How does this happen? Reverse engineering without test fitment? (Miniaturized Magnaflow downpipe)

After cracking the front O2 bung right out of the 240,000 mile downpipe/catalytic converter assembly on my '98 Volvo V70, I decided I might as well look into a whole replacement cat assembly. I've had good experiences with Magnaflow exhaust parts in the past and I liked that their option was stainless. I looked up proper fitment in their catalog and placed an order from a vendor that had it in stock.

What I received is a downpipe/catalytic converter assembly that is bizarrely miniaturized from the OE part and would never fit any known Volvo that I've ever seen.

All Volvo 850/S70/V70 turbos use variations of the same Mitsubishi TD04HL turbocharger, and they use identical exhaust flanges from 1995-1998(ish, when they switched to the angle flange). Whether it's a GLT, T5, R, etc, if it's a turbo P80 chassis and it's front-wheel-drive in that year range, it uses the same downpipe. 

Somehow Magnaflow ended up designing and selling to consumers a downpipe/catalytic converter assembly that is 20% smaller than the factory Volvo part in both piping and flange size. It's even slightly shorter, as if someone slipped with their mouse wheel while scaling a CAD drawing!

I'd just chalk it up to being a non-performance "standard replacement" part, but that little itty bitty flange doesn't have the recess that it needs to sit flush on the turbo exhaust output, despite having the right mounting hole spacing. There is no way this would possibly function without having a massive exhaust leak at the mating surface unless you were able to run a 1/8" thick gasket of some kind, and even then, it'd be a HUGE flow restriction.

What's strange is that I've only been able to find one other case of this specific part existing in the wild and all of the same issues were apparent on that one too. Even the smallest Volvo turbo used on this platform (13G) doesn't use a tiny little flange like this, or piping this small. How does a part get built and then repeatedly sold that is just this...wrong?

I'm utterly baffled by this. Magnaflow has not yet responded to any of my e-mails; the part shipped with a huge slip of paper inside saying "DO NOT RETURN TO STORE, CONTACT MAGNAFLOW WITH ISSUES". So right now I'm at a loss, but I'm probably going to just have a buddy glob some weld on the gaping hole in my OE downpipe to hold a new O2 bung while I figure out what to do with this thing.

I don't have an answer, but I'm going to go on record saying that's a pretty amazing berkeley up.

pointofdeparture said:

...as if someone slipped with their mouse wheel while scaling a CAD drawing!

This exact thing has happened to me before working in Solidworks. Can't remember if I caught it when creating an assembly in Solidworks, or if it didn't appear until the part was machined and in hand. Easy mistake for a single part, much harder to do for something like this downpipe that's really an assembly of several parts even when working with it in cad.

Perhaps they had seen a photo of the part and somebody thought, "Oh, I've already got this flange designed" and hadn't realized it was for a different application. Not good practice, but the sort of corner cutting I could imagine.

My bet is it turns out to be a bad Chinese copy and not legit Magnaflow.

isn't this what PPAP is for? This seems to be a huge miss. 

+1

In reply to Stampie (FS) :

Pretty sure it's legit based on Magnaflow's own CAD drawing, the packaging and included warranty paperwork, etc. Below is the CAD drawing on their site for the part I bought, and it sure enough looks 100% like what I received.

I should have known better, really. In the BMW E28 world there was a known issue of Magnaflow "direct fit" cats being made completely wrong for some time, and now that I've looked up other reviews it appears this is not uncommon. Stupid me for having brand loyalty 

Funny enough I posted about this on one of the Volvo forums I frequent and another poster had the same issue on a different Volvo, saying his $900 CARB-compliant part wouldn't fit and appeared to never have been tested. In a bind, he ordered a no-name Chinese one...and it fit perfectly!

https://www.magnaflow.com/products/23761-catalytic-converter-magnaflow-volvo-hm-grade-federal-epa-compliant-direct-fit-catalytic-converter

"Should we request a sample from this new vendor before we start having them run production parts?"

"They're way cheaper and we have late orders since the previous vendor went out of business, just have them start shipping it'll probably be fine."

This happens more than you would want to think.

I know for a while, CarbonMiata was making their parts without actually owning any Miatas to test-fit, which explains why their parts never fit worth a damn. That came to light when they introduced their NB decklid, a forum did a huge group buy and then every single person that got one could not get it even remotely close to fitting. They got talking with the head of the company and he revealed, he just went to a junkyard and pulled an NB decklid off a wrecked car and made a mold of it, and the decklid must have been warped/tweaked from the crash and he didn't notice. They asked "Well, did it fit your car?" and the guy nonchalantly responded "Oh, I don't own any Miatas, never have." Well how do you QC them? "I don't."

What sucks is that I feel like it's kind of a dick move to just return it to the seller and make it someone else's problem, but I've been waiting on a reply from Magnaflow (I sent them all of the photos you see here) for a few days now and haven't received anything. Ultimately it's clear that this isn't going to work, and it's not at that "close enough" point where I'd just find a local guy to weld on the right flange or whatever. So I may have to go that route.