Engine/Transmission (1994 - 1998) Variable timing P-pump?

[Hammer]

Why would you want to advance the timing on the higher end of the rpm band?. It would stand to reason as the charger/chargers get better lit and cylinder pressures increase greatly you would want to retard the timing some which would help lower cylinder pressures and allow the motor become more efficent. To take a competition built P-Pumped motor,which many are already at or above 45 degrees of timing and advance it even further,would create huge cylinder pressures and possible failures or breakage. Just curious???... . Andy

 

[Lightman]

As I understood it the p7100 and the VE would both advance timing. Reading an article in the TDR magizine many years ago you don't increase engine speed by just putting your foot on the go peddal and adding fuel the injector pumps advance timing similar to distribitor.



An article in the TDR magizine in the last couple of years stated the the VP44 was capable of variable timing, one of the reasons the 24 valve engine made emission standards in 99 thru 2002.

The P7100 can only be advanced by moving the location of the gear on the shaft. The VE and the VP44 both have variable timing. I wouldn't do this if you dont need to but say you start a diesel engine that is out of fuel with starting fluid you give it a light shot now and then tell it starts so you dont overload it and lock it up. Now your giving it a light constant stream to keep it running. Now you push harder on the sprayer on the can it gives it more fuel and more RPM's are the result. There is no timing control in a can of starting fluid other than the the cam opening the valves, which is unchanged with RPM. So there is simple proof RPM doesn't require timing change that anybody can verify if wanted. The P7100 is fixed timing in the Dodge application period. Some of the early 90's F700 fords ran a ford I-6 6. 6L with a P7100 pump with variable timing which was all accomplished in the gear.

 

[Mhannink]

Why would you want to advance the timing on the higher end of the rpm band?. It would stand to reason as the charger/chargers get better lit and cylinder pressures increase greatly you would want to retard the timing some which would help lower cylinder pressures and allow the motor become more efficent. To take a competition built P-Pumped motor,which many are already at or above 45 degrees of timing and advance it even further,would create huge cylinder pressures and possible failures or breakage. Just curious???... . Andy

hammer i dont think we are looking to advance it even farther. i think the goal here is to advance it to that point.



the way i see it is we want to set these pumps at say 25 degrees at 3500 rpm becasue that gives us lots of top end power. howver in doing that we cant drive the engine down the street. it knocks and pings and breaks stuff not good. what this variable timing would do is at idle its say 16 degrees good low end off the line power as the engine revs up the timing moves to 18 then 22 finaly 25 or whatever its setup to do. the result of this is a wider powerband and better drivability.

The P7100 can only be advanced by moving the location of the gear on the shaft. The VE and the VP44 both have variable timing. I wouldn't do this if you dont need to but say you start a diesel engine that is out of fuel with starting fluid you give it a light shot now and then tell it starts so you dont overload it and lock it up. Now your giving it a light constant stream to keep it running. Now you push harder on the sprayer on the can it gives it more fuel and more RPM's are the result. There is no timing control in a can of starting fluid other than the the cam opening the valves, which is unchanged with RPM. So there is simple proof RPM doesn't require timing change that anybody can verify if wanted. The P7100 is fixed timing in the Dodge application period. Some of the early 90's F700 fords ran a ford I-6 6. 6L with a P7100 pump with variable timing which was all accomplished in the gear.

lightman your senario is just what our 12v's do we add more fuel so it will spin faster. in fact all diesels do that. your right rpm does not regire timing change however power does. see as in gas motors diesel only burns so fast. in a gas motor the spark timing is advanced so that the fuel air mixture burns are the same time in the rotation.



here is an example of what im talking about you inject fuel into the cylinder at 1000 rpms the fuel burns in say 3 degrees of crankshaft rotation. so from 3 degrees btdc to 0 degrees tdc. no you accelerate the engine to 2000 rpms the pistion is coming up twice as fast as before but the fuel is still be injected at the same point 3 degrees btdc but casue the engine is spining faster it travels farther before the fuel is compltely combusted. so now its at 3 degrees atdc. well now its not be used as effecintly as before. so now lets vari the timing at 1000 rpms we will still inject 3 dgrees btdc but at 2000 rpm we will do it at 6 degrees btdc so that the fuel will have time to ignite and burn to create optimum power.



that is really the goal of variable timing. and maybe its one reason it has not really been approached in the after market world is cause it wont give is more power. just a wider power band. while joe blow public would like it on his truck. it is not the goal of most people in the performance world. everyone today is looking for outright power. the guy with the most wins.

 

[Lightman]

lightman your senario is just what our 12v's do we add more fuel so it will spin faster. in fact all diesels do that. your right rpm does not regire timing change however power does. see as in gas motors diesel only burns so fast. in a gas motor the spark timing is advanced so that the fuel air mixture burns are the same time in the rotation.



here is an example of what im talking about you inject fuel into the cylinder at 1000 rpms the fuel burns in say 3 degrees of crankshaft rotation. so from 3 degrees btdc to 0 degrees tdc. no you accelerate the engine to 2000 rpms the pistion is coming up twice as fast as before but the fuel is still be injected at the same point 3 degrees btdc but casue the engine is spining faster it travels farther before the fuel is compltely combusted. so now its at 3 degrees atdc. well now its not be used as effecintly as before. so now lets vari the timing at 1000 rpms we will still inject 3 dgrees btdc but at 2000 rpm we will do it at 6 degrees btdc so that the fuel will have time to ignite and burn to create optimum power.



that is really the goal of variable timing. and maybe its one reason it has not really been approached in the after market world is cause it wont give is more power. just a wider power band. while joe blow public would like it on his truck. it is not the goal of most people in the performance world. everyone today is looking for outright power. the guy with the most wins.

I know all this I was not arguing the usefulness of variable timing. I was simply trying to explain in an easy to understand way that it doesn't require timing advance to increase engine speed. I was also stating that the P7100 on the dodges is a fixed timing set up that dose not change with RPM. That was the reason for the quote from the previous post in my last post.

 

[Mhannink]

my apoligies(sp?) i thought you were arguing the idea forgive me for that and lets carry on

 

[Vaughn MacKenzie]

the way i see it is we want to set these pumps at say 25 degrees at 3500 rpm becasue that gives us lots of top end power. howver in doing that we cant drive the engine down the street. it knocks and pings and breaks stuff not good. what this variable timing would do is at idle its say 16 degrees good low end off the line power as the engine revs up the timing moves to 18 then 22 finaly 25 or whatever its setup to do. the result of this is a wider powerband and better drivability.

Exactly that's what would make the P7100 an optimal performer IMO.

Missouri Mule commented adding fuel advances timing. I think what he means is as you increase fuel while RPM remains constant you have a longer injection duration. On a 12-valve if I understand correctly fuel is sprayed at the same pressure and flow rate no matter the load and RPM, with the variable being duration which varies the power . . . in essence the 12v works like a duration box put on a 3rd Gen. So the question is which way on the crank position is the duration added. . . is it extended, or some added to both sides? I'm sure it's not added to the front end or it would be too advanced.

Vaughn

 

[WDixon27]

they way i see theres a couple ways of getting a advance without going into the pump, the first way would be relitively easy to pull off the timing change but hard to implement, set up the mounting of the pump to where it can be rotated in the gear case and control it with a hydraulic cylinder, the problem with this is all of the hard lines going to the pump not being movement friendly. the 2nd way requiers engineering a part to two and the change takes place in the gear case at the front of the motor, do it like the variable cam timing system on 90s bmws (vanos) it's a helical set of teeth and a piston controled by a solenoid and oil pressure, above a certain rpm the solenoid opens and oil pushes the piston out of it's cylinder advancing the cam in this case about 12* but the advance would depend on the cut of the gears, i beleave a system like this could be used to add advance but it would take a good bit of work and the costs may not be recoverable (who knows damn thing could take off like wild fire) i even think you could stage the advance with a bypass in the cylinder that could be opened to limit piston travel by bleeding off pressure till you closed it. comments/questions?!

 

[PSchwering]

Exactly that's what would make the P7100 an optimal performer IMO.



Missouri Mule commented adding fuel advances timing. I think what he means is as you increase fuel while RPM remains constant you have a longer injection duration. On a 12-valve if I understand correctly fuel is sprayed at the same pressure and flow rate no matter the load and RPM, with the variable being duration which varies the power . . . in essence the 12v works like a duration box put on a 3rd Gen. So the question is which way on the crank position is the duration added. . . is it extended, or some added to both sides? I'm sure it's not added to the front end or it would be too advanced.



Vaughn

SOI is close to constant. it varies a bit, but with RPM, not with Delivery. EOI Varies according to total fuel delivered.



Something as simple as double helix plungers will give you a huge step up over what we have. As delivery increases per stroke, SOI moves earlier, and EOI moves later. This will keep the fuel delivery centered over the desired injection time. Not exactly variable timing, But it will give you advanced timing when at high fuel delivery, & retarded timing when at lower delivery.



Anybody know where to get double helix plungers? I don't know if they were ever made, I know we studied the theory of it at one time. P.

 

[Mhannink]

i thing as i understand it is the rack in the pump controles the duration. when we do a pump plug and allow the rack to move farther we are changing the duration wich way i dont know. but that is basicaly changing timing.



one thought might be and if read correctly has already been done. is make a fuel rack that is electronicly controled. if we could start the duration sooner we could efectivly advance the timing. course the problem as i see it is as you got higher up in the rpm the duration would be too long at we would waste fuel at that point.

 

[bmoeller]

I just threw together a CAD file for a school project that is a timing cover with an adjustable pump gear that protrudes through the cover with a seal so a quick painless timing adjustment can be made



#ad

John Deere had that type of setup on a lot of its engines. The 466 (SAE hardware)/6076 (metric) as one example. Take a small cover off of the front, and loosen the bolts on the pump gear.



We can do that now, by loosening the gear with a special puller. Very easy to do.

 

[HoleshotHolset]

Don't take what I'm about to say the wrong way - I love what you guys are proposing here...



Don't get me wrong, I LOVE my 12-valve and always will, but what you all are describing has already been done for us (and then some... ) in the form of common-rail injection. You can control dang near anything you want... and most of it doesn't even require wrenches or screwdrivers.



As a die-hard 12-valve fan, I've come to terms with its limitations and extreme HP potential despite a few drawbacks. You never know, after I start playing with my common-rail engine, I might be swearing at it more than swearing by it.



Keep up the innovative thought!



Beers,



Matt

 

[Vaughn MacKenzie]

Thanks for making us mechanical power guys feel better there Matt :-laf

 

[HoleshotHolset]

I knew there wasn't a good way to say that...



There's always a time when you're heading down the path of diminishing returns on your investment - and it would seem that adding variable timing might be this sort of thing.



To say the least, introducing another point of failure to a system that has proven to be VERY reliable might not be such a good idea.



Matt

 

[KCloward]

But it'd be cool:-laf



I think it'd be a pretty cool add on to a 12 valve system and might just make it more reliable? Well we can always hope atleast.



Bryce

 

[Mhannink]

well theroititcly(sp?) it would make it more reliable at higher power levels since you would have the same top end along with a wider power band. at the same time your keeping your bottom end power within close to spec. this is obviously if you can make a system that works as reliably as the pump is already.



though on the other hand the marine engines run with 25 degrees timing wich is a lot more then we run and its the same b series at least i think it is. anyways they run lots of timing and have no issue

 

[Mhannink]

hey ya'll i just opened up a 3406 at school and they use a simalar pump as our ppumps they have a hydralic spring and hydralic hydralic. first word is advance sencond is return. the hydraulic hydraulic has something like up to 12 degrees of advance the gear setup the use doesnt look too hard to convert to our pumps

 

[HoleshotHolset]

though on the other hand the marine engines run with 25 degrees timing wich is a lot more then we run and its the same b series at least i think it is. anyways they run lots of timing and have no issue

The marine engines are also aftercooled and have an endless supply of cold lake/ocean water to keep 'em cool. They're also designed for steady state operation at high RPM - it's not the same as OTR. "Diamond B 370" marine cams run like garbage on the street - quite a few folks have tried them and hated 'em.



Beers,



Matt

 

[dpuckett]

Also keep in mind that the marine engines run lower compression ratios than our pickups. I think it's 17. 5:1 (ours) vs about 15. 3:1 (marine). That lowers cylinder pressures further.



Daniel

 

[Don Tanklage]

how does having the timing adv as the rpm increases help make more power?



what does a lot of timing do to lower rpm on these motors?



don

 

[Vaughn MacKenzie]

how does having the timing adv as the rpm increases help make more power?

Because diesel fuel always takes a few microseconds to ignite, so the faster you rev the motor the further down the piston is before combustion begins.

what does a lot of timing do to lower rpm on these motors?

Makes it rattle louder, harder to start because ignition occurs a bit too soon - before the piston reaches TDC.



Vaughn