Piker Porting (Intake Manifolds)
Does anyone have dyno data showing the benefit (or otherwise) of just changing the surface finish on intake manifold runners, or cylinder head intake ports for that matter?
Yes. Google Larry Meaux interview. He lays it all out. You can go to Chad Speier’s web page. He won’t do an intake manifold without a burr finish. If you want one of his intakes, you get a burr finish. It’s not an option.
I can tell you that every time I’ve done it, I’ve dropped jets sizes, cleaned up some cylinder to cylinder variations and they just drive better.
I haven’t had the chance to B2B a burr finish, but that will happen soon enough.
For what it’s worth, Warren Johnson gave an interview at Engine Performance Expo II. He said there has never been a flow bench that was made correctly, and he hasn’t used a flow bench in 15 or more years. You can search for it on YouTube.
A flow bench can and will lie to you if you let it. Testing a port at any one test pressure means little, as the port sees as much as 200 inches of water when the intake valve cracks off the seat. No test bench goes anywhere near that high. Most I’ve seen is 100 inches and it wasn’t a commercial bench. Once the piston is past about 90 degrees ATDC, the pressure in the port is low. Like 8-10 inches of water. So the pressure in the port isn’t static. It changes. As does the direction of the air. A flow bench can’t duplicate anything near that.
I still use a flow bench. I have to rent time on one, but if I’m doing something I’ve never done or tried before, I go to the flow bench.
Like anything else, it’s a tool. If you don’t understand what it does and what it’s limitations are, it will tell you exactly what you want, even if the engine wants something else.