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I have done the MS conversion on a B20E. Yes, the stock Bosch ..036 injectors are probably grossly oversized for the B20. Bosch rates them at 364 gm/min at 43.5 psi. I run the Nissan 280 Z FPR and the tested flow rate through the injectors is 519 ml/min at 38 psi. The flow test indicate that at 38 psi the injectors are pretty linear down to 1.5 msec pulse widths; but, linearity goes in the toilet very quickly below 1.5 msec. If the injectors are clean you can probably go down to 1.5 - 1.6 msec at 38 psi safely.
I did experiment with an adjustable Aeromotive FPR to drop the base pressure down to the design value of 28 psi specifically to give longer PW at idle. The Aeromotive was exceedingly sensitive to back pressure on the return line and I could not get it to maintain stable pressures so I ditched it and returned to the Nissan FPR which gave predictable results.
I initially ran the B&G firmware and switched to the MSExtra code running full sequential. I find operation with the MSExtra firmware with sequential definitely superior to the B&G code. With the injectors mounted directly on the head the injectors are very close to the valve and I find that the B20E manages transitions very nicely with very little TPS.dot. I think most people apply too much tip in and then add more when the engine responds poorly. Log your AFRs and TPS.dot during a few throttle fast opening events. If the AFRs go high during the initial throttle opening and then recover then you may need some additional TPS.dot (or MAP.dot if that is what you want). I use very little and the engine accelerates without hesitation.
With the MSExtra code and sequential injection my B20E will maintain idle between 850 - 875 RPM running with an AFR of 14.9. That is probably as stable as you will ever get with the D camshaft. An indication of the overlap on the D cam is that at 850 RPM the MAP is pretty high, about 50 - 55 kPa. A K cam would probably idle much better. If you are running batch fire you will probably need to run an AFR below 14.7 to get stable idle out of a B20E.
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