Hey Aaronm,
Based upon your target performance gain: “really want to increase the power available for pulling long grades. I find myself rowing the truck up the hill between 3rd and 4th gear.”
Keep in mind that for these 22s, especially the 22R, it will lose about 3 to 4 HP for every 1,000 feet increase in elevation. If you are pulling a grade or two and climb 2,000 higher you’ll drop about 6 or 8 HP.
I like your idea to experiment and tweak your engine performance. However, based upon your process of modification to gain incremental power, I would be careful to make sure you understand and monitor the changes. I would make one change or modification at a time.
For example, going to a hotter spark plug may or may not gain any power caused by “bumping up the AFM a tooth or two”. Can you read spark plugs? If you are serious about analyzing your modifications, I would suggest you consider installing a good A/F meter and carefully read the spark plugs. I would make sure I have a new O2 sensor and that the knock sensor is working properly. I would make sure the ignition timing is set properly and see that it is advancing correctly under RPM change. If you haven’t already considered it, a 3 row radiator may be a good idea for added cooling capacity and run fresh coolant at 50/50 mix.
As you know, you’ll be at the higher end of your RPM range for several minutes when pulling long grades, developing very high combustion chamber and header temperatures. A hotter spark plug may cause serious over-heating, pre-ignition, burn the top of the pistons, or toast the exhaust valves. If your gas is ethanol blended, you can actually go to a colder plug and advance your timing slightly.
Since you are into the finer tweaking stages, you can also consider lubricants. Lowering viscosities in your tranny, t-case, and diffs will help lower parasitic drag. I like Redline 75-85 for my diffs, and MTL for my tranny & t-case, and 10-30w Mobil 1 in my crank case.
TJMWO…
Please keep us updated on what you discover by your changes and modifications.
Gnarls.
