[gregrob]

On my buddie's Duramax

And that's just with a #4 tune, 180hp program. He has the hot +2 that will add 270hp.

Anyway, it's just kinda funny that we can't run more than 6ms until the injector can't recover and that's practically what they idle at.

I say if there's a way to make the injectors recover quicker we could get way more fuel out.

 

[hotwheels]

Anyway, it's just kinda funny that we can't run more than 6ms until the injector can't recover and that's practically what they idle at.

I say if there's a way to make the injectors recover quicker we could get way more fuel out.

Since when? Idle is more like 1.2ish depending on the injectors and what truck they are in. WOT can be as much as 10-13ish again depending on what truck. And they have many time more than that to recover. That PW only takes a few degrees of crank rotation at TDC compression and you have nearly a full two revolutions for it to recover. If you are trying to cram mad amounts of fuel then MAYBE but I'd be more worried about actually getting the fuel out you have by getting the oil in the injector fast enough in that short windwo rather than trying to get the fuel back in during the much longer recovery.

That is crazy long PW on the dmax though. I wonder how far the piston is down by the time it quits fireing.

 

[Diezel Dawg]

are u talkin James' truck????

 

[Charles]

At your rpm, and injector displacement, injector recovery is so far from anything you will ever be having a problem with.

Now, with icp lingering in your oil side because your poppet is hung open pissing away oil due to the ICP being higher than what the poppet spring can hold back......now that on the other hand will, has and is, reducing the distance the injector refills at rpm because it's an opposing force to the refill. The only thing to force the injector to refill is the fuel pressure pushing on the face of the plunger and the intensifier spring pushing on the underside of the intensifier piston. When you've got pissing ICP above the intensifier piston, you can start to get a refill issue. The very reason that injector flow rates drop on the bench when the ICP is jacked up like you run it.

As far as refill issues from the point of view of time between injection events, you need a lot more rpm and a lot more injector stroke to see that. And even then, I haven't seen it, but am only aware that it will likely be an issue for me at some point once the rpms come online with the B codes.

That belt driven fuel pump wasn't an accident on my truck. And the 200psi fuel pressure capability isn't either.

Can you say REFILL NOW.......lol.

 

[SeeYa]

On my buddie's Duramax

And that's just with a #4 tune, 180hp program. He has the hot +2 that will add 270hp.

Anyway, it's just kinda funny that we can't run more than 6ms until the injector can't recover and that's practically what they idle at.

I say if there's a way to make the injectors recover quicker we could get way more fuel out.

Yep, you can get alot more PW out of Dmax injectors then the Fords.

 

[gregrob]

As far as refill issues from the point of view of time between injection events, you need a lot more rpm and a lot more injector stroke to see that. And even then, I haven't seen it, but am only aware that it will likely be an issue for me at some point once the rpms come online with the B codes.

That belt driven fuel pump wasn't an accident on my truck. And the 200psi fuel pressure capability isn't either.

Can you say REFILL NOW.......lol.

His rev limiter is 3200 rpms.

 

[gregrob]

are u talkin James' truck????

Yep!!!! Too bad it already lost 5th gear, twice. :lookaround:

 

[gregrob]

Since when? Idle is more like 1.2ish depending on the injectors and what truck they are in. WOT can be as much as 10-13ish again depending on what truck. And they have many time more than that to recover. That PW only takes a few degrees of crank rotation at TDC compression and you have nearly a full two revolutions for it to recover. If you are trying to cram mad amounts of fuel then MAYBE but I'd be more worried about actually getting the fuel out you have by getting the oil in the injector fast enough in that short windwo rather than trying to get the fuel back in during the much longer recovery.

That is crazy long PW on the dmax though. I wonder how far the piston is down by the time it quits fireing.

I was watching it last night with the scanner. Idle was between 4.2-5.8, WOT in his 4th program was 20.8

 

[hotwheels]

I was watching it last night with the scanner. Idle was between 4.2-5.8, WOT in his 4th program was 20.8

Sorry Greg I should have quoted. I was refering to this.

Anyway, it's just kinda funny that we can't run more than 6ms until the injector can't recover and that's practically what they idle at.

I say if there's a way to make the injectors recover quicker we could get way more fuel out.

Not what the Duramax does. I don't know what they maxies have for injectors and what not but just just looking at PW isn't really giving a complete story. How big are the nozzles in comparasin to ours? That will have a big impact on how much PW they need. Also how much injection pressure was it running.

Reading back through your quote I do think I miss interpreted it the first time though. I thought you were saying that the 7.3s idle at near 6ms but you were saying that you can't run more than 6 and the maxies idle at 6. sorry.

 

[bean]

More then meets the eye with dmax PW, apples and oranges to a PSD PW. 20ms pw doesnt mean thier inj is open for 20ms.

 

[gregrob]

I thought you were saying that the 7.3s idle at near 6ms but you were saying that you can't run more than 6 and the maxies idle at 6. sorry.

Yep, that's what I was saying

 

[gregrob]

More then meets the eye with dmax PW, apples and oranges to a PSD PW. 20ms pw doesnt mean thier inj is open for 20ms.

I hear ya Ryan. I understand they're a completely different injection system.

Still though, 20ms is a set amount of time, right?

I was just wondering how much more fuel we could flow IF we could get the injector to recover. (not that it is possible) :ford:

 

[hotwheels]

As stated above you have many times more time for recovery as you do for the injection event. IMHO it's more getting the fuel out in the limited amount of on time than it is getting the fuel back in on the off time. At the higher rpms where that off time is much shorter the pw is cut back as well so you don't get as much fuel injected anyway so you have less to recover. Now if you were able to hold the injector open for 10-13 ms or more at say 4000 or 4500 rpm then you might have issues with recovery. However then you are going to run into issues with even the biggest hpo systems keeping up with two injectors fireing at the same time.

 

[HotRodTractor]

I can't believe with all the replies to this thread I am the first one to call BS. First of all at 3000 rpms 20ms of pulsewidth roughly equates to 360 degrees of travel of the crank...... I highly doubt that any benifit will come to someone injecting during the entire revolution. Second of all the units used to command injection events in EFI live are in microseconds. I am looking at a table right now that clearly states the longest pulse is 3900 microseconds in this fairly hot tune...... that equates to 3.9 milliseconds.

I would go back and check the units on the scanner again..... cause I know what kind of power this tune I am looking at lays down, and you sure ain't gonna touch it with a 180 hp program.......

 

[gregrob]

I can't believe with all the replies to this thread I am the first one to call BS. First of all at 3000 rpms 20ms of pulsewidth roughly equates to 360 degrees of travel of the crank...... I highly doubt that any benifit will come to someone injecting during the entire revolution. Second of all the units used to command injection events in EFI live are in microseconds. I am looking at a table right now that clearly states the longest pulse is 3900 milliseconds in this fairly hot tune...... that equates to 3.9 ms.

I would go back and check the units on the scanner again..... cause I know what kind of power this tune I am looking at lays down, and you sure ain't gonna touch it with a 180 hp program.......

You mean 3900 microseconds = 3.9 milliseconds?

I'll double check the units. I highly doubt he's running 2.8ms at WOT though?

 

[69W900A]

A millisecond is one thousandth of a second
A nanosecond is one billionth of a second
A micro second millionth of a second.

 

[HotRodTractor]

You mean 3900 microseconds = 3.9 milliseconds?

I'll double check the units. I highly doubt he's running 2.8ms at WOT though?

Damn it I fixed it.

I will bet he is running 2.8ms at WOT. Do you know what the injection duration of a p-pumped motor is at say 3000 rpms? How about an Sigma pump? The injection pressure and nozzle flowrates has a lot to do with the fueling.

 

[gregrob]

I will bet he is running 2.8ms at WOT. Do you know what the injection duration of a p-pumped motor is at say 3000 rpms? How about an Sigma pump?

I bet you're right, and no I don't know what the injection duration is, I do see where you're coming from.

At 3200 RPMs you have 3200/60 = 53.3333333 for revs per second, then if you want crankshaft rotation per millisecond you have 53.3333333/1000 =
.05333333 revs per millisecond.

How many cylinders fire per 1 crankshaft rotation? Wouldn't that tell us how many MS is spent on the cycling of 1 cylinder?

I think I can already see that 20.8 milliseconds is way longer than 1 combustion even in 1 cylinder so it would be useless to hold the injector open that long and wouldn't run very well.

Am I right??????

Must have been 20.8microseconds, which would = 2.8 milliseconds. Right???

So then my question is how do they make so much power on HALF the PW we run on a hot tune?

Boy that's confusing

 

[389SixPack]

Must have been 20.8microseconds, which would = 2.8 milliseconds. Right???

So then my question is how do they make so much power on HALF the PW we run on a hot tune?

Boy that's confusing

No, 20.8 microseconds is 0.0208 milliseconds.

But the more important thing is how many events are per cycle. Typical injection events in the d-max are 5, 7 or 10 injections at maybe 20usecs each over a several msec event.

 

[Haul_n_horses2]

Am I right??????

Must have been 20.8microseconds, which would = 2.8 milliseconds. Right???

Wrong! Back to school for you! 20.8 microsecconds is 0.0208 milliseconds.