Diffusing The Situation

29 Dec Diffusing The Situation

Sometimes diffusing a situation by calming everything down is the best way to solve a problem. A problem like this one.

We were experiencing some small runtime issues on the road with Scott’s turbocharged Explorer during our road testing portion. After a good amount of testing, we sat down to figure out the issue. As with before, we had it pegged to the airflow over the mass air flow (MAF) sensor. The way to remove the problem was by smoothing out the air over the sensor itself. In lieu of crafting an entirely new piece of pipe that wouldn’t really fit with the size specifications of the rest of the build, we made this instead:

Yes, it’s a diffuser, but not in the under-car sense. The purpose of this piece is to be installed in the piping directly prior to the MAF sensor. Like this:

The issue with the airflow over the MAF stems from a bend in the piping just before the sensor. When the air flows around that bend, the velocity of the air in various parts of the pipe can differ radically. This creates issues with the air flowing smoothly over the MAF sensor, which is really the best way to eliminate any possible issues stemming from this hellacious little guy. With the diffuser installed just after the bend, the air flows through it and evens itself out by the time it reaches the MAF, allowing us to then put our focus back on adding timing and creating power without spikes and hesitations during off-load and partial-load situations. To test our theory before cutting the part, we recreated the bend in SolidWorks, both with and without the diffuser installed, and even just in theory it helped out immensely:

So we welded it into the pipe, and put everything back together. The result? Our on-road testing gave us a night-and-day difference. With that issue resolved, we re-tweaked the MAF portion of our tune, and are now putting the finishing touches on the timing, which is where the power’s hiding. Results should be coming soon, as we’ve been working on it through most of last evening and into this morning. In the meantime, enjoy this picture of the diffuser being welded into the pipe:

Tomorrow marks Fluid MotorUnion’s final blog post of 2011. It’s been a great year, and a lot of things have happened, so we’ll be doing a Year-In-Review blog post tomorrow, going over some of the best FMU work from the past 365 days or so. It’ll be a fun read, so get excited! It’s almost time for the partying to commence!