6.5L P400 turbo diesel HP
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.
Clip from "6.5L Turbo Diesel Fuel Injection Tech Marine vs On-Road" by Jim Bigley
Here's a clip from a story I wrote in 2009 that addresses the topic of this thread.
Quote:
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/member...injectionc.htm