I doubt I'll even peg my MAF timing table, what then is the use of the boost timing table?
I doubt I'll even peg my MAF timing table, what then is the use of the boost timing table?
1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
2004 Corvette Z06 with longtubes.
A0010 just modifies whatever timing is produced by the HO/LO timing tables (whether pegged at 1.2 g/cyl or not)...
i.e. it gives you the convenience of having NA timing table plus boost timing on top of that (actually minus).
Last edited by joecar; May 2nd, 2017 at 09:36 PM.
Let's use my half ton as an example. At WOT here, the MAF is only getting up to .6 so with boost it still won't peg that NA timing map at 1.2. These are draw through applications (TB and MAF) if that matters. What am I missing?
1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
2004 Corvette Z06 with longtubes.
You're only pulling a maximum of 0.6 g/cyl...?
Have you scaled MAF/VE/IFR...?
~ posted by phone ~
The boost timing table allows you to specify timing to subtract per boost kPa.
The NA timing table specifies timing per g/cyl which is hard to correlate to boost kPa.
~ posted by phone ~
I didn't get my calc.vet done before that truck went to the body shop, but it seems in line with the wife's 5.3 Envoy (.56) and the neighbor's LQ4 (.64). Remember that my half ton is just an NA 5.7 and my elevation is 6000'+. It just seems to me that if I use both tables, they'll pull timing on top of timing. I didn't think boost mattered really, air is air as it enters the engine, right? This is an area in which I've been heavily conflicted of late. How does 100kpa here (boosted) compare to 100kpa at sea level?
1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
2004 Corvette Z06 with longtubes.
Ah, you're at 6000 ft, and we beach-city-dwelling-flatlanders tend to forget that there are souls living at elevation, my apologies...
since your elevation is preventing you from pegging the B5913/B5914 spark table axis, I would simply adjust A0010 to subtract a very small amount (if any)...
it now makes sense (I should have realized).
So do I just need to figure out at what boost level the MAF pegs to better wrap my head around this? Will I have issues when I head to lower elevations? This is a tow pig, it'll have a 3000# camper in the bed and a 10000# trailer out back.
1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
2004 Corvette Z06 with longtubes.
Yes, if possible find what boost pegs the g/cyl axis.
When you descend you will run into the problem that the g/cyl will be huge and you will need much more timing retard, so this is where A0010 will need to pull significant timing, especially since you're pulling a heavy load.
~ posted by phone ~
I don't understand why A0010 and my main timing table aren't using the same units.
1998 GMC Sierra K1500 5.7/4L80E, longtubes, 411 w/COS 5, marine cam/intake, Whipple. 91 octane at 6000'.
1997 GMC Sierra K3500 7.4/4L80E, 411 w/COS 3, Whipple, small cam.
2004 Corvette Z06 with longtubes.