Thinking about taking the next step: PIMPx and Injectors

[irsmart21]

Hey guys,

I am trying to make up my mind on what I should do.

I know I am going to eventually buy the PIMPx and bring my car into the 21st century. The place I am stuck is which injectors to get (60lb vs 80lb). My current setup is as follows:


I just got the head fixed and had an Engle cam installed. (http://stinger-performance.proboards.com/thread/5330/modern-performance-cam-issues)

The head had already been ported by Modern Performance, so I do not know how "extreme" the porting is, although I do know it is def opened up compared to the stock head I have. Here are some photos I took prior to installing it back in December, Not sure if the photos can tell you anything, but I figured you might be able to get an idea (https://photos.app.goo.gl/RxpVN3uIcClCynHz1)

According to the measurements I have taken (along with Shannon's help) it has been determined that my turbo is "a T04E 46 trim (compressor) in a stock T3 housing (machined to fit the larger compressor)" with a stage 3 exhaust turbine (http://stinger-performance.proboards.com/thread/5519/airesearch-t3-turbo-info?page=1&scrollTo=51260I)

I have a full 3" exhaust from turbo to tail and an 88 TC intercooler.

New engine harness and wideband o2 with spartan controller


Not sure what else would be needed to determine which injector size would be best. I know the biggest restriction has to do with drivability and being able to keep a good idle.

Any guidance will be greatly appreciated

Thanks!

[Stinger]

The porting is better than stock but it certainly wasn't ported by someone who had a flow bench, or was anything more than an amateur as far as porting goes.

The 60's should be enough to support what you have there.

[irsmart21]

Awesome, thanks for the insight on the porting and the suggestion for the injectors. Will the 60lbs be a good choice if I wanted to consider an Ethanol setup at some point? I know there is a need for a 30% flow increase to be able to run E85. I am just not sure how that translates here.

Now the next question: which brand should I be looking at for the injectors: the FID or the delphi/Seimens?

[Stinger]

No, they certainly won't be enough for E85. It requires 30% more injectors (since it requires 30% more flow) so you'd be looking at something in the 90lb+ range for the same power as 60's with gasoline.

Either brand is fine. Siemens is a "stock" type mass produced injector that can have a flow variance of up to 4% while the FID's are a custom performance injector that is flow matched to within 1%.

[mavereq]

I went with the 80's so I'd have room to grow. Now I wish I had bigger so I could run ethanol.

[irsmart21]

Am I correct in saying that the 80's are the biggest you would want to go for a street car?

Does it hurt to go with the bigger 80's right out of the gate? I know there are functional limits with idle issues and drivability if you go too big if you are not set up for it.

What would you do, Shannon?

[Stinger]

80's are as large as we suggest you run if idle quality is extremely important to you. Idle quality will go down as injectors get larger than that unless you're running a PiMPxs with cam trigger and associated wiring to run sequential injection.

I'd say what you do depends on how serious about running E85 and how important idle quality is.

[irsmart21]

I guess one of the last questions I have concerns the injectors and how they work. Do injectors always fire at their max potential or can they be regulated to function as, say a 60lbs injector. I am a bit ignorant in how they work. I guess are they ON when they are ON or do they respond to a voltage signal and their output is regulated by that signal sent?

I know this may be completely elementary in concept, but I am asking out of curiosity from the MPG aspect. Will running 80lbs injectors (in an application the may not necessarily need it right now) crush my gas mileage over the 60's or can I make the injectors work for the level that is needed for the setup I currently have?

As always, thanks for your guidance!

[Stinger]

Injectors control for with pulse width. This is how long they are open each engine revolution. The purpose of a tuneable who is to allow you to run different sized injectors and they perform correctly (same air/fuel ratio and mpg). The reason you run into a limit on how large you can go is because you run into a physical limitation of the injector itself, not the ECU. There comes a point where they inject too much fuel at idle because they are incapable of squirting any less fuel.

[irsmart21]

Thanks for the explanation, Shannon.

If I am understanding you correctly, expecting a >80lb injector to perform well at idle on our engines is a lot like expecting a 1/2 drive ft/lb torque wrench to be able to effectively measure or work as well as a 1/4 drive in/lb wrench when the smaller measurements are needed. Given the need to measure higher torque levels, it is just not feasible to expect that larger wrench to be able to accurately perform on the smaller requirements.

I guess I am picturing the usable range on the injectors as a bracket on a scale. As the top end abilities of the injectors increase and it moves up the scale there is also an equal increase up the scale as far as the bottom end abilities are concerned.

That being said, just to clarify, are you saying that the 80lb injectors are just small enough on the larger end of the injectors to be able to keep that good idle, or should I be expecting any issues with them over choosing the 60lbs?

As always, thanks!

[Stinger]

Yes, your examples are similar in theory.

It takes a certain amount of time for an injector to open and close (called dead-time). If the required injector pulse width drops below this time at idle, you're going to get more fuel than needed. The 80's get REAL close to the typical pulse width to idle a 2.3 so they will either idle the same, or be very slightly less ideal (in which case you can bump up idle rpm a bit so required pulse width goes up a bit and makes it idle perfect again).

[irsmart21]

Awesome!

Last question: Being that I do not want to splice my new Ron Francis, will I need the adapters to be able to connect the factory harness to the FID850's? I just want to clarify because I see in the chart that connector is stated as an EV1 (which I believe is the stock connector for a Ford harness)

Also, the links for the flow charts and dead times don't seem to be working in the FID product section.

Thanks!

[Stinger]

FID850's are EV1 connectors which is the stock type.

Links don't matter, each set is provided with their own flow sheet.