6.5L P400 turbo diesel HP

[mountenman]

Hi all. I'm in Australia and I run a 6.5L P400 Cobra engine in a non standard 1988 British Range Rover. This is a constant 4WD vehicle weighing in at just under 3 Tonne. The injector pump is a standard (but ceramic coated) Stanadyne rotary DB2 pump. This engine peaks out at around 200HP (at the crank) 170HP at the rear wheels. The output will be less if measured on 4WD Dyno which wasn't available to me. My question is: are there upgraded DB2 pumps available to produce substantially more HP and if there are, does anyone have experience/ reports on these upgraded pumps. I have reviewed a website for "Classic Diesel Designs" who list various upgraded DB2 pumps (obviously not all for GM engines). They list for example a 130cc DB2 pump for GM 6.2/6.5 rated at 400HP. Your opinions and advice greatly appreciated.

[Robyn]

Hi
Welcome to TDP...

There are DB2 pumps that can deliver more fuel and make more power.

Is your engine turbo charged ??

A turbo charger and a little tweak on the fuel screw in the pump can easily get the 6.5 into the 300HP range.

Adding more fuel to a non turbo 6.5 will make a lot of black smoke and little else...

[DmaxMaverick]

You have options, but if your P400 was delivered complete with the fuel system, it likely has a 4911 pump, which is the latest DB2. Another option may be a marine DB4 pump. Like Robyn said, there are a lot of things you can do to improve power, but without a turbo, there's little more to be had beyond more black smoke and tanked economy. EGT's also become very sketchy when you turn up the fuel, but do too little or nothing to turn up the air. The P400 is an awesome base to build on, and is capable of so much more. 300+ RWHP is not a far stretch, but you have to feed the beast what it needs.

[mountenman]

Thanks for the info. Yes it is turbo charged. I know the charger is off a 7.3 L Ford Powerstroke engine capable of 20lb boost. Current EGT at 60mph normal road runs is max of 250oC (530oF) leaving plenty of room to increase fueling. The pump was fitted with a ceramic sleeve in the advance piston bore to reduce wear. The technology is mostly available in USA and it's a little daunting to know what are truths about a product upgrade and it's claimed improvements and what is wishful thinking. Are you able to point in the right direction for these upgraded larger flow DB2 pumps.
Thanks

[Robyn]

Coooooool

With a turbo you can turn up the fuel .
The top needs to come off of the pump to do this.

Banks has a good writeup in their Turbo details for the 6.2/6.5 GM diesel.

You should be able to scare that up online.

BE CAREFUL WHEN REINSTALLING THE TOP OF THE PUMP AND THE SHUT OFF SOLENOID

The parts need to be just right or the shut off will not work and the throttle can be stuck at full fuel.

OK
Adjust the fuel to get a max exhaust temp at the outlet of the LH side exhaust manifold is no more than 1000F under hard pull.(Welding in a fitting into the crossover pipe is needed).....Remove the pipe and be sure no junk is left that could blow through the turbo

Keep the turbo pressure to the intake at no more than 12-14 PSI

A short puff of dark smoke when you mash the throttle is OK ....Pipe should be clean or nearly so once the turbo spools up...

NO COAL ROLLERS....This makes a lot of heat and does so quickly.......

Trying to get 20 psi boost is not a good thing.....Intake air temps will soar and so will EGT

Set the waste gate at no more than 14 psi....12 is even better....

A good guess on the Fuel setting is about 1/4 turn more than where it is at now...

As mentioned....The Banks data is good stuff.....

Fuel is power....Fuel is also what makes boost.....You can't get boost without fuel.....

A hard pull under full load on a hill is the the best test...

A hard pull where the engine is giving all it can should not see the EGT go over 1000F and for extended hard pulls 900F is a bit better....

The best thing for these engines is a free flowing exhaust out of the turbo......Retained heat after the turbo is hard on things.
Too much retained exhaust pressure (Pre turbo) chokes the engine.

Intake air temperature is critical. High intake temp results in higher EGT too
In your area where it can get HOT....a WATER ALCOHOL INJECTION SYSTEM that will turn on when boost reaches above 10psi will make things run cooler.

An air to air after cooler between the turbo compressor and the intake will help some.

The fairly low boost pressure of the 6.5 does not get much from an after cooler....but any cooling of the intake air helps.....

Good luck

Keep us in the loop

Just don't try to make this engine compete with the Direct injected Cummins 6.7.....or other modern power plants.....They are not designed to do that sort of power.....But you can wake it up some...

[DmaxMaverick]

It sounds like you pump is either a 4911, or an earlier model that's been "military hardened". Either of them are capable of boosting your power considerably, but adjustment is pretty much trial and error. As Robyn said, 1/4 turn is likely a good starting point, according to what you're seeing now and equipment. Robyn and I will disagree somewhat on the boost and temp limits, but it really depends on which turbo you have, the intake/exhaust situation, and general heat management systems. A good rule for max temp is 900-1000F POST turbo (according to Banks, for a 6.2L). 20 PSI boost is not necessarily a problem with the right turbo. A GMx turbo should never be run that high, as it's well beyond their efficiency envelope. A late model 7.3 Powerstroke turbo can do that easily, but charge air cooling should be high on the to-do list at higher boost levels, regardless. Water/alcohol is simplest, especially if an air-air after cooler is a difficult fit in your chassis. Either method is highly effective.

It sounds like you already have instrumentation, but exhaust manifold removal is not necessary if you need to drill/tap. Just do it with the engine idling, with NO cutting lube (cast iron should always be cut dry). Wear eye/face protection, as the iron chips will blow straight out the hole you made, but not violently.

[More Power]

Here's a clip from a story I wrote in 2009 that addresses the topic of this thread.


6.5 owners have often pondered the question concerning which fuel injection pump might offer the best performance, in terms of horsepower and torque. While at USDP, I looked at 3 highest rated fuel injection pump calibrations used for the 6.2L/6.5L diesel, two of them mechanical and one of them electronic - which was a civilian Stanadyne DS4-5521. Calibrated flow rates for the Stanadyne fuel injection pumps are rated in "mm3/Stroke" at specific engine RPM points. Of the Stanadyne fuel injection pump spec sheets I had access to, the following three were the most relevant.



6.2L Turbocharged 250-hp mechanical DB2833-4974, maximum fuel rate of 81.5mm3/Stroke @ 2000-RPM, and 68.5-73.5 @ 3600-RPM.
6.5L Turbocharged 310-hp mechanical DB4831-5722, maximum fuel rate of 79.0mm3/Stroke @ 2600-RPM, and 73-77 @ 3500-RPM.
6.5L Turbocharged 2000 model-year electronic DS4831-5521, maximum fuel rate of 89.9mm3/Stroke @ 2000-RPM, and 65.2-75.2 @ 3400-RPM.

The data for the marine DB4 mechanical pump didn't show a fuel-rate number at the 2000-RPM setting, indicating that the marine specification max fuel-rate at 2600-RPM was the more important data point. The max fueling data for all of the pumps I looked at occurred well below the max governed engine RPM. The thermodynamics of diesel fuel combustion likely requires a certain length of time for the fuel to burn during the power stroke. A higher engine RPM doesn't allow for enough burn time, so the max fuel-rate is scaled back as engine RPM rises - while simultaneously advancing the injection timing to increase the burn time.

To help understand the relationship between fuel-rate, boost pressure and 6.5L diesel engine power, let's consider the original LB7 Duramax 6600. This engine was certified to produce 300-hp @ 3100-RPM (at the flywheel) with a fuel-rate of 91.7mm3. This is according to an emissions plate fixed to the driver's side valve cover on the 2001 LB7 used in thedieselpage.com's project truck. The turbocharger used on the LB7 Duramax delivered a maximum boost pressure of about 20-psi. So, to get a 6.5L diesel to perform similarly to the 2001 6.6L Duramax, you'd need roughly the same fuel, boost and RPM. There are other marine specification DB4 mechanical fuel injection pumps available that supposedly allow the 6.5 to produce up to 400-hp when using twin turbochargers, a highly efficient water/air intercooler and an entire lake for engine cooling. For a realistic HP number in a pickup truck, we'd need to scale that back by about 25% - to something approaching 300-hp, and when using the right fuel injection pump, the right injectors, an air/air intercooler and of course the right turbocharger. A Holset HX-35 or HX-40 would be good candidates to experiment with - think in terms of an efficient 20-psi boost pressure above 3000-RPM. The factory GM turbo is far too restrictive and simply cannot supply the boost pressure and low exhaust back-pressure necessary for 300-hp. - Jim Bigley



The full story, that includes a lot more info, is available to subscribers here: https://www.thedieselpage.com/members/features/65fuelinjectionc.htm