TDI HEAD PORTING

[Henk]

Bit of a long shot, but does anyone have a dyno comparison of before and after porting?

[rixy]

id be interested in seeing why and how to properly port a TDI head, as i have ported and polished many many petrol heads for gti8v's and vr6's etc, but have never done a diesel. however im going to be rebuilding my 1Z tdi in a couple of months, and was thinking of doing it whilst im rebuilding the head.

[snakemaster]

i ported the head on my first 1z and could feel a benefit,

[rixy]

did you open the ports up then or just match them to the manifold and gasket etc, then port match the inlet? Or did you remove lots of material from inside the ports and make the ports a larger volume internally?? have you any pics??

[snakemaster]

did you open the ports up then or just match them to the manifold and gasket etc, then port match the inlet? Or did you remove lots of material from inside the ports and make the ports a larger volume internally?? have you any pics??

i opened up the ports about1 to 2mm each side , mached the manifolds ,and smooth off the throat and cleened up the swirel bump at the bottom of the inlet throat , and 3 angled the inlet valves , left the exhaust valves stock, and then polished the 8 off them , no pics sorry . i still got the engine (pump settings wrong and over reved = bent valves 5 year a go) its sitting in my shed so i will take a pic of the ports from the back of the head , i pick up a nother engine cheap so did not bother fixing up .

[rixy]

excellent, some pics would be awesome if you could :-) when you say cleaned the swirl bump up, do you mean removing it, or just polishing it up a bit??

Im hopefully gonna be removing the engine this weekend, and will split it, and start the work fter the weekend hopefully :-)

[theman53]

I would tread lightly on that swirl bump. One guy had a head ported for his TDI and it had white smoke all the time at idle. It was a few years ago on here and the guy tried tons of stuff, eventually put a new head on and all the smoke was gone. From what I gather from my engine machinist, bigger isn't better. Better velocity into the cylinder is better, and with the TDI you need a little turbulance aparently.

[burn_your_money]

Did he check compression. I remember reading about the first AAZ head on a 1.6 block and the guy was convinced it was a terrible idea because the motor was fine before doing the head swap. He did a compression test and was very low on compression.
I'm not saying that the bump can safely be removed, but one guy's experience shouldn't be taken as fact unless he went about it and covered all his bases.
I haven't seen the thread in question, so I'm just asking.

[theman53]

Remember, it was the TDI in a van. It went finally to Colorado or something where the new ower put a new head on. It checked out fine otherwise. I think Libby may have even looked at it.

[rallydiesel]

If you are building a huge turbo, high-revving, massive flow, track-only tdi, than removing the swirl hump can help. For any kind of daily-driver you need to keep it.

[RabbitJockey]

Did he check compression. I remember reading about the first AAZ head on a 1.6 block and the guy was convinced it was a terrible idea because the motor was fine before doing the head swap. He did a compression test and was very low on compression.
I'm not saying that the bump can safely be removed, but one guy's experience shouldn't be taken as fact unless he went about it and covered all his bases.
I haven't seen the thread in question, so I'm just asking.

i think i remember that, the head he put on had bent valves or something.

I would tread lightly on that swirl bump. One guy had a head ported for his TDI and it had white smoke all the time at idle. It was a few years ago on here and the guy tried tons of stuff, eventually put a new head on and all the smoke was gone. From what I gather from my engine machinist, bigger isn't better. Better velocity into the cylinder is better, and with the TDI you need a little turbulance aparently.

if i was doing a tdi head, i would gasket match the ports and manifolds, and yeah port it out down to the swirl bump thing, i dont think i'd touch the swirl bump, maybe clean off any casting imperfections so they are all even, and maybe even polish them up, but not really remove any material. and then flip the head over and open up the ports around the valve seats so they match the seat and continue that up in to the bowl/radius area and clean up the bowl, on the exhaust side u can try and make that turn not so harsh, i don't think i'd mess with the turn on the intake side because the swirl bump is in that area.  i think cleaning up around the valve seats will make the biggest difference, but u have to keep in mind also that the seat is off set a bit from the port and this one done intentionally to even out the air flow around the valves, instead of all the air flowing towards the more open side of the valve.  Before i did my head i did alot of reading, there is an old write up on how to port 8v heads, its a few pages long and has been posted here and on vortex.  i think it'd be awesome to mess with the swirl port, but with out more information on how it works and whether it can be modified i wouldn't touch it, i think gasket matching, cleaning up the ports, and opening up around the valve seats will make a good enough difference, enough for an amateur like me anyway

[rixy]

cheers for your reply's, especially trev0rby, makes alot of sense. I think i may well go down the route or cleaning and smoothing, rather than porting as such. Make irflow easier rather than more of it, as i;ve read the heads are good for well over the power output i want anyway, so i just want to make it easier and better flowing.

I also never "polish" a head on anything, i smooth it out using some emery paper on a flap bit ive made for my die grinder, but i never go more than 120 or 180 grit, as a polished port actually slows air down, and causes fuel to stick to it, meaning worse combustion, where as a slightly rough surface causes aggitations and swirls of its own. I know is fuel issue isnt a problem on the tdi as they are direct injection, but as i say, ive only ever done 8v gti's and the like, where the injector injects into the inlet.

I'll keeplooking for an explanation on the swirl bump, and for sme pics.......

[RabbitJockey]

Yes if I said the word polish I meant just to sand smooth not to literally create a mirror finish.  I have read the most important part of head porting is 1-2" before and after the valve seat.  Which doesn't apply that much for use since the valves are basically on the head surface but I would bet there are small gains to be had from doing some kind of bevelling the head around the valve seat on the deck, I know Malone and Dave at pp had discussed this and on one picture of Dave's head it looks like had done it to his aaz head

[theman53]

180 is almost polished LOL. From what I gather since we do not have the fuel and air in mix. On all the gassers I have ported I think I stopped at 80grit.

[JFettig]

I've seen lots of pictures of TDI ports without the swirl bump, one I drove and it drove just fine. All of these were done with use of a flow bench and either by shops or people I know who know what they're doing.

With that said, I removed the swirl bump on mine, and only opened the intake bowls slightly, smoothed them out quite a bit and I opened and cleaned up the exhaust ports quite a bit. I'm surfacing and doing a valve job on Saturday and hopefully can install the head soon, will report back.