Hey all...
I'm really sorry that it has taken this long to make any headway on this project. Since the original posts, we've been tied up with several other projects which have resulted in some delays. However, we're starting to make headway again and I'm really quite excited with where we're at with the build. Just where are we at? Read on...
At this point, I've not yet installed the Cylinder Pressure testing equipment but expect to have that up and running in the next week. Meanwhile, we've completed the stock dyno runs and datalogs and also the Stage 1 dyno runs and datalogs. The results were better than I could have possibly expected, especially considering that the block, turbo, and HPOP are all still completely stock.
The following links are to the compiled datalogs and associated dyno runs. The three test completed so far were:
1)
Stock Injectors, Stock Power Level
2)
Stock Injectors, Extreme Power Level
3)
Stage 1 Injectors, Extreme Power Level
The first two files are about what I'd expect from a 200K+ miles motor with stock injectors. However, what I found with the third set of runs with the Stage 1's surprised me a little bit. I tried a couple small changes between a few sets of runs so the 3 runs in the Stage 1 files are slightly different. The changes were subtle and done in a manner to see which produced not only the best peak power curve, but also the broadest and smoothest curves. The results are very clear and I've included some comments as well.
On run #1, I had set the ICP to 2900 PSI and went with a slightly higher injection pulsewidth of 4.00 ms. This will usually provide a broader torque curve and a lower peak power. However, in this case the results showed the highest power output of the three runs, peaking at 399 HP @ 2560 RPM and 926 Ft. Lbs. @ 2124 RPM. Power was above 350 HP from 2130 RPM to 3276 RPM and above 300 HP from 1917 RPM to 3490 RPM (just after the point where I let off the throttle). While ICP remained steady, the IPR D/C was a bit higher do the wider injection pulsewidth. However, it never climbed above 50% for the entire run which indicates to me that (1) we were not floating the poppets on the injectors and (2) we have a pretty solid working HPOP.
On run #2, I raised the ICP to 3200 PSI and dropped the injection pulsewidth down to 3.60 ms. My peak power dropped to 393 HP @ 2500 RPM and my torque dropped to 891 Ft. Lbs. @ 2225 PRM. Like run #1, power was above 350 HP from 2115 RPM to 3268 RPM and above 300 HP from 1967 RPM to 3531 RPM (slight higher RPM range, but similar width). With the narrower pulsewidth we did see a noticeable drop in IPR D/C, especially at upper RPMs. This helps to confirm some suspicions I have about the relationships between wide pulsewidths and ICP/IPR stability.
On run #3, I dropped the ICP to 3150 PSI and raised the injection pulsewidth to 3.80 ms. My peak power was 395 HP @ 2541 RPM and my torque was 898 Ft. Lbs. @ 2160 PRM. Power was above 350 HP from 2081 RPM to 3280 RPM (about 50 PRM wider) and above 300 HP from 1958 RPM to 3492 RPM (where the run stopped recording at 318 HP). IPR D/C stayed well below 50% (below 45% above 3000 RPM) and this was also, by far, the smoothest run of the three.
A few other things to note:
1) The boost (MAP) values are pretty useless, given the fact that despite the MAP sensor being a "3 Bar" range sensor, 1 Bar of the sensor is wasted on vacuum so the output is limited to only about 28 PSI. Combined with some other internal restrictions and adjustment for Baro sensor offset in the calibrations, this is further reduced to about 24 PSI. We will be soon adding a 5 Bar map sensor to allow for a more accurate boost reading as well as being able to accurately correct fueling based on boost values.
2) The SOI timing curve peaked at about 30º BTC at 3600 RPM. If we'd have pushed to 4000, it may have seen 32º to 34º based on the advance rate of about 1º per 125 RPM. Once we're able to test the cylinder pressures, we'll experiment with more aggressive curves to see just how significant the effect is by advancing SOI timing. I'm sure the answer is pretty obvious, as many PMR engines have already experienced, but it would be interesting to have some cold, hard facts to substantiate the theories. Also, keep in mind that elevated ICP not only has a modest effect on SOI, but it also has a pretty significant effect on the combustion point and burn rate of the fuel which can also be responsible for excessive cylinder pressures and ultimately lead to engine failures.
Given the nature of the test vehicle, I don't think I could have asked for a better set of runs. Based on the results so far, I'd say that my favorite run was configuration #1 due to the fact that we were able to make solid power with ICP pressures below 3000 PSI. There's a long standing argument that you have to have aggressive ICP pressures to make any power, and to some degree that's probably an accurate statement. However, the problem still centers around the limitations of the HEUI injectors and higher ICP may not always be the best solution, especially when getting into injectors with larger nozzles. Too much fuel too fast could cause extremely high cylinder pressures, and we'll see just how accurate that is once the Stage 2's are installed and the cylinder pressures are logged.
At this point, I've got a few minor modifications to complete before the step to Stage 2. First, I have the exhaust system, Wicked Wheel, and CP testing equipment to install and then we'll do another quick set of runs just to see what's what. After that, the Stage 2's go in and then we'll test the HPOP and fuel systems to see just where any deficiencies occur. I'm suspecting that both systems will need to be upgraded before we begin to push the envelope on those injectors. Following that, head studs, turbo, and 300cc-350cc injectors, which should push me to the 600 HP mark on a stock-blocked PMR engine. The next 2 months will be interesting!
Enjoy!