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I'm new here but I wanted to share a project that I'm putting together in my free time to help myself further understand what's going on inside the cylinder of an IC engine. I intend to share much, if not all, of the information that I am able to gather from this build along with some of the theory behind it if I'm able to understand it well enough. I'm a firm believer that explaining new information to someone else in a way that makes sense to them is the best way to strengthen and improve my own knowledge, so if there's anything you'd like explained I will do my best to answer questions.
Here's the Cliffnotes for what's to come:
What's different about this build?
I will be installing an in-cylinder pressure transducer in cylinder #7, based on feedback from a prior thread on which cylinder is generally the most sensitive.
I will have Wideband O2, exhaust gas temperature, intake port pressure, and exhaust port pressure on each cylinder to make sure every cylinder is running at close to the same conditions. I will make modifications to each cylinder to correct issues that I see to maximize power from a relatively mild build. There will also be a pressure and temperature sensor on either side of the compressor and turbine to characterize the actual efficiency of the turbocharger, since it doesn't appear that there's much available data out there on the Chinese GT45.
What are you going to use it for?
I intend to use the pressure transducer, coupled with a rotary encoder to measure crank position very precisely, to measure how much work a cylinder is doing per cycle. By paying attention to this, I won't have to guess on an optimal spark value or fuel value when I begin to work on the calibration - I can choose the right values based on what will maximize the amount of work done per cycle or what will be the most stable. I should be able to have a smooth idle with factory level fuel economy and drivability given enough time. I can also use it to measure heat release rates and pressure rise rates to protect components. If the encoder resolution is high enough, I may also be able to use it to diagnose how well each individual cylinder is running based on the predicted vs actual accelerations between segments (tertiary goal, will likely get put on the backburner for a while)
Goals:
1) Understand the combustion process and apply some of the information that I learned in school to maximize power output in a relatively mild build.
2) Understand he effects of specific (and common) modifications, such as different fuels, nitrous, water-meth, etc on combustion
3) Develop a data acquisition system that I can carry over between projects
4) Have a kick *** daily driven truck that I can put another 30k miles on without worrying too much about it. 600 whp should be the ticket for now.
5) Help people understand why things happen the way that they do.
Build Details:
Budget build, aside from the majority of the data acquisition. This is more of a research project for me, so I'm not going to be too torn up if I nuke a turbo or puke a rod through the block.
Truck: 2000 Silverado 2500 with 165k. LQ4, 4L80E, 3.73 Posi rear end, 4WD through an NP246 transfer case
Engine: Still have to build, but...LS9 head gaskets, ARP rod bolts and head studs, new gapped rings,new bearings in bottom end, LS6 cam, stock truck intake (instrumented), Deka 80's (will go smaller if I don't have good control of idle fueling)
Turbo system: eBay GT45, eBay forward headers with crossover built by myself, 2X Tial 38mm wastegates, 50mm eBay BOV, 3" down pipe w/exhaust cutout (eventually). For those concerned, I'm going to do some durability improvements on most of the chinese components to help them live a bit longer (ex: VSR balance the CHRA of the GT45, support the turbo on something other than the headers)
The build really isn't anything special, which is why I won't focus too heavily on it in this thread unless requested.
I'm sure I'll think of a few more details by morning, but I'm tired as hell and need some sleep. I'll try and update this thread fairly regularly as it is currently -27 F outside and I will be working only on the data acquisition and measurements until it gets to the point where my hands stop freezing to the tools.
As an engineer this sounds like a great project! Are you planning to do this on a test stand engine or installed driving around? You are talking about a ton of instrumentation that is not going to be easy to fit.
Another thing to consider is also actual cam position relative to crank and also cooling system pressure. It is common to put s pressure transducer in the cooling circuit now to see when you start to lift the heads, it would be interesting to see more scientific data from that if it's actually useful or not.
Are you planning to do this on a test stand engine or installed driving around?
Another thing to consider is also actual cam position relative to crank and also cooling system pressure.
I'm setting this up to be all done onboard - I doubt I'll have much of a passenger seat left after I'm done with this, haha. I think the wiring is going to be the most painful part, but as of now I'll only have modest amount of space taken up by the data acquisition. I'll have to package the charge amp for the pressure transducer, an NI MyDaq or myRIO for the high speed stuff (haven't decided yet), an Arduino or Raspberry Pi for the low speed stuff, and all of the power supplies.
Good thoughts on the coolant pressure though. It looks like the sensor I would use is rated for about 1kHz sampling - at 4 combustion events per revolution, that leaves me a little (but a very small margin) headroom to sample fast enough to catch a pressure pulse at max engine speed. It would be super cool to sample fast enough to be able to tell which cylinder is lifting, but chances are pretty good that I'd just end up averaging the signal to see a pressure rise over the expected value. If there's any other ideas that you've got, definitely let me know!
Today I'm working on the fuse box for the data acq, so I'll see if I can post up some pics of it a bit later.
It's been a while since I've got back to this thread, but don't worry - the project isn't dead. I've got it to the point where all of the hardware is up and working; now I'm working on the tune up. I'm still working on getting the data acquisition up and running from the electronics side, but I've been putting priority on getting hardware ready to go before I get too involved with the data side of things.
Anyways, since this project is really going to revolve around balanced performance on all cylinders, I decided to characterize the set of eBay Deka 80's that I picked up about 6 months ago. Let me say right off the bat that you get what you pay for, LOL.
Right out of the box 4 of the 8 injectors would not fire. 50 freaking percent. After a little bit I figured out that the pintles were stuck to their seats with some kind of manufacturing goo that had hardened during shipping and sitting. I was able to unstick them with a light push with the pick.
After doing a quick static flow test, I set out to characterize the dynamic injector response over a fairly wide range of possible operating voltages. See the charts below for data for the first and third injectors tested. Injector 2 had a stuck pintle that I didn't want to deal with so I swapped it out with the next one in line to continue testing. I am working through post processing this data to determine my pulse width adders and injector offsets, but I need to get some more data from the other 6 injectors so it might take the rest of the week. Each injector will take 325 runs @ 30 seconds per run at this injector pressure ratio. I'm focusing on a pressure difference of 4 bar and will likely not take much other data at other pressure ratios as I have a boost referenced regulator. I will need to look at how the injection time is modified by MAP but should be able to calibrate around it.
Anyways, here's the data. If you want the raw data, shoot me a DM. I will gather the rest of the data for the injectors throughout the week.
-Cal Injector 1 dynamic flow curve. Bad behavior at low supply voltages. Injector 3 dynamic flow. Looks better than Injector 1. 12.1 V injector linearity comparison of two currently flowed injectors. 13.1 V injector linearity comparison of two currently flowed injectors. 14.1 V injector linearity comparison of two currently flowed injectors. Injector static flow split for eBay Deka 80 lb (?) injectors
What are the units for the flow chart? What fluid are you using for testing? Good job!
Oops, forgot the units on a couple of them.
Static flow charts are in (lb/hr) on the Y axis and injector number on the X (for my reference - I will be pairing injectors to specific cylinders based on lean/rich trends during operation)
Dynamic flow and linearity comparison charts are in mg/pulse on the Y axis and injector pulse duration in microseconds on the X axis
Ended up springing for some "64" lb/hr (3 bar test pressure) flow matched GT500 injectors from TLF Performance. He tried to sell me some stock injectors and fessed up to it after I called him out and proved it with data.
Anyways, here's the data for the set. Tom had claimed 0.05% correlation between the set when I asked, but I figured it would be 5% spread. The set came in at 3.7% deviation around nominal on static flow and 4.3% deviation on linearity, so I'm not too disappointed.
After partial characterization of the first injector (nominal operating voltage and pressure difference of 4 bar across the injector) I spot checked the rest of the set and compared the linearity of the injector between the sets. Picture below.
Low pulse width adders were also roughly calculated. I should have done many more samples, but it's what I had time for. Again, pic below.
Finally, I couldn't find the 3 Bar MAP calibration curve for the one I purchased off eBay a while back, so I checked it and determined the linear gain and offset. R^2 showed very good correlation - I wouldn't be surprised if this knock off sensor used a good chipset for its internals. For those interested, the equation I have determined was:
MAP @ 5V = 314.12 kPa
kPa offset = 6.148 kPa.
There's something really kicking my *** right now though with the initial VE tuning and I'm not entirely sure why it's happening. Maybe I just have to get acquainted with HPTuners or something.
The truck has been fouling out plugs on one or two cylinders after a relatively short amount of run time. I've noticed a few things playing into it (EGR flow, IAC position learning) but after disabling all of that I'm still a bit stuck. I've disabled DFCO, STFT, LTFT, EGR, IAC learn, and a bunch of other stuff that should be modifying the fuel or air, but it still will foul out Software cylinder #4 after the initial start. The strange thing is that it will sometimes "clear out" at higher engine speeds, but it will still foul out at the lower speeds.
Anyone run into this issue before? I switched to TR55's to try to keep it alive during initial tuning and haven't had any luck. I was leaning towards a weak coil ground or coil over temperature (the forward and up headers run within ~3 inches of them) but I'm still kind of stuck. Wire resistances are all around 1.1k ohms (off the top of my head) and don't change when flexed. I've checked that the turbo isn't passing any oil through the intake or exhaust as well.
Any help would be appreciated!
-Cal
Injector static and dynamic flow data GT500 injector linearity comparison GT500 injector low pulse width testing eBay MAP sensor linearity test
I'll give that a shot tomorrow for sure. I've tried switching the coils between cylinders with no success, but I'll give the injectors a swap as well. Crossing my fingers that this is it, otherwise I'll swap back to the original truck injectors and calibration to see if there's something else going on
01-25-2019, 10:43 PM
Turbo LS Combustion Project
