This or That
Posted: Sat Jul 13, 2013 7:50 pm
My dad and I have begun discussing some upgrades we want to do to our '73 Mercedes 450SL, which is currently equipped with a very rudimentary speed-density which operates on a very low pressure that we're not very pleased with in the least. I proposed replacing the old system with a modernized, Megasquirt-driven custom system, which he quickly came on board with.
What we're not sure of, though, is whether we should fit it with coil-near-plug sequential ignition and sequential injection available with an MS3X system, or whether an MS2 (or plain MS3) running EDIS-8 and batch-fire would be sufficient? From what I've read, sequential injection puts less strain on the fuel rails and pressure regulator, since the pressure in the fuel rail isn't so severely depleted with every injection event. There's also the added benefit in the case of not spraying fuel onto closed valves, offering slightly better emissions (hah) and fuel economy.
As for sequential ignition, the only difference I could find is that a coil has more time to recover between ignition events. Other than that it's added complexity and cost. But hey, it'd be cool (dad's rationalization).
However, sequential injection/ignition require both a crank and cam signal. We've talked about having a tone ring fitted to the harmonic balancer for the crank signal, but would it be possible to use the old breakerless ignition driver (think 40-year-old Pertronix kit) to provide the system with a usable cam position signal? (Yes, the advance mechanisms would be disabled.)
What we're not sure of, though, is whether we should fit it with coil-near-plug sequential ignition and sequential injection available with an MS3X system, or whether an MS2 (or plain MS3) running EDIS-8 and batch-fire would be sufficient? From what I've read, sequential injection puts less strain on the fuel rails and pressure regulator, since the pressure in the fuel rail isn't so severely depleted with every injection event. There's also the added benefit in the case of not spraying fuel onto closed valves, offering slightly better emissions (hah) and fuel economy.
As for sequential ignition, the only difference I could find is that a coil has more time to recover between ignition events. Other than that it's added complexity and cost. But hey, it'd be cool (dad's rationalization).
However, sequential injection/ignition require both a crank and cam signal. We've talked about having a tone ring fitted to the harmonic balancer for the crank signal, but would it be possible to use the old breakerless ignition driver (think 40-year-old Pertronix kit) to provide the system with a usable cam position signal? (Yes, the advance mechanisms would be disabled.)