Warpspeed

Don't know anyone that will mod your housing for you, but If you are really desperate, I just discovered these guys up your way that will supply a new modified housing for a very big pile of money.

I plan to do a bit of final blending as well. Just realized that a further advantage of using a lathe is that the port does not have to be bored out parallel. It could funnel down to the opening under the flapper by a few millimeters, then do a bit of blending with a die grinder to finish it off. One final thought, it would be possible to thread the shank of the flapper disc and screw on a 6mm stainless half height nut. That could be finely adjusted for just the right amount of wiggle clearance, before zapping it on permanently with a welder. I have not done that yet either. Fortunately I left myself some extra length on the shank. I have not taken any pictures, and even if I had, have not figured out how to post them here yet. Hopefully its possible with just words to describe the whole story. A large area wastegate needs a large area actuator with a decently strong spring. I have just bought one of those cheapy Chinese 38mm external wastegates with the aluminium actuator that can be taken apart. Its possible to buy replacement diaphragms, and different springs are easy to source as well. Pretty useless fitting a 40mm actuator to a 40mm wastegate. Exhaust pulsing is just going to blow it open. Quite a few small details to think about, but overall pretty happy with how its all turning out.

A HEROIC effort by hjtrbo! Deserving of at least a Nobel prize I think... And I have just finished my own version of this great modification, I did pretty much the exact same thing, but in a slightly different way which proved to be a lot easier. The turbo housing I started out with was a Chinese 1.06A/R cheapy, and the flapper that came with it was only a piddling 33mm, and the hole a wobbly off centre 26mm. I just could not believe how small it all was ! I made a new 40mm flapper by turning down an old exhaust valve in the lathe. From a Ford V8 of course. Dead easy to do, and it cost me nothing. I should have made it 42mm, but it ended up being 40mm. The valve stem was turned down to 6mm, the same as the neck on the original flapper, and the hole in the swing arm which is deliberately slightly oversize. I first looked at doing all the machine work on the housing in a milling machine, and struck all the same problems as hjtrbo. So I transferred the turbine housing onto the face plate of my lathe. This has a few advantages, the biggest one being you don't need to remove the swing arm from the housing, which is a major pain. Just remove the flapper disc from the swing arm, which has to come off anyway. Tie back the flapper arm, and its then very easy to machine both the bore and the seat face of the housing. Just run a boring bar down the hole, making sure that the whole job is centred around the hole in the swing arm, (which is still fitted). The original cast hole is all over the place. I bored mine out to 36mm which should hopefully be enough for what I am doing. Its all MUCH easier to do in a lathe than a milling machine because of the way the tool can move on the lathe cross slide. Its also easy to get in right in under the swing arm with a facing cutter, something not really possible in a milling machine. I ran the seat out to 42mm diameter, I could have gone maybe another millimeter or two, but as the old joke goes, it easy to remove more metal, putting it back can be a lot more complicated. Anyhow, its all looking pretty good, and it cost me absolutely nothing to do, but being a bit cautious and slow, it took up a whole Saturday. Many thanks to hjtrbo for providing the inspiration !!!!