alpha-N tuning

[Brewski]

Hi guys! Has anybody been tuning an overcammed monster lately? The baseline: 406 inch Chev smallblock with a 280 @.050, .650 lift, 108 lobe center cam. Guesstimate 700 flywheel hp @ 7000rpm, 8k redline, 2-4 inches of vacuum @ idle (700-1000rpm, wouldn't idle below 2k on carb), 5000 stall converter, 13-1 compression, 110 octane leaded race fuel (hard on O2 sensors, using 5 gas for feedback). It's in an 88 Vette for a customer of a friend of mine, he built the engine (about $18k). Current file is: Req'd fuel: 406 inch, 52 lb/hr injectorsx8, 14-1 A/F = 10.8 u sec, here's the goofy part: VE table @90kpa on alpha N:
kpa 80 70 55 45 35 60 75 80
rpm 1000 1500 2500 3600 4700 5800 6900 8000
We had to go way rich to start it because of the high overlap cam (blows half the fuel out the tailpipe near idle), then gradually reduced it to get it to rev up. It doesn't get "on the cam" until about 5000 rpm, really wants less fuel below that except near idle. This is all without load. We plan on doing a dyno session before taking it to a test and tune at the dragstrip. Is there a way I'm not seeing to tune the VE table while the engine is running? We're using Megatune, the board is Megasquirt I v2.2, no ignition control. I sure wish I could have started out with a mild 350 for the first Megasquirt experience but nooooo, that would have been too easy...
Thanks!

[newtyres1]

On the VE table the LHS column should be labeled TPS, not kPa, and you can enter in the tps values in raw ADC or percent. Have you told Megatune you're running alpha-n? The code and Megatune need to be set up according to the instructions in the Megamanual and the readme files that come with the software, or on the MSnS-E site and readme files if you're using extra.

Ian.

[Brewski]

Yeah, that sounds a lot better. I should have mentioned we're using Megatune 2.25, Megasquirt I selected with Alpa-N enabled. It still shows kpa on the VE table but only highlights the 90 kpa cells while running (I assume that's the baro reading at 3800 feet, we're in Bend, OR). I didn't see any option to change the VE table to tps but I'll look for it, or if the software selection is what brings it up. I was also reading about MSnS-E last night and the 12x12 VE tables should help with tuning.

Thanks!
Larry

[ChaosAD]

<post deleted>

[gullwing]

I am planning on building a 55 hemi using a megasuirt II and EDIS-8 as well as a router board to keep sequential injection. I understand that I can run an apha-N or a MAP. Is there any way that the MS-II can be programmed to switch from Apha-N to MAP at a certain RPM say 1,600 or 1,800. This would allow me to use a more agressive cam. I know that the low vacuum at idle is a real limiting factor with MAP. I was wondering if through the wonders of modern science we can cure that?

[newtyres1]

I think MS-II has a hybrid alpha-n MAP selection. Have a look.