Max rpm our 7.3's can effectively turn

85_305 · Feb 25, 2013

silverpsd_06 said:
What dave is saying is that as the rpms of the motor go up your duration/window of the crank degrees to efficiently inject fuel gets shorter in actual time the duration never changes just the rpms.
So saying you are wanting to inject 2.1ms at 2500 rpm.. Now take 2.1ms to 6000 rpm there is not 2.1ms of time there to possibly inject fuel. The tuning causes this if the tuner doesn't pull back his pw as the time window gets shorter.

And to have two injection events going at the same time will self destruct the motor. There is alot more to the tuning side of it how they overcome the injection window getting narrower and narrower as rpms increase

The IDM only goes as fast as the PCM commands it to... There is no magical secret to horsepower lying in the IDM

:doh: that totally makes sense about somebody trying to inject fuel within 2.1ms when there physically isn't 2.1ms available at that rpm... that just made it click in my brain what everybody is referring to by saying that.

Maybe a stupid question, but is it possible to inject the fuel too fast? I had always thought the faster the better, but is it possible to inject fuel too quickly at lower/mid rpms?

silverpsd_06 · Feb 25, 2013

Its possible to inject it to early but as far as too fast i don't really see that being an issue the faster you can get it injected in your window the better off you are. Bringing fuel in too early or in mass quantities will break chit for sure.

Vader's Fury · Feb 25, 2013

There is some great info in this thread.... Glad people are still willing to share there knowledge of some of this stuff.

TyCorr · Feb 25, 2013

Well, Rob, its dead technology so nobody cares....

powerstrokenstang · Feb 25, 2013

Does the pcm have any kind of hard limit on timing advane? Just wondering

golfer · Feb 25, 2013

powerstrokenstang said:
Does the pcm have any kind of hard limit on timing advane? Just wondering

yep

stock is 135deg advance

TyCorr · Feb 25, 2013

golfer said:
yep

stock is 135deg advance

What frikking conditions would need to be.present where the pcm would decide it needs 135 ° advance?

Magnum PD · Feb 25, 2013

I talked to a guy that had a cummins, he told me there is an injection of fuel (I'm gussing) at the end of the exhaust stroke. Sound crazy?

TyCorr · Feb 25, 2013

Magnum PD said:
I talked to a guy that had a cummins, he told me there is an injection of fuel (I'm gussing) at the end of the exhaust stroke. Sound crazy?

Hell no! Thats the parameter that lets them be smoky POS's.

85_305 · Feb 26, 2013

Magnum PD said:
I talked to a guy that had a cummins

that was your first mistake

powerstrokenstang · Feb 26, 2013

TyCorr said:
What frikking conditions would need to be.present where the pcm would decide it needs 135 ° advance?

Lol maybe a stone cold engine at 3750 when its -50 degrees out.

Magnum PD · Feb 26, 2013

85_305 said:
that was your first mistake

Probably right. Don't see how it could be beneficial.

85_305 · Feb 27, 2013

Magnum PD said:
Probably right. Don't see how it could be beneficial.

hahaha

Gearhead · Mar 1, 2013

135 before top dead center is the maximium electrical advance. Remember, just because you tell it to inject RIGHT NOW, it doesn't mean that it is going to do it in any hurried fashion. When the oil and fuel are at freezing temperatures, you'd be suprised how much electrical advance is needed to get it to fire remotely close to TDC.

Charles · Mar 1, 2013

Gearhead said:
135 before top dead center is the maximium electrical advance. Remember, just because you tell it to inject RIGHT NOW, it doesn't mean that it is going to do it in any hurried fashion. When the oil and fuel are at freezing temperatures, you'd be suprised how much electrical advance is needed to get it to fire remotely close to TDC.

Sounds like another in a long list of problems that a mech pump cares not one *** about...

Screw Heui...