For comparison, here is a compressor map for the stock 1.6lTD, including the plotted line of the 1.6lTD engine's air flow (probably going up to about 5k RPM as plotted):
And for the TDI's VNT-15:
The stock 1.6lTD turbo mustered a whopping 70% peak efficiency! :shock: Comparing this to the upper 70's percent efficiency of the newer units, they really do make newer turbos that are more efficient don't they!
FWIW, based on just a quick calculation done in my head, it looks like the 1.6 liter engine is a good match for the efficiency area of the VNT-15 compressor over a range of boost levels.
PS - remember to convert between kg/s, kg/m, and lb/m before comparing different maps as needed. (At least all the conversion factors you'll need to know are: 60 seconds in a minute, and 1 kg = 2.2 lbs. :wink:)
Staley: at first I thought your compressor might not be sized correctly. But then thinking it through some more, I think it will give you an opportunity for great high-RPM performance!
At stock engine tune, it will work, but may not be an optimal application as it doesn't look like you're hitting the peak efficiency island. I ran my own numbers to check your work: Assuming you're going to run similar RPM and VE as a stock 1.6lTD, but have an extra .3 liters displacement of your 1.9l, that engine would see .12 @ kg/s at 1.65 bar at redline. Which is equivalent to about 16 lb/min at that pressure at redline. Looking at your compressor map, this is in the efficiency plateau, although towards the left side (so lower RPMs at that boost will not see as efficient of compressor operation.) Extrapolating the curve up to a higher boost to see where it falls, let's try 2.2 pressure ratio (about 18 psi). At that pressure assuming you have a good intercooler and assuming engine volumetric efficiency stays the same, you would flow 2.2/1.65*16 = about 21 lbs/min. You can see this is just touching maybe, or just off to the left of the efficiency island for that compressor. This generally seems to be the trend. A little bit too much flow capacity for ideal IMO but, headwork, cams, wind up that revv limiter, anything to make the engine flow more up to about 20%, will result in using the elusive peak efficiency plateau of that turbo. Bumping the revv limiter by about 1000RPM would seem to do the trick!
But another way you can look at it is, the 1.6lTD compressor never gets significantly more efficient than 70%. How big of a plateau on that compressor does the 68-70% plot cover?
If you find you are doing the bulk of your high-boost work in that area, you're doing at least as good as a 1.6lTD in compressor efficiency.
Topic: Ultimate Turbocharger Quest (Read 5914 times)
