Economies of Scale...
Randy,
Interesting. Larry has been doing this a long time and I trust his insight. Here is some data for the IO-390 and XP-400 which
might be a substitute for the IO-540. My question is cost. The IO-390 and XP-400 are over $30K. I can buy a used 540 for under 20K and I don't have to cut my cowling, make a new mount or mess with success. I'm not against the F4, I just need to see a good
why...Here's my argument, You get more bang for the buck from a IO-540 and with the right prop and CG, a great flying airplane. Right now I'm just comparing the IO-360(200HP) with the IO-540 (260-300HP). Larry didn't say which prop he used, that would help too.
First here are Lycoming HP/Weight/HP-Weight ratios:The IO-360 looks good on paper, The IO-540 looks better...
O-235-C1B 115 240 0.48
O-290-D2C 140 263 0.53
O-320-A2B 150 272 0.55
O-320-A2C 150 271 0.55
O-320-B2C 160 277 0.58
O-320-D2A 160 277 0.58
O-320-E2A 160 277 0.58
IO-320-B1A 160 285 0.56
IO-320-C1A 160 294 0.54
IO-320-E2A 150 280 0.54
O-360-A1D 180 284 0.63
O-360-A3A 180 285 0.63
IO-360-A1A 200 320 0.63
IO-360-B1B 180 295 0.61
IMO-360-B1B 225 274 0.82UAV engine!
GO-480-B1D 270 432 0.63
GO-480-G1D6 295 437 0.68
IGO-480-A1B6 295 469 0.63
IGSO-480-A1F6 340 498 0.68
O-540-A1A5 250 396 0.63
O-540-B2B5 235 395 0.59
O-540-B4B5 235 395 0.59
O-540-B4B5 260 398 0.65
IO-540-A1A5 290 437 0.66
IO-540-C4B5 250 402 0.62
IO-540-D4A5 260 402 0.65
IO-540-E1A5 290 437 0.66
IO-540-G1A5 290 443 0.65
IO-540-J4A5 250 409 0.61
IO-540-K1A5 300 470 0.64
AEIO-540-L1B5D 300 476 0.63
IGO-540-B1C 350 500 0.70
IGSO-540-A1D 380 530 0.72
IGSO-540-B1A 380 532 0.71
TIO-540-A1A 310 535 0.58
TIO-541-E1A6 380 632 0.60
TIOGO-541-A1A 400 663 0.60
IO-720-A1A 400 597 0.67
My IO-540 has 10,4:1 compression and cranks out (LyCon dyno in 98')300HP/385lbs at 2850 RPM. That equates to a HP:Weight ratio of .69, a bit better than the chart. Should I spend more on less HP to drop 100 or so lbs? OK, say I go with the IO-390 or XP-400 which weigh roughly the same as an IO-360, but cost 30K+ and give me less HP. Is it worth it? I hear my old college economics prof talking "economies of scale" again. My bottom line is design and bang for the buck.
From Marc Cook:
The tactic with the XP-400 was to provide competitive power -- it's rated for 210 hp at 2700 rpm now -- without resorting to a high compression ratio or extreme ignition timing. Displacement makes "easy" power possible, and to that end, Superior took the angle-valve 360's bore dimension from 5.125 inches to 5.25, and extended the stroke from 4.375 to 4.625 inches. Seems like a lot, but the cylinder bores only need grow a sixteenth inch from the centerline, meaning that existing head castings can be used. The barrels are new, of course, but the expensive pieces can be retained. (Lycoming boosted the IO-390's bore alone from 5.125 to 5.319.)
By using the 5.25-inch bore, Superior was able to use rings meant for Continental big-bore engines fitted to brand-new pistons that result in a modest 8.5:1 compression ratio. For reference, the standard, angle-valve IO-360's is 8.7:1. While everyone was told the IO-390 would have the same compression, it turns out to have an 8.9:1 ratio.
More displacement comes from additional stroke; for the XP-400 that's a mere quarter-inch more than the IO-360/390 engines. Superior was able to machine this extra stroke -- the big end is just an eighth-inch further from the main-bearing line -- from O-360 blanks. Like the IO-390, the 400 will use a counterweighted crankshaft. Crescent-shaped weights are pinned to the crankshaft at the back end to absorb high-order harmonics. In exchange for increased engine weight and rotational mass, the counterweighted crankshaft can make the engine smoother and will assuredly make life easier on the propeller. (These high-order vibrations can wreak havoc on a metal prop, and they're the primary influence that prop manufacturers check when approving a certain engine/prop combination.)
This engine packs a few clever touches, including a new Ryton (composite) sump with a choice of front- or rear-facing servo locations. The current IO-390 spec comes with a front-facing inlet only. Superior's roller lifters and specially ground camshaft carry over from the XP-360. Thanks in part to new case castings and the weight savings of the sump, the engine is expected to come in from 294 to 305 pounds ... which is 3 to 14 pounds less than is claimed for the IO-390.
Might be worth considering for your EVO
I'm not cutting my cowling anytime soon...
Respectfully submitted...
Smokey
IO-540 HR2
BTW: Found these on Barnstormers this morning...there were many more under 20K.
LYCOMING IO 540 C4B5 675 SMOH • $18,500 • AVAILABLE FOR SALE • Overhauled by Signature Engines 7-22-2007 includes all accessories. s/n L-4384-48 no prop strike • Contact Clark B. Swanson, Owner - located Clearfield, UT USA • Telephone: 801-564-2660 . • Fax: 801-475-1898 • Posted June 15, 2008 • Show all Ads posted by this Advertiser • Recommend This Ad to a Friend • Email Advertiser • Save to Watchlist • Report This Ad
LYCOMING IO 540 C4B5 1075 SMOH • $15,500 • AVAILABLE FOR SALE • Overhauled by Signature Engines feb 1 2007 No prop Strike all acessories included • Contact Clark B. Swanson, Owner - located Clearfield, UT USA • Telephone: 801-564-2660 . • Fax: 801-475-1898 • Posted June 15, 2008 • Show all Ads posted by this Advertiser • Recommend This Ad to a Friend • Email Advertiser • Save to Watchlist • Report This Ad
LYCOMING IO 540 C4B5 675 SMOH • AVAILABLE FOR SALE • Overhauled by Signature Engines 7-22-07 675 SMOH no prop strike all accessories included • Contact Clark B. Swanson, Owner - located Clearfield, UT USA • Telephone: 801-564-2660 . • Fax: 801-475-1898 • Posted June 15, 2008 • Show all Ads posted by this Advertiser • Recommend This Ad to a Friend • Email Advertiser • Save to Watchlist • Report This Ad