Familiar with them, our business was centered around Datsuns, Z cars primarly also the Dime, building and machining engines, a bit of custom EFI, in particular building and machining custom cylinder heads for customers around the world, low volume shop, all work done in-house, always struck me odd that half our business were customers in Europe.BRAAP- The Nissan L series engines go back to the '60s and I've built plenty of turbo and NA ones for street and road racing, won a couple championships with them. Never saw the problems you describe in ones built with Webers or EFI, all using stock crank, rods and fasteners. The heads were really bad flow wise for sure on my flow bench....
... Comparing this engine to even something remotely modern, say from the '90s at least and you're in a different world. Few people would pick such old engine designs to power aircraft these days in turbocharged form outside of maybe VWs and Corvairs, just because they are light.
The thermo calcs for these schemes have many caveats.There has been a great deal of work done with water injection in SI, CI and turbine going back into the '30s (or beyond?). Amazing how easily we forget the lessons of the past, but this uses the energy of change-of-state from liquid to gas phase to drop cylinder temps while raising pressures. Easily takes NOx to near zero. The aftermarket extreme turbocharging crowd knows this one quite well.
...so long as weight is comparable I don't see any benefit for one over the other in an aircraft installation.
Hydrogen peroxide works great when there is continuous flow and you want the peroxide to flash at a particular spot. Hydrogen peroxide rockets put the silver catalyst screen in the vicinty of the outlet from plumbing to combustion chamber. Getting peroxide to flash at the right time in a piston engine cycle might be tricky. I suppose with a direct injection nozzle, you could put it in only a little advanced on where your want ignition, like with diesels.Hydrogen peroxide might work. Not sure what mix with water would be ideal?
If you chase every good idea, you will run out of time.
Depends on the mission (which might not be stated in post one). Could be 30 seconds of boost needed to clear the trees or continuous cruise at high altitude. Those are different missions.The big thing working against all of these "added oxygen" systems is that the amount of oxygen needed per minute of flight is huge. Most engines need a lot more weight in oxygen than fuel. Saturn V first stage engines used 2.65 pounds of oxygen per pound of kerosene. With added oxygen systems, well, you start driving towards batteries for energy density... It really is a way lighter system to boost the manifold pressure with energy harvested from the waste stream.
Haven't been to HybridZ for a while BRAAP, hows things over there?
OP here, been an interesting discussion which seems to have answered my Q:
"In terms of engine complication and durability, boost is a viable alternative to a PSRU for the purposes i consider."
However, contrary to mechanical positive displacement pumps (or mechanically linked centrifugal types), turbo-charging has come a very long way (is nearly a mature niche industry) since i last visited the subject in the late 1970's. Hence, turbo-charger can provide both the TO torque (& power) that interests me, yet be somewhat invisible during cruise flight if desired, and overall provide better efficiencies and flight regime flexibility.
For someone who posted about sucking through a carburetor before the blower- My assumption is that once a person chooses to "complicate" a VW engine, that (close, individual port) EFI should be the foundational first step. Build out (or not) from that. Even un-boosted it should be a nice insurance system that allow use of max available HP with fewer concerns about engine management & potentially better longevity.
Regardless the boost type/system, i believe it was Frank Lockhart in 1926 - 27 with the Weisel brothers, who first demonstrated what a great difference intercooliing made in the effectiveness of supercharging, as well as mitigating so much of heat induces risks to the engine. The 3 continued to develop and refine intercooling until Lockhart was killed due to tire failure at Daytona beach in 1928. That's pretty old news.
Thanks, and carry on the discussion and diversions - there much of general interest.
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