January 2018 Update:
Worked on the composite intercooler ducts until I got sick of them, then delivered them to a small paint shop with the instructions, "call me when it's done." Many weeks later they called, noting that it was more work than expected... well, yeah, that's why I gave it to them! The pics show them freshly-arrived, sitting loose on the car. Saw one negative post later, that I had "ruined" the look of the car. Meh, it just changes it. Given that my design influences include: the Lotus Seven, sprint cars, the movie
Road Warrior, and IMSA race cars - it is what it is, deal with it.
Consequences of adding the ductwork: It's no harder to get in, but tougher to get out due to losing access to the overhead tube I used to hoist myself out with. Test drives showed both expected and unexpected benefits. Expected was that it provides a bit of shade, but unexpected was that it's reduced wind buffeting by about half! In hindsight it makes sense that it's preventing air from flowing up over the top edge of the windscreen, which generates a negative pressure above the passenger compartment, which in turn sucks in air from the sides, beating the occupants about the head and shoulders. Now it's more like a breeze than a hurricane.
As far as how well the ducting works thermally, I cannot offer up hard numbers because while there's an air temperature sensor on the outlet of the intercooler, there isn't one on the inlet side. That's mostly because there are no more spare inputs on the ECU and I don't currently feel motivated enough to add one through other means. All I know is that the IAT (Inlet Air Temperature) always reads ambient temperature. Anyway, with the ductwork done, it was time for a retune.
In early December I took the car in for a "checkup" by one of the best tuners in the U.S. The reasons for doing so included: not knowing root cause for why the engine blew up (this is Engine V2.0), not having a warm and fuzzy feeling that the previous tuner did everything right, me changing compression, cams, exhaust manifold, intercooler, and turbine housing, and being unsure whether
I missed anything in the tuning department.
The first thing the tuner asked was "why is cam timing locked out?" I didn't know because I stayed away from both cam and ignition timing. At home and on the street, there's no way to safely know what they should be set to, so I left them as set by the previous tuner. After correcting that, he then mentioned that ignition timing was off as well. At the end of the 4-hr session, the results of his changes were striking, finding 10-30% more torque between 2000-4000 rpm and 15-20% from 4000 on up. The improvement was enough that we mutually agreed to reduce boost to 15 psi, where it still produced 410 ft-lbs torque on 91 oct gas and 450 ft-lbs on E85. Horsepower was 475 on gas and 530 on E85. That'll do... (FWIW, there is a dash-mounted knob which sets boost and it's normally set really low.)
During the tune, he mentioned that IAT was high, which was surprising given the new intercooler and ducting. After repositioning a cooling fan however, it all started working. Immediately after a full-power pull, I put my hand on the inlet end of the intercooler and nearly burned myself, it was that hot. Half way along the intercooler body, it was warm, and the outlet end tank was at room temperature. Nice. As an aside, on the street it's not possible to do any sort of intercooler temperature testing, even with a second sensor. To really heat up the air, the engine has to be at full boost for more than maybe 10 seconds, and by that time the car's breaking every speed limit by a big margin.
I left the tuning shop knowing the engine was rock-solid in the tuning and power department, but with drivability issues still unresolved. For those of you who will be using aftermarket ECU, expect to spend many days adjusting idle, off-idle, and throttle transitions. That consumed several weeks of free time, but now the engine starts and idles smoothly without problem. Leaving or approaching stops, the car no longer stalls. Little stuff like this is a really big deal when driving on the street and makes the car much more, what, OEM?
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Midlana book: Build this mid-engine Locost!,
http://midlana.com/stuff/book/Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from
https://www.lulu.com/