Long story short, by '91 SE-R race car (NASA PTE) seemed to be low on power, so I put it on a mobile dyno at the track last summer. Below is a graph showing 4 pulls. Note, it was a hot day and I didn't hear any bad upper or lower engine noise. After the dyno I found compression to be 119-121 across all cylinders. Adding a tablespoon of oil got me +5psi on all cylinders. Blow-by through the oil-fill hole (valve cover) feels like a hair-dryer on Hi-setting, and the vc gasket I replaced about 10 hrs ago (track time) was leaking in several locations. After pulling the vc I check the chain/sprockets and they were on-mark, and the cam lobes were all smooth and looked great. I'm also getting a little unburnt oil appearing on the lip of the exhaust, and the spark plugs were dark/carbon. I have not checked fuel pressure nor the ignition system, but the engine does run smooth albeit low on power.
I will soon begin the project of an engine R&R, but hope to find a consensus that the current engine has wasted piston rings. Also, why does the dyno show irregular power from above 4k rpm? Is it the S4 cams exaggerating the compression loss?
Specs: OEM-JDM SR20DE high-port w/ JWT's S4 cams, flywheel, and ECU, timing at 15*, HS header (gen 5-6?), 2.5" -> 3" side-exit exhaust w/ an 8" cherrybomb, and HS cold-air K&N intake, UR crank pulley, and a gutted PS pump. Similar set-ups have dyno numbers around 150hp?