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"Built Dam Strong!"

02 January 2012

Justin's Bisimoto Header

It's been too long for an update, but, at least I now have several things to introduce. The first thing I will be introducing is Justin's header. This is a Bisimoto header that is, quite frankly, annoying. It has already been repaired, rather well, once, but the has cracked again and completely separated at the weld that joins the turn down to the tube that goes under the oil pan (which wasn't even angled correctly). I'll have pics of all that if I can find my camera, as that is suspiciously missing, which rather upsets me.

The plan with Justin's header is to not only fix it, but to improve upon it. I firmly believe that Bisi designed the header with such a large collector in order to intentionally shift peak torque to a point that would be beneficial to someone revving the piss out of an engine. The engine would fall back into the powerband and recover faster. I think this is why the Bisimoto header performs pretty darn well for drag racing. However, in my research, I think that having a collector that large is actually hurting power. Justin and I discussed this, and we decided that it would be an interesting experiment to neck down the collector even farther. I think this will actually help power production all over. We shall see.

In order to neck the collector down farther, I have to do some pretty interesting stuff. I am going to take a divergent cone, pie cut the sucker so it bends 90* and mates up to the existing collector, all while staying as tight to the pan as I dare. I'll also be adding some real support to the collector and a megaphone after the collector bend. This should be fun!

I'm not just going to hack up a bunch of nicely made metal, trying to get something to fit. I am making cardboard templates first!

The shorter template in the following pic is going to be the first one I start cutting on. I expect to have to try at least 3-4 times before I get something I would consider useable transfered to the metal. I will be cutting the cone on the welded seam side. I think this will look better and also be a bit easier to bend into a 90. I won't be cutting all the way through, just enough to remove a slice o' metal pie and ease things around the corner.  

Here is the collector welded to the 90* bend of the original header. That dark line is "enhanced" by using a dye penetrant test (sharpie over the weld, which is actually a no-no for stainless, but since I am cutting all that material out anyway . . . ). That is a crack straight through the effing weld bead. This makes me an unhappy camper . . . 

This last pic is annoying for several reasons:
1. I don't have my camera, so it came out crappy.
2. Bisimoto doesn't evidently care one flying fartknocking iota about how the headers are put together. These are the cap welds on the collector spike:


Justin, I will be smoothing all that mess out for you. That just pisses me off . . . 

That's it on projects for the evening. I'll have more pics sometime soon.