Thought I'd share results of my recent B engine tune-up and freshen. The engine was put together about 10 years ago by a small shop in Indiana with main parts from MM. This time she went back home to MM for the freshen.
It is a 4.15 x 4.375 with pocket ported Ed heads and MM 243@.050 .55" lift FT cam. I have put about 15k miles on it and this last summer enjoyed 2 full and long road race track days ending in 8 timed HSAX runs.
It runs first generation FAST XFI... the kind that is not self learning. Also a dual sync Accell distributor. I built and refined the EFI maps as best I could with data logging and adjustments. As I found out, the fuel curve/VE values at higher loads was a bit on the rough side.
Anyhow, I out-drove my "Hemi" oil pan on the track and had episodes of low oil pressure. I was still running well but I wanted to get it freshened before it got hurt.
The basic freshen was pretty uneventful. The bearings showed some distress and signs of heat but still had most of their flash. Caught in time and there is an oil cooler in my future. The cam was intact but beginning to show some distress so it got a new one... this time nitrided with EDM lifters. We were going to CNC the heads but the guys put them on the bench and they already flowed well. I guess the original pocket port was pretty thorough. Not much gain so just freshened up with new valves and good valve job.
The big gain was in the EFI tuneup. Scott Marrison handled the tuning. We decided to run it on the dyno with EFI and get the maps dialed in for best performance. The sequential injection was tuned, individual cylinder fueling was adjusted to compensate for manifold flow differences and fuel pressure bumped from 45 to 50. It picked up around 40 HP from the "tune up".
I was extremely pleased with the result... and looking forward to getting it installed and driving it. The guys expect the seat of the pants improvement to be noticeable. It is really super for a manual transmission with wide and flat torque and power curves. Pic and dyno sheet is attached. Now I have to get to work!
