Dyno results here
 

107hp, 194.8lb/ft torque at the wheels.

1980 240D 3.0VNTi 215k miles
Modifications: OM617.952, 4-speed manual, GT2256V VNT turbo, air-air intercooler, W115 300D intake, 3.46 diff, ALDA/EGR removed, Pyrometer/Boost/Exhaust psi gauges, bypass oil filter and Mobil-1 5W-40 synthetic oil.

The second picture shows how much boost I have at idle, it drops to 0 when I open the vanes.

Post your dynamometer results if you have some.

Any idea how that boost curve looks compared to a stock turbo? Doesn't look like much boost below 2100 or so like the stock turbo.

Here is my sheet from 2-13-06 with the KKK K26 turbo.

The boost curve is nearly opposite. :D

I notice now that the boost starts at 7 psi, thats pretty impressive. Did they not load the engine below 2000 rpm?

Just whatever it took to keep the rollers moving until he mashed the throttle.

Here is the graph where the vanes were set always open. Notice how the boost curve has a slightly more concave shape to it and starts at only 2psi.

Once I fix and sell the '79 I'm using the cash to upgrade and am aiming to beat that 107 HP. :D

Good job!

Also notice how your low end torque fell. The higher boost gave you about 4% more torque.

I'm not grasping why the maximum torque is only at 2300 rpm with a boost level of 8.5 psi.

Something is not right. There is no reason that this engine can't produce peak torque at 2800 rpm. Randy and others have dyno runs that confirm this.

This engine would have significantly more than 107hp if the torque peak could be shifted to the right.

Are you positive that the cam timing and IP timing are correct? Is the lift on the cam to spec?

Something needs adjustment.

I'm very happy. Almost 200lb/ft of torque down low where its useful and a broad flat HP curve. All without opening up the pump or using additional fuel through water injection. I can't wait to get that extra 30% when I remove the rack limiter and tweak the torque capsule. :D

VIDEO

Its probably mainly due to the VNT and possibly the w115 intake manifold. You may notice that the dyno run where the turbine vanes are held wide open it does move the peak torque to the right. The peak is lower, but it is more to the right. This just illustrates the advantage the VNT has at generating efficient boost over a wider range of rpms. The longer intake runners probably shift the peak torque a little lower too.

Now, there is a good looking set of curves. If the shape of the curve could remain the same and the torque peak raised...........it would be fabulous.

Yes, but the engine always had an early torque peak, it just never had a turbo that could supply air for it show.

I got 65lb/ft more torque, 10hp more power and much better drivability from only "bolt-on" changes with no additional fuel above stock, with better fuel economy on top of it!

Let me dust off my old PeeCee and see if I can get an overlay of my oldest and most recent graphs. Superflow does not have a Mac version of their dyno chart software.

Yes, I can see why you're quite pleased.

But, I'm still baffled by the inverted torque curve........it's just not common on these engines.

Well, neither is a variable geometry turbo. ;)

The VNT certainly explains the increase in torque down low.........but, it doesn't explain the falloff in torque from 2350 onward. It's my understanding that the VNT functions like a very small turbo at low rpm's and then, with its vanes open, functions nearly identical to the stock turbo at higher rpm's.