Garrett GT20 Project

[306Puggy]

Right, mammoth update, made some good progress today and taken a lot of photos! Was a bit nervous with the drill to begin with, my hands were shaking after making the first hole! And it certainly wasn't easy either. I had been trying with the holesaw for half an hour before I realised the drill was on reverse! I just assumed it was "rightly tightly, lefty loosely" like with screws but I guess not.

Once over the beginner errors I was able to make some progress. I decided I would drill the main exhaust hole in the adapter plate first and then plot the bolt holes in relation to that so that it would line up well. I had marked out a rough circle (using spray primer through a rough template of the mani mating surface) but I needed to find the center of it to begin drilling in the right place.

A quick Google search (actually it was a comment on a Youtube video of a less good way) revealed this nifty way:

Draw a square around the circle that is the same width and height and then draw two lines diagonally from one corner of the square to the other. Where the two lines crossover is the center of the circle. Below you can see the method in use:





If you look closely you can just about make out the scoring of a square, the diagonal lines are easier to see.

After half an hour of drilling with the drill in reverse and wondering why it wouldn't go through, I switched the drill to the forward setting and not soon after the arbor bit got through the metal and the holesaw started to bite, the arbor's bit snapped! Causing me to momentarily lose control of the drill and the holesaw to make this lovely pattern in the plate:



Luckily, there was enough of a groove in the metal for me to carry on with the holesaw without the guidance of the arbor bit digging into the metal.

Thought "right, that's going back to B&Q"!:



Sorry about the picture quality.

Once the hole was done I lined it up with the exhaust manifold and clamped the manifold to the plate:



Then with the manifold clamped to the metal plate I clamped the mani and plate to the bench



Yes, that is 3 clamps you see in that picture

Next thing to do was to use Samass's method to plot the bolt holes:



All holes done, plate on manifold (edit: this was after I had drilled the exhaust flange holes):




The next stage was to drill the bolt holes for the turbocharger exhaust flange.

I clamped the unit on the bottom bolt hole and then drilled the two top holes first:



Then I bolted them up to mark the hole for the bottom bolt:



This is a mockup of how I want the studs coming through:



That is upside down by the way, I haven't drilled the holes wrong.

And this is why I need to countersink the turbo bolts and make them into studs:





And this is eventually how it will look on the adapter plate when the studs are made up:



Right, that is all the fabrication documented thus far. On Thursday I am going to go to my welding guy and ask him to countersink the bolts and weld the heads into the countersunk metal to make the studs. The bolts I will be using are these screws:



They are M8 30mm long with a countersunk head.

I decided to get my welding guy to do the countersinking because I tried B&Q, Homebase, Toolstation and screwfix for metal countersinking bits for M8 bolts but they didn't have any/didn't have any knowledge of what the hell I was on about. Eventually found some in Wickes but at £10 pound a pop and not being sure which size I needed I decided it would be better just to get my welding guy to do it instead.

Oh yeah, the drill bits off eGay were utter crap. I thought I got a bargain but when they arrived they were "Tool Zone" in a shitty plastic case, the 8.5mm one went blunt after 2 holes! Luckily I had ordered a decent 8.5mm drill bit as well before I ordered the Tool Zone set.

If anyone sees any problems please say, I won't be offended, this is my first go at this kind of thing anyway. Oh yeah and as you might guess I wrote this all up in notepad as I pre anticipated internet explorer failing (which it did about halfway through me writing this on notepad).

Once I have the adapter plate made up I need to do the following:

Clock the turbo (easiest bit)
blank off recirculation valve
Sort out actuator mounting
Drill adapter plate for exhaust elbow
Get custom exhaust elbow madeup and welded to exhaust adapter plate
Get flange welded onto exhaust elbow
Drill and tap hole in mani for EGT gauge

Right, I think that's about it! May edit this with bits I forgot if there are any.