Here's something that would've helped me and might help someone else understand all the areas of concern when port matching the intake manifolds. It's not professional and it's not to scale, but I made it and thought i'd share.

If you have a dremel tool and a few free nights, this is an easy & cheap way to pick up a horse or two.

All of the Felpro intake gasket sets I've bought for this car have bad overhang from the top piece to the middle. This needs to be trimmed.

NOTE: Ignore the part about the intake port fin. I've removed my intake fins since i'm going turbo. This is not recommended.
NOTE: First pic of the assembled intake assembly is actually from a Fiero. The throttle plate is different among other things but the basic design is the same.

 

there are also casting lines deep in the lower intake that need to be smoothed out. hard to get a pic of this but you will feel it with your fingers.

 

When I ported mine, I noticed a big difference above 4500RPM. There wasn't that big drop off in power. I had access to a flow bench so I was able to balance each runner's CFM flow. It's a great upgrade for very little cost, just time.

 

I am working on my V8 base doing the same. When you ported yours, did you change the injectors or did you reuse the old ones?

 

I had already swapped in the 3.4 so I had 3.4 injectors.

 

yeah I don't think it would improve airflow enough to necessitate larger injectors.

 

My thought also, I am not so much concerned with uping the injector size. It is more do I put 30 yr old injectors back in. Multecs to boot!

 

yeap. it would be nice to get them flow tested to make sure you don't have any cylinders running lean.

 

Here is the post I did back, wow 2006, I feel old now. Anyway, the flow numbers start at post 21.

https://www.thirdgen.org/forums/v6/3...ed-intake.html

 

For the lazy people, drdave's results were:

BEFORE

Runner 1: 157.8cfm
runner 2: 143.6cfm
runner 3: 141.3cfm
runner 4: 149.3cfm
runner 5: 152.4cfm
runner 6: 143.1cfm
intake/TB assy: 418.7cfm

AFTER
Runner 1: 165.7 cfm
Runner 2: 162.9 cfm
Runner 3: 166.9 cfm
Runner 4: 162.0 cfm
Runner 5: 160.4 cfm
Runner 6: 161.7 cfm
Intake/TB assy: 432.2 cfm

 

I wonder why runner 1 flowed so much better?

 

and Drdave, did your gaskets fit as bad as mine, and did you have them trimmed on your before test?

 

I didn't trim the gaskets at all. I don't recall having any spots where the gaskets hung over the ports at all, I probably would have trimmed them otherwise.
Looks like Cardomain has updated their site since I added those pics, so everything is a mess on there, as far as trying to find the pics I had of the port work I did. Nothing is in order and the pics don't go along with the text that is displayed anymore lol.

 

yeah I have that problem when stalking people's pages. it seems not many people have messed with these old engines in a while. Even a lot of the old posts on here that had helpful pics no longer exist. I never understood why you had to have an online image host instead of uploading them directly to this page. frustrating.

I guess it was due to server limitations.

I also don't like how now when you scroll down you run into a "related" thread. I want the bottom of the page to be the bottom of the thread you're on.

 

can you elaborate on the CFM of the total assembly and help me understand why that doesn't equal all of the runner's individual CFMs put together?

 

If you scroll down to the blue header that says "Related Topics" and click on the little round symbol on the right hand side , you can "collapse" the related threads . The blue bar will still remain but the related threads themselves will disappear .

 

thanks for the tip orangebird.

here's a pic of my lower intake manifold after porting.

 

What type of cutters are you using? Also do you plan on going back and smoothing those tool scratches out?

 

i use carbide to start, then sanding cones and then sanding paper rolls. its pretty smooth to the finger. it looks worse than it is. ive been doing a lot of reading on air flow and air actually flows easier over a slightly rough surface. it creates a boundary layer that the air flows freely over. so I'm not too worried about it

 

look up veicomer . same principle

 

Sorry, for the delayed response. If I remember right, that was about the max that intake can flow in at a time, so that's all that can come out. I remember having that same question to my teacher too when I saw the results.

I'll see if I can find the actual project for it, I had a whole write up printed out for the project. I may have some more details in there about it.

 

thank you, i'd love to see that.

 

i guess what it means is the neck can only pass so much air to share with each of the runners.

 

I couldn't find it, must still be packed away with old stuff at my parent's house. But that's pretty much what I remember is that the throttle inlet/intake opening could only flow that much so that's all you can get. Since you aren't flowing all 6 runners at the same time you wouldn't need that much air going in anyway.

 

which means the individual runner gains are much more impressive and useful than the total assembly cfm