I have ported a handful of LS1 and LS2 TBs for friends and figured someone can use a good guide to DIY. Overall I found it very easy and it took me 3 hours total... from popping the hood to cleaning up and slamming it shut.
Tools I used... ( you can substitute different size sand rolls or even use flapper wheels if you like. I just used what I had at the time and it worked fine. You might consider using some 36 grit sand paper for the rough work and then come back with some 60, 120, 200 and so on and so on depending on how smooth you want it. The emery polish wheel does a good job by itself though if its all you have.
Air Compressor
Air Die Grinder
Air Spray Nozzle
3/4" Drum Sand Rolls - (60 grit I believe and I used 4 total although I only had 5 so I used each one for a while and flipped them once half of it wore out on the ridges your grinding down.)
2" Emery Polishing Wheel - (Its all I had to polish at the time and I will be going back with 500 - 1000 grit sand paper and re polish for a mirror finish... otherwise its plenty smooth enough... its as smooth as stock surface if you ask me)
I believe this takes less time with air tools vs the dremels... but that should be expected. Either way it will work... just take your time and sculpt it down feeling with your fingers until it feels smooth and at the same angle as the sides of the TB.I stayed about 1/4 of an inch away from the TB Blade... and just brought the two ridges on the top and bottom of the TB down to create more of a circle instead of the stock oval shape. You need to stay away from the area close to the TB blade when close because minor changes in this area will scrap your TB because of idle problems. The TB blade closes and makes a pretty tight seal only allowing a set amount of air through. The amount of air let through is what determines your idle. Take material off in the area 1/4 infront, behind or directly under where the TB blade sits closed and chances are your going to be buying a new TB. Your trying to eliminate the ridges just outside that danger area and transition as smoothly as possible into that area without every touching it.
Additional Options
1. Knife edging the TB blade
I personally didnt do this because I felt it was pointless and I knew if I screwed it up it could cause idle problems. K.I.S.S. (Keep it Simple Stupid) is a good way to think about this.
2. Halfing blade rod
EDIT: Not a good idea, has been proven to cause issues from stress put on the half shaft while modifying it. Can cause codes, improper idle etc. Best to stay away from this... although it can be modified correctly without these issues... but dont trust just anyone to do this. Most like myself will tell you that the risk isnt worth the rewards or possible issues later on down the road.
3. Opening up the backside of the TB where it makes contact with the intake manifold.
EDIT: Very possible to do by hand... it just requires a very steady hand familiar with the job to ensure the "critical" area isnt altered... causing codes/idle issues. Probably not something to do yourself unless you know exactly what to do. Ive successfully done it multiple times now with a specific method to significantly reduce chances of scraping the TB.
This is what you should have once you removed the bulk of the material with the sand rolls. I did go back around a few more full turns with the sand rolls to smooth it all out good and make it one continuous angle. I took many pictures because I wanted to try and give people a good view.
Here are pics of it after its polished with the Emery Wheel...
You can use other ways to polish if you really want to make it look nice. In all honesty though this surface is smoother then stock imo and works fine. It was quick and easy, maybe next time I have the TB off I will touch it up with some 1000 grit sandpaper for ****s and grins. Smoother the better though so its really up to you how far you want to take it.
I think I could have gone a little wider on the top and bottom ridges but I didnt want to go too far and felt this was more the sufficient.
Same ball game for the most part except your removing more material. Some people epoxy up the void to help smooth the airflow and increase efficiency. I wouldnt recommend it after talking with WRP about it. Here is a very informative quote from WRP that needs to be in this thread.
"The epoxy procedure on the LS1 TB is my concern. I've had a couple of LS1 TBs come back after 30-50k miles with chunks broken out of the epoxy after it had been oil soaked for extended periods. I would imagine the chunks went into the engine. 2-3 years ago I tested an epoxied unit against one of mine un-epoxied and did not see a measurable difference in the hp increase on the dyno. My conclusion is it is not worth the risk to someone elses car and I sure wouldn't do it to mine. Another problem I had was from a TB I purchased on ebay. The seller had halved the blade rod and knife edged the blade. Friction had broken the edge of the blade down, it was used. Guess where the little particles were going. I don't knife edge blades either."
I also didn't max this TB out because it was my first attempt on the LS1 TB. It wasnt my TB also so I didnt want to screw things up. I took it to a comfortable spot and left it there knowing everything would be fine. There is plenty more material that can be removed to smooth the transition into the void area by rounding the edges more. Once I do one like this I will get some updated pictures...
Linear Mode
