Ford modular v8

I think the Rover engine started out life as the Olds F 85 --and also became the Leyland Terrier truck engine (from second hand information ) there was a magnesium block version made here some twenty years ago by a bunch of ex Commonwealth Aircraft Corporation tradesmen --CAC made the French ATAR engine under licence and other high tech work before they closed down . It was intended for drag racing and maybe circuit racing but would seem to be ideal for aircraft use --I don't know what became of it .

 

if you go with a Rover engine go with the later ones with main cap crossbolts (Rover's version of a '4 bolt' bottom end).

The 4.0 will have these.

 

Despite the virtues of these various engines, they still can't get around one major fundamental requirement- power to weight. Smaller engines run a PSRU to reasonable benefit, but if you're going to go DD, then the biggest displacement in the smallest package is going to win every time. A 4.0 liter Rover may be light, but it is still a V-8, so it's no featherweight. It's power to weight will not be as good as a similar size and weight LSx, for instance, because you can punch the former out to well over 7 liters which instantly drags the power/weight scale way over to the favorable side. And I'm not sure what the modular Ford weighs, but it is dragging around 20 extra pounds in cams and chains which instantly drags power/weight to the bad side. This extra 20 pounds may serve the engine well in an automotive application by allowing superior high RPM breathing, but that same virtue becomes a liability when swinging a propeller at 2800 RPM

I guess what it really comes down to is a not what is readily available in a junkyard, but the best ratio of torque, weight and cost. One should look at that first, and forget about the nameplate on the valve cover.

 

The 4.0 Rover V8 weighs 150kgs, I'm confused, do you mean that a 4 cylinder that weighs 150kgs will be lighter somehow?

That may well be true but of course there are classes of plane that have maximum weights and that 45 extra kgs over a Rover V8 needs to be bought into consideration or you may end up with no carrying capacity.

 

Of course not. A production car V-8 is going to weigh similar to another just based upon its configuration. If you are going to choose that configuration, it should be the one with the best power to weight. If that drives you to more HP than you need, then pick a different engine configuration that is lighter, yet still provides an efficient power to weight.

Of course, which means that you would likely be better off with a "regular" aircraft engine... More favorable power to weight in that HP class.

We've discussed it before at length - The traditional aircraft engines rule the roost in the 150-200 HP class. It makes no sense to take a fairly heavy configuration (V-8) and try compete at that power level. The only place where a V-8 starts to make sense is 300HP or more. Of course the V-8 can be made to run at 180 HP, but at that point its just a science project, not a valid powerplant choice from a requirements standpoint. Such an engine would have about as much practicality today as an OX-5.

 

We have, and you're right - in principle.

But I have to disagree a little. :nervous: All that you've said is true for airframes that were designed for Ly/Con engines, but it isn't so true for airframes designed for a heavier engine. Take the Percival Vega Gull:

Percival Vega Gull
(Gipsy Six power) 1510lb useful load, 1020fpm, 660mi range

its engine had a 2.34 lb/hp ratio versus the o360's 1.43 lb/hp ratio, and yet it was and is still a good performer.

The Model A powered Piet isn't nearly as practical, but it does fly, and its engine only has a 5 lb/hp ratio. I think that any engine with a weight/power fraction below 3 lb/hp can be a useful powerplant in an airframe designed for it. Take the Vdub conversion, a 50 hp VW in a Teenie Two will have 2.9 lb/hp and works well because it was designed for it; the Tipsy Nipper is the same, as is the Jodel D.9 Bebe, and the Druine Turbulent.


Some examples,

Lycoming 0360: 1.43 lb/hp

gipsy six: 2.34 lb/hp

Wright J-5: 2.36 lb/hp

All alloy modular v8: 2.50 lb/hp

Iron SBF 5.0L: 2.92 lb/hp

Pietenpol model A: 5.00 lb/hp

Caveat: Of course, if you take a Vega Gull and put in an engine with a 1.43 lb/hp ratio, you still win. All I'm saying is that an auto conversion can be useful and economical if done right...

P.S., one bright spot with these modern auto engines is the ignition system, they are very reliable.

 

There is no doubt in my mind that a V-8 (or any reliable engine, for that matter) can be made to fly well in an airframe designed for it. However, an aircraft will ALWAYS fly "better" with a more efficient power to weight. Just as a Jenny would fly much better with a modern 200 HP V-8 vs. the 90 HP slug that was the OX-5, a hypothetical airframe designed for a 200 HP V-8 would fly better with a 200 HP aircraft engine of half the weight. Remember, the Wright Bros main challenge was finding an engine not of sufficient HP, but one that met requirements for power/weight. Power to weight has been the hallmark of efficiency ever since.

Keep in mind that I'm discussing power to weight from a "optimal" scenario vs a "good enough". I think everyone here knows I am a fan of a V-8 aero engine!

 

The only way we can have a logical and intelligent conversation is to use REAL weight numbers... Not false ones that give one motor an advantage over another one....

The Lycoming 0-360 is 180 HP... Lycoming posts a 293 lb weight for it....

Guys , That is a striiped down, almost bare motor.... Add all the components needed for it to actually run. like baffles, starter, intake system, fuel system, exhaust system, alternator, mags, ignition harness, oil, flywheel, prop, oil cooler.. etc, etc, etc....... I have taken a complete. running 0-360 lycoming off a flying plane and weighed it and it is WAY more then 293 lbs.... Almost 100lbs more......

If we are going to argue, then we need to add apples to apples..... IMHO..

 

Agree. I consider the need to design a new airframe just for the engine to be just part of using an auto conversion; that is probably a deal breaker for many people, but I'm basically a dreamer, I'm mainly looking at potential although there are people like Stol and others that do make it work.

 

That is one problem with talking engines in general even, unless you've actually weighed one, it's difficult to get a realistic number. I weighed a Corvair that I have with the cooling tin and fan on, but no flywheel, and it was just about 312 lb. All of that junk does add up..

 

Yes, that's one area where we all hit the wall. The data really isn't out there. However, if comparing direct drive to direct drive, I think it is a solid bet that a 200 Lyc is going to beat a 200HP V-8 in power to weight. And the reason of course is that the V-8 power does not scale like a Lycoming. The LS family ranges in displacement from 4.8 to over 7 liters, yet retains the exact same outer dimensions and nearly the same weight. OTOH, adding power to a Lyc means adding substantial real estate in the form of a longer case and crank as well as additional cylinders. When going from 360 to 720 inches in a Lyc means literally doubling the overall size and weight of the engine.

But I think I dragged us down this aircraft vs V-8 rabbit hole and that was not my intent. My intent was to illustrate/question what I perceive to be an unfavorable configuration (cammer vs. pushrod) from a power to weight perspective. As I said earlier, the cammer adds a lot of trash to the engine that does not help an aircraft. It's like sticking with VVT on the LS series... The nearly constant RPM requirement does not benefit from that complexity. Will a cammer fly? Sure... But there are more efficient choices (Based on my admittedly limited knowledge of every possible V-8 configuration available today).

 

Sadly the real documented weight numbers are surprisingly very rare considering how many times engines are moved around in workshops and also transported.

There is a very unreliable long list of engine weights that has been on the net for years, pay no attention to it.

The only weight that counts is a "running state" engine sitting on scales with picture evidence so if anyone can remember to do that in the future would be a benefit for all.

 

Yep, it has always been difficult to find solid weight numbers for engines in "running state". I like to look at the total powerplant package weight, including engine, re-drive if applicable, prop, spinner, exhaust, and all cooling system components. And don't forget oil coolers, fuel filters and pumps, dry sump oil tanks (if applicable) and all those oil hoses, full of oil. The weight adds up quickly.

Our most recent Radial Rocket RG build used a 425 HP M-14PF with a four blade MT CS prop. Powerplant package weight for this setup is easily 700 pounds = 1.65 lbs/hp. Plenty of performance with this engine.

The P85 variant of this same airframe will be using an LSx V8. I'll be sure to weigh this package. Performance comparison will be interesting I think!

 

Thought you were going with a traditional SBC... Did you change your mind or was the LS the plan all along?

 

Original intent was to use the traditional SBC, but it turns out that the $ are essentially the same for a ready to go stroker in the 400 cid range, for either engine architecture (400 cid meets our minimum shp power goal without buzzing the engine). In this light it makes sense to go with the more advanced LS engineering, with ignition and fuel set up with some redundancy. Future power increases look to be easier with the LS design as well.

Jeff

 

PSRU or DD?

In any case, looking forward to updates!

 

PSRU. I think DD V8 is a good low cost option to get in the air, however for the P85 we want the power and competitive engine hp/wt that you get when you spin up a V8 into the 3500- 5000 rpm range.

Jeff Ackland
Altitude Group LLC
About The Radial Rocket

 

Getting way off the path here, but what ever became of the BBC that came off the nose of the Legend prototype?

 

Sold to a local drag racer IIRC.