Self-Porting Job on the Plenum

[BlackenedSVT]

So I picked up an FRPP 70mm throttle body with another stock plenum for $50 from someone i know. So im thinkin, now that i have a 2nd plenum, I should *try* (at least) to port the intake so it flows better with the new 70mm t/b.

My questions are:
- Is there any problems with porting the plenum?
- What kind of dremels and other tools that I will need to port the plenum.
- HOW exactly should you port the plenum? Like, is there a certain "shape" (for lack of a better word) you want to form to improve the airflow? Should I port the t/b intake opening to 70mm as well?

- Also, what kind of cleaners do you use to polish the plenum when I'm done?



Any help would be apreciated. I relize this MIGHT throw off my A/F ratio if I port it too much...or something. So let me know what you guys think. I just figure I have my stock plenum and t/b on now, so when i put the new 70mm t/b on, it has a 2nd plenum already on it, so i might as well try porting it...

 

[StangPro]

The castings are terrible, so expect to spend about 3-4 hours doing it if you're an experienced Dremeller. Be sure to tape off the flanges before you start to prevent them from any damage. Personally, this has saved my behind a few times now as the bit got out of control or the shank of the Dremel hit the flange as I was working the port.

you'll need quite a few (read: A LOT) of sanding rolls, a nice assortment of grinding stones, and a few carbide cutters will help.

Remove the EGR bump at the bottom near the flange, and remove the casting lip about halfway into the port. Also, spend some time rounding the corners of the throat area, and working on the 90 degree short side radius to smooth it out as much as the casting allows.
Don't look to remove material and hog it out as much as round out the exisiting port.
When you're done, hit the thing with copious amounts of brake cleaner to rinse it. Repeat several times and make sure you clean out the vacuum ports and EGR hole very well.

On the extrior, you can smooth it all out and remove the lip around where the stock horse sticker is for a nice clean look.

We'll have a detailed write-up with pics posted in a few weeks once I get caught up finalizing a fe wother install articles. I'm running behind right now.

 

[BlackenedSVT]

The castings are terrible, so expect to spend about 3-4 hours doing it if you're an experienced Dremeller. Be sure to tape off the flanges before you start to prevent them from any damage. Personally, this has saved my behind a few times now as the bit got out of control or the shank of the Dremel hit the flange as I was working the port.

you'll need quite a few (read: A LOT) of sanding rolls, a nice assortment of grinding stones, and a few carbide cutters will help.

Remove the EGR bump at the bottom near the flange, and remove the casting lip about halfway into the port. Also, spend some time rounding the corners of the throat area, and working on the 90 degree short side radius to smooth it out as much as the casting allows.
Don't look to remove material and hog it out as much as round out the exisiting port.
When you're done, hit the thing with copious amounts of brake cleaner to rinse it. Repeat several times and make sure you clean out the vacuum ports and EGR hole very well.

On the extrior, you can smooth it all out and remove the lip around where the stock horse sticker is for a nice clean look.

We'll have a detailed write-up with pics posted in a few weeks once I get caught up finalizing a fe wother install articles. I'm running behind right now.

Yeah pics would help a LOT! The other plenum (the one I'm porting), that is attatched to the 70mm T/B that is yet to be installed, is actually an EXTRA. So i dont need to unhook anything on it, because its unhooked and has nothing on it already. Its just laying in my garage. So i should only have to unhook the plenum and then go to town porting it. But the porting sounds a bit hard from your description. Do I have to worry about OVER-porting it? Like making the walls way to thin? (not that I would make them paper thin, im just wondering about overporting it).

 

[twogts4us]

Another tip - take it easy on the floor of the plenum. As you look into the plenum from the TB end, you'll see where the walls round pretty wide into the floor...those wide, round corners can be radiused nicely, but at the other end, as the air is to make the turn down into the the manifold (well, actually into the true plenum of the whole intake system, but let's not split hairs here), you don't want to take too much of the floor out as this will just increase the angle at which the air must turn to get down there. This is one reason many suggest a spacer in between the plenum and the manifold. And I agree - I got more power from the spacer than I did just the port and polish, although I never did test them each, individually.
I dont think you'll overdo it - It would really be hard to, honestly.

 

[Slider]

Here is a post that I made about porting the stock elbow.
http://forums.stangnet.com/showthread.php?t=544606

 

[BlackenedSVT]

Is a dremel the only kind of tool you could use to port the plenum out? How about a small grinder and then smooth it out with a dremel?

 

[Slider]

Is a dremel the only kind of tool you could use to port the plenum out? How about a small grinder and then smooth it out with a dremel?

Actually a dremel is not a good idea. The problem with is the grinding stones and sanding rolls that it uses are too small in diameter. This has a tendency to gouge out and leaving a lot of small channels in the surface. The best thing to use is either some type of air grinder or drill that can use the larger sanding rolls and grinding stones. They will remove a lot more material (there is a lot to remove in some places), and they will leave you with a much better finish. You can use a dremel if it is all you have, but it will be much more time consuming and difficult.

However, I did use a dremel for several specialized tasks. The main reason I used it was that I did not have a cutting bit for my grinder, but I did for my dremel. There is a lot of material to remove in some places (e.g. EGR bump), and the cutting bit can remove a lot of material fast. You will go through a lot of sanding rolls or stones trying to get rid of all this material with out a cutting bit. The dremel cutter has a terrible tendency to gouge the metal, but I just went back over it with the sanding rolls in my air grinder to smooth it out. There are also a few tight places here and there where the small dremel is a little easier to use.

 

[mity2]

all that time and sanding tool, isn't it cheaper just by C&L?

 

[JohnyD05]

I used a die grinder connected to my air compressor, i think the die grinder was about 20 bucks at walmart, you can get 60 grit grinding wheels with it, and then i got 80 grit sandpaper attachements then polished it by hand with 220 grit paper.came out alright i wanted to get some polishing things for the die grinder but i couldn't find em.

 

[Slider]

all that time and sanding tool, isn't it cheaper just by C&L?

For some yes, but I already had the tools and my time is free. I invesed $0 in the project and about 4 hours of my time. Seems like a pretty good deal if you ask me.

 

[mity2]

i guess. i don't have time nor patients to just sit th ere and sand stuff for 4hrs. but if u have tool and time, i guess thats the way to do it.

 

[BlackenedSVT]

What are the extact tools I would need and how much are they?

I have an air compressor at my shop where I do all my mods, but its a little broken at the moment with a leak.

 

[JohnyD05]

What are the extact tools I would need and how much are they?

I have an air compressor at my shop where I do all my mods, but its a little broken at the moment with a leak.

you can get a die grinder at walmart for a lil under 20 bucks, pick up the 60 grit grinding stones (5 bucks) they have there too and then i got sanding rolls for the die grinder from home depot, another 5 bucks. then some 220 or finer sandpaper for polishing. thats about alll i used.

 

[BlackenedSVT]

you can get a die grinder at walmart for a lil under 20 bucks, pick up the 60 grit grinding stones (5 bucks) they have there too and then i got sanding rolls for the die grinder from home depot, another 5 bucks. then some 220 or finer sandpaper for polishing. thats about alll i used.

Well (1st): I dont have a Walmart near me in Jersey, so will Lowes or Home Depot carry this? (i'd imagine). And (2nd): is the Die Grinder electric, air or battery powered?

Would you happen to have a write-up on "how to port/polish the plenum"??

 

[JohnyD05]

Well (1st): I dont have a Walmart near me in Jersey, so will Lowes or Home Depot carry this? (i'd imagine). And (2nd): is the Die Grinder electric, air or battery powered?

Would you happen to have a write-up on "how to port/polish the plenum"??

yeah lowes and home depot will have the same thing. its air powered.
as far as porting widen out the bore of the whole intake, smooth off the casting marks and then just polish her up, i left the bump in front of the EGR some people remove it, thats up to you, i just kinda did it by eye and feel as to waht i felt was good, you can search on stangnet there should be a write up sorry i don't have one for ya.

 

[Jackie Chan]

that tb sucks...just buy an accufab plenum and tb used off the boards.

 

[Joel's98GT]

http://redpony.org/intakeporting.htm

what stangpro said is right on, i port these for people in my spare time and it is a very time consuming proccess even after you have done a few.

One place where i spend the most time and take out the most material is taking out all the matierial to radius the corners of the floor.

BEFORE

AFTER