...it’s a start I guess. This is what I was doing yesterday. Bear in mind this is power at the wheels, not the crank; and it’s virtual dyno, not a real one, so the results aren’t totally reliable. For example, the green run was the last and iirc I feathered the throttle slightly and then got back on somewhere between 5000-5500rpm. Foot jumping ahead of my brain as we were catching up to a truck. Still good for a before and after picture though.
I would be happy for some input from Oppo’s mechanical/tuning types though. The guy that did the tuning said he couldn’t understand what the issue was, but there definitely was one. He tuned a truck almost the same as mine on 87 octane, and had the same issues. Knocking all over the place on stock tuning, and a persistent knock at 4300rpm. He started with that as a base tune for me, and even though I ran 89 octane based on his information on the other truck he had on his website, the 4300rpm knock stayed. Everywhere else it took more spark advance, but we ran into knock retard at 4300 every time. As a result, the peaks are pretty much identical to the other truck, but lower down in the rpm range.
Any ideas what could be strangling this thing? The only thing he could think of was the exhaust, on the full size trucks it’s 3" all the way back, in mine it’s 2 3/4" dropping to 2 1/2" after the muffler. The intake side looks OK.
If that’s really all it has to give, well OK. But based on the results he’s gotten with full-size truck 5.3's, I don’t think so. There’s something there that’s killing the potential, and that’s what bugs me.
Anyway, the main thing is it shifts better and actually downshifts and digs in when I want it to instead of torque management coming down with a banhammer and taking 40% of my power.