After some more reading and thinking, I am going to make my own airbox over the throttle trumpets without worrying too much about the theoretical details. As long as I make sure that it ducts cold air into the engine and is big enough that re-filling isn’t an issue, the potential losses from mis-tuning are minimal. Without a dual-chamber with a butterfly/door or other other adjustable volume setup, the potential gains are minimal to small and only in a very limited rpm range. Helmholtz tuning is apparently most effective at low rpms, like under 3500rpm, and I am having trouble finding anyone who has done the calculations on custom airbox for a higher-rpm engine and found any gains on the dyno, and have found some folks who have tried it and haven’t seen any measurable gains over just winging it.
So, tuning with different trumpets and different exhaust sizes, lengths and configurations will make a difference, but it seems the airbox is unlikely to make any real difference.
I also found what should be a good solution to the challenge of fitting the oil temp sensor without a lot of complexity. As you guys may remember from a while ago, I was having trouble figuring out where to put the sensor in the oil plumbing because the front of the exhaust side of the block is getting fairly crowded, and the supplied sensor with 3/8” NPT threads is too big to install easily. The sensor that came with the management is a GM sensor which came on many cars and trucks from the early 80’s onward. I found a 2007 Saturn sensor which has the same connector, is supposed to have the same output, and has M12x1.5 threads, which will be a lot easier to install someplace, perhaps even right in the oil cooler sandwich plate!
