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Re: Dual STI build log
You’re absolutely right Paul. The latest posted diagram makes a lot more sense to me. I’ve posted a comment on the AeroElectric forum to solicit comments. I’ll share any pertinate ones here. I will say again though that there is no reason to isolate/insulate that forest of tabs from the firewall in our particular instances. It’s made to be mounted that way, hence the big through bolt is part of it. It actually happens to be part of an engineered strategy to help prevent ground loops. The way the wiring is shown in the second drawing is a fine way to wire the ground circuitry also.
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Re: Dual STI build log
I've done exactly as Jim describes. I have a ground buss attached to the tabs and the battery -ve attaches at one end. I haven't separated Avionics and other systems. I'll read Bob Knuckols book again and try to understand why you would isolate the Avionics ground buss locally from structure and then run a separate wire to another ground point. Unless there's an issue with noise ..... but doesn't sound like it from Jim's post.
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Re: Dual STI build log
Hey Dustin... I'm sorry for spending so much time on your thread, except to say I'm enjoying your build, and it looks great! I said I'd pass on any comments made by Bob Nuckolls about the potential forest of tabs issue. He had a good reply as did several other people. You can check it out on the AeroElectric forum if you wish. http://forum.matronics.com/viewforum.php?f=3
The last paragraph of his reply, which speaks to insulating the bus from the airframe -
"Insulating your ground system from the
airframe is not recommended and has
no demonstrable value. However, running
all airframe grounds to the firewall thru-
stud bus is not a 'bad' thing to do either.
Bob . . ."
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Re: Dual STI build log
I appreciate everyone’s input. Thank John for looking into this.
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Re: Dual STI build log
Yes, sorry to hijack your thread, Dustin. Some very interesting reading about the ground systems and I'm glad it doesn't look like you have to change anything :D
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Re: Dual STI build log
Engine is hung, cowling is trimmed and fitted. Starting to work on getting cam-locks in and then working on intercooler, and naca vents. I think the plan is getting the intercooler figured out, naca vents installed, then plumb and finish the engine. Then back to working on avionics. I can see we have lots to figure out so I am guessing this part of the build is going to go slow. Ordering a throttle cable will be depend on how the inter-cooler sits. When we where trimming the cowl, I used a trick Nikk showed us about using tape to figure out where the cut goes. You basically lay tape one the lower cowl with the tape on the edge of where the cowl needs to go. Then put the cowl on top and then match the edge of the tape that is showing. Now you have the line of the lower cowl and you can mark a line. Cut the line off and you have a perfect match. You have to ruff cut to get close so you can see the tape below. Thanks to Scott for the prop flange thingy. Not sure how you would do this without it!
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Re: Dual STI build log
I wish there was more to report but there has been a bunch of head scratching. Working on the cowl I ran into the problem of my naca vent hitting the turbo and not having enough clearance. Crazy thing is 1 of the 2 builds has an issue. My brothers plane is tight but has clearance. Not sure what the different between the two is. Little differences add up when it comes to the cowl. Mine, there was no way that the Naca was going to clear so I had to modify the vent. I am worried about getting enough airflow, but I guess time will tell. I think we are defiantly going to leave the cowls unpainted for possible mods that may need to take place. Mic, one of the dual STI's in Canada sent us one of his 915 intercooler to see if it will fit. I need to get some more ducting and I think I will be able to get the 915 intercooler on the side to work. I am going off Kitfox recommendations to only run on the top of the engine as our last resort. The side should work. Just need to figure out naca vents to feed it fresh air and heat shield it from the turbo/header heat. Once I get the inter-cooler plumbed I think we are back moving forward. I will be able to get the throttle cable routing figured out, which I can then get the panel drilled and get powered coated and ready to start wiring. We can then start pluming the motor and working on the firewall wiring also. While we have been waiting for the intercooler to clear customs I have been working on getting the butt rib close-outs installed. Hinges built and doors installed. Also got the bubble windows and latches installed. I had no mishaps with the acrylic which I was nervous about. I now have taken the doors off and put away for safe keeping until final install. As I wait for parts to arrive for the ducting on the intercooler I think I am going to start working on getting the windshield started, but nervous about messing it up. Fingers crossed! Here is come pictures for now!
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Setting the clearance of the radiator off the cowl.
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Getting ready to modify the NACA to clear the turbo when installing the cowl.
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Hopefully the vent does not restrict to much airflow to cause overheating issues???
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Vent is done and visually looking from the front you can't tell.
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It now has adequate clearance. Hard to tell in the picture but there is about 1.5" of clearance now. Still need to heat shield it but I think it should be good??
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Naca opening cut.
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Cowling is getting closer!
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Butt rib closeouts done, hinges installed!
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Windows installed and weather-striping installed and latches installed!
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Sometimes you just need to roll it outside!
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Intercooler is going to work I think!!
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Found a K&N filter that fits and now just need to run a little tighter bend to get the discharge side of the cooler to intake. Not optimal running tight bends but running low boost should be fine.
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Re: Dual STI build log
Making more progress with more questions answered this week. In an effort to help mitigate high oil temps we are going to try a heat-exchanger. Should help keep the water temps down on the ground, and help keep the oil temps down in the air. This was recommend to us from Edge performance. Thomas ran one on his engine. Dropped is oil temps 30-40 degrees and only minimal raise in water temps. Spoke with John and they are recommending on the 915 installs to run a lip extension on the bottom of the cowl. I think we are going to cut the cowl and extended the lip 1" to improve cooling. Intercooler is installed and moutning brackets made!
This week I am going to work on getting the heat shielding and baffling done for the intercooler. Waiting on some Naca vents for the intercooler, and also for the intake. Due to the fact that I feel the 915 may be suffering from over-pressurizing the cowl, we are going to go smaller rather than larger naca vents for the intercooler/intake. Also when we add the lip to the bottom we are going to try and increase the amount of exit air, for the added air from the Naca vents. We are going to leave the cowl unpainted, so we can do some testing and hopefully help anyone else coming behind us. Also solved the throttle cable issues I was trying to figure out. I am going to go the route that Doug and Scott went and remove the spring and run a direct cable. Went with the Mcfarlane venier cable but they only sell it in a cable not a solid wire. Thought I would be able to run it into the bing 90 to mount to the throttle body but the cable is too thick to make the 90. With the cable so thick it should work going straight to the throttle body. Once I get it all mounted I will post some pictures that will make more sense. Worked on building a throttle arm and mount for the cable. Finished cutting the panel for the throttle cable and now hopefully my brother can get his done this week so we can get them off to the powder coater. Now its time to start plumbing the engine and as soon as I get my panel back start on wiring. At this point I am doing as much as I can but I seemed to be waiting on parts. Should hopefully in the next couple weeks also receive our new intake that mounts the injectors on the inside.....fingers crossed!
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Re: Dual STI build log
Slowly but surely....... Progress update.
I have been working on ducting for the inter-cooler and heat-sheilding the inter-cooler. Inter-cooler can be an interheater if not done correctly. Trying our best to make sure we keep the heat from the engine from heat soaking the intercooler. Only thing left to do on the heat shield is install some heat shield.:D I think I am going to use the HP insulated heat shield to line the aluminum. We will also use it to protect the fiberglass bottom naca to keep the turbo from cooking the cowling. I have used this stuff next to the turbo on my snowmobile and it has held up when the turbo starts glowing. Naca vents are also going in for the intercooler and intake to the turbo along with radiators. Installing therm with some fiberglass resin. This week hoping to get the panel back from powder-coater and get it off to get silk screened. At this point just hoping to continue to make progress and keep figuring things out. OH.... Big news! Third time is the charm. FAA kept send back the registration but just recently received the registration back from the FAA! They are both officially registered.
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Re: Dual STI build log
Congrats on the registration Dustin and way to persevere. Progress looks really good. Enjoying the build photos. Thanks for sharing.