cjblmr

Ok, I've read the smc faq thread and still have a question on the smc and its effect on timing. In the thread someone stated that they saw a dyno graph plot of ignition timing on a car with some type of map limiter and that timing was all over the place and several people tore into him that map doesn't have any effect on timing and blah blah blah. Well I I tend to disagree, but have yet to hear any sort of difinitive answer on this subject. From my somewhat limited understanding map has a profound role in ignition timing advance or retard. As does rpm, and cts. Map is the ecu's guage of engine load. Now, someone let me know if I understand this correctly, but an engine under higher load will require more fuel, more fuel creates faster burn time/ faster combustion and thus more retarded ignition timing is required to allow complete combustion by x degrees after top dead center. Now, map voltage is increased as vacuum decreases, ex. WOT or high engine load, as this voltage increases the ecu should respond with more ignition retard. It seems to me that to reduce this voltage would cause the ecu see a low load condition and reduce ignition timing retard or cause more advanced timing than would be desirable under any given engine condition. I'm just trying to get more of an understanding on this if anyone has any input. I'm looking at this as a possible solution when I do go turbo , but I want to understand its effect. Also would a btm be able to fully compensate for the timing effects for the smc?

cjblmr

anyone

zip

When using the SMC or any fuel controller with the factory ECU, you will always need to retard the timing either manually (distributor retard) or by using a boost timing master device (i.e. MSD BTM or MSD DIS2 for distributorless ignition). Even standalones have more conservative ignition timing tables under boost compared to stock NA timing tables.

slwazgsr

so how much do you have to retard a turbo charge vehicle than?

cjblmr

hey thanks for your input zip, it would still be interesting to see a data log or dyno plot of timing to have some idea the degree of retard you would have to manually adjust. But , it is still the budget route and not a bad alternative I suppose

senpai

Go way of the GN guys: alcohol injection

BlueSi2k

I remember those posted graphs comparing the vafc hack with a hondata base map. The timing was more advanced under boost. With the base timing retarded 4 degrees at the dizzy, the maps were very close under boost but off boost driving would also be retarded and therefor be a little sluggish. I would reccomend retarding the timing about 4 degrees. HTH