bit more go than it got from the last tune.

Used to hit high 18s with whatever weird tune it had on it when i first got it. Tamed back to below 16 currently.

[lachlan]

some places price them on weight or size . other just a flat rate . there is big business in recycling them . they have platinum in them . its pretty hard to extract on a small scale at home though

http://www.metalcorp.co.nz/pricelist.php check under "other"

[McDoof]

Andy. Ask Matt to do you a base tune. He can email you the file. If you don't have tactrix then I think Daytona lives in Tauranga. I'm sure he'd lend it to you for loading up a tune. Otherwise if you're in Auckland at some point I can load one up for you.

[Andy_Mac]

Cheers man, but already got a tactrix. Used it for my last cryotune. Could go back to him but the idea of doing it on a dyno and getting it done straight away rather than a month of f'ing round would be worth the extra coin. Quite like the idea of differing boost maps based on SI drive mode which i believe he can do too.

[Marky]

I reckon we could fumble our way through it if you wanted, can't really break anything trying

[McDoof]

 Andy_Mac said:

Cheers man, but already got a tactrix. Used it for my last cryotune. Could go back to him but the idea of doing it on a dyno and getting it done straight away rather than a month of f'ing round would be worth the extra coin. Quite like the idea of differing boost maps based on SI drive mode which i believe he can do too.

PM Matt and book it in. And yes he can do the SI drive boost maps.

[Andy_Mac]

 Marky said:

I reckon we could fumble our way through it if you wanted, can't really break anything trying

Yea i'd be keen to give it a shot. Might have a go at getting the heatshield off tonight to see how bad the downpipe bolts are.

You still wanting to have a crack at getting the rom off yours with my laptop and cable or you get there in the end with yours?

Have PM'd Matt on here. Not sure if i'd have more luck getting hold of him on here or the liberty forum so hopefully hear something.

[sobanoodle]

 Andy_Mac said:

Have PM'd Matt on here. Not sure if i'd have more luck getting hold of him on here or the liberty forum so hopefully hear something.

PM'd him on here and on club.liberty - still waiting for any response.

McDoof, you have a PM too.

[Marky]

 Andy_Mac said:

Yea i'd be keen to give it a shot. Might have a go at getting the heatshield off tonight to see how bad the downpipe bolts are.

You still wanting to have a crack at getting the rom off yours with my laptop and cable or you get there in the end with yours?

Have PM'd Matt on here. Not sure if i'd have more luck getting hold of him on here or the liberty forum so hopefully hear something.

I still will get your help - I've lost my cable it seems haha

Just short on time these days, daylight savings will help bigtime. I have access to a hoist & proper garage if you get really stuck

[Andy_Mac]

Haha thats an expensive toy to misplace.

Probably worth your while now you should be able to give the wife's car a bit of a tweak too.

Only thing i might struggle with is actually getting it out underneath. The ramps and jackstands i've got are only 300-400 high so navigating it out might be a pain.

[Andy_Mac]

Had nothing to do today so decided to get stuck in to the removal.

Was going to originally try take it out as one piece but decided that would be too much of a headache manoeuvring out

Does that gasket look alright or would it be worth replacing? The centre ring looks sweet but the surround is pretty flakey.

Guessing taking both cats out is the way to go. Are they internally attached at all? Looking at them I feel like i could just smash it out and then maybe get a wirewheel in there to break up the rest of it.

[Marky]

They're held on by like a wire mesh around the whole inside of it, highly advise doing this with a mask or a strong wind outside - the stuff is like asbestos to breathe in apparently

[Andy_Mac]

Yea heard it was fairly carcinogenic so wore a mask. Ended up using a hole saw on a extension piece. Then the big smashy smashy bar.

Got all the wire mesh and other steel pieces out too. All back together now. Just got to find some time to do some logging to see how bad the overboost will be.

Can see why they're such a huge restriction. Never thought the holes would be that tight