Porting/Polishing

[TurboSPFI]

I've never ported or polished anything and was wondering if there were any certain processes to follow when doing this.

 

been considering P/P my turbo and heads

 

also, what kind of "grind bits" work best? do i need multiple? how bout carbide burrs? i know they can take alot off quickly, but that might be the issue?

 

how bout P/P my VF2? bore out the wastegate? anything?

 

thanks

[MilesFox]

i use a dremel with the flex extension, i will use one of the metal blade type bits to get my shape, and follow thru wuth stones. be careful as stones will clog up, so use light to moderate pressure and a medium rpm under load. finish up with the sanding drum

 

i like to use the cylindrical stones for most of the work and the cone stones for tighter splaces. when selecting stones read the details on the back of the package to pick the best one for aluminum, as the stones come in different textures and colors depending on their intended application

[NoahDL88]

metal bits made for ally won't clog nearly as easily as those for steel, they will have bigger spaces between the flutes.

 

having my engine machining certificate, I should warn you that you need to be extra careflul when poring by hand without a flow bench. if you take off too much in any one area you can severly reduce velocity and loose a dramatic amount of power, my .02 would tell you that you should just smooth up the ports with a sand paper type cylinder or cone. just try to smooth out the transitions and don't get too carried away, bigger isn't always better, especially on these motors.

 

If you're gonna port and polish, you should get a 3 angle valve job with some bigger valves, that would be your biggest restriction.

 

As far as the turbo, i'd leave it alone and get a bigger one, ask WJM which one he's using, that would be a good start.

[erik litchy]

on my non turbo heads there wasnt really any areas that really needed lots of materail removal. the worst part being the exhaust where it transitions to a cylinder. the intake side all there was really was bowl work, and the exhaust bowl area, to gain flow id have to add materail not remove it. the casting is quite odd under the valve seats there.

[4WDFrenzy]

I used a set of die grinding stones that I bought at Wal-Mart for like $10. They worked great. I also used them with the cheap $18 corded drill that I bought there as well and mine turned out great.

 

If you are going to use a Dremel though, buy a Dremel brand tungsten carbide bit for it. It works well, but you have to be extremely careful when applying hand pressure to it as it will cut into the cast iron very quickly. And if you aren't careful, it may cut deeper into it than you may have wanted.

 

As far as porting & polishing the turbo, make the inlet to the exhaust snail rounded and tapered, like a funnel or the bell of a trumpet. In theory, the funnel shape will decrease the turbulence often occurs in this area and it should aid in the responsiveness of you turbocharger as well. I would also advise removing the compressor snail and go over the inlet, inside(as much as you can reach),and outlet with 2000grit sandpaper. The best thing to do though is to send the compressor snail out to be bored. This will allow the turbo to move a bit more air under boost and also increase compressor efficiency a tad. I hope this helps.

[gravelRX]

Well timed post. I was just asking about this in my up pipe fab post.

 

Jay

[TurboSPFI]

is there anything else we need to know?

 

dremel sounds too easy for porting and polishing

[BoostedBalls]

be careful using stones on nonferrus metals! They clog, then heat up, expand and POW pieces everywhere!

 

You can use the small fluted carbide bits on aluminum without clogging issues if you use a special wax/grease for the tip, also makes smooth cuts. If you use the large fluted carbide bits for port work, I hope you have a real firm grip and a very steady hand!

 

As far as porting the turbine housings- I would only knock the casting slag off the surface and open the inlet enough to match the up pipe so you won't have a recuction step.

 

Here's a good article on porting your turbine housing http://www.gnttype.org/techarea/turbo/turboport.html

 

-Chuck-

[lagwagon]

I p&p my heads when i rebuild my ea-82. I use a flexible dremmel with the metal bit. I just removed the casting marks on both intake and exhaust sides. But I only polished the exhaust side. From what I was told there is a bumpy texture to the walls of the intake side. this helps mix the air with the fuel so don't polish this side. By polishing the exhaust side it is a lot harder for carbon to stick to it. Also make sure your gaskets match up well and don't leave a little lip inside.

[archemitis]

when i do harley heads, i use the bits made for aluminum. they dont clog, but they do take out a huge amount of metal at once. they make the chips fly, and if you get even a little out of controll, you dig a big hole.

 

when im doin little heads like these(where hitting a water jacket is a big deal), i use the cheap conical bits made for steel. they clog up, but are more forgiving if you slip.

 

realisticaly you should take the valves out and sharpen the valve guides, and enlarge the port a bit around it(the guide). and you should have your valves recut with at least 4 angles, as i think subaru used 2 or 3 maybe.

 

or a safer bet for a first timer. just use sanding rolls, and clean it up alot.

 

for the guys doin it without taking the valves out... make sure all of that sand and aluminum is outta there before you cram it down into the cylinder.

 

you can get as much as 10% hp from a good flow job, from what i've seen.

[TurboSPFI]

10 hp?! *runs to start porting/polish!*

[Vanislru]

is there anything else we need to know?

 

dremel sounds too easy for porting and polishing

I've done several turbo's and a dremels fine. For any of the turbo's that our cars came with all you really need to do is the side the exhaust enters in from the header. Feel inside and you'll find a lip abou 3/4 " in. Grind it smooth and around the passage into the wastegate if you have any boost creep prob's. Removing that lip is where any efficiency gains will be had. Don't worry about the compressor side.