Nice work! That's got to be the TB from your Mustang.

What did you have done to the butterfly shaft? The butterfly looks totally different on the after shot. Lower profile. :drool: Did you have that one bored and the butterfly replaced? My TB shaft takes up 78 square mm of the intake. I was thinking about shaving it down... but yours doesn't even appear to have a shaft anymore. What gives?

In some cases (and only from SOME manufacturers) when throttle bodies are made, the butterfly doesn't seal properly around the edges because they were like a thousandth of an inch off somewhere. So the manufacturer uses solder to fill the cracks. If you see this on your throttle body (it sometimes looks like corrosion) DON'T try to polish that off of the mating surface where the valve seals. You can end up with a high idle if you do. I have a picture of one with the solder on it somewhere... A machinist warned me about it.

Thanks for the tip about the jewler's rouge. Many of the automotive rouges have carnuba waxes in them. Maybe a jewler's rouge doesn't. I was thinking about using ZOOP seal when I finish, and wax would probably prevent the ZOOP seal from sticking. That stuff is mad expensive, too. Check it out. www.zoopseal.com

 

Yep, that's the TB from the Mustang. The original casting was horrible. You can see in the first pic that the leading edge had a huge lip on it. I tapered that down. There was also a nasty ridge inside, which I completely cut down too.

As to the butterfly - I removed half of the shaft myself. You can't see in in the second pic, but I basically cut off the top half of the shaft. The bottom half is left, and is threaded, so the screws can bite into it. I'm going to countersink the screws so that the heads don't stick up and cause any obstruction either. I completely polished and knife-edged the butterfly too. Overall there's a good 10-20% more cross flow area than there was before. (Edit: You can even grind down a significant amount of material off the bottom shaft too, if you really want to go radical. The shaft doesn't need to be anywhere as thick as it is, you can easily grind down a couple millimeters. Just make sure you leave some meat around the screw holes.)

I've heard ZOOP is good, never actually tried it though. I'm still partial to the Al Oxide paste. Lots of companies make it, you can pick it up just about anywhere.

 

Again, nice work. Some DSMers that have bypassed their FAIV valve use that Mustang throttle body. Isn't it like 75mm or something like that? Or is that the BBK? Some DSMers use that TB. I might when I get a sheetmetal intake manifold.

Do you ever worry about its structural integrity? I'm going to be running 24PSI soon, and I hear that some people have durability issues with high boost and modded throttle bodies. That's been the only think keeping me from hacking mine.

 

Stock for the V6 is only 60mm. They're 65mm for the V8. That's for 99+ (new body style). The 94-98 V6 TBs were - get this - 50mm(!!!!!). Talk about strangling airflow...no wonder the 94-98 V6s only made 140hp. You can get aftermarkets, like BBK, in just about any size you could want, though. 70mm, 75mm, whatever.

Actually it's funny you mention that, I was going to say something about boost before. If you were running high boost, I might be inclined to leave the shaft alone. Or at least take it VERY easy on the 'meat removal' part. If you've ground the shit out of your shaft, then try to run 20 pounds of boost with it, it wouldn't surprise me at all to see the shaft twisted and snapped. You could help prevent that by making sure you have good pressure-release hardware upstream from the TB.

To be honest, though, I think I agree with you. I don't know if I'd mess with the shaft at all under that much boost. When you're boosting, smooth airflow isn't as critical as it is NA, so I'd probably be more inclined to just go with a bigger TB (if you even need it), and not waste time haftshafting.

If you're talking about the integrity of the actual aluminum body itself...I highly doubt that'd be an issue. You'd punch through a gasket way before you blew a hole through aluminum.

 

that TB looks awesome. that would yield some gains correct? im a performance dork. i had to ask

 

Depends on the rest of the engine, really. That particular TB is a 60mm from a 2000 3.8L V6. The stock TB can flow a good 300-330cfm, which is actually enough to feed a 3.8L V6 up to about 5500-6000rpm pretty easily. So the stock one wasn't a major restriction, and so polishing/halfshafting doesn't net you a world of gains. In other words, the stocker flowed about 300cfm - mine all cleaned up as above flows about 330-360cfm, which is better, but since 300cfm was just about enough to begin with, there really isn't a huge performance increase.

Remember, when building an engine, it's NOT about bigger is better. It's about matching, and getting each component suited to every other component. THAT'S when you start to make serious power. An 80mm TB flows a ton of air, but on a 3.8L V6, won't do shit beyond what a good 60mm TB would do.

 

Update:

22 hours in... All rough cast is gone on everything that isn't under a timing cover or covered by flanges. Even the detail stuff is done. I'm finished wet-sanding with 220 grit. I estimate another 10-14 hours and it will be ready for the polisher. I hope I don't wake up with a blister on my thumb.

This is the coolant return side of the head. It's done with 320 grit now and you can start to see dull reflections of nearby objects in it. Things are moving right along now. I'm past the worst of it.

I'm going to use aluminum oxide polish as DanM suggested, after I finish with the 320, and hit it with 400, 600, 800 grit. I also have 1000, 1200 and 1600 grit, but that would be totally unnecessary on this piece.

 

PS: If you're doing a rough cast, get one of these. Buy several 5-packs of fine-grit sanding tubes. You will destroy the contour sanding pad (black and yellow things) within minutes sanding on metal, so stick to the jigs and sanding tubes.

This thing probably saved me 10 hours, and lots of blisters. It costs $80 with extra sanding tubes. A worthwhile investment if you ask me.

Dremel Contour Sander:

 

Nice work man. :thumbup: And good call on the Dremel tool .. I was gonna ask at first if you were doing all that by hand. I've done a few by hand, and it's not fun at all, as I'm sure you know. Takes hardcore dedication.

Don't you wish they'd just make god damn FLAT exterior surfaces?

 

Yes. But if that were the case, then everybody would do it, and it wouldn't be so cool to have everything polished, would it? The most beautiful polished surfaces are the contours IMO.

That sander works great, but if I could just get a waterproof 1/2" random pattern orbital sander with a swivel tip, I'd be in heaven, donkeys would be flying, horses would grow feathers...

The jigs of the Dremel sander are still a little too big, but since the smallest one is only 1/4" wide, you can reach some nasty stuff that you can't with your finger tips... and you can reach it at 40,000 RPMs (which is why this thing saves so much time). You can do the dirty work with power tools, but you still have to do all of the 220 grit+ finishing sanding by hand if you want a good finish.

I have to go play santa clause. As much as I want to get this project over with, I may have to put it down for a few days, or else all I'm going to get for X-mas is a lump of coal. I'm determined to have it done by new year's, though. I'll post the progress.

Merry Christmas everybody.