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Can fuel pressure be added to drop duty cycle a little ?

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I've done my first run out to the limiter and logging shows injector duty at 98%. This is a NA VQ37 with full bolt on's only, stock injectors and fuel pressure at 52psi static as per OEM spec. The 98% was at 7650rpm.

AFR's were reading quite rich at 10.0 vs the target of 12.0 so that will be a factor.

I'd be kinda surprised if the stock injectors were sized that close to the limit where bolt on's only can max them out ?

In any case, to try and get back some duty cycle is it a non-terrible idea to raise the fuel pressure a little or are there reasons this is not a good option ? I would like to avoid buying a new set as ultimately I don't know where the engine build is heading at the moment.

Yes you could drop injector duty by raising FP, BUT the effect is going to be small.

12.8 AFR is as rich as I go on this NA motor, 12.5 for added internal cooling. Once you are there, as compared to your 10 AFR, very likely the duty will be reasonable between 80-90%.

The increase in flow will be the root of the amount of pressure increased. 10% more pressure? 3.162% more flow.

As others have commented, around 13:1 for petrol would be best power/torque for the engine - correcting that would completely remove the concerns of injector limitations - and would also negate your idea that the OEM injectors weren't up to basic "bolt on" upgrades.

Running richer than the engine actually needs - it'll tell you, but that 13:1 range should be close - will have only negative effects, such as significantly increased fuel economy, increased ring and bore wear, oil dilution, frequent spark plug replacement because of fouling, etc, all of which are going to cost you much more money than getting it tuned correctly in the first place.

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