Intake Manifold runner flap delete?

[Quattr007]

APR and CTS have released kits to delete the flappers like this:

http://www.uspmotorsports.com/CTS-2....ap-Delete.html

The apr kit says you need an update to your apr tune, but the CTS kit doesn't seem to mention tuning.

First, has anyone done this and what was it like.

Second, would using the CTS kit without a re tune screw things up, and if so, how do you tune for it? Like if you had maestro, what would you alter?

[ericpaulyoung]

Not recommended modification. I have run without flaps before and it is bullshit. Plus the gains are minimal at best.

- Eric

[Quattr007]

I wasn't dead set on doing this but I just wanted to know what the relationship is between the runners and the tune-I understand it can be problematic, but why?

[ericpaulyoung]

Ah, good question. The runners help produce a flow shape that produces a better combustion process at low rpms or more accurately at low air flow rates. As for what the shape is; the flow at lower flow rates has a lower velocity, so the runners force the flow through a smaller cross section so that the velocity is increased. Then this faster flowing air is also redirected so that it only moves along the top of the combustion chamber in a direction from the intake to the exhaust valves. This hits the quench pad on the exhaust side, and is defected down into the cylinder, then against the upward moving piston on the compression stroke, then against the intake side of the cylinder wall, then against the intake side quench pad, and finally along the combustion chamber head again. This swirling turnado entrains the spray of fuel making an entrained plume that passes the spark plug zone off center. If the spray was directly at the spark plug, then it basically just soaks the plug gap and causes misfires, especially when the cylinder is still cold. This is why the RS4 injectors are also problematic, they mess with this flow pattern. The quench pads are squish zones that "squirt" air at the spark plug during the very last part of the compression stroke to aid this further. However, aftermarket pistons, and definitely pistons that have a larger dish to reduce static compression ratio, will not have the opposing face for the squish pads to work, so they are pretty useless and actually cause dead zones during the burn (which is why you will see extra carbon buildup on these zones with aftermarket pistons). So you can actually reshape the head to allow a better "tornado" flow pattern to form and also gain some extra volume to fill with pressurized fuel and air and make some massive power at similar dynamic compression ratios as a higher dynamic CR engine.

- Eric

[RazzleDizzy]

Very detailed. Nice.

[Jay-Bee]

Very detailed. Nice.

Probably the single best explanation i've heard yet on intake flap and combustion chamber swirl/squish basics.

EPY

[Tanner]

The self study guide for our 2.0T can be found here: http://vw.nate-online.com/techdocs/2.0L%20FSI.pdf

On page 15 it covers this a bit but Eric's explanation is much better.

[ericpaulyoung]

Thanks for the props.

Here is the rough machining I did to remove the quench pads from my head. The work was done by hand with a dremel, so not the prettiest. However, I cc'd the chambers on the finishing run and they all match 50.5 ml +- 0.5 ml (about as accurate as I can discerne with the medical syringe that I used for cc'ing them).

[ericpaulyoung]

You can see the evolution here; the bottom combustion chamber is already finished and smoothed.

[ericpaulyoung]

And here the head is with all combustion chambers done, and fresh back the machine shop with a fresh resurfacing completed.