# LS3 FWF prices

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#### Toobuilder

##### Well-Known Member
HBA Supporter
Log Member
With a 180-200 hp Lyc, or a 210 hp Cont, they cruise @ ~135-140 kts...
So slightly slower than my 180 HP Hiperbipe when loaded with people, bags and gas.

I used to fly form with my buddies O-300/Aeromatic Swift against my RV-8 and it was absolutely no contest. To be fair, this engine and prop was NOT a good match for the Swift, despite some significant personal attention by Kent Tarver on his prop.

#### rv7charlie

##### Well-Known Member
Those speeds I gave are probably at about 55-60% power. The 200hp Lyc I owned burned about 9gph in cruise we never ran the engine at 75% because the aero 'wall' for the airframe was roughly at 135-140 kts. IIRC, my partner's other Swift, a Cont 210 hp, burned about 9.5-10gph, and was only a few kts faster. Takeoff was a lot more interesting, likely because it swung a bigger prop. Neither would go much faster, no matter how much fuel you fed them.The big drag inducer isn't the canopy arrangement, or the wing slots, or the gear wells. It's the pinched fuselage well forward on the wing chord.

I'd still want one in the hangar next to the RV6 & the RV7(project), if I had stupid levels of extra money.

#### TXFlyGuy

##### Well-Known Member
Another consideration instead of automotive conversions is marine engine conversions. Then again, what I've heard (weasel word) is that it's seldom the engine per se, it's the accessories, cooling, PSRU, vibrations, etc that are the problem.
Not to mention electronics. PSRU, cooling, vibration...not a problem.

#### skydawg

##### Well-Known Member
Marine engines do have some advantages, such as being available in left or right rotation, and crank shaft are often different due to greater drag/loading (which is closer to aircraft loads as there is no transmission to ease shaft loading or stresses such as pulse or torsion cycles). But as mentioned above, most marine engines are simply modified car engines. There’s even a V8 outboard engine. there are a few other mods, such as intrinsically Safe electrical components on gasoline engines (such as starters), and EFI with dual RPM limiters, but not needed with open engine bays such as an aircrafts’.

just like airplane prop speeds, boat props must also be reduced, which is typically done with simple gear boxes, whereas cars now use computer controls and multiple ratios Which signifi reduce loading on engine. A car engine isn’t really designed as a direct drive, and torsional and asymmetric loads can really be a problem, regardless of crank shaft strength (engine crank bearing structure is weak spot). so, using a tougher marine crank shaft, sometimes designed for lower RPM torque, doesn’t solve the real problem. A good gear box takes solid engineering and quality components, which adds significant cost to a FFW conversion (coat being the initial topic of this post).

the 450 HP V8 on our C172 test aircraft is a modified marine block for a number of reasons, and it’s proven reliable so far. The c172 airframe was only rated to 220HP so its flat rated to less than 220HP….. we did do some test flying set at 250 HP as well, but 210-220 seems to be a sweet spot for a number of reasons…. the airframe flat plate drag coefficients obviously don’t change regardless of engine power. we can change the EFI parameters pretty easy via WIFI within a couple of minutes, which allowed us try a lot of different parameters in a short time. There’s 2 ECMs, a main and a redundant AUX EFI system in our design to meet part 33 redundancy requirements, so we could even program the standby ECM in flight, which really accelerated the process and allowed a quick fine tuning which is not possible with typical aircraft engines, which is kind of cool.

so, for what it worth, marine versions have a couple of advantages over automotive versions for aircraft mission, but I don’t think it’s worth the extra money in most applications. Modern car clocks are bulletproof, Spend on the gear box and dampening prop loads.

#### sming

##### Well-Known Member
There’s even a V8 outboard engine.
Try 600hp V12
320.000$i read somewhere? That buy a lot of lycoming... wonder where the base engine comes from. Edit: make that 77.000$, pretty nice for a v12 with contra rotating props!

But I love what and how your are doing your engine, hope we can see it in something more exiting than a 172
That marine engines are all automotive based (and cost as much as aircraft engine) nowadays tells alot about the constraint of regulations and why we can't have nice things
Keep it up!

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#### skydawg

##### Well-Known Member
thanks for comment. Our target is about same as factory overhaul cost with trade in of original core to a overhaul shop (which is estimated to be valued at $8k-$12K depending on engine and hours, ect...) So, for about \$26-29K you get a whole new power plant including prop. The cost of just a below O-360 (w/o prop, mount, ect..) is well north of 2X that.

Our goal is to offer an alternative to overhaul for about same cost, which gives you better performance and less than half the operating cost.

#### rv6ejguy

##### Well-Known Member
The weight of this engine package doesn't make it a suitable replacement for an O-360 though...