Badunit

Being a neophite on the matter and not knowing how many degrees are between the pilot injection and main event or the length of either pulse, it seems like a duration box could

1) decrease the length of the pilot pulse and have the main event come on sooner and/or

2) decrease the dead time (if any) between the pilot event and main event so the main event could come on sooner or

3) remove the pilot event totally and have one long main event.

Any one of these would likely increase the noise of the engine but would allow the extra duration to come on sooner rather than later.

Push Rod

As far as I know, the TST box is the only duration and timing box on the market. But the only information I have about the VA box is from what I've read on threads here, and the information on their website. So I can't be quoted on that.

As far as why VA wouldn't do timing, I really don't know. You'd have to ask VA themselves about that, or a VA dealer. Pure conjecture: The code throwing that the timing boxes such as TST and Bully Dog ran into were related back to timing advance. Perhaps VA decided to avoid the issue by not doing timing? Again, pure conjecture.

I'm going to throw something else out there for the anti-pressure box lobby (). Higher pressure = better atomization = better burn. Especially as injector size goes up. You wanna run aggressive injectors, then you'd better be prepared to boost rail pressure.

Rod

doug

good points rod. So basically you have the trade-off between:

1. extended duration, which may have both a favorable consequence (burn "quality" if you will) and a disadvantage (EGT)

2. larger fuel charge due to either larger injectors or higher pressure, which may have both a favorable consequenc (lower EGTs) and a disadvantage (burn "quality").

Maybe the "burn quality" thing is bogus too, I don't know. it would be interesting to see how the VA duration only box performs, EGT wise.

I expect that VA is also working on a timing/duration box, as is Edge.

And I just learned from Precision Diesel that the VA box works for the 600 as well as the 305. And that it does NOT do timing.

cquestad

It sounds like we need some tests or real world experience with those 100 or so new VA's that have hit the streets before we can conclude anything. Now if we could just figure out who has those...

It seems like VA's pressure box was safe on the EGT side. Hopefully they applied the same theory when designing the new duration box.

mjf6175

CQUESTAD---BINGO! I too favor the VA since it appears they "error" on the side of safety. ALthough I am one of these that favor a non-pressure box I was enticed by VA's C3 since it appeared not to raise the pressure too high. Yeh it didnt make those bragging dyno numbers but would feel comfortable with what it was doing, getting 60-80hp under the curve and a peak to peak of 30. Then the news of the NEW VA and my half-a@@ logic thought 'Hey maybe they are still being conservative here and avoiding EGT issues" I can only hope they have followed the same pattern of development. I am on the side lines wiating to hear the results.

AK RAM

Oh sure. Forget about us poor SO drivers. Not feeling the love here!

cquestad

AK RAM...how did you end up with a SO anyways? Do they not have the HO up in Alaska?

AK RAM

Oh, so now it's funny....everybody wants to pick on the slow SO. Quit bust'n my chops! It was CHEAP....OK!

Push Rod

Actually, the longer the duration, without appropriate timing advances, the worse the burn "quality". You're spitting fuel into the cylinder that has no chance of being burned, and will instead ignite just before the exhaust valves begin to open. As its exitting the cylinder, its coming onto full burn, further excited by the bit of boost that leaks over to the exhaust side to aid in cleaning the exhaust area of the cylinder head. This is why we're seeing such massive EGTs on aggressive duration boxes like the TST. Alot of fuel is burning as its exitting the cylinder. Not much point in burning the fuel at that moment in time, is there?

Now, with the cat equipped 600s, we need that heat to allow the cat to work properly, and as such, the 600s use a main pulse thats timed even later than the 03/04s. So extending the pulse, without appropriate timing advances, is even worse, EGT and burn wise.

We're starting some tests right now with regards to stacking. As the market currently stands, I don't feel there is an ideal box out there. TST is the closest, as far as pure technical advance and adding fuel in an appropriate manner (at least at the lower settings. Our jury is still out on 9x9). The Edge EZ, in my opinion, is still the best of the inexpensive, easy boxes. 40 HP, 10 more than the VA, right "where you need it" at 17-1800 RPM, and another 10-20 more up top all for about 50 bucks more than the VA.

Rod

doug

ahh, thanks for the explanation Rod. So moderate duration should be good for the 305s, and a little extra timing in there should do the trick. huh. throw in a little pressure and bingo you just described two staked VA boxes (assuming they come out with a timing/duration box...)

wonder how those VA duration-only boxes behave in the EGT category.

AK: not to worry, the VA duration box works on the SO.

here's a dyno run for the SO -- got this from VA. red is HP, blue is torque. If I interpret correctly, there are three runs: stock, level 1 and level 2

here is the same box on a 305. this run is stock and level 2 only

cquestad

Wow...still worried about EGT's/Turbo. Looks like TST type performance!

draebi

Well I called Precision Diesel and they told me that it would work with the SO, HO, and 600. They told me they helped out with the development of this box and it actually adds 130hp and 275tq to the HO(do not know if this is peak to peak or not). They said that the timing advances is what is causing the other boxes to throw codes and still has not been completely figured out due to these engines being so complex and somehow reading timing from multiple locations. This is why they do not do the timing advance yet, but the box is totally reprogrammable and so if they add that then they can update the box.
I asked about the stacking the box with my VA pressure box and they said they had not done it but it is physically possible and thought it would work but they recommended starting it out on the half pressure setting. They said stacking it on a 600 would probably be putting too much fuel in there and cause problems but with my HO it should be fine as long as tranny could handle it not to mention EGT's with stock turbo.
Some have been comparing pressure boxes and I have tried the VA and EZ both on my truck back to back and the EZ is a little faster but the VA makes my truck run so much smoother at idle with absolutely no surging like with the EZ so I decided to keep the VA on mine. I will run this pressure box for a while and make sure the duration box has no initial glitches then I will probably switch or maybe even stack once I get my guages and can monitor things a little closer.
The new VA box is retail of $795 but can get at Precision Diesel for $695.
Oh, yea almost forgot he told me that I would see a little more MPG increase with the duration only box than I am getting with the pressure box.

doug

yea, I know what you mean. But look more closely - the VA peak is higher in rpm, not as high, and tapers off more quickly towards the high end. That makes it more of a towing box and less of a dyno day box. for example, check out the level 1 performance of the VA.

Even on the highest setting, the VA makes only about 1/3 of the HP gain as the TST does at 2900. Unless I read the graph wrong, that is a significant EGT advantage -- again, more of a towing box than a dyno day box.

JRG

Doug, what is a MODERATE amount of timing from the volumizer? I had asked befor about a box with injectors and the volumizer is a cheeper, milder TST type.

If I did go with the new VA, would any "updates" be FREE? ie. timing.

JRG

doug

Yea, volumizer plus injectors is still definately an option to consider. to be honest I'm not sure how much timing is "moderate" and what is "radical" and I don't know how much timing the volumizer provides. I'm hearing timing advance on the order of 10 degrees on the TST, and that this is "radical" but thats just me repeating what I'm hearing.

The only cautionary note I can suggest here is that an injector and a pressure increase do the same thing -- increase the instantaneous single charge density of fuel from stock levels to a really big, but still short, squirt. At some point, as you increase the charge density of the squirt, I'd think there would be a diminishing returns and that over-fueling (smoke and high EGTs) will result. But I have to note too, that there are alot of guys running EZs and injectors. I just don't know how much smoke they make and what the EGTs do.

I can only guess that the Volumizer does mild timing because they can do it succesfully (no codes) , and that the more radical timing advance has not been solved yet -- pending of course the TST effort. I think they are making progress there.

on the other side of the "higher pressure = better atomization" argument is the fact that you're only increasing pressure by about 10-15 percent even for the big pressure boxes (an exception to this might be the Ramifier. they have arguably the highest pressure increase over stock at low RPMs) . Mabye thats enough to make a difference I don't know. The VA is only a few hundred pounds increase and insignificant in terms of percent pressure increase (at the high HP levels of course). Anyway, I'm not sure if pressure actually represents a swirl or atomization advantage. you still have to balance that by the need to overcome the highly dense, single event fuel charge and the fact that the charge itself burns at some non-zero rate (not instantaneous). especially with an injector -- you're not spreading the fuel charge out over time, you are increasing the instantaneous charge density (same squirt duration, higher squirt density)

the duration argument includes the suggestion that you reduce the potential to dump fuel into the cylinder at a faster rate than it can burn, and that (in the pressure box plus injectors case) the fuel vapor pressure might get so instantaneously high that atomization itself is limited simply because of the large single blast of fuel in a short period of time. the result is smoke and EGTs

But at the end of the day, all I can say is that is fun to speculate about this, and that I wish we had a diesel combustion engineer on the board! All this after-market engineering is really just moving the engine away from its original design point in more than one variable -- charge density, swirl, pressure, duration, etc.

I would propose that for the same truck on the same dyno on the same day producing the same countinuous power output with different boxes within the capability of the turbocharger, that EGT differences would be of enormous interest, and that the box with the lowest EGT represents the one more completely burning the fuel and more completely converting potential energy into kinetic energy.

JRG, in answer to your question about the VA duration box and the potential for timing upgrade. In my opinion from what I know, I think its too early to say. that would certainly be wonderful but to be honest, I'm not close enough to the VA marketing goals to answer that question. The duration box itself is very new, and we are only speculating that a timing/duration box is around the corner. If they architected the box correctly, I would think they would be in a position to offer a timing upgrade later down the road for an upgrade charge, and that it would not be free. But thats just me speculating...

And this may be simply a matter of words, but I wouldn't draw many similarities between the Volumizer and the TST box. TST (in my OPINION) probably does a much more radical timing advance and of course does not raise fuel pressure. volumizer is primarily a pressure box with a little timing.