Car: 1998 Eclipse Rs
420A engine

I Got a new dremmel tool last weekend. I have decided to port out my throttle body. I wanted to know a couple things first:

1. What is the max diameter I can port it out to?

2. Will this affect anything (mass air flow sensor or other things)?

3. Tips and little tricks that may help?


I know there are numerous threads for this, sorry I'm a little short on time to search around. If anyone can, please send me any threads or post anything you think may help. I want to do this right the first time. Thanks Everyone!

>1. What is the max diameter I can port it out to?

57mm or so just make sure you don't touch the part where the butterfly seals or your car won't idle right.
>
>2. Will this affect anything (mass air flow sensor or other
>things)?

the 420A engine doesn't have a mass air flow sensor. the spyder (4g64) and turbo (4g63) engines do though
>
>3. Tips and little tricks that may help?

get it bored or get a jeep TB

I remember glancing at some of those posts about the jeep throttle body, I Just haven't been checking reading posts about it. What type of Jeep do I get it from? Is this a junkyard item?

http://www.dimensia.com:81/jimbo/JeepTBfor2gnt.html

dude, just port it out yourself. and Polish it up with the dremel too. That's what I did :). Don't forget to get the gasket for it and all. This is a good mod.

you can't 'port' the Tb without making a new throttle plate.. and any porting you do to the TB not around the throttle plate, won't help at all, because where the throttle plate closes is the smallest part in the TB.

remember guys.. he's talking about the TB not the intake manifold! you can port the intake manifold all day long without problems. but in order to port a tb you need a very nice machine to make sure you make the new opening perfectly round and right in the center, and you'll need to make a new butterfly.. all of which you can't do with a dremel.

actually, i was looking on mine, cuz i ported and polished it, and it funnels down about a 1/4 inch before the throttle plate, then widens back out. i just worked on getting rid of that slope, and matched it to the bore diamater of the throttle plate. i ported mine and ddnt have to make another plate. time to put it back together now!

interesting to design it like that... I guess purhaps they made it smaller before the plate so that the flow would match (because the plate is going to take out some of the flow abilities).. weird.. anyway.

yes the only thing you can do without making a new butterfly plate is just to remove the hump before the plate, its still a nice mod, gives a little more get up and go