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Injector Sizing

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I am converting to flex fuel soon to be able to run E85. Consequently I will also be purchasing larger injectors (my fuel pump is already sized properly). My question is, if i plan on having headwork done and a bigger cam in the future, should i oversize my injectors that i will be purchasing now to cover that power gain with the future head/cam? Or just purchase injectors for the e85 conversion only and not for future expansion. The main purpose of this is to avoid purchasing multiple sets of injectors.

Thank you!

Injectors can be tuned down, and it’s most certainly better to run an injector at a lower duty cycle to achieve power goals that to buy injectors that your working them 90% or 100% duty cycle to achieve preferred power. So that being said, just get the injectors you plan to use in the future, and tune them for your setup now and will be just fine. What’s the application??

The application is a 2.3 turbo ford. My concern is its batchfire, so i was worried about drivability at low rpms and at idle. But if they can be tuned down, i will go with the larger ones. Thank you!

Hi Tyler,

As Ryan said, I would just go for bigger injectors now. Most good quality late model injectors will still give great drivability at low PW. Although there will be a point where you can go too big and idle, light throttle will be compromised.

I would set out your power goals for what you want later on, see what size injector you require for X power and on which fuel you tend to run. Then compare to your power level now. If you think you won't be using much of the injector it might be worth getting a smaller set now. Although it means you end up spending more. It also depends how long you plan to keep the car at its current stage of mods before going to the next step where you require bigger injectors, if it does have some light throttle and idle issues, can you deal with it for a short period to save some money.

I will take that into consideration, thank you!

I would be trying to at least get to semi sequential injection if the ecu allows.

I do not know if it does or not, its a megasquirt ecu.

What model Megasquirt is it?

A little complicated to say. Its a ecu built by a company thay specializes in my application, so its their ecu with ms3 software built-in and uses tunerstudio. It is called a pimpx ecu. Mine is for a batchfire efi application, so i am doubting it can be changed unless i make the switch to a distributorless ignition?

If it still uses the ms firmware and tunerstudio i would hope so. Does it allow you to view/change triggering setup? I assume it is just a very basic dizzy driven at half engine speed with a single pickup and 4 blades? If you can change the trigger settings a missing tooth crank trigger for semi sequential or crank trigger plus convertig the dizzy to a single tooth 720 reset would be a massive advantage to idle and low load drivability.

Yes it does allow me to view/change the triggering setup. Its the stock ford TFI module distributor, so whatever that is. What do you mean by "change the trigger settings a missing tooth crank trigger for semi sequential or crank trigger plus convertig the dizzy to a single tooth 720 reset?"