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Originally posted by Jon_Bmw View PostPressure bends on pipework - No
Generic Half shell pressings on muffler outlet - Fine, no problem
Welding quality on muffler outlet pressing - The weld to the muffler outlet looks a bit poor, as indeed does a fair bit of the MIG welding.
Cat Cone design - Its ok
Hanger wire design - Looks a bit poorly thought out.
X pipe design. - Its ok.
By the way, this is the normal standard for a custom exhaust. Nothing horrendous, just not as well thought out as an OEM part. But this is normal, an OEM part has hundreds of thousands spent on development and even more on tooling with around 18months from conception to start of production with a team of perhaps 10. A man in his shed has a day, maybe two with a couple of grand at his disposal if he is lucky!
I was just commenting on what make really, the exhaust will be fine and potentially more free flowing than the standard one. Is it as "good", well that's an opinion thing...
Thanks for that explanation. Out of interest, is there a better way of bending the pipes? What would a better weld look like?
I'm going to fit it and see how it goes, if it's not for me I'll revert to the gutted pipes
Build thread: https://www.z3mcoupe.com/forum/showthread.php?t=19347
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Also where can I get an exhaust gasket quickly? I've looked all over
Build thread: https://www.z3mcoupe.com/forum/showthread.php?t=19347
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Originally posted by mnbrennan View PostAlso where can I get an exhaust gasket quickly? I've looked all over
My BSL. Breadvan Sport Lightweight.
S54 - 18" BBS RS GT/KW V3/H&R/Rogue TM/AC Schnitzer Flippers/Brembo Calipers/CSL Discs/PFC Pads/20mm Spacers/Carbon Fibre Roof/Fibreglass Bonnet/Fibreglass Boot/Lexan Window/Custom Cages Roll Cage/Lithium Battery/Recaro Pole Positions/Schroth Harness/Randy Forbes Braced Floor/Airbags Delete/Lightweight Door Cards/UUC EVO3 Short Shift Kit/E34 M5 Clutch/UUC Single Mass Flywheel/Vibra Technics Competition Engine Mounts/3.46 Diff/Prospeed Exhaust/200 Cell Cats/Strong Strut Brace/ESS+ASA Supercharger Kit/Alpha N/497bhp - 1315KG
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Manifold to cat. I've been trying to find something for ages.
I also need something to clamp the mid section to the backboxes.
Build thread: https://www.z3mcoupe.com/forum/showthread.php?t=19347
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Originally posted by mnbrennan View PostAs Jon has explained its a custom exhaust
Thanks for that explanation. Out of interest, is there a better way of bending the pipes? What would a better weld look like?
I'm going to fit it and see how it goes, if it's not for me I'll revert to the gutted pipes
A is a pressure bend like you have. B is a mandrel bend, although it is also tighter radius. As you can see the mandrel bend, despite being tighter radius, there is no loss of tube cross sectional area. This is because there is a mandrel inserted into the tube whilst it is being "pulled" around the former(bend die);
I will try and get a photo later of a good weld and post it up
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Thanks. I assume therefore there will be a restriction in airflow through that bend, as the cross sectional area through the bend is smaller
Build thread: https://www.z3mcoupe.com/forum/showthread.php?t=19347
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Compared to a mandrel bend of the same size, yes.
But if they oversized the pipe from the factory specification your cross sectional area may actually end being the same or bigger than OEM.
Generally the biggest restriction in the exhaust will be the catalytic converters. Those fitted are aftermarket and will almost certainly be 100CPSI and a lot less restrictive than the 4-600 (i'm afraid I don't know the exact OEM spec) CPSI version the OEM exhausts runs.
One word of warning if the car ever feels sluggish or reluctant to Rev, check the cats haven't failed. I have seen numerous failures of aftermarket Cat substrates where they end up twisting internally and blocking the gas flow.
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How do you know?
I have just re bled the brakes this evening with BMBabe and fitted 15mm spacers to the front and 10mm.
Out for a quick drive and came back with the biggest grin. The car stops and turns so much better than before the work. I love it!!
Build thread: https://www.z3mcoupe.com/forum/showthread.php?t=19347
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How do I know it's 300bhp or how do I know it'll be ok?
I just think on an N/A car with modest torque that piping should be fine. If it was a turbo car, the slight bend reductions might be a cause for slight concern in terms of absolute best flow but on n/a it too free-flowing can harm things, which is why I think de-cats pipes are not often favoured.
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Originally posted by mnbrennan View PostHow do you know?
I have just re bled the brakes this evening with BMBabe and fitted 15mm spacers to the front and 10mm.
Out for a quick drive and came back with the biggest grin. The car stops and turns so much better than before the work. I love it!!
Nice one, well done for doing such a major overhaul yourself
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On a related side note, I used Zero Exhausts (Kent) for some work on my old Z4MC a few years back.
https://www.zeroexhausts.co.uk//
The guy is an artist and I can't recommend him highly enough if you're after custom exhausts at a sensible price.S50 M Coupe
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