March 30, 2010 - Results for the intake runner length testing.
This was interesting. Not because of what happened, but because of what didn't.
Each engine setup was dynoed three times in quick succession, because I found the first one tended to be erratic. The second and third would be almost exact copies of each other. When I was done, I went back to the beginning to test both the silver runners and the filtered option.
Here's the biggest difference: Short (blue) vs long (red). The shorties did indeed suffer in the midrange, with the biggest difference right around 4500. They didn't gain much up top though, which is a bit odd. Cam limitations? The medium and short runners were basically identical. The silver runners and the black ones of the same length were identical despite the difference in lip design.
But here's the really telling test: Filtered (blue) vs unfiltered (red). That's where my high-end gain came from last time. I'm a bit surprised by this, because the ITG filter I use on the Seven makes no difference at all. It's a big boy and apparently very free-flowing. Something will have to be done - read on for more.
So, the long runners were the winners. Everything else was the same. The short runners make the same power as the ones that came with the throttle bodies.
I need to quieten this car down for a 92 dB day at Laguna Seca in a bit less than two weeks. Ideally, I'd build a plenum to enclose those long runners and see what happens. But there's a way to cheat. A friend who runs a business selling parts for Titan race cars has a nice Pipercross 600 plenum I can use. I'll have to stick with the short runners to fit it, but it's a quick and easy way to quieten the car and bring in cold air. It should be here on Thursday and I'll fit it then.
tags: dyno, intake, IRTB, plenum |
THE DIARY