Timing modifiers
Posted: 2022 Dec 15, 12:05
Please forgive my ignorance. I'm trying to understand the difference between the FBGIO timing tables and the CRAI8 timing tables.
Some background: I have a centri supercharged 1998 non-PI mustang, that I'm dropping a newer 4.6 into with a Whipple. Old motor is bone stock NPI. new motor is Stock PI heads and cams, with 23cc dish for ~9:1 compression. It will be dyno tuned after I break in the new clutch, but I don't want to wash the cylinders or detonate it while I'm breaking it in, so I'm trying to build a base tune for the first start up and few hundred miles.
I have a rough understanding of my BAI1 strategy, at least I've dialed fuel in for my 90mm maf and 42lb injectors, and it hasn't blown up yet with my old centrifugal blower. I thought a PI strategy might be a better starting place for the new motor, and the FBGIO looks like the cats pajamas so I thought I'd try using as much as I could for a starting point.
I'm looking at the MGZT tables, and they're quite different from my old BAI1. MBT is up to 13* less advanced, Borderline Knock is 6-12* more advanced over much of the 1.0 load range... I like the look of the MGZT table, and it is scaled up to 1.6 load right off the bat which is a bonus. I'm just trying to understand if the timing table differences are on account of the PI heads and cams versus the NPI stuff, or if the strategies use different modifiers to arrive at final spark based on these tables. Or is there some much deeper gap in my understanding of spark advance that I'm not even aware of.
Thanks in advance for your help.
BAI1
MGZT
Some background: I have a centri supercharged 1998 non-PI mustang, that I'm dropping a newer 4.6 into with a Whipple. Old motor is bone stock NPI. new motor is Stock PI heads and cams, with 23cc dish for ~9:1 compression. It will be dyno tuned after I break in the new clutch, but I don't want to wash the cylinders or detonate it while I'm breaking it in, so I'm trying to build a base tune for the first start up and few hundred miles.
I have a rough understanding of my BAI1 strategy, at least I've dialed fuel in for my 90mm maf and 42lb injectors, and it hasn't blown up yet with my old centrifugal blower. I thought a PI strategy might be a better starting place for the new motor, and the FBGIO looks like the cats pajamas so I thought I'd try using as much as I could for a starting point.
I'm looking at the MGZT tables, and they're quite different from my old BAI1. MBT is up to 13* less advanced, Borderline Knock is 6-12* more advanced over much of the 1.0 load range... I like the look of the MGZT table, and it is scaled up to 1.6 load right off the bat which is a bonus. I'm just trying to understand if the timing table differences are on account of the PI heads and cams versus the NPI stuff, or if the strategies use different modifiers to arrive at final spark based on these tables. Or is there some much deeper gap in my understanding of spark advance that I'm not even aware of.
Thanks in advance for your help.
BAI1