Presenting the Piper M041.
I was actually quite surprised how good this looks, their product imaging kind of under-sells on my initial impression but I think there's a reason for that which we'll get to...
As stated, the manifold features 1.5" primaries into a 2" collector which actually bottlenecks into a 1 3/8" spigot to accommodate the standard downpipe (yes even on their full 2" system). In metric ID that's 3x 35mm pipes converging into a single 30mm downpipe.. No matter what unit of measurement you use that is always going to seem strange when you consider that conventional exhaust design principles dictate narrower primaries should converge into a fatter downpipe.
The logical explanation for this and the one I'll stick with unless someone can offer a technical alternative, is just that the manifold has been designed within the dimensions of the original item to easily integrate with the standard exhaust and make it a more appealing 'click & fit' product to people who don't know a great deal about exhaust design. The manifold dimensions are therefore based on marketing & not necessarily on the best performance.
Anyway, onto the finer points...
You can see here the merge in the collector is a mess. This is a shame because the welding that's visible on the outside looks alright. This is like the most critical performance area too. I'm really going to have to clean this up with the dremel or something.
As for the flange, great penetration of the welds here and you can see how much heat has been put in to make sure its solid & gas tight.
Unfortunately, the weld actually bulges on the flange surface in places preventing the face from sitting flush against the cylinder head and crushing the gasket properly. The flange is also warped slightly from the heat - This is normal during the fabrication process;
what I'd expect to see here on the final product is a nice skimmed flat surface ready to mate to the engine but they haven't even tried to achieve that. As it is this will barely seal and it's pretty frustrating having to send a new manifold off to be skimmed before I can fit it.
Nobody wants a raw flange.
I'm also going to have to weld on the lower mounting tab that's missing, to prevent the manifold being strained & cracking when the engine rocks - a problem I'm all too familiar with.
Now don't get me wrong, I don't want to bash Piper. Most of their manifolds are twice the price and I expect on a different level.
I think it's awesome that they've made a manifold available at this price but that itself needs to be taken into consideration: To build this thing in the time required by this price point there are key details that have been overlooked - as such it seems up to the end user to sort it out and make it functional. You can't expect perfection but I'd like to have seen and been told exactly what I was buying beforehand - communication has been quite poor tbh. I've still no idea how this thing affects the torque curve of the engine for example and the guy at Piper stopped replying to my email when I asked these questions
As it is I'm not too disappointed, though if I weren't able to identify and correct these problems myself I might be a little more pissed.
I bought it for the new engine but given that I don't know what the performance is like I might test it on the current engine over the next few days to get a feel for it, assuming the flange will seal.
Garry, you may well get your video
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