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I just added some extra spark at cruise and now the BLM's are slightly rich, so I'd normally reduce the VE in that area but I was wondering what's better: higher VE at cruise with less spark or lower VE with more spark.
Increased volumetric efficiency sounds good but it now looks like I need less fuel with the increased spark which also sounds good?
you like to have as much spark as possible with lowest VE possible, that makes most MPG. Also that generates a bit more heat but if fans are able to keep temp. in place then You are good to go. Just avoid knock situations.
best regards
Honestly I am not sure why people think lean automatically generates more heat. It does not.
Just looking over a couple of logs, I have one with spark around 30° degrees at cruise and another with it changed to 35°, if I look though the logs until I find points where the MPH, RPM, KPA and throttle position all match then the one with 30° spark gets about the same MPG and has a slightly higher VE requirement.
30° at 59 MPH cruise and 50 KPA on paper doesn't sound like a lot of spark advance though?
Its not! My L31 with the marine cam liked about 38-40* at that KPA and 2,200 rpm @ 70. At 2,800 rpm running 70 with aluminum heads I run 48 at cruise now. I cruise at about 40-45 kpa now.Quote:
Originally Posted by Kitch