# 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

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 HBA Supporter The weight of this engine package doesn't make it a suitable replacement for an O-360 though... #### Orange4sky ##### Well-Known Member 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 would think that massive grill and the 50’s cooling design might have a bit to do with it’s Cd as well, no? The weight of this engine package doesn't make it a suitable replacement for an O-360 though... I just read a PRSU companies’ comparison presentation that was chock full of unfair or just plain incorrect information regarding traditional aircraft engine’s costs and weights. For example, it used$90 as the cost of IO-540 air filters as if an experimental owner could not use a comparable \$10 aftermarket unit. The incredibly “optimistic” weight comparison claimed the LS3 FWF was 24lbs less than an IO-540 K. The numbers from my installation of an admittedly slightly lighter O-540 B came out to 151 lbs less than the corrected LS3 numbers.

It’s a good thing that some companies do not resort to overly optimistic marketing claims, but they are a rare breed indeed.

#### rv7charlie

##### Well-Known Member
The massive grill & 50s cooling design has little to do with the original 85HP version's slow speed; the 85 HP engine on a 1600-1700 lb gross weight a/c took care of most of the speed issues.

If that massive grill & 50s cooling design was still present on the big engine models, then you'd be right, but virtually all the versions with 189-200 hp Lycs or 210 hp Continentals have 'modern' cowls & cooling systems.

On engine weight comparisons: Shouldn't your gripe about comparing air filter prices also apply to comparing engine weights? I'm not well versed on Lyc's 540 engines, but I'm pretty sure the O540B is a parallel valve engine rated at about 250 hp, while the IO540K is an angle valve engine rated at about 300 hp. I'm also pretty sure that the K weighs at least 40 lbs more than the B, (the 4 cyl angle valve 360 weighs about 30-35 lbs more than the parallel valve 360), and if we're comparing HP apples to HP apples, we should probably be looking at the 375 HP GSO580C, which weighs about 560 lbs, bare.

More stuff to remember: a/c engine weights are 'all over the map', even within the same engine series; Lyc 6cyl engines can vary by up to 50 lbs on Lyc's own spec sheets, depending on how the engine is configured for a mfgr. IIRC, I've seen that big a spread even within groups that all use the same type cylinder (parallel or angle valve). Also, the 'spec' engine weight is only a very loose indicator of what the engine *installation* will weigh. Even the 4 cyl engines will gain almost 50 lbs (sometimes more) by the time they're capable of flight on the nose of the a/c. Remember, most engine weights are 'bare'; with at most the weight of the mags included.

Stuff scales. It's fairly difficult to beat the weight (or even the cost) of a 4 cyl Lyc with an alternative engine (though both can be done). But when HP requirements get above 300, it starts to get fairly easy to beat a/c (piston) engine weights, and especially, prices.

#### Orange4sky

##### Well-Known Member
If that massive grill & 50s cooling design was still present on the big engine models, then you'd be right, but virtually all the versions with 189-200 hp Lycs or 210 hp Continentals have 'modern' cowls & cooling systems
Ah. That makes sense. Thanks.

On engine weight comparisons: Shouldn't your gripe about comparing air filter prices also apply to comparing engine weights? I'm not well versed on Lyc's 540 engines, but I'm pretty sure the O540B is a parallel valve engine rated at about 250 hp,
It’s fairly inexpensive to get ~300 hp out of an experimental O-540 B or E parallel without adding any weight. 8.5:1 compression pistons, porting, cold air intake, electronic ignition, tuned exhaust.

Don’t get me wrong. I‘m 100% for converting auto engines for aircraft. I’m just appealing for real world numbers. I just don’t think it’s a slam dunk at the lower horsepower end.

I have seen a few really good LS swaps on Seabees.

I think the weight penalty at under 300 hp for a lot of installations is an issue. Above that, the LS makes a lot more sense.

Anyway sorry to go so far off topic…