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Larger Injectors

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I am bouncing around 98% duty cycle on my 450cc injectors and will be switching to 750cc injectors soon. Are there some tips and tricks to adjusting the fuel tables (ex. 450 / 750 = 0.6). This would mean about a 40% decrease to the values in the main fuel table. Or, do you pay for dyno time to set the tune?

I look forward to your insight.


Do you have a VE based ECU ? if so, in theory you will only have to change the injectors settings.

As Ludo mentions, if you're using a VE based ECU then you just need to adjust the injector data to suit your new injectors. This 'should' have you close in AFR however you may still need to make small changes to get back on target.

If you're using a ms based ECU then you can start by applying a multiplication factor much like you've figured out to get the AFR back in the ballpark. Due to difference in non-linear flow between different injectors though, you will always need to do a bit of work to get a ms based ECU back to the correct AFR.

Check out a webinar we did that may be of some help to you here -