54mm Throttle Body Update!

As most of you who have been following this blog may know. I was lucky enough to pick up a free PT3 (F22A6) engine. After inspection the head was found to be in perfect working order. So then came the rebuild process as I now needed a new intake adapter for my individual throttle bodies. The PT3 intake ports were much larger than the P0B head that my original throttle bodies were designed for.

Not to say that the 46mm throttles were too small for my original build. However, with the added flow with the new head comes the requirement for a larger throttle plate.


These were a no brainer when it came to updating using a bike throttle body. 54mm throttle bodies should be enough........for now.

I realize that some people may be thinking. With the money that I have spent on all these throttles. I could have bought a set of off the shelf brand name throttles. However, I have still only spent just over $600 on two sets of used throttles and adapter manifolds. That's still 1/3 of a name brand set and $300 cheaper than the rip offs. It's amazing how much you can save when you take the time to learn to design, fabricate and weld. Helps to know a few people as well ;)

The exit port on these throttles is a 95% match to the PT3 intake port. Just the right amount of taper! Anyone familiar with any of Honda's performance intake ports may recognize this shape. Minus the injection port! ;)

They are a much larger throttle in diameter so I have been sent back to the drawing board for a runner design. Picture 4 of these side by side, sorry no pictures yet, I only have two of the 4 so far. Other two are on route.

The shower head w/velocity stack is a much welcome design. The injectors that come with them have a flow rating of 491cc @ 43.5 PSI, and a single stream 15° spray pattern. As a secondary injector, they should help in the higher rpm ranges.

I am currently working on a digital file that I will be sending along with a slab of aluminum to a buddies shop for a trip through his CNC laser table. It will end up as an adapter plate for these throttles. These throttles are not going to end up permanently welded onto runners.


Stay tuned for updates! 



The old 46mm throttles will no doubt become part of another build that I have in mind. Maybe an individual throttle, Boosted 2.2L. Possibly into something with a hatch. A straight line machine.