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Got the secondary injectors mocked up with some 3d printed parts. I'd like to cast them out of aluminum as a final version but will have to look into some backyard forges to do so. Rev 3 of the secondary mounts and injector caps will go on the printer tomorrow morning.
The upstream injector mounts are proving to be pretty tricky to get to fit...it seems like there's a semi complex spline that I'll have to figure out to get them to fit the way I want them to.
Secondary injector mount close up. Secondary injector mount mockup. Will need to do something with the frontmost cylinder to secure it.
Are you going to put some type of heatshield or heat tape around the wires in the bundle, or at least those running right below the down pipe?
Yep, I'll have some kind of radiant shield to cover that. I'd like to put the wheel well closeouts back on to help with rain driving, so I might just end up making some sheet metal shielding for the downpipe too. It's a little ways back on the project list, but I'll get around to it before too long
That thermocouple will have a long time constant due to thermal mass of the material... Dealt with that before, if you want timely data, you need a TC with a finer/smaller tip.
That thermocouple will have a long time constant due to thermal mass of the material... Dealt with that before, if you want timely data, you need a TC with a finer/smaller tip.
Yep, that's a very valid point. In an ideal world, I'd have an exposed tip thermocouple of the same diameter, but I'm just using what I had from previous projects. I'm a little leary of going to a <.125" diameter probe, though. I intend to daily drive this rig and would like to remove any doubt that the probe will fatigue and go through my engine, but I'm being a bit cautious. I should (crossing fingers) have a little headroom with the PCJ's and oil cooler to do some extended steady state running, but if I don't I'll definitely add the cooling capacity to make it happen.
As a bit of follow up information on Jake's comment, there's a good chunk of info here: https://www.omega.com/en-us/resource...-response-time
The important takeaway from that page is that not all thermocouples are created equal. The "time constant" that is mentioned is essentially the response time of the thermocouple to a sudden change in temperature. After a sudden change in temperature at the probe tip, it takes 4 time constants for the thermocouple to read 99.8% of the final temperature.
For the 1/8 diameter probes I'm using, I'll be looking at a 40 second dwell time at certain points to be certain that the indicated temperature is within 98% of the actual temperature. The good news is that, as mass flow rate increases, the time that the air has to absorb or radiate heat to its surroundings decreases. Towards the upper flow limits of the modeled intake temperature map, I can assume that my IAT sensor reading is close to the temperature of the air entering the combustion chamber, so I'll focus on temperature model correlation mainly around lower airflows where the air can absorb enough heat before entering the combustion chamber to make the temperature innacurate.
If you have any questions, just shoot me a PM and I'll be happy to discuss!
-Cal
I had to hammer my coolant crossover pipes down with a rubber mallet, and cut away some reinforcement ribs on the manifold, to get a TBSS manifold to fit with a LS6 valley cover. How is the clearance with the octopus in this picture?
I had to hammer my coolant crossover pipes down with a rubber mallet, and cut away some reinforcement ribs on the manifold, to get a TBSS manifold to fit with a LS6 valley cover. How is the clearance with the octopus in this picture?
It's tight. Very tight. The main areas for concern is the end of the nozzle holder and the valley cover as well as the steam port crossover tubes to the center fed tubes. I'll get a pic for you when I'm able
Had a bit of a slowdown last year but things are slowly spooling back up. The truck ran, drove, and hit boost for about a week before tearing it down to swap the engine. It's currently running but I'm dealing with a warm idle oil pressure issue. Thinking loose bearing clearances and piston oilers are overwhelming the M295HV pump capacity at idle. I have an M365 installed right now that will be getting tested this weekend. Hopefully it's the magic bullet, otherwise I'm pulling it and endlessly feeding the thing junkyard 5.3's until I get the data I want.
Engine build took way longer than anticipated. Maybe I'm too ****, maybe I'm not. We'll see shortly, I guess.
Short breakdown on what took so dang long:
Cerakoted piston crowns, valves, combustion chambers, crossover, headers, turbine housing.
Valve job with new guides and stellite valves, all done by yours truly. Seat width is HUGE, but I guess I wanted it that way since the name of the game is extended power runs.
Retaining plate and crush style combustion pressure sensor adapter. Had to design a holding clamp that bolts to the head since the minor diameter of the pilot drill in the head was larger than the M8X0.75 for the pressure sensor. Added some new lifters, trays, pushrods, springs, rockers, LS9 gaskets, ARP studs, forged rods/pistons, balanced crank, LS6 cam, and dual roller timing set too since I only wanted to do this once.
Got distracted a bit by some header heat shielding - currently about 80% done with multi layer steel/fiberglass/aluminum shields (on top of a standard header wrap) to keep stuff around the headers cool.
Primary/secondary injector mounts and caps are cast (backyard casting style, lost 3D printed parts with Suspendaslurry in a 356 alloy) and need machining. Massive pain in the *** so far....kind of making me wish I had just bought an aluminum manifold and welded bungs on from the start, lol. Rails are partially done, just need to bend them around the crossover, cast the mounts and weld on.
BTW, MikeGyver, I ended up canning the octopus and building in the meth injection to the backside of the injector adapter. Things got too close to the valley cover when assembled. Could have messed around with tubing runs inside the valley, but it wasn't worth it.
Injector driver circuit boards are getting a redesign. Putting all 24 channels on a single PCB for reliability sake. Didn't want to try to make a multi board SPI network work in an underhood environment.
Finished up the runner pressure-temperature combo board as well and just need to finish the code to make it all work. Hard to find motivation to write more code at home after doing it at work all day, but it's slowly coming along. Ended up with 16 pressure sensors and 16 thermocouple amps on one board.
Trans got rebuilt with an HD2 and some new internals. Will probably be looking for another trans shortly to rebuild and give a proper dual feed, rollerize, and rebuild. This one should give me a chance to put some miles on it first to get things sussed out, but I'm not super confident that the parts I didn't replace. Had to weld a bellhousing ear and would like to get a clean core to start with too.
Might post pics later of some of the stuff if anyone's interested.
Hopefully will have the cooler stuff up and going shortly, just trying to focus on getting this thing driving before winter.
I'll grab some heat shield pics when I get them all finished up - still a WIP at the moment.
Here's where I landed on the injector adapters. Still needs final machining (and maybe a re-cast if I'm picky) but not bad for a first attempt at aluminum casting.
Step 1: Model and 3d print parts. These will sit on top of the runners and will bolt through. Will require windows to be cut to allow them to actually spray into the manifold. You're looking at both aux injectors, temperature measurement (thermocouple) on the left, WMI (or maybe nitrous?) port in the center, then a compression fitting for a pressure tap. 3D printed models Alternate view
Step 2: glue 3d printed parts to a 3d printed sprue and gating system, then coat in a layer of ceramic shell material followed by silica sand. Before/After Coating molds in Suspendaslurry and silica sand
Step 3: Burn plastic out of the molds Burning the plastic molds out
Step 4: Pour. I used a backyard foundry I picked up off eBay with good results. Pre pour
Post pour
Step 5: Remove shell from parts
Each of the lines visible is a layer of sand and ceramic shell material.
Current progress - needs machining.
End result was ok, but I could do better. Will be recasting a few parts to fix some porosity issues. Next steps are to get machining jigs printed to help with fixturing, then I'll drill the holes for the injectors and NPT's for the aux and data acq ports.
May 28, 2020 | 11:29 PM
