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Dual Injector Locations

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I'm building a sheetmetal intake for a methanol EFI project.

I think I have three options for dual fuel injector locations, none are ideal, looking for some shared experience.

First location is side by side on the outside of the runner. Only two fuel rails, easy access to injectors, can mount them at about a 45deg angle to the airflow. Downside is the tip of the injectors will only be about 3/8" from the wall of the runner and I'm afraid the spray pattern with wet the runner.

Second location is one over the other on the outside of the runner. Now I'm at 4 fuel rails which isn't great but OK....the biggest thing is now the injectors would need to be closer to perpendicular to the airflow.

Third location is one injector on the outside and one on the inside of the runner. I could get both injectors at about 45 degrees to airflow but the inner set and inner rail would be a PITA to service and I expect with the Meth that they are going to need to be accessed pretty regularly.

Any input on tradeoffs or possible other locations?

Hello Brian it would depend a lot on what the engine rpm is going to be and what the engine is being used for. two side by side is easy as you say to service but is pretty inefficient in practice, having one close to the valve and one further away can work well but if staged will work even better. i have played a little with this on high rpm motorcycle engines and found we lost a lot of power below 5000 rpm when running both injectors together compared to running the closer one to the valve below 5000 rpm and then both after 5000-11000 rpm we made even more power when we turned down the closer injector pulse width at full throttle, my theory is that the fuel has more time to collect oxygen on its way to the combustion area, we did also find the injector time needed to be a lot different for the farthest away injector, this was a lot of testing,

Thanks Ross.....motor is a V6 thats going to be about 300ci, 8500 - 9000 rpm, ProCharged for drag racing.

Stacked vertically makes most sense to me too. I'll play with things this weekend and see how much angle I can get on the injectors so they are not perpendicular to the airflow. They will be staged as you've said so maybe I can get the one closest to the valve pointed towards the valve as much as possible and the upper one be more perpendicular which will only be on when the air is ripping through there anyway.

Attached Files

that will be perfect they are fairly short runners so the angle you ae holding them on will be great

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