Figured I'd post up some pics of this evening's project. I decided I don't have the extra cash laying around for a fastman TB right now, but I do have quite a bit of experience porting Eaton M90 casings & exhaust manifolds for 97-03 GTP's. SO.....I started by pulling the TB off & removing all the sensors. After removing them I gave the sensors all a shot of electronic safe cleaner. I worked a dremel stone bit carefully around the lip where the plates come to rest. After removing all of that extra lip & smoothed it all out, I cutthe air horns off& ground them flush with the TB base. Then I pulled the screws & blades out of the throttle assembly. I marked where the rod needed to be thinned out & used a heavy grinding stone to do the bulk of that work. Picked up a set of new screws for the throttle plates at Ace Hardware for about $0.30 each & cut them down flush with the thinned rod.

FYI...the stock throttle blades are 50mm...the throttle body itself tapers inward toward the top to about 47mm though...this is the area that needs to be worked heavily. So now the top of my TB is 52mm and tapers down to 50mm at the plates, so they still seal perfectly. I didn't touch anything below where the throttle plates come to rest.











these aren't final pics, still a little more polishing work to do, but at this point I'm all done with the grinding stones & cutoff wheels

 

That looks very good. If possible, see if you can get some brass stock and make some brass butterflies. They seal better than aluminum and will make a difference. If they didn't, then Mr Arcand wouldn't be using them

 

I'm not totally confident in my abilities to cut a perfect circle for new blades...nor do i have the tools/materials to do so. I'd be really angry with myself if i went to alarger opening and then couldn't get the blades to seal.

for the time being this should work for me, the major areas i wanted to amend were right above the blades there's a lip that's around 47mm, removing the air horns, and thinning outthe throttle shaft.


any other comments/criticism?

 

Are you going to knife the butterfly edges? so it cuts through the air I knifed the edges on my SU carbs for my jaguar and it made a difference

 

Holley has an engineering center in western Kentucky
where some work was done on those throttle bodies.
Several years ago I asked an engineer there about the
'air horns' outside of the bores that everyone cuts off:
this engineer claimed that those air horns actually improved flow
and he chuckled about people cutting them off.
Obviously the air horns require extra aluminum in the casting
and it is hard to understand why they would put them there if
they did not serve some purpose.

Reducing the size of the throttle shafts
sharpening the leading edges
and perhaps adding some 'dimples' prior to
where the shafts bolt on
might improve the airflow from the stock 620-640 cfm.

There is a lot of information in Chrysler's patent on these throttle bodies:

http://freepatentsonline.com/4905647.html

Notice in Chrysler's patent they claim the special shape necking down to 47 mm (called a venturi) does not reduce maximum airflow.
When you make a claim in a US Patent it is equivalent to swearing an oath in court.

For the benefits of putting dimples in the right places
SuperChips technical director Jim McFarland has a patent on
using dimples on top of pistons:

http://freepatentsonline.com/6170454...mp;stemming=on

And another patent shows the advantages of using dimples on plates, wings and fans:

http://freepatentsonline.com/5540406...mp;stemming=on

Note in the above patent the section where they show you can 'prove to yourself' that dimples work by playing with a wooden model airplane propellor before and after putting dimples on it.

As with all airflow modifications
you 'shoot yourself in the foot'
if you fail to check the MAP sensor reading
before and then after
a throttle body change.

 

Formotorcycles the equivalent of airhornshelp low- and mid-range power and torque, but work against you at high rpm.

In the lineup of some brands, the same basic engine is used for different models but the intake tube (works like an airhorn) will be longer in models that need low speed torque (ex: "adventure" or touring bikes) than in models meant for high speed (ex: sport bikes).

Some brands go further and have sport bikes with airhorns within airboxes that efffectively change length according torpm & throttle settings.

My guess is that a truck being a truck, these airhorns are there to improve work performance - I mean low speed grunt.

 

My form of a venturi is the total of the atmosphere being shoved into 52mm. Thats a bit of a bigger venturi than the 50-47.

 

Hankl makes a good point about the air horns "Obviously the air horns require extra aluminum in the casting
and it is hard to understand why they would put them there if they did not serve some purpose."
I need more torque at 2000rpm so I don't come out of overdrive when driving on the interstate. So, would a Fastman TB or one like pictured above with the airhorns removed be a step in the wrong direction for me?

 

God put ticks on earth, im pritty sure there was no reason for that

 

My fastman TB outperformed in everyway the stock TB with airhorns. More off-the-line throttle response, and improved power in the upper RPM range, and I also gained a solid 2 mpg. Chuckle at that Holley engineer.