Compression Testing

After the very concerning drop in power measured by the dyno when Evans Performance Academy was recording the "live tuning" session, I wanted to do some basic sanity checks to make sure the engine was in good health. We were already suspecting a failing catalytic converter so while I wait for the replacement to get here, I figured I'd go and pull the plugs and do a compression test with Rad's help.

Um the non-zero zero point for the gauge lol - 4-13-2019

The gauge I got actually read zero when we first started but I didn't secure it properly to the hose so during the first test the gauge actually flew off the hose onto Rad then onto the header then onto the ground haha. I think that messed up the needle position so I'm noting that the actual "zero" for the gauge is at 20psi so I'll subtract that from all the readings. I followed the instructions from Rob Robinette (https://robrobinette.com/S2000Compression.htm) which has me testing the compression with the engine at operating temperature. This worked out nicely since I drove over to Rad's house to do this anyway so the car was warm when I got there. I'm going to note here that the oil temperature when these measurements were taken was 152F. The tests measured 251,249,240,249 (pictured reading - 20psi):

Cylinder 1 - 251

Cylinder 2 - 249

Cylinder 3 - 240

Cylinder 4 - 249

Not quite sure why Cylinder 3 is reading lower than the rest but it's still within the acceptable deviation. I looked back from when I bought this engine from David Goatly and all cylinders were at just over 240 so I think this is fine. I'll keep an eye on this cylinder in future tests to make sure it doesn't drop below 240. The sparks plugs are looking ok too (the photo has it look quite a bit darker than it is in real life).

Spark plugs in order with cylinder 1 on the left - 4-13-2019

I drove her about 200 miles today and she drove smoothly as ever and the clutch slippage felt on the dyno and during testing afterwards is not as bad now. I'll be changing the clutch and flywheel anyway since I don't want to wait for complete clutch failure at some future event and have to try and limp it home. Not having a trailer anymore really makes you care about reliability. At least for now I'm more at ease since there's no indication that the power loss is due to something bad inside the engine. I also sent the oil sample from the last oil change over to Blackstone Laboratories so I'll be eager to see what the result of that analysis is.