i have a 2005 ram 5.7 bored out, cai, true dual, diablosport programmer, i think i might need to upgrade my fuel delivery system

i really have looked very hard to see what my stock injectors flow so that i can go one "step or two up" with upgraded flow, i've tried to get some answers i am probably saying this the wrong way but i'm not sure

if i was going to get new higher flowing injectors does anyone have any suggestions? i'm also looking to get new fuel rails, plus a 90mm throttle body, but for now i think the injectors should do, i could be wrong but i'll find out when i go to get it tuned, and see if the throttle body is a must, but if anyone has any ideas on injectors that would be great, which ones people use, do you like them, and hopefully where can i get them, thank you so much

 

What kind of pistons and rods are you using? You had to change them out if you bored out the motor. If you got the right set-up, I would save up for a Supercharger kit. That will come with the whole fuel system upgrade.

 

just an FYI: The stock injectors operate no higher than 70% duty cycle.. An injector can comfortably operate at 90% duty cycle before it reaches the outside of the 'safe' parameter..

If you swap out injectors, and you do it right (which CAN be done if you are comparing apples to apples, or your engine to a precise same build engine of someone who's done it before- I'd figure that is hard to do seeing as how you are 'bored' over), you will need to ALSO implement a wide band a/f gauge, and have software available to manipulate the delivery.. otherwise, you'll be shooting in the dark..

you can glean from this what you will, but I'm trying to help you out- take it for what it's worth: Don't mess with injectors.. you're a LONG way out from needing to address them.. Unless you dramatically increase the displacement OR you boost, you'll be more than fine with OE injectors..

one more thing of note: the OE injectors are Seimens.. they are top of the line.. to 'upgrade' will be $700~1k or thereabouts to replace them, and that before wide band and tuning..

 

Usually you max out the fuel pump before you max out the injector duty cycle....

I personally would put a higher flowing fuel pump in first, and then see where I was at.

Once you get a higher flowing fuel pump in, take a log of WOT in 3rd & 4th gear and see if you are getting above 90% Duty Cycle and at what RPM it is at.

If you are at 90% Injector Duty Cycle in 4th gear anywhere above 4500 RPM you will max out your injectors in 5th gear at roughly 3000 RPM, which means it's time to get bigger injectors.

So what are your duty cycles as of now?

And Drew is correct, you WILL need a Wide Band O2 Sensor! That is a MUST!

If he is .20 over or more he will likely need to address the fuel system, but I would still replace the fuel pump first.

What are your goals for the truck btw? (will help us better address what you might need to do first)

 

I don't understand this.. what am I missing? engine speed is the thing, right? does it matter what gear it happens in? is there that big a step between gears that the engine would be that loaded?

 

Higher Gear means higher load... load can also be called Volumetric Efficiency (VE).

I had a Subaru STi for awhile, and while tuning it, I would be at 90%-95% Duty Cycle at the very top of 3rd and then in 4th gear I would be at 90%-95% until about 5000 RPM, and then 5th gear would be okay until 3800 RPM....

So no engine speed is not the only thing you have to consider... you have to consider engine load based upon the gear you are in.

Read this:

http://tunertools.com/articles/Load-Control-101.asp

That explains how load (Volumetric Efficiency aka VE) can be calculated, now since our engines have MAP sensors instead of MAF sensors there are some additional calculations required in order to obtain a Calculated MAF value in order to complete the equations.

You can read these articles for those conversion factors:

http://obdcon.sourceforge.net/2010/0...lute-pressure/

http://www.motor.com/magazine/pdfs/022006_05.pdf

The second one is a PDF and its purpose is to explain the differences between calculation methods, but almost all of the equations can be substituted because after all we are talking about the laws of Physics...

Does that explain it any better?

The affect that the gears have on it is that the higher the gear the higher the resistance of the system on the motor.

Example is if you get on a 10 speed bike (or w/e speed makes you happy) and put it in the "highest" gear it has it will be very very hard to try and make the bike move from a stop, but if you put it in it's "lowest" gear it becomes VERY easy to start moving from a stop.

So the higher the gear the higher the "Load" on the engine, which basically means that the engine is working harder (needs more Air & Fuel) to produce the same Torque as it did in a lower gear. This is keeping it extremely simple as there are other things to explore such as gear sizes & types and what they do to effectively increase/decrease torque and/or rotational velocity... so we'll just leave it at that for now.


Here is a little graph that will show torque curves for each gear vs RPM (this is Wheel RPM because it is used to calculate Torque on a Dynometer, but Wheel RPM can be converted into Engine RPM by a few simple calculations)



So the "flatter" the curve here would indicate a more constant acceleration, where as a more "peaked" curve will indicate an increase and decrease in acceleration. Your acceleration is actually decreasing the moment you reach peak torque, which is an example you don't feel the same "push you back in your seat" feeling when the gears increase... (disregarding traction/friction to help you conceptualize it a little better).

So as you "accelerate" you move faster (increased Velocity), and once you reach your "peak torque" your car can no longer increase the change in acceleration (change in acceleration is called "Jerk"), so you begin to approach a constant acceleration dependent solely on RPM, thus the curve dips down.

So if you were to consider RPM as an infinite variable you will see that the torque curve will become nearly 100% flat indicating a constant acceleration.

So put it all together and your Injector Duty Cycle will actually increase as you increase gears, which is why 4000 RPM in 4th gear usually requires more fuel & air than 4000 RPM in 3rd gear...

I cut a lot of the specifics out, so if I lost anyone anywhere in there let me know and I can try to elaborate some more.

 

sweet.. Thank you sir!!!

 

Here is a just a little more to help you understand HP & TQ:

Torque is the amount of angular Work being done,
Power is the work per unit of time.

So,
So If you apply these equations to engines (in general)
Then
So,

To get units of torque we divide HP by our .10472 radians/second value and get:
So then we see that,
So that is why Torque and Horsepower graphs must cross at 5252:

Here is why in equations:
So if you go look at any HP Torque Graph (Dyno-Chart), you will see that Torque will always be greater than Horsepower at BELOW 5252 RPM and Horsepower will always be greater than Torque at ABOVE 5252 RPM.
Torque is the same as Force, only Force is a push or pull and Torque is a twist. If we want to calculate Acceleration we fall onto the simple equation:
We know that more Force or less Mass will allow you to Accelerate faster.

Torque gets converted into Force (from twist to push) when Torque applied to your axel turns your tires and the tires act on the ground.

The ground is stationary, which means your car will move forward.

Now, converting engine Torque to Force allows me to point out that Torque accelerates your car, not Power.

Power is only the amount of work per unit of time.

How does that relate to cars?

Simple. In a car, Power is simply the amount of work it can do at a given RPM. Let me give some examples.

Let’s say that you can do 100 Torque at 2626 RPM. Horsepower = 100 * 2626 / 5252 = 50 Horsepower.

Example 1:
So your car has 700 torque at the wheels, but your wheels are only spinning at 375 RPM.

 

Any time.... I hope what I've said helps...

 

You learn so much on here its crazy, yall prolly ovewhelmed the OP lol!!