Mefi 1 - 2 -3
 

MEFI 1 - 2 -3 what's the differences in each version and advantages? Just want to learn...

MEFI 1 was the earliest and simplest. Easiest to learn if you want to tune yourself. Least amount of fidelity but will work fine in non boosted applications. If you have a MEFI 1 currently and want to build a NA motor it would be fine.

MEFI 2 slightly different than MEFI 1, but for all intensive purposes the same.

MEFI 3 had significant changes in ability to tune and added fidelity, but takes a long time to actually upload the file.

MEFI 4a/4b probably the most robust and popular, but more complex to tune but can be used in boost applications etc.

IF it was me and I had an existing MEFI system and associated sensors and controls I'd use it. If starting from scratch I'd opt for one of the Holley marine systems or MOTEC.

For Mercruiser a MEFI 2 --- A true Mefi 2 with MEFI 2 software was only in the 350 HO mag and the L29 7.4 L thats all. This info was taught in Merc class for many years.

MEFI 2 case with MEFI 1 software was in everything else from 1996 thru 1998

MEFI 3 was in 1999 thru the end of 2002 for the small blocks and 4.3 -- MEFI 3 for the big blocks stopped in very very early 2001 cause the 496 was out with PCM 555 totally different than any MEFI

Backing up info ---- MEFI 1 a true MEFI 1 with MEFI 1 software was 1993 thru 1995 and that had Guardian mode only/ Until one got to MEFI 4 and up 5 thru 7 as well.

KEM is using MEFI 7 NO OEM marine manus for new engines use MEFI anything for the past maybe 4 years or a tad more.

MEFI 1 thru 3 are NLA. The conversion is MEFI 4.and harness adaption if one wants brand new .

Thanks for the replies and education. That said I have a 1997 502MAG and wondering what upgrades I can do over winter for added HP without going forced induction. Open to suggestions and what would be expected gains? Procharger offers a kit to make 600+ HP Bolton but states if engine bumps limiter it goes lean then BOOM because limiter shuts fuel off at 5050RPM. I'm thinking about 500-525hp is my goal.

thanks