Porting the Throttlebody

[rougeben83]

Went from this:

https://sl-i.net/FORUM/images/imported/2008/01/P1060210-1.jpg

https://sl-i.net/FORUM/images/imported/2008/01/P1060211-1.jpg
I'm not sure what this little lip is at the top of the tract...maybe it helps with partial throttle? It's interesting to note the 2.5RS TB doesn't have this lip. (it also doesn't have the hole for one boost sensor, but that's another story) Anyway, that got taken out...

To this:
https://sl-i.net/FORUM/images/imported/2008/01/xy5-2.jpg

The screws for the plate were also trimmed flush to the bar, and the edge of the plate was knife-edged a little bit (not shown here).

Driving around...I'm not ready to make any performance claims yet...but it seems to pull all the way to redline more noticeably whereas before it would pretty much top out around 5.5k rpms and I would just use the rest of the revs to hold the gear (like in autocross). I wasn't expecting anything even remotely noticeable doing this, but I'm pleasantly surprised.

Right now I think it was worthwhile, since it was free :lol:

[MoclovFlop]

Very interesting. What dremmel bit did you use for the initial grinding? Did you notice any TB response changes?

[Jedi Taxi]

when i was working with my jeep throttle body, i used an orange dremel bit. its corse enough to take away plenty of aluminum, but like i said, its corse, after using it, i would say use a a metal polishing bit.

[Reason]

Cool stuff, here is mine.

http://i2.photobucket.com/albums/y16/EJ25Legacy/DSCF0068-1.jpg

http://i2.photobucket.com/albums/y16/EJ25Legacy/DSCF0069-2.jpg

[Huffer]

I'm lost. I can't see any changes. I understand that the screws that hold the butterfly flap on have been cut down, but am I supposed to be looking at the interior of the tunnel as well?

[rougeben83]

Yeah, the part closest to the airfilter got ported out about another 3mm in diameter and then tapers smoothly all the way to the throttle plate (I took out that lip and the little ridge before the TB plate on the bottom part of the tract as well.

You're just eliminating any thing that may cause turbulent flow of air into the throttle body. Some people go even further, like grinding down the bar to have an even less round profile, but it was just too much trouble for me. (it's still an N/A EJ25 after all :) )

I used that bit that looks like A in the pic:
http://faqlight.carpassion.info/dremel-bits.jpg to take away most of the metal- the metal is pretty soft to begin with.

Then used a couple of grinding stones then sandpaper, rubbing compound, then jeweler's rouge just to make it a little shiny.

I would note to just use a grinding stone then a fine grit sandpaper to finish on the tb plate if you want to knife-edge it - it's even softer metal than the TB, what you don't want is ending up nicking the edges of the plate as that helps create the seal when the TB is closed @ engine idle.

Oh yeah, while you have TB out, it would be a good time to do the coolant bypass mod if you want. (which I did).

[2.5GT]

When i did mine, just used a higher/lower grits of sand paper, and sand it down to complete smoothness ...lol and then buff it out with some metal polish..it shines :grin:

[rougeben83]

When i did mine, just used a higher/lower grits of sand paper, and sand it down to complete smoothness ...lol and then buff it out with some metal polish..it shines :grin:

Yeah, most people use the sanding drums...they start off with the flapper sanders first to take off material, then go from there.

I had those extra bits already so I just used those. I think using the sanding drums would give a more even finish like w/ Reason's ported TB, but well, I'm not really that concerned with looks as long as it performs :lol:

[2.5GT]

try wet sand it too aftwards...gives it that smooth feel :grin: