The two throttle body holes in the front area:

I have finished porting the bottom area where the EGR (?) holes are. Question is how far can I port the sides. They flare in towards the middle and look like they impede air flow. Anybody know the maximum amount I can port this out?

 

Its pretty thin as it sits. I wouldnt cut too much from that area, maybe 3/16" thick at the least. You can have it welded up and open it up somewhat. Putting a bigger TB on?

 

Is that a trick question? Gonna tell me I don't need a bigger throttle body?

No...putting on an Accel Intake, runners, removing smog equipment...and porting my plenum while I'm at it.

I can cut 3/16" at the most...or that's what you recommend I cut? Just want to clarify.

 

I'm not sure on the early plenums, but on mine, there was plenty of meat there to smooth / radius the whole thing. You don't have to go nuts trying to open it up, it's pretty much a dead spot as far as flow. You just don't want to leave sharp edges that will add to the turbulence coming from the TB.

 

Well if its just the stock TB, grind it to slightly larger than the size of the gasket for the TB. What I meant about thickness is you dont want the aluminum of the plenum to be any thinner than 3/16" when you are done, might be risky to go more than that.

 

GTA,

You can safetly go about this far:




This gives some more views:

 

I just rounded it out more when I did mine

 

Here are a couple shots of mine:





I got quite a bit of material off of that area, but I was crossing my fingers the whole time.... I really had to tell myself to stop towards the end there! .... Porting that plenum is so....... addictive .....

 

The EGR walls were a piece of cake...took me a little longer than I thought to do them...but easy. The side walls though, I was so nervous I was gonna go through them and then be screwed for a plenum. So I played it on the conservative side and just did some mild radiusing on them. I figure as long as the EGR walls were gone, that was the biggest restriction anyway.