Max rpm our 7.3's can effectively turn

Gearhead · Dec 11, 2013

To make the power curve worth a damn you would have to inject the same amount of fuel at 4000 rpms as you do at 2000 rpms but in half the time. Unless your HEUI injectors can slow down the time-space continuum it isn't happening. You can get the injectors fast enough to maintain an acceptable power level at 4000, but chances are you don't need to be running that high in the rpm band unless you just need a little rpm for sled pulling and the gearing puts you there.

Tim @ P.I.S. · Dec 11, 2013

Gearhead said:
To make the power curve worth a damn you would have to inject the same amount of fuel at 4000 rpms as you do at 2000 rpms but in half the time. Unless your HEUI injectors can slow down the time-space continuum it isn't happening. You can get the injectors fast enough to maintain an acceptable power level at 4000, but chances are you don't need to be running that high in the rpm band unless you just need a little rpm for sled pulling and the gearing puts you there.

How do you know its the injectors and not the tuning:swordfight:

Hotrodtractor · Dec 11, 2013

Tim @ P.I.S. said:
How do you know its the injectors and not the tuning:swordfight:

Fyziks

Tim @ P.I.S. · Dec 11, 2013

I must not be hip to this new lingo.

Chvyrkr · Dec 11, 2013

Physics...

97BambiBasherPSD · Feb 20, 2014

HRT what all did you have done to your truck to turn the 5200RPM?

Hotrodtractor · Feb 20, 2014

97BambiBasherPSD said:
HRT what all did you have done to your truck to turn the 5200RPM?

I find it easier to explain why these engines can't spin RPMs and let people draw their own conclusions. Its no one single part or piece, but the whole package, and some of it just has to do with the history of what we are dealing with. I don't have time to type out everything, so I am going to give a quick bullet pointed crash course and come back later if necessary.

1) HEUI injectors are SLOW to inject fuel. In the engine combustion process you only have so much of a window to inject fuel which is best described in crank angle degrees, ie how much does the crank turn during the injection event. As RPMs increase the actual period of time to travel through that crank angle window becomes less and less - so to make a certain level of power, a certain amount of fuel needs to be injected into the cylinder in that window.

2) Because the injectors are slow at injecting fuel - many tuning habits learned over the years are to counteract the slow injectors, sadly that cause PW that is physically too long to inject that fuel to make good clean efficient power.

3) Computer limitations. The factory PCM communicates with the IDM using two main signals that we care about, the FDCS and the CID - these two signals tell the IDM what cylinder to fire and for how long. The length (pulsewidth) is determined by rising and falling signals on the FDCS. The problems gets to be when the falling and rising happen too close together (long PW), the IDM gets confused.

Now the three of those items combined lead us to a place where the injectors are still slow, tuning is attempting to correct for slow injectors by injecting longer, and the IDM is getting confused because of it causing pops, cracks, and just generally hurting RPM and power production.

So if you want to make it turn some RPMs, you need injectors that inject fuel quickly and controllably, You need tuning that is setup to turn RPMs, take advantage of injector speed, and pull back on PW as RPMs increase to keep the IDM and its signals happy go lucky. Making the injectors faster is more than just injectors.... ALL the support and control systems around them need improvements to make them happy. There are several threads that discuss this primarily located on PSN. Perhaps we should import those discussions over here in a new thread it would certainly spark new and updated conversations about it.

97BambiBasherPSD · Feb 20, 2014

Bringing those threads over here would be great! Iv read the whole article and it all makes sense perfectly but what you just said clarifies everything perfectly! Thanks Jason! So if I recall correctly I thought I remember you saying you had a few ideas for injectors that would help the slow issue. Am I right?

It sounds like we know why they are slow and what we need to do to fix them but it seems like the technology just isn't there just yet is what I am gathering from all of this

Sent from my Pear phone 5 using Tapatalk

Strictly Diesel · Feb 20, 2014

Seems to me that some of those threads might represent a "Best of Charles" collection...if I remember right. Great reading, if not for the technical info...then for the pure entertainment of watching Charles tell people they are stupid in 300 different ways.

Vader's Fury · Feb 20, 2014

I miss those threads....

What ever happened to Charles? Did the 7.3 haters finally chase him off?

Hotrodtractor · Feb 20, 2014

Vader's Fury said:
I miss those threads....

What ever happened to Charles? Did the 7.3 haters finally chase him off?

He is doing pretty good and enjoying fatherhood when I talked with him a few weeks ago. He is still working on his 7.3.

Hotrodtractor · Feb 20, 2014

97BambiBasherPSD said:
Bringing those threads over here would be great! Iv read the whole article and it all makes sense perfectly but what you just said clarifies everything perfectly! Thanks Jason! So if I recall correctly I thought I remember you saying you had a few ideas for injectors that would help the slow issue. Am I right?

It sounds like we know why they are slow and what we need to do to fix them but it seems like the technology just isn't there just yet is what I am gathering from all of this

Sent from my Pear phone 5 using Tapatalk

There have been constant improvements as time goes along. I have some stuff that exists and some stuff that might never manifest itself into any type of functional part simply because the cost associated is more than I want to spend and no one else will ever want to spend it either.

I have some new stuff that hasn't been put into a truck yet. Guys have called me wanting it, but not until I have had a chance to prove it out in a truck under my control on my schedule. That is what happens when I develop something on my own dime that costs more than I'd ever get out of it. LOL