Fuel Moto ported throttle body
- Thread starter NGOT8R
- Start date
Porting an intake always helps, just like porting heads. But to take best advantage of it, they both need to be done, and most likely a cam change to take advantage of the increased airflow available.
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To be really effective, the heads and intake should be match ported. That means sending them to the same guy who prerably has a flow bench so he can test before and after.
I also know from doing this on drag cars, it only makes a noticeable difference at very high RPM. At low RPM it can actually hurt you. A little roughness in the ports will help to atomize the mixture at lower RPM. Porting will help at higher RPM where the air velocity through the ports reaches a point where parasitic drag becomes a factor. Parasitic drag increases with the square of the air velocity, so as you double the flow, parasitic drag increases four fold. The higher the RPM the more critical it becomes.
I also know from doing this on drag cars, it only makes a noticeable difference at very high RPM. At low RPM it can actually hurt you. A little roughness in the ports will help to atomize the mixture at lower RPM. Porting will help at higher RPM where the air velocity through the ports reaches a point where parasitic drag becomes a factor. Parasitic drag increases with the square of the air velocity, so as you double the flow, parasitic drag increases four fold. The higher the RPM the more critical it becomes.
Great info BluesBelly and RoadWarrior! I noticed that in the video, the combustion chamber and ports were polished to a mirror finish. I imagine that would make for a better flowing head, as carbon deposits probably won't build up as easily as they would on rougher surfaces.
We match ported and polished when we ran small blocks, which were turning upwards of 12,000 RPM. When we switched to big blocks that were only turning 7000 RPM, we weren't seeing enough gain to justify the expense. It would be interesting to see a dyno sheet before and after a port and polish job.
Port wall smoothness requirement is a lot different between a carbed engine VS one that is port injected. With port injection, there is no fuel suspended in the airstream in the intake tract, so you are wanting to pack as much air volume as possible at all rpms.
I got bored yesterday and started porting the stock throttle body. Most of the work was done by hand, although I did use the dremel a little. I figure I still have several more hours worth of work ahead of me to get it shaped the way that I want it. Here's what it looks like so far.
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Update: Well folks, I got a little carried away this afternoon and while trying to completely remove the hump that runs along the roof of each intake tube, I ground off too much material and ate through the seating surface for the injector on the left side. Now let me be the first to say; I don't consider this to be an epic failure at all. I see it as a learning curve, as well as an opportunity to help others avoid the same mistake, should someone else be adventurous enough to go down this road like I did. Good luck!
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Were you just making it bigger everywhere, or are you thinking about how the are is going to make that turn?
Yes. I was trying to completely eliminate the humps on the ceilings of both intake runners. It's still salvageable if I want it to be. I could have my machinist buddy press in a new fuel injector insert and tig weld it in place for a leak free fit, but it won't be free. Having said that, I think it would be more cost effective to just put that money towards a new throttle body.