I figured I'd start this thread up now that the overhauling of the Series II L67 is about complete. It might be a little premature, but I'd figure I'd share my thoughts on some of this stuff before it actually happens (and y'all get to giggle at my mistakes when I make them
Recap of the basic plan goes like this:
Car is currently a 1990 Bonneville LE, LN3 motor, 440T4 transmission, stock 253 ECM with ASSK prom. Mods that will carry over are the intake with K&N filter. While the car is equipped with a Fogger NOS system, that'* a secondary consideration to what I will be doing. I'm not going to tune the car for the NOS, I'm going to tune it to the new motor and then tune the NOS system at a later date using new jet sizes.
The new motor is a Series II L67, bored 0.030 over, with M90 Blower, 1994 Throttle Body adapted to use a TV cable to the transmission.
Based on yesterday'* data collection run up I-95, the stock LN3 has the following state of tune with the stock ASSK prom:
BLM is averaging 127, Integrator hovers in the 120 to 130 range.
KR is 0 on 87 octane with brief jumps to 3 if I lug it up-hill on throttle light enough to not unlock TCC.
O2 values at WOT through all the gears are 0.888 to 0.905 vdc
This is about the state of tune I'm going to try to achieve on the new motor, using mid-grade gas.
Tools in use: Actron scanner to monitor the ECM while it is running. TunerCat 2.11 software with type $5B config to edit the prom. And an old JDR Micro-devices EPROM reader/burner to generate new proms.
I can also confirm the presence of a speed limiter on the LN3. I found it in the ECM constants table set to 115mph. That, along with the RPM fuel cutoff values are going to get moved to their maximums as the first test, to make sure the software is decoding the eprom correctly. (In other words, I'm going to alter a few values in the stock PROM and try them out on the stock motor before the swap, just to confirm that the software is working correctly.)
That'* about it for starters. I'll post some shots of the process as I go along.
If there is any real interest, I'll post the PROM bin files along with dumps of the tables so any of you LN3 folks can follow along...or mess around with your own 87-91 H-Body.