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Thanks for the input guys.
I have been thinking about this for a long time now, and I have considered almost (I think) everything.
There is no reasonable explanation for not wanting a factory IO-540 except i don't *want* to do it that way..........of course if all else fails, you know.
I considered and rejected an auto engine because:
1. From others experience they found it to be too ungainly in a somewhat "nimble" airplane.
2. I havent found a single reduction box that I like. Don't like belts or chain drives and the gear reduction systems are prohibitively expensive (nearly 10k).
3. This design would screw up the lines of the best looking bipe ever (IMHO).
4. Still can't get a viable fix for the radiator placement. A P-51 scoop just won't look good on my airplane.
Someday I will build a Lancair with a hot LS1/6, but not for this project.
Steen now makes plans to use the M14 radial (ala sukoi) but again they disturb the lines and at 50k plus acc, it's a little out of my league for this project.
Turbo prop? Glad I wasn't the only one sick enough to consider that route, but after driving a C207 w/allison 250 (soloy gearbox) I would want something bigger and although I can get a TPE-331 for a fair price, I don't think so.............
So, where does that leave me?
4 or 6 cyl air-cooled.
I am dead set on going EFI. I can no longer justify bendix injection and a carb is out of the question. I am equally offended that we still use those awful magnetos (okay maybe I'll run one just in case, but personally I don't see the need for it).
For weight alone, the 4cyl appeals to me, but the power is down a little from what I want (180/200 vs 275 ish) so whats a guy to do?
FORCED INDUCTION.
Okay with regard to (beep beep) I still think a centrifugal blower is a better choice in theory, but there are just too many issues (mounting, drive system, belt reliability) If I could just run it off my accessory gearbox (maybe where the mag used to be) then maybe.........
But for now, I think a turbo would be a neat idea. Yes, they are currently used to compensate at altitude, but that's not the only use. I have flown supercharged radials (R1830,2000,2800) so I know that it's possible BUT.......
Turbos have also come a long way and it's possible by matching housings and compressor maps to the desired results to get a very effective combination. That combined with a high quality adjustable wastegate I can tailor my turbo to the motor. I don't plan on competitive aerobatics in this thing (or else I would get an extra or something similar) maybe a 60/40 split X/C to inverted.
As far as my research has gone, I don't think boost is going to be an issue. I don't intend on putting just *any* turbo in here, but a specifically matched unit. On a street car the turbo has to deal with a nearly 6000rmp range, boost too early, crap on the top end, good top end, no power down low. But, I am only looking for a 2000rpm range, so I won't be asking the system to operate out of its best range. That combined with a constant speed prop the motor may never get out of boost. BTW I am only thinking maybe 8psi max.
As far as Lycoming vs Continental, I am a Lycoming fan, but it would be easier to fab an intake manifold on a Continental (port placement) so I am afraid I will be going that way (if I go this way). I have found a few IO-470s for around 6k and I can live with that.
So, am I nuts here? It may sound like I have made my mind up, but I am still very much in the planning phase here. Any thoughts and advice is welcome.
Pete
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