MegaSquirt trigger wheel sensor solution, What's your design?? Options

[draganc]

Hi guys!

I’m planning to upgrade my D-jet system on a 75 2.0 (2056) with a MegaSquirt system.

I’m still debating how to mount the trigger-wheel-sensor and would like to see some of your solutions.

Thank you for your input,
Dragan

[Jake Raby]

We haven't seen any benefits of sequential on a street engine, even at high RPM, batch fire also generally makes more torque. Single cylinder fuel trim may not be able to increase performance overall, but they can be used to eliminate EGT delta between cylinders. These generally exist due to induction and exhaust system packaging compromises and they can kill valve jobs.

There is NOTHING worse than a system that is impossible to interface with.

[JamesM]

We haven't seen any benefits of sequential on a street engine, even at high RPM, batch fire also generally makes more torque. Single cylinder fuel trim may not be able to increase performance overall, but they can be used to eliminate EGT delta between cylinders. These generally exist due to induction and exhaust system packaging compromises and they can kill valve jobs.

There is NOTHING worse than a system that is impossible to interface with.

From what i have read on the theory behind it the only advantage to sequential injection would be at low RPMs and most likely only have a slight effect on emmissions and possibly efficency. The bennifit supposedly being that with sequential injection you are shooting the fuel into an open valve where as in batch injection at least half of your injectors are shooting on closed valves. This is all fine and good when engine speed is low, injector pulses are short, and the time the valve stays open is long. As the engine speeds up under load the time the valves are open gets shorter and the injector pulses get longer. Before long you are firing your injectors on valves that have not yet opened or already closed.

At what point in the engines range this occurs depends on the engines fuel needs and and the injectors used but you can do some quick math to get a rough idea.

3000 RPM is 50 RPS or one revolution every 2ms and that is for the entire rotation, depending on the cam used the time the valve stays open is going to be some fraction of that. You can look at Megasquirt to see how long your injection pulses are but in most cases an injection time of 2ms is passed well before 3000 rpm, in fact the megasquirt manual states that you want your pulse width at IDLE to be no less then 2ms, meaning even with sequential injection, the majority of the time you are still injecting on a closed valve.