Ported & Polished AHU project

[secondgen]

Cross-posted from Vortex as the diesel forum there is d.e.d. dead. And ya'll may get more entertainment out of it here.

Recently acquired a rust free '98 Jetta from a friend when it dropped a valve on the highway. Found a cheap extremely low mile '98 TDI complete motor (<100K mi.) the motor was in really poor cosmetic condition so I stripped it down, then painted and resealed the whole motor. Added a factory ABA windage tray/oil pan gasket.

I hadn't originally intended on hot-rodding this, but it's got a slightly larger than factory turbo, chip and a bunch of other work, so while I have the head off, I'm going to work my port magic on it. I've also had some lengthy and beneficial discussions with a local fellow that races a 1.6TD. He's seen incredible gains with minimal port work so the length I'm going to should be....interesting... And before you go saying I shouldn't, know this isn't my first rodeo. I have considerable experience with porting heads and am confident even with a factory sized turbo I should see decent gains from my time spent here. The factory casting and ports are absolutely horrendous. It's almost embarrassing. Especially the exhausts. Ugh!

At any rate:





Incredibly clean, makes the mileage believable




Removing valves, wood block bolted with old head bolts to keep valves from opening. a bunch of the keepers were "stuck".


Some substantial work is going into these exhaust ports. And this is just a gasket-match. The throats and short-side radii are awful.


Intake port "ridge" on left and knocked down on the right.


Another angle on the "ridge" ( at 6 o-clock) from where they bored the hole for the valve seats.


Same port with the ridge knocked off and blended into the bowl


Working the bowl.


Unique swirling bowl shape compared to the gas motors I'm used to porting.



After some hours you get a nice smooth 120Grit finish on the ports






The narrow valley is rather difficult to get a nice smooth finish on, I may go back with some 240 once I get more narrow bits.



Intake ports needed no port matching, they are almost exactly the size of a factory metal gasket. So no enlargement of the ports was performed, just bowl, short side radii and polishing.

The exhaust ports however. *sigh*

Roughing the exhaust ports in to just under the final port size with an aluminum specific carbide at low rpm. Not worried about going into a water jacket, the metal is pretty beefy in the outer area. port match blended back into the throat to just before the valve guide boss.


Jeweled


My eyes need a break. 6 hours is enough for one day.

Finished up the exhaust ports. Didn't take the short side radii down as much as I'd like, but seeing as I'm not exactly sure how thick that area is I went as far as I was comfortable. The rough "jewel" finish is taken down with 60 grit cartridge rolls, finer tuned with 80, then 120, 240 and lubricated cross-buffs.

80 grit stage, working out the remainder of the rough-in marks. Can still some remaining carbon and the rough finish up by the guide boss.


Final finish ends up like this:


I'm not very concerned that the exhaust isn't completely "neat" being that it's already such a vast improvement over what it was stock. If I were replacing the guides i would have taken them out and done some finer finish work around the boss area.



Wasn't satisfied with the final finish on the intakes. Went back and finessed them a little bit.





Overall, pretty pleased with how it came out.



Next up, matching the turbo manifold to head, and turbo to manifold....

[vanbcguy]

Looks fantastic!!

[theman53]

The exhaust look bad but in reality they are not. I have only seen a 10% increase in flow on the exhaust side of the 8v vw diesel cylinder heads, but the intake on the IDI's I have seen over 40%. My machinist has a flow bench to measure. I will not say that the TDI is the same as the swirl bump and intake is completely different, but the exhaust ports are almost the same as the IDI. Porting will help for sure, but don't expect to see huge #s on the exhaust side. Also, the more volume you add to the exhaust side will hurt spool if you have a bigger turbo. Looks like a good start.

[410]

Yep, looks really good!  Do you plan on a 3 angle valve job as well?

[Alleslowbuged]

Hi,

this really looks goods. It's the first time i see this "crappy" looking exhaust port of an VW TDI head, as i am more into the idi stuff. Anyhow, i completly agree an huge gains, which could be achieved with port and polishing. I have an AAZ with the biggest porting, which is possible (in fact it is even so big, that we hit one water jacket in one exhaust port), but the car has really have good power figure and enormous power on low boost levels. I have also made other mods, but i belive, that beside the injection pump, the porting is main mod for reaching good power figures.

But i also go with "theman53", that the very big exhaust ports does only help with a valuable bigger turbo. I can promise (i check all sizes of turbos on my car) that beside of a little downside on the spooling side, the big exhaust ports will not hurt your engine to much with a small turbo, but will valuable help with an bigger turbo. Anyhow, i would go the same way as you and port the hell out of both ports, as long as the head is available on your work bench.

Good luck with your project and keep us informed.

Best Regards
Alleslowbuged   

[Syncroincity]

Great work and pictures!

What did you use for the sanding/polish phase, drum sander or flap, or both?

[secondgen]

The exhaust look bad but in reality they are not. I have only seen a 10% increase in flow on the exhaust side of the 8v vw diesel cylinder heads, but the intake on the IDI's I have seen over 40%. My machinist has a flow bench to measure. I will not say that the TDI is the same as the swirl bump and intake is completely different, but the exhaust ports are almost the same as the IDI. Porting will help for sure, but don't expect to see huge #s on the exhaust side. Also, the more volume you add to the exhaust side will hurt spool if you have a bigger turbo. Looks like a good start.

When I say "bigger" turbo, I'm talking really slight. The car came with the stock turbo(GT1544 - 454083-2), that I was told was "bad". The replacement turbo is a generic one with no tags or etchings. The castings however have different A/R's when compared to the factory Garrett spec sheet for the OE turbo. The no-namer has a .47 Turbine A/R (compared to .35) and a .42 Compressor A/R (compared to .33). I didn't measure the wheels on either side when I had it apart so I don't know more details.

My goal wasn't (isn't) to make some huge numbers or gains. Gains are gains. Minimal work in my experience yields surprisingly decent results. The factory turbo manifold itself is almost the exact size of the manifold gaskets, so nothing really to be gained there. But in the stock head's trim, there's a good 3mm step from the head to the manifold. While some would argue this helps with reversion, it also abruptly slows the velocity of the exhaust gasses coming out. In my mindset, you want to keep the gasses out moving the same constant speed, with the least amount of obstructions and changes. Port matching the exhaust ports and blending them all the way back into where the short side radii begin, keeps the exhaust moving at a nice slow taper and at more/less the same velocity all the way out. Granted the velocity may be a minute amount slower when compared to the stock port dimensions, but the reduction in the reversion step and end port size shouldn't hurt spool.

Your argument/points are absolutely valid if we were talking massive port size or a with a turbo that probably has no business on an otherwise mostly stock motor.

Yep, looks really good!  Do you plan on a 3 angle valve job as well?

I hadn't originally planned on it, I was trying not to have to bring it to have a valve job done. But at this point I'm considering it, as I really don't want to hand lap all the valves. If my machinist isn't swamped and can get it done soonish, it'll likely go for a nice 3-angle.

Great work and pictures!

What did you use for the sanding/polish phase, drum sander or flap, or both?

For the bulk of the knocking down of the rough finish(s) I use cartridge rolls on a short-tipped 4" mandrel. 60 or 80 grit typically. The tight radii on the intake ports makes using the flap wheels useless, their OD is too big to get into the smaller radii of the corners and "the valley". Went through quite a bit of my stockpile of small OD cartridge rolls on this project. The final finish after I'm done getting the ports even and smooth, is done with these cross buffs:


The coarse grit ones are used dry to smooth out the finish on the intake ports. The exhaust ports I use the same coarse ones, but lubed with a ton of WD-40 or equivalent as it leaves an even finer finish. Some would argue the finish is too smooth and hurts velocity (the golf-ball theory) but a nice smooth finish makes it harder for carbon and debris to hold onto, potentially also hurting performance. People have their own way, and this is the way I do it, and have had very good luck with, so it's what I stick with.

[theman53]

Using terms like velocity then you are probably 10x ahead of most people that port. If you understand velocity then you will be fine doing your porting. I was just sharing the little bit I know about it and making sure that you didn't just have a "make it bigger and it  will be better" type attitude.
While you have the stuff out the short side of the stock exhaust manifold is even worse than the exhaust port in the head. Watch thinning it too much as it isn't thick but there are tons of gains there. Same with the stock intake manifold. It is best just to start over there. It is pretty much horrible.

[secondgen]

Using terms like velocity then you are probably 10x ahead of most people that port. If you understand velocity then you will be fine doing your porting. I was just sharing the little bit I know about it and making sure that you didn't just have a "make it bigger and it  will be better" type attitude.
While you have the stuff out the short side of the stock exhaust manifold is even worse than the exhaust port in the head. Watch thinning it too much as it isn't thick but there are tons of gains there. Same with the stock intake manifold. It is best just to start over there. It is pretty much horrible.

I've encountered port jobs of the mindset you describe. They're dreadful. I've had to "fix" previous "port & polish" jobs from other people. Again, dreadful. Way less work starting from a stock, unmolested head.