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-   -   VP Dynamic Timing Vs. Advancing (http://www.competitiondiesel.com/forums/showthread.php?t=72393)

sstockton 11-25-2009 07:58 PM

VP Dynamic Timing Vs. Advancing
 
The VP44 pump as we all know has dynamic timing. This means that injection timing advances or retards based on Engine RPM, and load. Obviously there are limitations to the range in which the pump can operate.

So, what I want to know is...

If you advance timing through the use of a timing box, i.e. an edge comp, edge ez, power puck, smarty etc... Are you just advancing the low end timing? In effect bringing it closer to the timing at full advance, and decreasing the function of your dynamic timing, or does it extend the entire range of the dynamic timing?

Just curious if anyone has thought about this, or knows the answer. Thanks,
Sean

okish 11-26-2009 01:30 AM

There is only a certain amount advance the pump can make, and it is in direct correlation with how much travel there is in the timing piston assembly to rotate the cam ring. The timing piston is controlled by the internal pump and by the timing solenoid. Without the timing solenoid, the advance will be solely based off of the speed of the pump. The timing solenoid allows for more advance at lower pump speeds as controlled my the pcm on the pump. A timing box just allows for more timing than what the pcm wants.

Those are my thoughts on it and from experience working on rotary pumps. A VE pump can only control timing by pump speed and my a KSB solenoid to increase case pressures and base timing.

sstockton 11-26-2009 12:51 PM

But it likely doesn't change the total advance, just starts the advance sooner, and/or reaches full advance sooner. This is based on the assumption that the PCM will command the pump to reach its maximum advance under stock parameters.
Sean

okish 11-26-2009 01:02 PM

Quote:

Originally Posted by sstockton (Post 927772)
But it likely doesn't change the total advance, just starts the advance sooner, and/or reaches full advance sooner. This is based on the assumption that the PCM will command the pump to reach its maximum advance under stock parameters.
Sean

No, it probably does not change the total amount of advance. That is limited by the amount of travel of the advance piston.

sstockton 11-26-2009 01:24 PM

Thats what I figured. It just brings it in sooner, somewhat limiting the range and function of the dynamic timing.
Sean

01CumminsSport 11-26-2009 01:32 PM

since there is only so much timing that the Vp can do by itself couldnt you put in a ofset key way to add more base timing, and wouldnt that also add more total timing or would this throw a bunch of codes and not run right

sstockton 11-26-2009 02:08 PM

I'm actually testing that right now. I'm running the gear advanced 1 tooth which is 5* as there are 72 teeth. I'm just curious if it would be better to run more mechanical advance and no timing box, and retain the dynamic timing, or run some mechanical advance with a timing box.

So far, no codes with mechanical advance, and it runs great on the street. I would like to get on a dyno soon and do some back to back testing, with it advanced vs. not advanced, and I also intend to run back to back at the drag strip this spring when it opens back up. Like I said, on the street it seems great. Even with a hotrod pump, I'm running lower EGT's and less smoke than I was with my SO vp.
Sean

01CumminsSport 11-26-2009 02:24 PM

i have the 6 deg key ways that i use for cams, i was thinking about installing one of them so that the gear train is still lined up so that the TDC marks on the gear are still correct. I also think it will make more power up tor with the increased timing, ill have to go give thins a try bec i know my truck doesnt have enough timing for 4K with my injectors because after 3500rpm the smoke starts so get a little thicker and i know im not out of air

sstockton 11-26-2009 03:40 PM

Yeah, the timing is nice that way. I still get a fair amount of smoke down low, with the box cranked up, but once boost is built all the smoke is cleared up. The TDC mark is a little off this way, but in all honesty, you can feel when the truck is at TDC or BDC, and its really close to lined up. I'm not sure if a cam keyway, would make the same difference in a VP. Is the shaft the same diameter? That will determine how much offset there is.
Sean

Rollin Coal 11-26-2009 04:05 PM

hmmmm........ subscribing

01CumminsSport 11-26-2009 04:12 PM

it shoulnt matter the shaft diameter bec the gear size is the same so the rotation is at the same speed it just moves it over a little, even if the diameter did matter it would only give me more timing which wouldnt hurt anything, i think. i might just do the 1 tooth idea anyway because thats a known degree movement, now to just pull off the front cover and do it

blkram 11-26-2009 04:23 PM

A local guy has been running his vp with I think a 2-4 deg key and his truck runs sweet, spools his 64 nice and the truck cleans up good with 6x16s, they have done it to I think like 2 other trucks so far and have had positive results.

Rollin Coal 11-26-2009 04:30 PM

what does the adrenaline offer with the pulse, up to 10* advance over stock? i wonder if another 5* is going to be pushing it.

Clunk 11-26-2009 05:04 PM

Does the P1690 show up?

P1690 Fuel Injection Pump CKP Sensor Does Not Agree With ECM CKP
Sensor.
Problem in fuel sync signal. Possible injection pump timing problem. Low power, engine derated, or engine stops.

01CumminsSport 11-26-2009 05:30 PM

Quote:

Originally Posted by Rollin Coal (Post 927963)
what does the adrenaline offer with the pulse, up to 10* advance over stock? i wonder if another 5* is going to be pushing it.

the pump can only advance it so far, were trying to get a even more timing out of it by physically advancing the timing,

Rollin Coal 11-26-2009 07:25 PM

Quote:

Originally Posted by 01CumminsSport (Post 928000)
the pump can only advance it so far, were trying to get a even more timing out of it by physically advancing the timing,

i fully understand. but if you push base timing ahead and add electronic timing you may end up with too much. this is assuming the ECM wont compensate for the gear being out a few degrees.

sstockton 11-26-2009 07:34 PM

Thus far, I haven't thrown any codes, and the truck seems to run really well. My point with the shaft size, is that the keyway moves the shaft relative to the gear. On a smaller diameter shaft, the same offset will cause a greater difference in degrees of rotation. I have a stock VP and an extra cam, so I will check and see how close they are. You could probably take the info for both of them, and figure out what the difference would be.

Side note- how do you like the advanced cam timing? Are you running a stock cam or an aftermarket cam? If so, which cam?
Sean

BrettWINspeed 11-26-2009 07:41 PM

The cam key's and vp key's appear to be the same. You can try Terry down at Diamond Diesel in Oakland to get the key's, he's said he can get them when we inquired about them. As for Dyno time I think this is some testing we'd like to see and we've never had the chance to do it. Maybe we could work something out with you to get on the Dyno for the testing on a Friday night, Sat, or Sun.

TURBOLVR 11-26-2009 07:56 PM

Quote:

Originally Posted by BrettWINspeed (Post 928107)
As for Dyno time I think this is some testing we'd like to see and we've never had the chance to do it. Maybe we could work something out with you to get on the Dyno for the testing on a Friday night, Sat, or Sun.

:woohoo::pop:

BrettWINspeed 11-26-2009 07:58 PM

One thing I just thought about is could 1 tooth actually equal 10* or 2.5*? Pump speed is equal to 1/2 engine speed.


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