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DS4 pump mods

Does this white crush ring wear out or have some issues depending????

With bad lift pump would the vacuum in the first few chambers be high and stress the little white "crush ring" making it deform back and forth more than normal such that it might deteriorate the transfer pumps ability to maintain expected psi and flowrate ?????

Really high Lift pump pressure might blow out this white crush ring. And increase houisng pressure significantly but the expected differential to charge pressure might get screwy ??? I don't know what all happens.

But lift pump pressure of up to about 15 psi seems to just help ensure complete fill and slightly increase charge pressure due to better transfer pump operation and increases slightly the throughput of diesel through the IP.
 
Turbine Doc said:
IIRC max output is 92^3mm/1000 max flow, but advertised as 80^3mm @ Stanadyne's site, on my scan tool @ WOT 100% engine load the display just shows 80+, I have no idea how much plus is out there he's enabling with his reflash. When I was stock S (L56) GM program max was 56^3mm, with stock F (L65) limit was 65^3mm
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I have scan XL... Can i read flow with that scan tool? If so... how?
 
You can only read up to 80mm3, that is fuel rate if it has the measurement. It peaks at 80 because it peaks at FF in hex values. Its an 8 bit value that only goes from 0-F. The ALDL definitions has a multiplier of 0.3125, and so does the PCM. FF = 256 in decimal multiplied by 0.3125 is 80. That is the max that can be requested, but not the max that the DS4 can output, because you can redefine how long the pulse width is at 80mm3. Only at higher RPMs will it go over an actual of 80, becuase the max pulse width is already commanded for 80mm3 at lower RPMs.
 
Woody35 said:
i dont think the transfer pump is going to like fuel coming in at 100 psi but i wouldn't really know. the cp3 injection pump on a dmax can only take roughly like 15-20 psi before it can become damaged im pretty sure.
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I think you missed my idea.................

Can the transfer pump be REMOVED FROM THE IP and run a Air Dog, FASS pump setat 100 or so psi?????
 
Well, the transfer pump is also kinda a flowrate metering system. The Fass would be regulated at 150 ? psi but GPM would not be controlled.

I have been pondering this ..... According to Bison's thread on DS IP rebuild.

Tranfer pump pressure at engine rpm
16 psi at 150 rpm
45 psi at 600 rpm
100-104 psi at 1500 rpm
143-147 psi at 3400 rpm


The IP mechanisms uses this gpm and associated pressure build up and differentiates the timing advance piston to work with the expected pressure differentials. That is why you would have to have an external timing control.


What bothers me and I haven't figured out is .....


How does it regulate pressure ? Pumps pump a flowrate restriction to flow builds pressure. Something like y rpm will yield x gpm. Then as rpm goes up so does gpm. If the restriction to flow is steady as gpm rises pressure will rise.

The IP can inject fuel or it can reciculate. Looking at some estimated numbers and you do some rough math at 11 miles per gallon at 50 mph yields about 0.076 gpm injected through the injectors. At 24 mpg and 50 mph 0.034 gpm is injected. That is an appreciable change in flow for the downstream resistance to flow for the transfer pump in and of itself. There are other factors too each stroke of the injector a bit of fuel is recirculated to the tank. So depending on rpm (injections) there is also a small change in demand for the transfer pump flowrate. Again lots of variability for demand also if its not injected does it just dump pressure to housing or totally recirculate some internal to the IP. I don't think the return line surges quite that much so I believe it does recirculate inside the pump.

I wonder if the weight of the vanes being whipped around has something to do with variable pressure build up of transfer pump. Otherwise I would think the transfer pump would get kinda deadheaded if you were heavy throttle one second then totally let off no fuel injected (pcm takes over back to idle controls) and all of a sudden the resistance downstream of the transfer pump changes significantly but the flowrate of transfer pump is set ?????? Or do the plungers still pump through just not inject so the transfer pump pressure is not spiked???
 
The DB2 returns extra charge pressure and fuel right back into the inlet,don't know on the DS4 ,but its probably the same,just different by design. This is a bad design for keeping the pump cool,but good for waste oil fuel,since the IP is kind of a huge heater. There is a vent wire on the DB2 that helps flow some fuel through for lube and cooling,guess this could be changed for more flow,but it will waste charge pressure.
 
The pressure may just be regulated by the sizes of the openings and what not and Stanadyne or GM engineers mapped it and determined what pulse width was needed at each RPM/pressure to meter a given volume of fuel.

So if you can achieve 150psi charge pressure at 2000rpm then you can achieve much higher fuel rates if you max out the pulse width.

So the 150psi air dog replacing the internal IP transfer pump would be a good mod on a race truck. Or design a progressive regulator that increases in similar curve but at higher pressures all through it and you can also customize the pulse width in the PCM program to smooth out any problems. So much of the programming is dependant on the values though that everthing would become skewed
 
It would help the most if the charge pump is unable to keep up at full throttle. Is there a place to check charge pressure on the DS4 ? On the DB2 I drilled and taped the bottom bolt for a gauge. I also think I should put a gauge on the other side of the metering valve also, I bet the pressure is 1/2 as much as charge pressure. There is a chance that the DS4 charge pump is no where near 148 psi when at full throttle and a big tune.
 
buddy said:
The pressure may just be regulated by the sizes of the openings and what not and Stanadyne or GM engineers mapped it and determined what pulse width was needed at each RPM/pressure to meter a given volume of fuel.
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It should be fairly linear similar to oil pressure more rpm gives more pressure. But in that case the down stream restriction is more or less constant.

But there seems to be a pretty big variable on down stream of transfer pump fuel flow demand. The tank return is a max pressure build up constant restriction but the fuel being injected is quite variable (comparing idle fuel rates to max fuel rates injected). I can easily see it being a predictable map if the fuel metering took place after full plunger pumping (as in metering solenoid allows what's not injected to be dumped and or recirculated). In the metering after plunger fil then the pump through rate would be a function of rpm and predictable reguardless of fuel injected variations.

At the base of the inlet is a mechanism for excess charge pressure to recirculate back to transfer pump inlet.

I believe the "bango" screw with extra button head on PMD side is for measuring charge pressure; Bison mentions it in his thread.


OR probably it just hit me the pressure spec is a minimum pressure tested at max fuel output and when fuel injected rate is low it builds max charge pressure and vents back to transfer pump inlet. In that case it would be easy for a reprogrammed fuel output curve to exceed transfer pump flowrate at lower rpm and thus almost require a feeding the beast mod to up inlet pressure so output pressure is higher for the transfer pump so you can use the new programmed fuel rate.

edit ....
Well dang that doesn't keep the hydaulic timing differential going. Unless the the fuel metering solenoid does double duty dumping the plunger charge and kinda sorta venting charge pressure too ????

edited it again because I mis typed my thoughts.
 
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kojo have you have experimeted with high rpm tuning on the ds4 like heath has. supposedly thats where all the power is coming from when he makes those 150mph runs is at 5000 rpm
 
Its easy to run fuel up to 5000rpm, but the engine isnt going to like it unless it is set up with good airflow, intake and exhaust. An ATT runs higher RPM much better than a GMx.

With higher gearing and some honed heads and exhaust manifolds and ATT I could probably hit 150mph. The 5 speed manual would make that a lot better though. Basically how Heath set up his racer but with twin turbo.
 
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i just cant wrap my head around that there is enough fuel up in that rpm range to provide enough fuel for 400-500 hp or what ever heath is running. im sure those headers and custom cam work wonders for getting fuel up there but i think schiker posted specs of a DS4, DB2 and DB4 fuel rates at rpm and the DS4 was making max fuel output at 1800 rpm.

i guess its all in the programming. the vp-44 which is the same type of pump as the ds4 doesnt like high rpms and cant make big power there. i was mistaken they were similar in performance charasterics.
 
It wasn't me who posted output specs. I don't have a source for specs. Be careful comparing the 6 cylinder pumps to 8 cylinder pumps. There are 15 degrees available rotational difference between them. And I think I have read there is some significance to that.

Kojo does that book go into depth on the IP. My helm manual is mostly for the truck and no so much internal to the IP. I don't think GM and Stanadyne had much faith in dealership service of the IP.
 
Fuel rates can be max at any RPM, the higher the RPM the more internal IP pressure so the more fuel gets metered for a given pulse width. And you have more cycles of that fuel rate, so you consume a lot more fuel at higher RPM and max fuel rates. Twice as much fuel consumed at 80mm3 5000rpm as 80mm3 at 2500rpm.

The PCM programs all maxed them at 1800rpm, that doesnt mean it has to stay that way.
 
Woody35 said:
kojo have you have experimeted with high rpm tuning on the ds4 like heath has. supposedly thats where all the power is coming from when he makes those 150mph runs is at 5000 rpm
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No i havent, i have noticed it really gives power at high rpm's, but i havent raised rev limiter. i think it would need at least balanced engine and maybe stiffer valve springs to take more rpm.

I believe too heaths race truck uses rpm to make power.
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schiker said:
Kojo does that book go into depth on the IP. My helm manual is mostly for the truck and no so much internal to the IP. I don't think GM and Stanadyne had much faith in dealership service of the IP.
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That book is mostly fuel system, and most of that book is pump and ecm things.
There aren't any torque specs, clearances etc for pump, but for example there is pretty well explained how fuel metering system works and things like that (by the way it is spill valve)
 
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