How does this look for a port on a s4 intermediate housing? Also, end housing are next, is there anything I need to watch out for while porting? Any tips or tricks? I've done searches, but I can't find anyone who's ported their own engine that felt the need to talk about it. (Although I did find what was supposed to be a great thread about engine reassembly, but now all but two of the pictures are dead)

 

pic is hard to see but from what i can see it looks like there is burrs on the edges, burrs can tear a side seal to shreds or shatter it. blend the trailing edge(flat edge nearest the top of the iron) of the port smooth as it enters the iron sealing face so the seal won't catch it as it sweeps over the port as well. go over the face when finished with a fine grit sanding block to smooth out the surface and remove any burrs.

one thing i cannot emphasize enough is NOT TO TOUCH the inside of the port as it enters the iron nearest the eccentric shaft bore, this is where the oil seal tract is, if you take much material off in this area you will have possible lubrication issues as well as oil burning internally in the engine.

 

Awesome, that's what I was looking for! The burrs will definitely be gone by assembly, so far I've just been doing the rough cut. Since it's an older iron, it's possible to barely see the wear path that the seal follows as it goes by, and I've been leaving a good millimeter or two in this area. Would there be any use/interest in posting a template when I'm done? Or would it just be useless without dyno numbers?

 

no one posts templates because it is tough to get them sized properly plus as far as i'm concerned it isn't about the size of the opening but what you do with the flow path is what counts. back cut under the thin lip as the port enters the iron for a more direct airflow path = higher airflow velocity and higher overall potential for power.

 

Also smooth down the runners leading into the ports a bit. It doenst have to be glass smooth, 80grit or so should do the trick.

 

Anything better to do this with than those tungsten carbide Dremel bits? I picked up one, but smoothed it out before I finished my 3rd intermediate port. Those sandpaper rolls in the picture are freaking AWESOME, but they're too big and I'm too careful to get close to the edges with them.

 

Air compressor, die grinder, carbide bits and such from Racing Beat or wherever else you can find them

 

carbide burrs like 87FC said, good for about 100 port jobs, you can find them at most tool outlet stores.

i go over the port runners and port match the runners to the inlet size and knock down that wall thickness, this can be done quickly with the carbide burrs, then i go over the runner with a large sanding drum roll on the dremel and finish it off with a 120 grit flapper wheel to give it an almost mirror finish. porting the runners allows you to port match the intake manifold for even more gains.

 

Yeah, racing beat has a whole list of the recommended bits for different jobs.

 

racing beat doesn't make porting bits, i never understood why people prefer to pay a middleman.

 

+1 on this! People put way to much emphasis on the port timing templates. Its all about the inside work.

 

Yeah, but people sell templates for $20-50, if there weren't a need, they wouldn't make them. I was just figuring I'd help out someone who didn't want to spend $50 on a sheet of paper.

 

How thin can you safely make that lip? I would like a little more hp while I save up for a tII swap, but I'd also like to replace the engine because I want to, not because I have to.

 

i cut it down to almost a knife edge as it enters the iron but this takes some skill depending on what tools you have to work with.

as i said, no one posts templates because then you would have to give dimensions to be sure the scale after being transferred and printed is exactly the same. if someone prints up a picture and it isn't to scale and they cut into the oil seal tract or go too wide and it eats a corner or side seal then it just isn't worth the headache of posting up a porting template.

 

You're probably right, if I don't get any interest before I put the engine back together this weekend, I'll just forget about it. If someone wanted it, I was going to include detailed resolution instructions, and include a horizontal and vertical line exactly equal to a certain number, and make the template big enough that they can use the o-ring channels as a guide. So far noone's been interested at all, so I'll probably just forget about it. Just trying to help a brother/sister out.

 

it is a nice offer, i paid $75 for racing beat templates because i couldn't find any online. it is a good idea though since i see a number of people trying to freehand their ports recently and well, personally, some of them look like ***.

 

I'll see how easy it is to do and maybe I'll do it anyway. If I can ever get done with these jerks on the BMW forum who think that an RX7 is a waste of a car.

 

Nice, the real tungsten carbide cutting blade worked a lot better than the tungsten carbide whatever the hell I had yesterday did. Here's the rear housing. Hopefully it's a little clearer than the last one. I also rounded over the edges using 150 grit sandpaper so that it's completely smooth to the touch. I tried 800 grit, but it didn't seem to do much to it.

 

Oh, on a seperate note, is there a real good way to clean out those o-ring channels? I'm hoping to put it all back together this weekend.

 

you can port the secondary port larger than that, you barely touched them... i port between the sec. and 5/6th ports 'til there is a hairline bridge left, open up the duration a bit.

pick up a pocket flat tip screwdriver at the store, works great for cleaning out the o-ring channels.

 

180grit is all you want to go. Any more then that you are doing more harm then good.

 

That's good to know, I'll widen them out a little later. Since I didn't want to buy a porting template, I went to Mazdatrix website and looked at their porting how-to, and blew the dychem photos up in Photoshop and used their pictures to figure out where to port to. They pretty much just went up from 5/6th ports, and just went down from the bottom port. Now that I know, I can port that out some.

 

MT didnt close it latter for a reson. But wth no point for me to exsplain that one again b/c people will just get there pantys in a wad.

 

Actually I don't know if there was any harm at all rubbing it with 800 grit. :P I probably would have gotten farther rubbing it with a paper grocery bag.

 

this is the porting on my engine...pretty aggressive but still streetable....as you can see there is still plenty of room for more on there

got so into smoothing it out there was even some porting done to the 6port sleeves...its almost a mirror finish