Yet another porting thread

[kenamond]

Okay, I've been reading porting threads for hours now, but I still have some questions. I've got alot of intake mods in the mail or waiting in the garage (K&N FPIK, solid UICP and LICP and MAS-to-turbo pipe, FP Big28 unported, gaskets, studs, bolts, nuts, washers) but exhaust will be stock until I get this first batch together.

As for porting, here's what I'm doing.

I'm going to port the turbine inlet (oldman's porting tips were killer!). I'll take out the step and open up the wastegate passage to (hopefully) dodge creep when I get a larger exhaust. The wastegate exit looks good: the flapper opens up 90 degrees, but I'm not sure if it will hit the O2 housing when the two are mated. I'm not sure if the Big28 comes with an enlarged wastegate opening, but I can open that up while I'm at it if needed.

I'll port the stock 2G mani collector but leave the flap.

Also, I'm going to gasket match the O2 and turbine housings. I already scribed the gasket onto both, and it doesn't look like there's a whole lot to grind away - maybe 1/8" at the worst spot.

I haven't decided whether to port the exhaust mani ports. Everyone says that the exhaust ports on the 2G head aren't much larger than the mani and may not buy me much, but I haven't traced the two and compared the difference. Suggestions are welcome. The mani's off, so if it's worth it, I'll do it now.

I'll get an electric die grinder (looking for a ~$50 one) a couple of carbide double cut burs (different shapes) for the coarse work, and a stone bit to clean it up. I have a Dremmel, and will use sanding barrels, hand sanding and then polish to finish.

Questions:

Which burs should I get? Some say the flame and radius tree burs worked well, but oldman said he used a cylinder radius end bur. I think the cylinder radius end bur would be great for making flat cuts in the mani ports and collector, turbine/wastegate outlets, O2 housing, and wastegate flapper opening, but would be tough to get a nice cone in the turbine inlet. The flame and radius tree burs would be good for porting the turbine wastegate inlet passage, but the flame bur doesn't seem as well suited for the conical portion of the grinding in the turbine inlet as the radius tree bur. I'm thinking I'll get the cylinder radius end and radius tree burs from ruffstuff, but this leads to my next question.

Which length shank should I get? ruffstuff sells them in 2-1/4, 4, and 6" lengths. I can see that the length would help me in the conical part by giving me more room without the grinder body getting in the way, and it would let me reach deeper, but I'm worried that if I try to apply pressure with the longer shank that it will fatigue and break as it flexes at ~25000 rpm.

Will I need more than 1 stone bit?

Is it worth porting the mani to match the 2G head?

Next, should I port out the wastegate passage in the turbine and O2 housings more than the gasket (and grind the gasket to match)? If so, how much and where? I'm not sure what I'll end up with, and I may replace the O2 housing, but if it's worth it in the semi-short term (after I have a 2.5" or maybe 3" exhaust), I'll do it.

Wisemen have said that the flap in the collector of the mani serves a valuable purpose and should NOT be ground away, but is there any tweaking that I could/should do to it while I'm in there?

Finally, is it worth it to port the mani/turbine to 7cm for a Big28? If I do this and eventually (inevitably?) get a larger turbo, the mani would already be ported, but I'm not sure if there are problems with doing this to a Big28 - is 7cm too large?

Okay, that was long. Thanks!

 

[kenamond]

Okay, I got a flame and cylinder sphere head burr. I'm on my way to the store(s) to see if I can get a decent variable speed electric die grinder for ~$50. Still wouldn't mind some feedback.