Polo 9n 1.6 n/a project

**NachoBides** · 20-05-2018, 03:20 AM

Some updates for those interested. Regarding the intake manifolds, I've found that the ones from the 6n/6n2/lupo gti with engine codes AVY/ARC are the best flowing among the OEM options.

VS the 1.4 aub one I'm using right now.

Polo 9n 1.6 n/a project-vw-seat-skoda-1-4-16v-kolektor-ssacy-036129711da-3399358421-jpg

I need to get one from the gti in hands to compare it, apparently for some reasons its flowing a bit more than mine. Fortunately there is a friendly spare shop in my hometown, so when I get there I will visit it.
Now regarding aftermarket ones there aren't many options obviously. The most popular is the one from dbilas, which is tested and is flowing quite well.

Flowtec Saugrohr VW, Seat, Skoda 1,4 16V mit 74kW - dbilas dynamic
Quite expensive at 800euros, I'm not willing to dispose that kind of money. If only I could find a used one.

Another option is one from a greek fabricator, used in Greece in various setups both N/A and turbo. It's also tested with good results. Reading older topics in a greek forum, the price was around 450 euros. If I'm not mistaken this is the correct photo.

Polo 9n 1.6 n/a project-gallery_4_66_78538-jpg

I also found this one on youtube with the brand name Auto Art. It looks similar to the above one. But I couldn't find any further info. Go to 0:20 and you will see it.

This one comes from Vw Motorsport Polo 9n S1600, but I think it was never available for the public.
http://www.vwmotorsport.com/vwpics/I...i%20engine.jpg

This one also from a greek Polo 6n2 S1600

Polo 9n 1.6 n/a project-file-p=file-1329752092262-jpg

The cheapest option is ofcourse the OEM 1.6 gti manifold. I can exchange my aub one for it, in case I won't find a reasonably priced or a used aftermarket. More updates regarding the head and bottom end coming soon.

**sambb** · 20-05-2018, 04:05 AM

As well as flow you need to consider the correct runner lengths that will mesh with your chosen cams rev range. ie the length from plenum wall through the runner to the back of the intake valve matters big time if resonant pulse tuning will work or not. From watching mates engines go together I know the builders spent lots of time on calculating all that kind of stuff before selecting (or making) the intakes.

**NachoBides** · 20-05-2018, 04:19 AM

Solid advice! That's the reason I'm trying to discover all the available options and find the best for my target, always listening to the advice of my tuner and mechanic.
If I'm not mistaken, shorter length runners help for better results on high rpms and longer ones give better response down low. If you look on the photos above the 1.6 gti manifold has shorter runners than the aub I have. That's the reason it gives better results in cars with aftermarket cams and mods that help them rev higher.

**sambb** · 20-05-2018, 12:34 PM

I'll be keen to see how it plays out. A mate of mine with a Renault Clio RS w172 went through what you are doing now. His cam wasn't big enough (we do sprints and hillcimbs not circuit stuff so much) for quad throttle bodies, so he tried all the different Renault sport iterations of each NA inlet and also some apparently aweosme aftermarket carbon trumpet ones as well. The impact they had on the car was enormous forcing cross the board timing and fuel changes. For the cam he had ( a W182 clio inlet) the Renault sport long runner beat all the aftermarket ones and still had the best top end? Results were sometimes counter intuitive so like you are doing you need to consider everything. He's changing to a W182 head now (same cams) and because they have different inlet port angles/lengths they are going through it all again re intake selection - incidently they've modded the megane 59mm throttle body you showed and taken it out to 60mm with new internals.
Same was true of the exhaust too. The supposed better 4-2-1 extractors weren't as good as the 4-1 that everyone said to get rid of. The calcs said go with 4-1 and they did. On inspection they found that the union of the 4 pipes at the collector didn't have one of those spear head pulse guides things and the mech didn't like the angle at which they arrived into the collector. So they cut the collector open, welded a pulse guide in and made the preferred extractors even better.
Have you seen the tissue paper test of extractors that you do with compressed air? - our mechanic guy demonstrated a bad set of aftermarket extractors versus a good set of OE ones. You place a tissue covering the extractor port of what would be the next cylinder in the firing order ie the one that would pulse down to the collector next. You then give a little burst of compressed air down the extractor port that would fire before it. If on that burst the tissue over the other port gets sucked straight down and flies out the main pipe then collector scavenging/timing is decent and back pressure isn't bad. They did it on some bad extractors and the tissue would fly off into the air in the opposite direction = back pressure at the collector etc etc and other likely problems. Its a non scientific but apparently a very easy way to quickly weed out what is utter crap and what might be designed well enough to consider further. could help

**sambb** · 20-05-2018, 12:50 PM

Here's the pulse guide they made to enhance what was already there before welding it back up again. Last pic is with it all back together looking into the end of the collector.

**NachoBides** · 20-05-2018, 01:37 PM

Nice info there! I have heard the trick with the tissue in the past, but didn't remember the exact process. I will try it on the stock exhaust manifold I have just for fun.
Also after reading some threads on greek forums, a 4-1 type manifold is better suited to my project as I'm looking for top end power. Fortunately my exhaust fabricator is very good, he has made full custom systems for numerous powerful turbo and N/A cars. He knows his stuff, so he can help me.
55mm exhaust pipe is apparently a little bigger than needed, so I may go with a 52mm one.
As for cams I lean towards dbilas. They have been used with success in similar setups and maybe I can find some used ones with low mileage. Reprofiled cams are hit and miss, I don't want to risk it.

The stock compression ratio of the engine is 11.5:1. Quite high for a 1.6 16v 105hp unit. To compensate for the slight compression loss due to aftermarket cams I may have to skim the head a little bit, or maybe use a thinner head gasket.
Eventually, the engine block I'm going to use will be a 1.6 with AZD code. It is cast iron rather than the stock aluminium one.