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Did you get the Megasquirt, and spark? If not, how do you plan to work the timing? Boost retard, and such.


Curtis - The latest/greatest MS-II V3.0 boards have spark control built in. The MAP sensor provides the signal to the ECU that manifold pressure is "X" amount in excess of 1 Bar (measured in kpa) and the fuel and ignition timing lookup is calculated from the bin tables you write to the ECU.

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Frank, how come a 4bar MAP sensor? Don't you lose some resolution over a 2bar or 3bar?


Eddy - Resolution might degrade slightly, but the 4 bar sensor is the only one available that includes the second MAP sensor to correct baro pressure real-time. Since it's a direct replacement for the 2.5 bar standard sensor, no further "untested" modifications will have to be made..... it's on the board and in the software. I'll try it and see what happens... worst case is a swap back to the regular sensor that requires a shut-down and restart to reset the ECU calibration. I think the real-time correction might be very nice to have if the accuracy is acceptable - I'll want to ask about it before I get to the tuning stage, though.

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I do think this is a much better alternative to trying to fool the ecu with a smart FPR.


I'm still stubborn enough to believe that I could get the FMU to work fine with the redesigned fuel rail and a larger fuel pump.... and maybe an MSD boost retard unit, but I don't want to find out I was wrong..... again. <img src="/forums/images/graemlins/shiner.gif" alt="" />

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Do you have a boost control strategy? All I read says tune the off boost first, and sneak up on the boost fuel maps, erring on the rich side.


That's right - at least for the fuel map. MegaSquirt now has some software called "MegaTune" that can get pretty close on the fuel map.

The tricky part will be the ignition curve. The only way I see to do it right is to use a steady state dyno... where you can set up at a fixed rpm and fixed load.... and tune the ignition for best power at safe EGT. A standard torque roller ain't gonna get the job done. I have no idea where to find the dyno that I need, so I expect to haul the truck to some race shop near Charlotte Motor Speedway - maybe the 3SI folks can help me - haven't asked them yet. In any event, I'll probably rent the dyno for the day - it'll likely take all day to dial it in.

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Too lazy to review all this to see if the pos. disp. blower has a waste gate...


No, the pulley diameter and rpms limit manifold pressure... right now, I'm pegged at 7 psi with a 2.6" dia. blower pulley. Actually, there is a waste-gate of sorts.... the bypass valve, but its purpose is to keep the blower off-line until manifold vacuum drops to a few in-Hg... lets the blower free-wheel until needed to save parasitic HP loss..... but once the blower hooks up, it's on line until you get off the stupid pedal.

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum