106 GTi port polish throttle body - Saxperience

James93 · 21st August 2016, 15:59

Want to have a go at port and polishing my throttle body on the track slag, what do I need to do this? Any guides? Seen them on eBay for about 70 notes and would rather do it myself to save some money. What's needed? dremel? Metal Polish etc?

Anyone got a guide I can follow etc? Thankyou

welshpug · 21st August 2016, 17:48

pointless exercise, you wont gain anything as you're not making the throttle plate bore any bigger.

Chipwizards · 21st August 2016, 19:32

Quote:

Originally Posted by welshpug

pointless exercise, you wont gain anything as you're not making the throttle plate bore any bigger.

Not true. The throttle bore is machined to give progressive opening so one side (the top) of it has less cross sectional area than the bottom. Also, it has a sharp-edged ski-jump sort of profile that is certain to cause boundary layer separation on the downstream side.

On a motor with the usual mods, cammed, exhaust, good induction etc a ported body, if done properly, is worth between 2 and 4 bhp.

Polishing it does nothing at all, it's the shape that matters not the surface finish.

Chipwizards · 21st August 2016, 19:52

Rather than pay £70 for one I'd put the money towards a die grinder and carbide burr and do your own. They take all of 15 minutes to do with a good grinder and burr.

stevo67 · 21st August 2016, 22:23

Change the screw that holds the butterfly valve,to one with a flat profile will help improve airflow.

Chipwizards · 22nd August 2016, 00:06

Quote:

Originally Posted by stevo67

Change the screw that holds the butterfly valve,to one with a flat profile will help improve airflow.

DON'T do that. They are riveted in place after the screws are tightened so they don't come loose. Locktite breaks down so can't be used. If you remove and replace the screws you're in danger of one disappearing into your engine, something I have seen happen several times. Riveting them properly is automated in the factory and very difficult to do successfully by hand. Besides, the difference in airflow and power would be immeasurably small.

axsaxoman · 22nd August 2016, 08:21

and the downside of removing the lump is that you don,t get as smooth a transition from very light throttle to larger openings --can make it a little jerky --
but thats why they put it in to start with

no free lunch

stevo67 · 22nd August 2016, 16:58

Quote:

Originally Posted by Chipwizards

DON'T do that. They are riveted in place after the screws are tightened so they don't come loose. Locktite breaks down so can't be used. If you remove and replace the screws you're in danger of one disappearing into your engine, something I have seen happen several times. Riveting them properly is automated in the factory and very difficult to do successfully by hand. Besides, the difference in airflow and power would be immeasurably small.

Ok fair do's.I'd seen it done & seen throttle bodies offered for sale with the mod done,so thought it was the norm.

James93 · 22nd August 2016, 20:56

Pretty sure I read in here somewhere that it increases induction noise, obviously I would love ITBs but they're expensive for a decent set plus management and I'm poverty spec and tight as arseholes.. Is it true the intake noise becomes louder with porting the Tb, love an induction roar

James93 · 22nd August 2016, 21:02

https://youtu.be/MP_XnOxOhZEAs you can hear in vIdea it's all exhaust noise really want a bit more of a bark upfront

Chipwizards · 22nd August 2016, 22:03

Quote:

Originally Posted by axsaxoman

and the downside of removing the lump is that you don,t get as smooth a transition from very light throttle to larger openings --can make it a little jerky --
but thats why they put it in to start with

no free lunch

Indeed, but with a little progression added to the ignition advance tables they can be made pretty smooth, albeit at the loss of a little bit of fuel efficiency.

What you really need to completely ruin the way they drive is some big numb throttle body from America (well probably from China via America) where anything bigger MUST be better because it's bigger, right?

:-)

AXracing · 25th August 2016, 13:22

Quote:

Originally Posted by Chipwizards

What you really need to completely ruin the way they drive is some big numb throttle body from America (well probably from China via America) where anything bigger MUST be better because it's bigger, right?

Lol so true. Just like there love of huge turbos

axsaxoman · 25th August 2016, 16:52

bmw 740 4lite v8 and revving to 7k only has a 60mm t/body making 350 bhp --so no need for bigger on engine half the size + less than half the bhp