Ford Power Stroke Nation banner

1 - 20 of 39 Posts

·
Registered
Joined
·
5,346 Posts
Discussion Starter #1
I posted this in another thread but I figured amidst Charles' long posts it would get lost so here is my message:

Well in my opinion if you are smoking you are not only wasting fuel but you could be saving one thing that is important on a HEUI truck..... HP OIL CAPACITY! If you are pumping a bunch of fuel in after Top Dead Center and not generating anything but heat and smoke, that fuel isn't doing you any good, so why not save the fuel and more importantly HPOP oil and run at a higher ICP which will make more power because you can empty the injector faster in the "window" you have to actually use the fuel..... This will generate more torque and horsepower across the board. You have to dance with fuel pulsewidth vs Oil pressure on trucks without extra HPOP capacity... Even on a truck with stock ADs and a fresh 17 degree hpop!
 

·
Registered
Joined
·
2,411 Posts
I saw your earlier post of this Matt, and I have to agree. It's common to experience laggy turbo response with too much fuel at the low end. I also agree that higher ICP, while keeping the stock HPOP system happy, is key. Granted, noisier, but very important nonetheless.

Smoke may be fun, but what does it accomplish? It usually pisses people off or looks cool, but why have excess. Obviously, it takes fuel to make power and it takes air to burn the fuel, but where does one draw the line between how much fuel is needed to light the turbocharger most effectively and how much can one back off of the fuel and maintain (or increase) HP?

I think we agree that not enough HPOP causes excessive smoke. I think it's why the better "10K Mod" modules out there work as well as they do...especially in the mid-level settings. There is enough HPO to not cause a check engine light (and subsequent default to preset IPR DC%), but you're still getting decent power gains.

I can see that I have strayed far away from your original thoughts so I think I will stop here before I start talking about different brands of cat litter.

Gale Banks says:
Black smoke is bad...unless you clean it up with 12 progressive stages of N2O.
 

·
Registered
Joined
·
5,346 Posts
Discussion Starter #3
My point is that if you are smoking and only holding 2300 psi with the IPR all the way closed..... why not pull the pulsewidth back and empty more fuel sooner thus making the injector effectively faster by running 2800 psi?
A happy engine at WOT is a happy engine.... what noise were you referring to?
 

·
fueled by Colecovision
Joined
·
3,060 Posts
.....and more importantly HPOP oil and run at a higher ICP which will make more power because you can empty the injector faster
the injector flowbench doesn't support this statement.

As much as I'd LOVE to empty xxx cc's in x ms...increasing the pressure doesn't increase the flow much...and in many cases, flow drops above certain pressure.

everyone likes to say "speak up" if you know something...and folks get hung up in a circular logic triangle where some folks contend that no information is exchanged...or "given" away...

well, there it is.

We've been running 2800-3000psi max for years...for a reason.

take care~

Dave
 

·
Back to Civilian Life!!
Joined
·
2,469 Posts

·
Registered
Joined
·
2,411 Posts
I can appreciate BOTH points of view. Dave, thank you for your input. Fluid dynamics support your findings. Matt, it stands to reason EXACTLY what you are saying. I believe that you AND Dave are on the right track with the 2800 PSI mark.

There's a limit to how much ICP you want, but I feel that the "smaller power number people" (the ones in MY demographic) are fully happy with the increases that don't involve a ton of black smoke anyway....they just want a more responsive truck that has a bit more get-up. Increasing the ICP moderately is a GREAT way to do it....more power with less smoke than simply jacking up the FDCS PW and hoping that the HPOP can deal......

I really scared myself with that "more power with less smoke" statement. I KNOW I've read that somewhere.....but it's true.
 

·
green member
Joined
·
297 Posts
With tolerances being far from tight, IMO, from the factory(alliant) it's no surprise that higher pressures cause erratic fuel delivery.

There's prolly a happy point with each set of custom built injectors that a bench would show even delivery at high RPM and ICP. But how many people ask what ICP their injectors were flowed at and what was the spread between all 8?
 

·
Registered
Joined
·
2,031 Posts
unlike a gas or alcohol engine, diesels make their power on the lean side.
 

·
Registered
Joined
·
90 Posts
Diesel engines for the most part will make black smoke while still lean of stoichiometric, this is called the black smoke limit of the motor, usually around 18:1. You can make more power by going beyond the black smoke limit because you are still lean of stoich.
The newest motors w/ dual CP3's, and not running any egr can probably push the smoke limit down close to stoich but I don't think the 7.3 is capable of it.
 

·
fueled by Colecovision
Joined
·
3,060 Posts
Hey Dave,

I get that the flow rate doesn't improve much beyond 2800psi, but does the flowbench show any appreciable gains between ~2300psi and ~2800psi?
absolutely...

then it starts fading fast...

TIME is what the HEUI injectors respond to...and TIME isn't something anyone has at high(er) rpm.

Pressure is there for crispness and throttle response..and all your piddly-ass daily driver concerns...

but (ICP) pressure to get more fuel in faster??? :hehe: and pressure isn't going to make up sh!t if you can just "click" on over to another ms of PW...

this is the problem...obviously.

You should have seen my face when tons more pressure actually started dropping flow...I was simultaneously stunned & intrigued...and have spent the last 2+ years beating these F'n HEUI's into submission with all kinds of hairbrained ideas...most didn't work...but the ones that did...:D
 

·
Registered
Joined
·
242 Posts
absolutely...

then it starts fading fast...

TIME is what the HEUI injectors respond to...and TIME isn't something anyone has at high(er) rpm.

Pressure is there for crispness and throttle response..and all your piddly-ass daily driver concerns...

but (ICP) pressure to get more fuel in faster??? :hehe: and pressure isn't going to make up sh!t if you can just "click" on over to another ms of PW...

this is the problem...obviously.

You should have seen my face when tons more pressure actually started dropping flow...I was simultaneously stunned & intrigued...and have spent the last 2+ years beating these F'n HEUI's into submission with all kinds of hairbrained ideas...most didn't work...but the ones that did...:D
Thanks for the reply.

What about the scenario that Matt spelled out, where you have a hybrid (of the MM variety) injectored truck that is dropping ICP (down to the 2300psi range) at WOT? If you are already giving it more PW than it can handle at a given RPM (injector open time is greater than the power "window" available), wouldn't it make sense to scale it back some to gain some ICP and deliver more fuel per unit time?
 

·
Registered
Joined
·
5,346 Posts
Discussion Starter #13
Hey Dave,

I get that the flow rate doesn't improve much beyond 2800psi, but does the flowbench show any appreciable gains between ~2300psi and ~2800psi?
probably doesn't improve much beyond 3000 psi because the poppets can't hold the pressure..... Injectors that can't return back to zero position are at diminished capacity...
 

·
Registered
Joined
·
2,031 Posts
stoichiometric for a diesel engine is 18:1 isnt it? so then the black smoke limit would be 19:1 or more? has anyone done any testing to see what ratio the power starts dropping off at?
 

·
fueled by Colecovision
Joined
·
3,060 Posts
Thanks for the reply.
If you are already giving it more PW than it can handle at a given RPM (injector open time is greater than the power "window" available), wouldn't it make sense to scale it back some to gain some ICP and deliver more fuel per unit time?
Did you not read what I just typed?

Scaling back PW to increase ICP will result in LESS fuel.

I don't know why that is so hard to grasp.
 

·
Registered
Joined
·
853 Posts
i'm new to performance and have learned alot on this site in the last month, thanks guys.
from what i understand in laymans terms more smoke doesn't neccesarily mean more power, just like a loud harley doesn't mean its fast.

i guess people associate smoke with power and noise with speed. a common misconception?
 

·
Registered
Joined
·
1,921 Posts
So say you have 2 ms to inject fuel, to actually make power. 2ms of injection will not tax your oil volume. So youre injecting 3 ms of fuel, of which the extra 1ms youre injecting is atdc and totally past the "window" of which you mechanically have to inject the fuel and make power with. this extra one ms of injection causes your icp to drop from 2800psi to 2300 psi. So considering if you cut off that extra 1ms you have on the tail end of the window that is not making much added power anyways, and your icp goes back up to 2800, wouldnt it stand to reason youd gain more power, considering 2800psi of icp will inject more fuel over 2ms than 2300psi. I

I dont think theyre arguing that 3ms of fuel @ 2300 psi delivers a greater volume than 2ms @2800, but rather is that extra ms @2300 being delivered past your opportune "window" helping add as much power as say the first 2 ms at a higher pressure.
 

·
fueled by Colecovision
Joined
·
3,060 Posts
So say you have 2 ms to inject fuel, to actually make power. 2ms of injection will not tax your oil volume.
Well...true IF you have a slow set of injectors...but I can guarantee you that in the competition arena, a proper injector can tax a single HPOP at 2ms.

So youre injecting 3 ms of fuel, of which the extra 1ms youre injecting is atdc and totally past the "window" of which you mechanically have to inject the fuel and make power with. this extra one ms of injection causes your icp to drop from 2800psi to 2300 psi. So considering if you cut off that extra 1ms you have on the tail end of the window that is not making much added power anyways, and your icp goes back up to 2800, wouldnt it stand to reason youd gain more power, considering 2800psi of icp will inject more fuel over 2ms than 2300psi.
Since SOI timing is "adjustable" who says that that extra ms of PW 'has' to be after the window of opportunity to make power?

To put it another way...2ms at 3000psi will flow a TON less fuel volume than 3ms @ 2000psi...on all but a handful of injectors that are out there.

I dont think theyre arguing that 3ms of fuel @ 2300 psi delivers a greater volume than 2ms @2800, but rather is that extra ms @2300 being delivered past your opportune "window" helping add as much power as say the first 2 ms at a higher pressure.
see SOI timing comment above.

---

take care~

Dave
 
1 - 20 of 39 Posts
Top