Discussion and questions related to the course EFI Tuning Fundamentals
When setting the MBT, will you need to do that at all your cells? Meaning would I need to find the timing at 2000, 2500, 3000, 3500, 4000, 5000, 6000, 7000? What is the best way to calculate if you don’t have a Dyno available?
Hello Kris it is almost impossible to do perfectly without a dyno but a good idea is to data log in a boosted application MBT is also pretty much the same point of minimal boost. i will try and explain.
if a boosted car is set to run say 8psi spring pressure with a controller not being used and starting with a conservative ignition table do a pull to redline then check the log. save it, now add two deg to the boost table and run it again. check the log against the first log particularly the boost log you should notice the boost decreasing in certain or all areas, this means the engine has become more efficient so the power would have most likely increased.
if no decrease of boost is seen check the fuel mixture to see if that has got leaner of richer (leaner showing it is also becoming more efficient)
if that has not changed then remove timing until it does and then start adding it again until you see the decrease in boost.
once you have a baseline you can then start just adding or subtracting at each 500 rpm and watching again what the boost is doing, ideally add timing until the boost doesn't move any lower this will be pretty close to MBT,
This is an example only but one I have used when I have not had a dyno available I also must mention the use of some sort of knock device to hear for knock while road tuning is in my opinion a must have.
i think this post may get a few different examples come out also