Common rail heads

Markus L

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My 1.9 VE made over 370 bhp with just slightly ported head so why CR wouldn't do big power? These are not naturally aspirated engines so if you want more air just add boost. 2260 is not even near to choke with 250 bhp.
 

named tintin

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I literally give up.
Clearly some people are beyond reading.
Not me, i'm still reading, all this is very good info.

You have a very nice car btw... congrats.

I've reread again your build thread, so with your set-up you'r still running on Lambda calculation in the ECU?

The only thing I find strange, is the linear figure of what's supposed to be maxed out, the VE efficiency of that engine is not linear, when there is not enough air, you should have more and more smoke as the RPM increase.

I'll be curious to see VCDS log of the various fueling parameter of your car.
 

diffas

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My 1.9 VE made over 370 bhp with just slightly ported head so why CR wouldn't do big power? These are not naturally aspirated engines so if you want more air just add boost. 2260 is not even near to choke with 250 bhp.
16 valve heads easily outflow even slightly ported 8v heads. Problem with those is valve control when having increased flow on boost and emp. Luckily there is a fix for that. gtb2260vk is indeed good for 300+ hp so plenty of room there.
 

Macradiators.com

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There is also a 297hp tune in US i think, A3 big turbo audi here on forum with WMI
I imagine a dyno being 10-15 hp too optimistic but 45-50 difficult to believe.
From what i've been told its a matter of fuel atomization, quality of burn and timing and not an air flow question to make hp on the CR engine.
Numbers show it flows enough air, more than any BKD 16v engine, and much more than 8v heads.
 

Markus L

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16 valve heads easily outflow even slightly ported 8v heads. Problem with those is valve control when having increased flow on boost and emp. Luckily there is a fix for that. gtb2260vk is indeed good for 300+ hp so plenty of room there.
Well, this kind of basic stuff like stiffer valve springs should be done before you judge the head is too restrictive. Of course if you ask vendors what to do they recommend head porting and lots of other stuff they want to sell you. I think it's just wasting money.

I'm sure 400 bhp could be done with stock ports.
 

Macradiators.com

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Van Vught Tuning in Holland , Johan is present on forum ..he can enlighten us if he wants
Following his tunes on FB and seems he does a freakin' good job
IIRC his 2.0 CR Golf has 270hp on stock pump

295+hp and 540Nm

 
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TDIsyncro

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Johan has consistently gotten 270 to 280 hp on his cr tunes. He would also agree that 28xhp is the flow limit of the head. You can put a bigger turbo on to try and push more through but emp just goes much to high for gains to be reasonable. The emp will have direct impact on peak cylinder pressure and how long your engine will last before it destroys itself, for those who think just putting a bigger turbo is answer. As already pointed out, head work is necessary. Johan and myself have already test a regrind cam on OEM head and it did not help. There has to be head work done to support the cam grind. Head work includes valve changes.
 

diffas

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Like pointed earlier the problem is not in the head flow.
 

Macradiators.com

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Yeah Marko, great having some number to back up the claims.

3 angle valve job done , camshafts and some head work




 

Markus L

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Johan has consistently gotten 270 to 280 hp on his cr tunes. He would also agree that 28xhp is the flow limit of the head. You can put a bigger turbo on to try and push more through but emp just goes much to high for gains to be reasonable. The emp will have direct impact on peak cylinder pressure and how long your engine will last before it destroys itself, for those who think just putting a bigger turbo is answer.
No need for bigger turbo, GTB2260VK is good for 300+ bhp.

As already pointed out, head work is necessary. Johan and myself have already test a regrind cam on OEM head and it did not help. There has to be head work done to support the cam grind. Head work includes valve changes.
It's quite obvious that you don't get any gains with regrind cam if valves are already floating. I agree that a headwork needs to be done; stiffer valve springs are definitely needed.
 

xjay1337

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Like pointed earlier the problem is not in the head flow.
What is it exactly then?

Not me, i'm still reading, all this is very good info.

You have a very nice car btw... congrats.

I've reread again your build thread, so with your set-up you'r still running on Lambda calculation in the ECU?

The only thing I find strange, is the linear figure of what's supposed to be maxed out, the VE efficiency of that engine is not linear, when there is not enough air, you should have more and more smoke as the RPM increase.

I'll be curious to see VCDS log of the various fueling parameter of your car.

Thank you.
Im not putting logs up I'm afraid. We have proven headflow is limited, oh well.
People will only blame the terrible tune :)

We will have special turbo and head built soon.

Terminal speed and 1/4 mile times speak words over claimed dyno figures anyway.
 

TDIsyncro

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No need for bigger turbo, GTB2260VK is good for 300+ bhp.

It's quite obvious that you don't get any gains with regrind cam if valves are already floating. I agree that a headwork needs to be done; stiffer valve springs are definitely needed.
I think you need to reread my post. Gtb2260 is good for more than 300+hp on lots of engines but not on OEM cr engine. You missed my point.
I have not done the calcs to see if there is float due to emp and imp at those low boost levels. Certainly on my engine it would be a problem without upgraded springs. I am doubtful it is a problem on 280 hp cr. "It's quit obvious..." lol.
 

TDIsyncro

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Macradiators, thanks for posting pics. Nice work. Did Marko do the head? What are the specs on the dbilas cam grind? I am curious what they did with it.
 

Bobby Singh

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I think in the next month or so we'll have results.
So far cars at 255, 270, 280hp all seem to be pulling approx same times and trap speed.
 

Ranch

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It seems you just want to make things complicated when they are simple , reliable and work well already.

Pump piston and TDC events are not important in multi piston pumps. 2nd piston is always off and this would mean it has no sense, its a parasite.
Instead The entire system works as an accumulator of pressure, i'm told they teach this in mechanics university here where they study this stuff.

Also rotating the pump at half the speed just because you imagine there is a cavitation problem might not get you far.
umm, on my vm 2.8, It has the cp3 pump. It's also timed so the impulses coincide with TDC. You better believe there are impulses.. even with the internal cascade type pressure valve, it does have variance. Ever put your bare hand on a common rail when it's running? By stating
'variance'... I mean anything over and above a perfect smooth pressure.
My pump runs 2/3's crank speed. It's pretty easy to watch it turn exactly 1/3 revolution to the crankshaft's half turn.
My pump has a single lobe, so each plunger fires consecutively, every 120 degrees.
So it takes several laps around the sun to get all the timing marks aligned again. There is no 'accumulator'. just a simple pressure relief valve at the end of the rail.
So, I'll keep on aligning the pump during each TB change, just as the manual specifies.
 
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Macradiators.com

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Would be nice to see a print of that manual stating how to time the CP3 LOL
There are no marks on the cp3 to align it ..so how do you do it? Please enlighten us once more.
Maybe you open the head and put a dial gauge inside and bring it to "tdc" ..but then you torque the bolt it goes bananas for sure ..
 
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turbobrick240

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Would be nice to see a print of that manual stating how to time the CP3 LOL
There are no marks on the cp3 to align it ..so how do you do it? Please enlighten us once more.
Maybe you open the head and put a dial gauge inside and bring it to "tdc" ..but then you torque the bolt it goes bananas for sure ..
I believe the shaft on the VM 2.8 cp3 is keyed such that it can be timed to injection events. I doubt it makes any real difference though. The fuel rail probably absorbs most of the pump pressure wave pulses.
 
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DPM

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some are timed, some aren't. I'm sure the difference could be made up for with tuning.

CP1 might have three pistons running at whatever speed, but one of those pistons is defeated under light loads.
Want to try and work out what pulses *that* produces?
 

Macradiators.com

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Andrew measured the pulses on the CP3 and were minor compared to oem CP4.1 pump.
Just in case you skipped it it reads 295hp and 540Nm
Why some dont make the power it's a mystery

 
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Ranch

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Here ya go with proof the 2.8 has timing marks. Why would they go to the effort and cost to do this, and specify it in the service manual?


- FUEL INJECTION PUMP

The Jeep VM 2.8L CRD uses the Bosch CP3a injection pump - the CP3 is used also on the Cummins 5.9L I-6 CRD and the ISUZU\GM DuraMax 6.6L V8 CRD



DESCRIPTION
A radial 3-piston pump, with a medium-pressure gear-type fuel lift-pump attached to the back, is used as the high-pressure pump for common-rail fuel pressure generation - in this system it is capable of pressures between 300-1600 bar (4351-23206 psia) Note: 1Bar = 1 atmosphere, or 14.73psia
A spring-loaded cascade overflow valve regulates internal housing pressure
Regulated internal housing pressure is oem-specific
The pump shaft is driven by the timing belt at 2/3 ratio to the crankshaft.
Fuel pressure is generated independently of the injection process.
A fuel quantity solenoid valve regulates injection pressure
The pump is lubricated by the pumped Diesel fuel and is not responsible for fuel injection timing.
The CP3 and drive gear is indexed such that it can be timed to coordinate pumping pulses with injection events **

OPERATION

- LIFT PUMP

DESCRIPTION
The gear-type pump has two functions
- draws fuel from the fuel tank in this application
- increases fuel pressure for regulation to housing pressure required for internal lubrication and supplying the high-pressure injection pump


OPERATION
Instead of using an external fuel supply lift-pump, this fuel system uses a supply-pump attached to the rear of the high-pressure pump body. This fuel lift-pump is driven by the end of the high-pressure pump shaft, and can generate over 20" vacuum at the fuel inlet at high rpm.
The lift pump draws fuel from the fuel tank through the fuel manager\filter.

The outlet of the lift pump provides pressurized fuel to a branched circuit internal to the high-pressure
pump flange, which supplies both the Fuel Quantity Solenoid valve and the Cascade Overflow Valve\regulator. Because the gear-pump increases fuel flow and pressure as engine rpm increases, pressure and flow is regulated by the COV.

The COV and supply-pump are not serviced independently of the high-pressure pump.

- CASCADE OVERFLOW VALVE

DESCRIPTION
The COV is located on the front cover of the high pressure pump.
The Cascade Overflow Valve has three functions:
- regulation of lubrication fuel to the internal moving parts of the high-pressure pump
- regulation of the fuel pressure being supplied to the Fuel Quantity Solenoid valve
- return excess fuel to the fuel tank
This regulated internal pressure is known as housing pressure, and is determined by engine displacement and power requirements - the 2.8L CRD requires 5bar (73psia)
For comparison, the 5.9L 6-cyl Cummins CRD requires 12.41bar (180psia)

OPERATION
The COV has a spring-loaded center spool-piece that has a drilled channel with three passages: one for initial low-pressure lubrication, one for lubrication at housing-pressure , and one for overflow. The valve is operated in three stages based on the level of pressure at the inlet.

Stage 1
When the fuel pressure entering the tip of the COV is between 0 and 3 bar (44psia), pressure is too low to overcome
regulator spring tension and fuel flows through the center channel, only . This passage always allows fuel flow through to the pump center-ring and lubricates the pump bushings and internal moving parts. This circuit also allows air to bleed during initial cranking and returns the air to the fuel tank.
The COV is in Stage 1 during cranking, only.

Stage 2
When the fuel entering the COV exceeds 3bar (44psia), but is less than 5bar (73psia), the spool-piece
moves against spring tension aligning a second passage for lubrication purposes.
Stage 2 can be reached during cranking and initial start up.


Stage 3
When fuel pressure exceeds 5bar (73psia), the spool-piece aligns with the overflow passage. This stage
relieves the pressure into an overflow circuit that sends the fuel back to the inlet side of the gearotor pump, thus limiting maximum fuel pressure to 5bar (73psia).
Lubrication fuel continues to flow through all channeled passages during this stage.
Excess fuel is sent back to the fuel tank through the fuel-return circuit
Stage 3 is reached at over-pressure

- FUEL QUANTITY SOLENOID

DESCRIPTION
The Fuel Quantity Solenoid valve is located on the back of the front cover of the high-pressure pump. The solenoid is pulse-width modulated by the ECM and meters the amount of fuel that flows into the high-pressure elements inside the high-pressure pump.
The solenoid is inactive up to 30 seconds after IGNition switch is initially keyed to ON position to allow maximum fuel pressure to the fuel rail during cranking and start up. ECM assumes FQS valve control when CPS signal and rail pressure are within acceptable limits

OPERATION
The Fuel Quantity Solenoid valve is a pulse-width modulated valve that controls the amount of fuel sent or delayed to the high-pressure pump elements inside the high-pressure pump. The ECM determines the fuel pressure set point based on engine sensor and rail-pressure inputs. If the actual fuel-rail pressure is too low, the ECM commands the solenoid to allow more fuel to flow to the high-pressure pump. This minimizes the difference between the actual fuel-rail pressure reading and the set point. The ECM will also operate the solenoid to delay fuel, reducing flow-rate, if the fuel-rail pressure becomes too high.
The FQS valve is commanded open by the ECM to allow the high-pressure pump to build maximum pressure (1600bar, 23,206psia), or closed to decrease pressure.
Thus, rail fuel-pressure can be increased or decreased independent of engine speed

The valve also has a fuel tank heat-protection function* that meters the exact amount of low-pressure fuel to the high-pressure pump to prevent excessive injector-heated fuel from returning to the fuel tank.
Temperature of fuel from the fuel tank is measured at the fuel inlet in fuel manager head via a temperature probe in the inlet side of the fuel-heater module.

High Pressure Pumping Plungers
The FQS valve supplies three high pressure pumping chambers. The pumping chambers have one-way
inlet valves that allow fuel to flow into the chambers. The valves then close as the fuel is compressed,
causing the high pressure fuel to overcome a spring-loaded ball-and-seat outlet valve.
All three pumping chambers are tied together in one circuit internal to the pump and provide high pressure fuel between 300bar (4351psia) and 1600bar (23,206psia) through a steel line to the fuel rail.
The pump is driven at 2/3 engine speed and is not responsible for injection timing.
CP3 function is to provide fuel at high-pressure, while the ECM controls injection pressure and timing.
The CP3 shaft is keyed to the drive gear and indexed such that timing can be set to coordinate the pressure waves of the pumping pulses with injection events **

- FUEL RAIL

DESCRIPTION
The fuel rail is mounted to the cylinder-head cover\intake manifold. The rail distributes regulated high-pressure fuel equally to the fuel injectors.
A pressure sensor is screwed into the rail so ECM can read and regulate system pressure.
A pressure solenoid is screwed into the rear of the fuel rail to allow regulated overflow return to the fuel tank.

OPERATION
The fuel rail stores the fuel for the injectors at high pressure. At the same time, the pressure oscillations which are generated due to the high-pressure pump delivery and the injection of fuel are dampened by rail volume.
The fuel rail is common to all cylinders, hence it’s name “common rail”. Even when large quantities of fuel are extracted, the fuel rail maintains a constant inner pressure. This ensures that injection pressure remains constant from the instant the injector opens to the end of the injection event.


- FUEL PRESSURE SOLENOID

DESCRIPTION
The Fuel Pressure Solenoid valve is screwed into the rear of the fuel rail. The solenoid controls and maintains constant rail pressure by a pulse-width modulated control current transmitted by the (ECM).

The tip-end of the FPS uses a knife-edge type high-pressure seal. The knife edge actually deforms the metal in the fuel rail in order to seal the surfaces.
The FPS must be replaced if it is removed from the rail - each replacement must establish the knife-edge seal to prevent leaks at 1600bar (23206psia).

OPERATION
In de-energized state, the FPS valve is closed as spring tension forces the ball into the
ball-seat - spring tension limits minimum rail pressure to 100 Bar 1445psi. When the engine is started, the solenoid valve is additionally held closed by electro-magnetic force. When running, fuel pressure counteracts the magnetic force of the coil and spring tension, opening the valve . When the engine is running, the valve is always open to a varying degree, controlled by the ECM.

The ECM senses operating fuel pressure by the rail pressure sensor signal.

High pressure fuel in the rail flows to the ball-seat of the solenoid valve. The specified
rail pressure required by the system is set by the FPS - the ECM sends a controlled current thru the solenoid, building up a magnetic force which corresponds to this specific pressure. This magnetic force equals a specific cross-sectional outlet at the ball-seat of the valve, which allows excess fuel to flow through.

Rail pressure is altered as a result of the controlled quantity of fuel which flows off.

Controlled excess fuel flows back through the return-fuel line, into the tank.

*By reducing fuel at the inlet to the high-pressure pump with the FQS valve, which reduces excess fuel through FPS valve without reducing rail pressure, ECM can control in-tank fuel temperature.


This is cut and pasted from online service manuals. OK, it's not quite the 'impulses', but more of a pressure wave. looking into the exploded view of a cp3, you can see there is a plunger always coming up during rotation.

I guess I go with the fact that the ecm 'looks' at rail pressure, and sets it accordingly to engine demands. Why on earth wouldn't you have the max pressure exactly when an injector is fired?
 
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Macradiators.com

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Please Stop with the nonsense, on all the other applications there is no timing bmw-peugeot-renault-citroen -mercedes NO TIMING
Sprocket rotates freely on shaft so no way to time it . GOT IT?

The only way to time it on all the other cars in the world would be to fix everything at TDC .. remove piston cap so you can access the piston with dial gauge ..get piston in position, then block the pump in some miraculous way to tighten the sprocket and belt on it .. would never be perfect anyway as there is no adjustable sprocket on the shaft.
Is this more clear to you now? ITS a MYTH and has been proven time and time again.

This is about cylinder head work so lets keep it about cyl heads, would be better.
 
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turbobrick240

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Why VM wanted to clock the cp3 on their 2.8 is a bit of a mystery. One theory is that it is for NVH, specifically that the pump operates slightly more quietly when the pressure pulses are timed to injection events. I don't think you'd see any difference at all on a dyno.
 

Ranch

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Why VM wanted to clock the cp3 on their 2.8 is a bit of a mystery. One theory is that it is for NVH, specifically that the pump operates slightly more quietly when the pressure pulses are timed to injection events. I don't think you'd see any difference at all on a dyno.
Good point, and I wondered about this (reduction of possible underhood noise) a couple years ago after watching hundreds of posts on this exact same subject on Lostjeeps.com
The guys who perpetuated this argument swore they didn't 'feel' any difference in a non aligned pump. I only added my 'findings' directly from VMMOTORI.. too bad they didn't specify 'why'!!


Macradiators.com Please Stop with the nonsense, on all the other applications there is no timing bmw-peugeot-renault-citroen -mercedes NO TIMING
Sprocket rotates freely on shaft so no way to time it . GOT IT?

LOL, 'freely'?? really?? how in the heck does the shaft turn then? LMAO.
Besides, I'M not the one who veered the 'porting head' thread off track with the inclusive
timed pump statement.
 
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