Powerstroke vs Duramax dependability
Lead Driver
Joined: Sep 2006
Posts: 5,665
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From: Cartersville, Ga
That linked didn't work, but this should: A Peek Inside the Duramax L5P
Logistics Pro
Joined: Jan 2013
Posts: 3,778
Likes: 153
The new Duramax is impressive. The connecting rods look very much like the Powerstroke design now, except I think they are thicker on the GM engine.
Locating the DOC on the back of the turbo is going to be very advantageous for emissions control and regen strategy. I'm curious - where does the regen "9th injector" go, or is this design now like the Ford and injects diesel into the cylinder on exhaust stroke?
The new turbo appears very impressive. By integrating the electronics into the turbo housing, I would think replacement cost would be much higher.
I really like the gear-drive water pump. If the accessory belt fails, you still have cooling. On the other hand, the water pump is integral to the engine. If the bearings fail and the vanes eat at the housing, coolant could mix with engine oil. That is why Ford made their pump(s) external.
Some things I don't like: the outboard exhaust manifold design seems archaic compared to the Ford reverse flow design (which they pirated from a GM concept). Why would you have the added plumbing length (lag, heat loss) and additional exhaust pipes in the way of access...when you could use the reversed flow method?
The lifters and pushrods and pushod guides. It is clear GM was looking to gain HP and revving speed by lightening these up. They look much weaker than the previous LML parts, and vastly weaker to the design on the Powerstroke. What is worse is the fact that this engine still uses valve bridges so one pushrod operates two valves...instead of Ford's design which runs 32 individual pushrods. Yes, GM's design is lighter and promotes faster revs...but will it be long-term durable?
Same thing with the camshaft. The lobe width is much smaller, which is possible because the lifter is smaller. Again, lighter weight, quick power.
The Denso fuel system looks pretty good. The pump is a triple eccentric design. The fuel pipes from the rails are all length-balanced and tightly packaged. Time will tell if it is reliable. The CP4 pump is a pretty mature product at this point.
Overall? I still think the Powerstroke is better.
Locating the DOC on the back of the turbo is going to be very advantageous for emissions control and regen strategy. I'm curious - where does the regen "9th injector" go, or is this design now like the Ford and injects diesel into the cylinder on exhaust stroke?
The new turbo appears very impressive. By integrating the electronics into the turbo housing, I would think replacement cost would be much higher.
I really like the gear-drive water pump. If the accessory belt fails, you still have cooling. On the other hand, the water pump is integral to the engine. If the bearings fail and the vanes eat at the housing, coolant could mix with engine oil. That is why Ford made their pump(s) external.
Some things I don't like: the outboard exhaust manifold design seems archaic compared to the Ford reverse flow design (which they pirated from a GM concept). Why would you have the added plumbing length (lag, heat loss) and additional exhaust pipes in the way of access...when you could use the reversed flow method?
The lifters and pushrods and pushod guides. It is clear GM was looking to gain HP and revving speed by lightening these up. They look much weaker than the previous LML parts, and vastly weaker to the design on the Powerstroke. What is worse is the fact that this engine still uses valve bridges so one pushrod operates two valves...instead of Ford's design which runs 32 individual pushrods. Yes, GM's design is lighter and promotes faster revs...but will it be long-term durable?
Same thing with the camshaft. The lobe width is much smaller, which is possible because the lifter is smaller. Again, lighter weight, quick power.
The Denso fuel system looks pretty good. The pump is a triple eccentric design. The fuel pipes from the rails are all length-balanced and tightly packaged. Time will tell if it is reliable. The CP4 pump is a pretty mature product at this point.
Overall? I still think the Powerstroke is better.
Hotshot
Joined: Apr 2013
Posts: 10,120
Likes: 652
From: NH
Thanks, Don.
One other thing I noticed is the crank pulley / damper. On our trucks, we use a nice tight four-bolt mounting assembly. On the L5P, they are using a press-fit with a single locating pin and what they call a "diamond dust friction band" to prevent slippage of the crank pulley. I prefer the bolted version. Granted, GM is not relying on the accessory pulley to spin the water pump, just the power steering, alternator, and A/C. But their method looks just like a car engine crank; Ford's looks like something out of a piece of heavy equipment.
One other thing I noticed is the crank pulley / damper. On our trucks, we use a nice tight four-bolt mounting assembly. On the L5P, they are using a press-fit with a single locating pin and what they call a "diamond dust friction band" to prevent slippage of the crank pulley. I prefer the bolted version. Granted, GM is not relying on the accessory pulley to spin the water pump, just the power steering, alternator, and A/C. But their method looks just like a car engine crank; Ford's looks like something out of a piece of heavy equipment.
Senior User
Joined: Jan 2017
Posts: 275
Likes: 2
From: Nebraska
When i test drove the new 2500 the thing felt like a boat compared to the New Superduty. Even with the new engine in the Chevy the Ford still felt lighter and more responsive. And it really annoyed me that there is no boost guage in the chevy. I tried all of the big three before i bought and the Superduty just couldnt be beat in my book.
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