Throttle Body Porting [Archive] - GrandAmGT.com Forum

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KillNThrill24
09-27-2012, 10:24 AM
anybody got a link or anything on how much to port? or if its even worth it? i dont have the money to buy a ported TB. my UIM is ported for a 65MM already and i just want to get a little more air through if i can for free. i have 2 stockers so if i mess one up im not terribly worried about it

AaronGTR
09-27-2012, 04:23 PM
Waste of time. Don't even bother.

There is really nothing to "port" in the TB the only thing that will make a difference is having a larger diameter opening with a larger throttle plate in it. The rest of it is already smooth and opened up as much as possible.

The former RSM racing sold a 61mm TB back in the day that was a bored out stock TB with a modified shaft and new plate installed. I had one then sold it when I bought my billet 65mm TB. Then of course there are the billet sizes you can get (62,65,68). You can also use the stock 65mm TB from the LX5 DOHC engine, with an adapter from WOT-tech (but they are out of stock right now).

Basically if you don't have the money to buy one of those options, don't waste your time on anything else because it won't work.

KillNThrill24
09-28-2012, 01:42 AM
thanks Aaron i had figured seeing as the plate would remain the same size that no matter how much port work was done that since the plate would still have the same opening size, that it would have the same air flow. maybe when i get a few $$$ ill pick up an LX5 TB and get an adapter, or if its around the same cost for all that just pick up a 65 from Milzy or WOT if they have any.

since im already on the subject of porting, i just thought id ask instead of making a new thread, what about porting the LIM? i finally got an EGR off an 02 and opened up the EGR on the UIM i got from you and installed it today and man what a difference in throttle response. since the idiot i got my tires from put 205's on instead of 225's i had pretty bad TQ steer bone stock. with the ported UIM from you the TQ steer got far worse lol

now IIRC you ported the UIM, if thats the case, could you give me any tips on porting the LIM? im probably going to wait until i can get a LIM from the local JY and degrease it, check it for cracks, etc, and port IT instead of having extra down time to port the one on my car.

thanks again :)

AaronGTR
09-28-2012, 11:23 AM
Yeah, you can port the LIM as well, BUT....

It's quite a bit more difficult, and easy to screw up if you aren't careful. There aren't a lot of bits/tools that can reach down those long runners, and it would be near impossible to really open them up and keep the size the same throughout the runner doing it be hand. The only way that would really work is to extrude hone them, which is expensive.

The best thing to do is stick to cleaning up things around the ports. You can gasket match the inlet side pretty easy so it matches the porting on the UIM. On the outlet side where they match up to the head you have to be very careful though. If you change the shape too much you can actually hurt airflow into the head ports and hurt fuel mixing from the injector too. A lot of people will smooth down the bump in front of the injector holes but that helps with mixing the fuel into the air stream so you don't want to do that. About all I did with mine was make it a tiny bit taller and smoothed out any really big casting defects.

chris_gt_74
09-28-2012, 04:21 PM
thanks Aaron i had figured seeing as the plate would remain the same size that no matter how much port work was done that since the plate would still have the same opening size, that it would have the same air flow. maybe when i get a few $$$ ill pick up an LX5 TB and get an adapter, or if its around the same cost for all that just pick up a 65 from Milzy or WOT if they have any.

since im already on the subject of porting, i just thought id ask instead of making a new thread, what about porting the LIM? i finally got an EGR off an 02 and opened up the EGR on the UIM i got from you and installed it today and man what a difference in throttle response. since the idiot i got my tires from put 205's on instead of 225's i had pretty bad TQ steer bone stock. with the ported UIM from you the TQ steer got far worse lol

now IIRC you ported the UIM, if thats the case, could you give me any tips on porting the LIM? im probably going to wait until i can get a LIM from the local JY and degrease it, check it for cracks, etc, and port IT instead of having extra down time to port the one on my car.

thanks again :)

I got my LX5 65mm throttle body second hand and the adapter from WOT-TECH, both together for less than $80. If you look around real good the throttle bodies can be had pretty cheap. The adapter however unless you get one second hand they are gonna cost around $50. You will have to do some minor modding to get the ball on the end of the cable to work with the different style but it's a pretty easy fix. The hard part for me was bending and adapting the stock 3400's throttle cable bracket to fit the throttle body and not change the cable's stock amount of cable slack.

For the price you can't beat it. But it does require modding to get it to work right and still look good.