ShopTalk Forums | Aircooled VW Tech & Restoration Help

Has anyone on here tried porting and polishing the turbine or compressor housings on their turbo?
Did you notice any difference in performance?
I’ve done my TD04-13T but am yet to drive it.
It will be a couple of months yet before I drive it to notice any difference and I plan to get it back on a dyno to compare graphs...... but just wondering if anyone has had any experience in this?

Porting and polishing the turbine housing can have a small (positive) effect on the efficiency and flow. Polishing the compressor cover will have a slight negative effect on surge behaviour (a bit of roughness will shift the surge line slightly to the left, increasing the mild surge area) and won't have that much effect on the flow.

I'm interested to see what you find. Are you doing other things that would alter the performance of what it was before?

buguy wrote: ↑Sat Aug 31, 2019 6:05 am I'm interested to see what you find. Are you doing other things that would alter the performance of what it was before?

The only other changes I’ve made are to relocate my charge cooler rad to the front of the car and a new Wastegate..... so there may be some difference in charge temps, however, that won’t effect the flow of the turbo and when it starts to run out of breath and how far into the rpm range it can hold peak boost.

My research on this subject suggests a marginal decrease in spool time, but the added benefit of flow should enable the turbo to hold peak boost for longer and an overall smoother boost curve..... this is likely to affect the torque curve rather than the overall BHP output......

We’ll see in a few months.

I'm interested. I haven't been able to really try to hold boost yet. Ive always had a boost cut, signal loss, or traffic, or way too much speed to keep my foot in it. I need to get my boost cranked down so I can try. Seems like at 25-28 psi I'm having to shift pretty quickly. I've never had to wring this thing out, so holding it to higher rpm's is difficult for me to do mentally.

So, just a quick update on my observations so far..... It seems to spool quicker, but this will be confirmed when I put the car on a Dyno
I also added an intake trumpet to the mix....
My butt dyno is telling me that the “hit” is harder when it comes on boost too..... again confirmation needed from s Dyno session.
I thought I could hear a little bit of surge on the freeway when I was in top gear at maximum load, but it was intermittent and I couldn’t create the condition on purpose..... so maybe just my ears hearing noises I hadn’t noticed previously.
Overall, I’m very happy with the results!

Nice. Sounds like it was worthwhile then!

(For what it is worth) As a general thought porting and polishing can be good and negative when modifying things (in general). Porting and polishing intake ports, or, especially exhaust runners, and heads, can have good and bad outcomes to them. The guys I know (knew) usually used a flow bench to keep track of airflow especially if you are getting aggressive with port sizing and shaping size especially the valve pockets. Sometimes it doesn't take much to go from positive to negative outcome.

As far as general porting, the manifolds connections areas are usually matched to the heads to get rid of any "step up or step down" between the two. Changing the shapes of things also can make positive or negative changes in airflow (turbulence) or, in some circumstances, the fuel mix. Polishing the exhaust is a mixed thing as the solids in the exhaust can quickly get obstruct of the glass like work you've done when the particles stick to the sides of the port.

What you showed there (and I know next to zilch about "puffing" an engine) looked pretty good but again, I don't know that much about turbos and the way they work especially as to what, if any, effects, especially negatives, they can overcome or be affected by them.

Lee

Here’s an onboard video I recorded earlier today.

https://youtu.be/OFirmK0wSuA

way cool video

Love the vid en your facial mimics LOL!

and the fact you polish your turbo inside!

Wally wrote: ↑Sat Oct 12, 2019 2:28 pm Love the vid en your facial mimics LOL!

and the fact you polish your turbo inside!

It’s the grin factor Wally!.... Anyone with a turbocharged VW will have experienced it and completely relate!

I don’t know what effect the polishing of the housings has had yet, but it feels much more alive than I remember when I last drove it 5 years ago.

I have a few jobs to finish first, but I plan to take it to the Dyno for a check up.... ensure AFR’s are still ok and see whether there are any differences in the power delivery.

I’ll try to get a video when I do this and also post a copy of the graphs so that differences can be compared.

I'm jealous of how nicely your car appears to shift. Mine is a much slower process.

buguy wrote: ↑Sun Oct 13, 2019 6:25 am I'm jealous of how nicely your car appears to shift. Mine is a much slower process.

I’m using an old Scat short shifter, but to be honest, the nylon bushing on the shift rod needs replacing, so I get lots of metallic clunking noises and sometimes struggle to find 2nd when changing down..... If it looks slick, it’s because I’ve gotten used to it!

I do like my Scat shifter too..