I'll post up the graph in a few just wanted a prelim on why I would be getting very smooth, roller coaster like oscillations up near peak horsepower? I'm guessing they were at least 10 hp swings, peak to valley, very smooth not jittery at all. This was after 1.85 Comp Pro Magnum roller rocker, Doug Thorley Header install. Previous dyno was much more smooth. Gains were almost 30 HP and 15 ft/lb

After the pull ended and it started to slow down I noticed the front right side of my car would move up/down like only the right side was going over a bump. Tires are brand new, solid speed/load rating that wasn't exceeded, they are fine.

What's the likely cause of this oscillation? Bad strapping, shock/strut going out? I do feel it slightly from time to time depending on the road I'm on.

I'll get the dyno graphs up in a few.

Oh car is FWD.

 

Did you put in stronger valvesprings? It could be valve float.

 

Yes, low mileage LS6 yellow springs went in, like they have without problem in many other LS4s. What would be causing the floating? Could it be improper install?

 

I would guess a bent wheel/ bad tire based on what you have posted so far. I have also seen driveshaft balance issues cause dyno graph "oscillations".

 

need to see the graph.