Billet Throttle Body

I have been experimenting with different throttle bodies and decided to try to build one myself...just for fun. But it works too! Everything except the idle adjusting screw and spring is new.

Stock Throttle Bodies

I've refurbished several Throttle Bodies (TBs) and have also enlarged the throat dimensions of several. Tests show a small but easily measurable increase in performance with a big TB. The picture below shows a stock (but reconditioned) 2.0 liter TB on the right and an enlarged TB on the left. When refurbishing, I clean everything, replate all the steel parts, polish the throttle disk & bore, and insert porous bronze bushings for the throttle shaft.

One of the modifications I make to TBs is to add an external, adjustable stop to them. These two pictures show this modification. The external stop keeps the throttle disk from resting on the ID of the body. Most old TBs without this modification have a groove worn in them which causes the disk to stick when moving from its rest position, especially if the shaft is loose in the body (because it can move sideways and detent in the groove when at rest).

As the two pictures below show, the enlarged TB has a 6.369% larger ID. This results in an 18.5% larger throat area, which gives approximately 10% more output from the otherwise stock 2.0 engine. The enlarged TB shown is the first one I did and is a bit smaller than subsequent attempts, which were bored to 50mm (1.9685") with a throat area that is 23.6% larger than stock.