Home porting question

[Turbo6Smackdown]

How many people here home ported their upper halves? What was your results?
Specifically, what are the pitfalls of home porting your manifold... Am I guessing that you could end up with some cylinders getting more air than others?

 

[Pablo]

I'm not sure what you mean by "upper half" but I have ported my manifold and cylinder heads.

Getting everything perfectly even airflow wise would require quite a bit of testing. The stock setup does not flow evenly as it is. So as long as you keep the runners more or less even in their physical dimensions I don't think you are going to make the airflow distribution much worse or much better. It's really not very hard to do, just time consuming.

Without porting the heads I doubt you will gain very much by porting the intake manifold. Testing on my low buck home flow bench showed me that changes in the port of the head did next to nothing for airflow. That section is really not much more than an extension of the intake manifold.

If you want to make big gains open up the valve throats, blend to the short side, and grind out metal from the biased side of the valve guide.

 

[Turbo6Smackdown]

Yes. Upper half meaning heads/intake. And when you say that the stock stuff doesn't flow evenly already... Hmm.. So, in theory, could I do a nice job on the first two throats/ports (the two torwards the front of the car) on the heads and manifold, and just leave it like that, to compensate for the front cylinder leaning condtion?
And without a flow bench, I shouldn't really mess with the valve throats then should I...

 

[Pablo]

To answer your question about the intake manifold, no, probably not. The reason for the rear cylinders running leaner is not because of the runners, its because of how air enters the doghouse, hits the back wall and then is pushed out the rear runners. I don't believe opening up the front runners will accomplish anything since they are not restricting airflow.
Though I personally have not tested it, it looks like the Power Plate does a pretty good job of fixing this issue. That's why I own one. As far as how much it cuts total airflow, I'm not sure. When I have time I plan to pursue a different method of correcting this airflow imbalance.

As far as needing a flow bench to work on the heads... no, you don't need one. I will *guarantee* an increase in airflow if you open up the throat to around 85-90% of the valve diameter with proper blending upward.
I toyed with one to figure out what worked and what didn't. Once I figured that out on one port all I did was duplicate that on the rest of the ports.

 

[Turbo6Smackdown]

I understand it's from the plenum design, but the air still has to eventually reach the runners correct?

Opening up the front runners, wont allow more airflow than the rears?
I too run a powerplate, but I think I am done with it. Even though it does even things out, I'm in that real small minority, that still thinks it's a restriction nonetheless.
At any rate... How do you know one throat flows about the same as the others, without a tester?

 

[Pablo]

They don't flow exactly the same because the ports all have minor differences that affect flow. Furthermore, depending on your measuring equipment, there are variables that can change your measured flow rate slightly from test to test.
You can however make sure the throats are all very close to each other by measuring their dimensions. In my case I ground an intake valve down to the diameter I wanted and used that as my "go, no-go" gauge in the valve throat.

I doubt most porters flow every port they do. It's a lot less time consuming to get a shape they want on the bench and then take some measurements. Once they have those they apply that to the rest of the ports. Like I said though, opening up the valve throat is a no brainer. When I say it improves flow, I'm talking about a massive and immediate improvement from JUST doing that.

 

[pajo]

port

Hey Turbo in my opinion you need to do some reading and then some more reading to get in to the "zone" of porting which is black sience on it's own.If we all had flow benches at home we might get better but without them it is a guess work -just my two cents ..Here is a sticky for you to read if you havent done allready.http://www.turbobuick.com/forums/engine-tech/258301-follow-my-port-polish-project.html

 

[DailyDrifter]

I ported mine, but havent got the car put back together yet to see how they work. Its not hard. Do your homework. Buy the bits from summit and a good air compressor. Also dont forget safety glasses . I'll try to post some of the diagrams and findings that I found helpful later tonight.

 

[charlief1]

^^^ I'm with Drifter on this one. It's not rocket science and it will help the car get more air. I never thought about using an old intake valve to check the size and now that I think about it I'll be doing an exhaust valve as well. Really good tip for sure, thanks.

 

[Turbo1dr]

How many people here home ported their upper halves? What was your results?
Specifically, what are the pitfalls of home porting your manifold... Am I guessing that you could end up with some cylinders getting more air than others?

I ported my own stock heads. The car ran a 6.53 at 107 in the 8th mile with a 214-210 roller cam. They pretty much stopped flowing well below .500 lift. 181 to 187 cfm isn't that much of an increase from .400 to .500 cam lift.

#'s on one intake valve
Lift:
.100 = 57cfm
.200 = 112
.300 = 160
.400 = 181
.500 = 187
.550 = 189
.600 = 193

 

[DailyDrifter]

There were captions that when with these pictures......... but I dont like to read too much . Just Do It . The last 2 pics came for gnttype.org. Dont worry about the floor of the head too much, concentrate on the roof, thats where most of the power will be made. If you look at the pics from ttype.org and compare them to the "Port Shape" pic, you can see the similarities (sp), seems even the stock Heads are halfway decent .

 

[Turbo6Smackdown]

I have all the tools.. I just didn't want to end up with a set of heads, where one area is flowing more than the rest. This was just a probe, to see if it was indeed an exact science or not.. I'm beginning to see it's not... sort of..

 

[charlief1]

Just remember to take your time and read up so you have a better idea of what you need to do. It really isn't that hard once you get done with your first set it's a breeze.

 

[Pablo]

There were captions that when with these pictures......... but I dont like to read too much . Just Do It . The last 2 pics came for gnttype.org. Dont worry about the floor of the head too much, concentrate on the roof, thats where most of the power will be made. If you look at the pics from ttype.org and compare them to the "Port Shape" pic, you can see the similarities (sp), seems even the stock Heads are halfway decent .

I tried a lot of the things that first picture shows.

What I found on my diy flow bench was that expanding the biased side outward actually hurt flow on my heads.

I did however find that raising the floor DEFINITELY helped flow. I took modeling clay and placed it on the floor of the port just before the hump. I shaped it so it would be a smooth transition. Even with a huge hump, the airflow increased dramatically on my diy flow blench. You could hear a difference in the air entering the port, it sounded much smoother. Whether this translates into more power in an actual running engine remains to be seen. I wasn't feeling pioneering enough to try and run this hump (made out of an epoxy), but its just something to think about. I wouldn't take material from the floor of the port. All I did was slightly smooth out some of the casting humps.

 

[Turbo6Smackdown]

I will definitely do a lot of reading... I now know my mission.

 

[pajo]

port

smart thinking - get your self some junk heads ,build a flow bench and go to town ..good luck ..

 

[Walt03]

Can you use epoxy in the ports for permanent modifications then grind on the epoxy?

 

[it's just a six]

Can you use epoxy in the ports for permanent modifications then grind on the epoxy?

Yes you can use epoxy,but it wont be a permanent fix. Eventually the epoxy starts to chip/flake a bit.
One trick thing to do,,,if you can get a mig welder & zap several spots on your cyl head intake ports with the wire feed (where you want to add epoxy) & cut the wire pieces short so there will be some type of better surface so your epoxy will stick better,other than just a port wall or floor or roof.

If you do not know what you are doing, you can hurt the flow of your cylinder heads,just like if you do a bad valve job...it cant kill your flow.

Send it to a professional shop that knows what they are doing.
That's my two cents.

 

[Turbo6Smackdown]

I see.... So if one is without a flowbench, then I suppose several heads will need to be 'ruined' before one truly learns the ins and outs...

 

[Turbo1dr]

I see.... So if one is without a flowbench, then I suppose several heads will need to be 'ruined' before one truly learns the ins and outs...

EXACTLY!