Would it be worth the effort to port the plenum and port&polish the factory runners and port&polish and siamese the factory base?i know i could make more power with bigger runners and base but i just had a baby so money is all but gone for a while so i was just wondering what you guys thought any help would be great ....thanx

 

Do a search for "siamese base", "siamese intake", or "siamese TPI" and you'll find all your answers.

 

I just siamesed my plenum and runners this weekend and I went from pulling to 4000 to 4800. Makes me VERY happy. I would have done the base too but OMG is it alot of work. Im dead serious when I say plan to have the car down for a solid week if you want to port it all. But hell you may as well get the book and port the heads while your in there . Just sayin; had I not been squeezed for time it woulda happened...sigh.

 

I am currently poerting my entire intake eysye,. I have siamesed the plenum and opened up the TB opening to 58mm. I have Edelbrock runners and base. I am ust smmothing out the throats on the base and runner though.

I have a question for F-Body Demon. When you siamesed the plenum how did you address the actual siamesing of the runner walls? Did you leave some material or just make large ovals? Did you do anything with the runners to smooth out the incoming air flow? What do you think about siamesing the TB opening? Pics would be great for everybody. I will post mine when I get to the desktop. I appreciate the info on the performance gains.



Here are the pics what do you think???

 

Firechicken, I actually siamesed the throttle body ports on the plenum to match the gasket when I removed the EGR hump. As well as to angle the walls out and in so as to allow the air entering the plenum to begin to expand from the throttle body immediatly. Not sure if it was a good idea but it works.

And as for the runners I removed about 1/2 inch of runner including the plenum by creating a bridge between the two ports about 5/8 inch wide in the center of the two. After that I addressed the runners by grinding out 1/4 inch material and then using a rounded bit I was able to make a very gentle hump to allow the air to spill from runner to runner in order to attempt and create the borrowing effect between runners to make a little more power.

For the ammount of money invested ($50 for bits...of which I used $15 ) I believe it was worth it. I just was getting kinda pissed off running the engine to 4k and having it die. Felt like I was driving a desiel truck. Now I can rev to 5k with power and 5.5k without having the engine just howl back at me in amusement wondering why I think it should be making power up there.

 

just one question do you guys gasket match all the ports with a certain gasket? what is the process of gasket matching anyways, ive heard it said but dont technically know how to do it?

 

I tried to gasket match as good as I can. Basically it's using what ever gasket you are going to run (stock or larger) as a template or guide. You install the bolts with the gasket in place. Mark out any metal you see that protrudes past the gasket area then grind it away. You do this to both pieces that the gasket goes between.. The idea is to have the same exact shape from one part to another. The trick is to make sure the gasket is lined up perfect.




Guys, take a look at the pics above and weigh in on my work. Don't be afraid to be truthful it's how I learn.

Any pics of others work would be great!!

 

what is a common gasket that is bigger than the stock ports though? and what do you do for gaskets when you siamese the plenum? also what are you using to cut with, i tried porting my tpi stuff and i used a carbide bit with a dremel and it SUCKED! took forever and the cuts didnt come out smooth at the front of the plenum like yours are.

btw your porting looks great man nice and smooth!

 

Just yank the whole intake.

For a weekends worth of time and a intake gasket set, you can port the base and plenum all in one big shot.

By themselves u might get a tenth or two, doing both should gain u a few tenths.

Just look at the base when u pull the runners off.

Not much more work at that point either, might as well seal the deal.

It wont be as good as a ported aftermarket base, but u said your money is tight and it will be better than stock lol

later
Jeremy

 

Very nice work dude . You went a little further with the plenum siamesing than I did but I doubt it will be a problem. I think the way your getting it set up is going to yeild a stout intake that will spin up to 5000+. IMHO

 

For runner gaskets, Mr. Gasket has an intake runner kit that has 1.75" opening to cut to. I think stock is around 1.5 or so. If you get a stock gasket some have a visible sealing ridge that can be ground away to make a template alittle larger than the stock size. When making a siamesed intake you have to first siamese a gasket exactly as you want it. You use that same gasket for both sides Then the gasket you made is your guide for everything.

I use a 1/4" die grinder with a double cut carbide bit. Usually a cylinder shaped one with a domed head or a tree shaped one. They are about $20 at Fastenal or Grainger. You need to keep the bit well oiled with either gear oil or penetrant. The aluminum will gum up the teeth if you don'. The bits cut very well but are unforgiving if you miss or mess up. Go slow and check your work. Don't get to wild and pay attention to the head as it will cut into thing you may not notice your cutting into. I then used an 80 grit flap wheel about 1" diameter to smooth it all out.
If I get a chance I will take a pic of the rig and the bits I used.

Thanx guys.