So i started to port my intake. Does this seem like alot to take off when gasket matching the intake? Also around were the injectors are should i even bother porting there?



The Blueish Purpleish area around the ports is what i would be taking off.

Gasket match it, you do have to remove alot of material.

You can smooth down and knife edge the injector humps, but be careful, make sure the injectors with still seat!

For what its worth, keep in mind what that hump is there for. The hump creates a venturi effect as air rushes past it. A venturi effect is what causes the fuel to be dawn into the air enhancing atomization.

My personal choice is to leave the hump but smooth the leading edge real nice. Just my choice.

What i ment is the hump above the injector opening in the port opening.

If you stick a pencil into the bung where the injector seats, the tip will be pointing at the "hump." It's the rounded, raised area at the base of the injector inside the runner.


I doubt the hump has much to do with venturi effect, as you're looking at it 180* from the way the charge crosses it. As soon as the air passes the peak of those things, it begins to tumble, introducing turbulence within the runner. This can be good for atomization, but machining them flat to a knife edge allows for greater volume of intake air at velocity into the combustion chamber.

Sorry but it does create a venture effect just like a carburator does. Its just not a full round venturi. Same air principals are used in reverse hood scoops to draft warm air out from under the hood. I suggest you do some reading Brian.

Get rid of the hump BUT be sure that you do not take too much off. If you do you will have to weld it back in.

DO NOT touch the "upper" hump! It will do nothing for flow and it will do everything bad if you try to port that out.

And fucking Terry is correct Bri, lol. Basically (unless you want to get into Bernoulli's blah blah) it acts as a venturi by the narrowing of the channel (or the cross sectional area being made progressively smaller).

But I believe the larger air movement (and removal of the obstacle for turbulance) offsets any losses of the speed of the air that you take away. And yeah, there are a few porting type guys that agree with me (and Driggs you know a couple of them ).

Oh yeah, to the OP; Do not exact match port (try to make the intake the exact size of the head ports)unless you are going to align and pin your intake. You should make the intake ports (on the C shaped intake you are porting) just slightly smaller than the ports on the head. Basically there is play when you put the intake on the head. You want to allow for the fact that you are not going to be able to exactly line up you intake with the holes. If you make them the same size and don't line them up exactly, you have basically made an obstacle for the air to hit as it comes up to the head. That generates turbulence as it hits that "wall".

Captain Caveman

96 RS Turbo 11.414 @ 119.62 MSNS, Crower 2 NA cams, BW366, 10.5 comp, UDP, 60mm TB, W/A intercooler, 3.55 tranny 567.9whp 430tq
97 RS NA 13.188 @ 103.87 MSnS powered 12.5 comp, Crower 3's and 219.4whp with 175tq
98 RS DD 12.5 comp on stock ECU, LTH, Crower 2's, Koni, GC, Hypercoil, DG hats
99 OZ 5sp Stocker 15.856 @ 85.97
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I read the tumbling of air was for smog control

Better atomization = more complete burn = cleaner exhaust. Side effect, more power if you can get more air and fuel in with the same rate of atomization.

Smog is just that.....its fog in front of your eyes so you can see the truth!

I agree, smooth down the injector bump, but do NOT remove it. Also, I think if you are naturally aspirated you really want to leave it there and do only a little removal/smoothing of it, if you're going turbo still don't get rid of it but i think you can get away with removing a little more of it, since you're forcing feeding air in the car and can get away with it some more.

"Tutto fa brodo."

Todd Scungio
98 RS
15.173 @ 90.70 MPH

And also a 2011 Ralliart

Balderdash! Take that hump the fuck out!

Venturi effect is nice for low- to mid-range, as a naturally aspirated intake charge is going to be moving at a relatively slower velocity and could benefit from a boost of acceleration just before the combustion chamber. At the same time, any protrusion reduces the cross sectional area of the runner, which results in a reduction in runner capacity (volume), which results in a reduction of flow at the upper limits.

On a street car with mild mods, I would be in favor of giving the injector humps a bit of love for more charge velocity, but on a car like Mark's I'd even machine down the injector itself if it helped ensure a clean, non-turbulent shot into the combustion chamber.

They teach you that in Volumetic efficency engineering 105 at University of Pheonix?

When I had my head port and polished he also did my intake he didnt take out alot he just tried to match it to my head somewhat.

Naturally, I was assuming he wanted his car to operate better on the top end but still have some low end and mid range. (a.k.a as you said Brian, a street car with mild mods) If you want all top end and that's it, then grind away.

"Tutto fa brodo."

Todd Scungio
98 RS
15.173 @ 90.70 MPH

And also a 2011 Ralliart

i dont know how you guys feel about extrude brush honeing, but i had my mothers stock intake sent off to a shop out in tampa to be extrude honed as 1 peice seeing as how our intakes are made up of two peices, when it came back the injector humps were milled to create a ramp going from flat deep in the intake to half its normal size rite at the injector, they said it wouldnt hurt to take it all the way out, its just the honeing brush started at that point n milled it down so it could get the rest of the wall. they told me that the speed and the velosity arent great enough on such a small displacement motor to even worry about atomization because the time it takes to enter the cylander is more than enough time for atomization. they said a total of an 8th of an inch was taken out of the port walls. either way... no ill effects.

I intend to remove the hump. Gasket matching helped considerably on my motor. It was a fun project too.

What i intend to do, something i have discussed with someone else as soon as i considered porting my intake and then finding out what the whole venturi effect and atomization thing was, is to mill the humps flat. Then create three small dents/dimples in roughly the same spot , if not a better spot, in the shape of a triangle to accomplish the same task. Works the same way to create the turbluance but doesn't take away from the overall volume and doesn't effect speed.

No obstuction + venturi atomization = more ponies!!!!

95 RS sold...