I thought we were discussing the 617??

But, regardless..........5400 rpm for a peak is impressive.

I'll send you three cans.............

That was my point, if it can happen for the 603 then the 617 can't be too much different.

What's positively amazing about that graph is the torque curve. It peaks at 3800 but stays reasonably flat all the way out to 5100 rpm.

Contrast that curve to your curve with the VNT. The torque curve peaks fairly low and takes an immediate dive resulting in very little HP increase over stock.

This has to be as a result of different injection pumps.... right? As the 617's IP is more of a limiting factor than what ever turbo happens to be on the outside of the engine.. at least for one dyno run anyway..or am I all mixed up here?

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46 WDX Power Wagon

84 300TDT daily driver

I always thought that the prechamber was a major restriction to the performance of the engine. Think about all that flow tying to squeeze through 4 or 5 pin holes. I think this has already been discussed, but what about drilling those holes out? What are the likely results? Can't affect CR too much. Could definitely affect cold startability, and probably noise. Anyone happen to know for example if the prechamber is the same for turbo and NA motors? I know on my SD-33T the prechamber is different for NA and Turbo models (granted that prechamber is a totally different design).

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For Sale: 1982 MB 300TD
1995 Chevrolet Suburban 6.5TD

Sold: 1980 IH Scout Traveler- Nissan SD33T Diesel

The "flow" is quite small. At 70 mph steady state, each cylinder uses .017 ml per cycle. It's not a lot of fuel. Even at maximum power, this figure might rise to .07 ml per cycle.

Fuel doesn't necessarily flow through the PC holes. It is the exhaust gasses from the combustion that occurs in the prechamber... so significantly more than the fuel . That being said, I don't think it would help much if any. Velocity can be a good thing since it insures that any diesel not burned in the PC will still be atomized and burn well.

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John Robbins
'05 E320 CDI - 240k
'87 300TD - 318k

That's probably true. A significant amount of combustion must take place right in the bottom of the prechamber. There is insufficient time for the fuel to progress into the cylinder.

I'm talking about forcing .6L of air through those holes and then back out again each cycle. Think about how much restriction those orifices create in that process. There is a small indentation in the piston, Anyone happen to know the volume left in the cylinder at TDC vs the volume of the prechamber?

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For Sale: 1982 MB 300TD
1995 Chevrolet Suburban 6.5TD

Sold: 1980 IH Scout Traveler- Nissan SD33T Diesel

Don't know the split between the two, but the total is 29ml.