Diddly squat update #4251.56
Put the shop back together
Dug out one of the spare parts I had. I had traded a pair of decent grey belt retractors a few years ago with the goal of replacing the passenger side on the cutlass because a mouse chewed a hole through the belt. I had the drivers side still sitting around and the buckle was missing the trim and the belt was fraying on the 2+2 so I swapped the belt. Old, left, better, right.
And tuning. When this thing hits 88mph (you know the line lol)
I had the 80lb injectors cleaned and flowed when i went through the engine. Now that I have it running the tune has been off in odd, all over the place locations. The injectors did open up 3-5% when they cleaned.
It was consistently 10-15% rich at idle and 10ish% lean up top. I also lost about 1.5psi with the same pulley vs the old setup. So stuff changed. New cam, different compression, yada yada.... There are some reasons why it makes sense and some reasons why it doesn't. Anyways new build so I am over analyzing. I am also referencing a wideband sensor that is near 9 years old with 20k miles so who knows haha.
Nothing is telling of a problem in commanded idle trims, commanded vs observed RPM, and no obvious misfires. This new cam seems to 'lump' harder at idle and I have been chasing a 'ghost' misfire assuming thats why it's rich, but all the header primaries are warm. 10% rich switching to under 3% error at 1500rpm and then 10% lean under boost just seems odd, it seems like the whole fuel map 'tipped' with 1500-2000rpm being the fulcrum. I can't find a misfire so I'm chalking it up to its just a new cam and cleaned injectors so stuff changed and it needs a retune.
I think the rich at idle is due to injectors being cleaned and lean at boost is a better cam. The current cam is a direct replacement from BTR of the one I had (Stg 2 Blower) but the new one is the 'torque' series and better in some way I am unsure about. The new cam must flow better under boost and it's lost some PSI so its just flowing the same CFM at less boost so its more efficient which is good. Spent a couple drives tuning it and its within a few % of commanded now so it's fine. I also switched the blower pulley from the 2.55" to 2.75" to pull some more power out. I can only run 11.50 at sick summer and the car has run 11.10 at 127mph so its going to bust out of my allowed tech speed, especially if its using more fuel at less boost with more compression. It was making 11.5psi on a 2.55" pulley but now its 10psi. I am hoping the 2.75 pulls another 1.5psi out and I can make 8.5psi and some timing out to trap in the 122's and maybe yank some timing out.
So more fuel under less boost with more compression is good for my goal of 10's, but not good to turn in a pass every day on sick summer, so time to slow it down haha.
Hopefully the weather holds out and I can get some test passes at my 'home' track which is reopening this year under new management in 2 wks. It's been closed since 2021 so it will feel good to go back home and get some test passes on the new setup.
