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Staged injection on Motec m800-Help

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Hello guys.I want to disable second injection on a motec m800 even if I have 4 injectors plugged in the ECU as secondary.

1)If I insert 0.0 on Secondary Inj Ratio I turn off the secondary injection.Is that correct?

2)f I want to turn on Secondary Injection just in case that I have increased temperature on my Intake manifold, let's say 20% secondary injectors and 80% primary injectors when 40 degrees of Celcium on Intake.Is that possible?

3)Finally,can someone explain what's going on with primary/secondary balance on/off?It sums at 100% but I cant figure out how it works.

Thanks mates

1. Yes, entering a Secondary Inj Ratio of 0 will disable the secondary injectors.

2. I've never used secondary injection for this purpose however I can't see any reason why you couldn't configure the secondary injection balance table with AT as one of the axis. You could then tune the ratio as you like based on perhaps AT and RPM.

3. I'm not completely sure what you mean here but if you're referring to the values in the secondary balance table they work like this:

With a value of 100% in the table, all the fuel is supplied through the primary injectors.

With a value of 0% in the table, all the fuel is supplied through the secondary injectors.

With a value of 50% in the table, half the fuel will be delivered via the primary injectors and half through the secondary.

Ok Andre thank you for your reply.My problem is that some guys installed 4 injectors on the intake(on a naturally aspirated car with a 20 mm restrictor on the intake manifold) to cool the air.I dont agree with that installation but they dont accept to remove the injectors so I want to turn them off with my tune file.Thanks again

I'd be doubtful that using the staged injection would have much influence but it would depend how far upstream the secondary injectors are placed. You are however in the perfect position to test it and see. Personally if there was no advantage I'd keep the installation simple and remove the secondaries.

I am attaching a picture to show you what is going on.4 injectors are installed for secondary injection and 4 injectors are installed for primary injection(same cc/min).I think they are placed too far away from the engine and we dont need that injectors on a 600 cc engine with 20 mm restricton on the intake manifold+N/A engine.Maybe I am wrong but I dont agree with that installation and they dont seem to understand that's why I want to have your opinion on that.Maybe they are right and not me.Thanks again Andre

Attached Files

I try to keep an open mind about most things as occasionally you will see a result that goes against your previous experience. That's why I said I wouldn't necessarily write off the secondary injectors. Test them and you will see if they prove their worth. It's quite common on highly tuned N/A race engines to use staged injection with the secondaries mounted outside of the intake trumpets. The aim here is typically better atomisation and a more homogenous fuel/air mix rather than charge cooling though.

Thanks for the advice Andre.I will test it on our engine dyno and check what is better.Really thank you for your help

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