For those who were following my quest to improve the gas flow into the Stealth exhaust can to my City X. Things moved on recently as I have been cleaning out the exhaust tarnish on the inlet pipe prior to filler going in.
Getting the tools to wire brush the inside of a curved pipe is difficult enough. The larger flex drive could only reach half way round the pipe. I started using a small flex drive from a powered screwdriver kit. This pushed the brush all the way into the can, but with no handle to control, the flex doesn't have the rigidity or thrust (it's his age
). So I just pushed it in and out and let it thrash about a bit. More work needed if the filler is to stick.
The result of having a semi clean pipe is that I can now see better without the black lining, which just soaks up any light you shine into it. I have discovered another sudden step in the pipe!
The curved pipe is a larger diameter than the main pipe through the can and meets it with a but joint.
So there are two steps wider going into the bend (one from the XBs standard header; 46 to 50mm, and one from the welded inlet stub to the curved pipe; 50 to an estimated 55mm?in places) and one excentric step narrower going out; est 51 down to 48mm. Sorry, but unless it was designed to work like that, I suspect this may be what is stalling the gasses at higher speeds.
I have decided therefore to forgo my dinky pipe throttle insert as it cannot influence this inner step and may make things worse. I will go straight to Devcon shaping. Standard off the shelf stainless exhaust pipe sizes suggest the main perforated pipe and exit to the can is 48.4mm ID tapering out to 45.22mm, which is what you would expect. I would have said that idealy the XB9s header should go into a 46mm butt joint tapering gently round the bend to match the perforated tube width. Still you pays yer money!
Fortunately or unfortunately, depending on your position, the step down just before the can is excentric at maybe 2mm and all to the low or outside of the pipe bend, so I should be able to reach it with the Devcon filler. Depending on how things go, I might lay filler around the whole outside curve of the pipe to reduce the diameter closer to the entry and exit widths.
Sorry still no pictures as I am not on line with a photoshop account!
Getting exited now filler time approaches.
Just need to find some curved ended spatulas to shape the Devcon as sanding will be difficult deep inside the pipe!
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I suppose I could have just moulded a series of flats by setting the can at a series of angles, but that would take weeks to cure them all. Oh well, what flows in can just flow out, and it did when the can was stood on end and heated. A quick wipe around with a mop on a screw driver and it's clean to start again. 