White_FC

Howdy all, it has come time for me to start porting my intermediate plate.



I've practiced on an old junk plate, even did a brideport on it just for a fun , now im pretty confident i've got the skills down to do a proper port job on this plate.



What'd i'd really like to know is what shape, size and how far in what directions I should do it. I know that sounds like I know nothing, I have a fair idea of how far I can got without running into problems, basically I would just like others experience and input onto what THEY have put into their engines, and how the different ports perform.

I don't particularly care about fuel economy or low down power, that is not the goal of this engine.



So if anyone has some pics of their ported intermediate plates that'd be awesome for a start!



This is a S4 N/A plate by the way, in a forced induction environment



Cheers, Nathan.

Ronny_

I have just done a set, and have got templates I could mail you if you like..

Cheers

Ronny

BDC

I personally pay alot of attention on the primary intake ports depending on the focus of the vehicle. Just about all of the engines I do lately are for cars that are high-powered street cars (but still "street cars"). Even on the half-bridgeported setups, I keep the primary ports small to retain some low-end throttling ability and low-rpm charge velocity. It's VERY important. If you hog the primary intake port out, you'll gain it on the top-end, but you're losing it on the low-end which will make the vehicle more "doggy" out of the hole and at stoplights, etc. It;s something to consider.



I'm of the opinion that achieving both a wide power band and highest peak power/torque is fundamentally based on charge velocity by doing everything you can to keep the intake charge flowing as quickly as possible as it transitions and twists from the port runner to the port outlet. Bigger isn't always better.



B

Fluid Dynamics

I did my primaries with a small / medium runner and port volume but with much later closing, and love the result. The car is more drivable now than when it had stock primary ports.

fdracer

how smooth is the transition w/ small primaries and extreme secondaries. it wouldn't seem like a smooth transition if all of a sudden the secondaries open and you have a huge rush of intake flow all of a sudden.

White_FC

Thanks but no thanks dude, im in Australia, so postage probably wouldn't be worth it, I should be able to find a template locally.



But if I'm only going port them a tiny bit like it seems BDC is suggesting i do then I don't think i'll bother with a template!



So Fluid Dynamics how much later closing are we talking about here? do you have any pics of them?



I'm curious aswell as to what the transition is like.

I'm also contemplating using a webber manifold with a twin throttle body injection on it, which would effectivly kill my low end air velocity into the primary ports anyway, so should I just port them bigger in this case?

BDC

Crud, I really hate it when I'm about to post, something else takes over this window, then I go 'Back' and my window is blank.



Anyways, I don't think there's a reason to use a port template for this. Some people may disagree with that but I'm of the school of thought on porting that greater overall and peak power is made not by following the "bigger is better" methodology but instead by removing any turbulent spots, reducing a port wall's boundary layer thickness, and finding other ways to maintain and sustain high intake charge velocity (keep the air moving throughout the turns and twists as much as possible without any loss in speed).



The stock intake ports are miserable!! They're roughly cast, the port tunnels have a large boundary layer due to the rockyness of their respective walls, the port outlet is turbulent on the long radius (near the oil control ring pathway) where the side housing facing lays down on and over the edge of the casting, and the transitioning on the tops and bottoms of the short radius are rough and hard-angled.



I don't believe using a template for the primaries is necessary since the work done on the port ought to be done, in my opinion, more on removing these stumbling blocks that it already has: Edge and even out the long radius with the casting of the port outlet (where the outer oil control ring rotates around at its outer edge), radius the top and bottom of the short radius (the portion of the port outlet edge closest to the inner water jacket o-ring land), and remove the rough casting on the port tunnel to thin the boundary layer out (and speed up the charge moving through the centre of the tunnel as a result).



Here's a couple of photos including a before and after comparison shot of what I'm talking about. Look closely at the differences:







On this picture, you can see the mating of the cast iron to the side housing plating evenly to remove that large point of turbulence where the outer oil control ring o-ring runs around. The port closing timing isn't drastically changed; just ramp it up a bit at the outer edge to allow for the side seal to pass over safely if you extend the width of the port outlet (thanks, Judge Ito).







On the above picture here, you can see the before and after changes done. The rear (left) chamber intake port has a much smoother flow -> thinner boundary layer and smoother transition overall as the charge twists and turns into the combustion chamber vs. the front (right) chamber intake port.







In this picture you can see the changes done to better transition the charge as it goes from the port tunnel to the port outlet. Nothing radical is needed; just radius the turns better and angle the underside of the short radius.



No template is needed; keep the primary ports smaller.



B

White_FC

Wow, awesome work BDC!!

That looks really really nice.



Have you ever done much more agressive timming on the primaries though? Since im not overly concerned with longetivity or fuel economy in this motor I was thinking about maybe doing a slightly bigger port?



I know you did say bigger isn't always better, and i've definatly taken in your advice for the transitioning, but what about making it 'bigger' or have slightly more agressive timming? any advice about that?



(basically im just looking for a bit more power

BDC

Thank you!



To answer your quesion, "yes" I've done a more aggressive primary port but I didn't like the way it decreased low-end throttling. I was using the older 8.5:1 S4 turbo rotors so the problem was a bit more exacerbated. If the car was for strict drag or some other high-RPM use, I think hogging the primaries out might be worth considering. But, since most of us do stock cars, I don't believe it to be a good idea. Instead, I vote for retaining overall port size but focusing more on how to retain charge velocity throughout the port as a whole.



B