wingandprop
Member
Hello everybody,
I know from reading this forum that some folks get a bit testy when they see others making technically inaccurate statements about engine or accessory design, installation, or function. That will not be a problem with this post. I say that because I am equipped with a nearly universal lack of knowledge about any of the above issues and will make no claim of knowing exactly how just about anything works. What little I do know is just enough to get myself in trouble. Indeed, it is my hope to stay out of trouble by getting your input on some very basic questions. Although the engine I am interested in is a Ford, my questions are not specific to that engine, so I have placed this question here in the general discussion.
To start with, my goal is to build an Airdrome Airplanes SE-5a. This actually avoids a lot of the preliminary arguments you sometimes see about whether an automotive engine is or is not a good choice for the airplane in the first place as the Hispano Suiza engine used in the original design was largely derivative of pre WW1 automobile racing engines. The arguments that are often raised about weight and power ratios for an automobile engine vs. a certificated engine don’t apply either because the original 200 hp Hisso was about 450 pounds, far heavier than the engine I am hoping to use, yet the new engine will deliver the same power as did the original Hisso. The debate over whether a re-drive should or should not be used, it’s weight, etc., also doesn’t have much impact as the original design used a re-drive, but one considerably heavier and less reliable than what is available today (it had the occasional, and rather unpleasant, habit of leaving the airplane and taking the propeller with it). In short, all the arguments you hear about whether an automotive engine is or is not a good idea have pretty much been pre-empted by the history of this design and the fact that I am not trying to maximize performance, but to duplicate it (at least to some degree).
The engine I am looking at is the normally aspirated Ford Duratec 37, the V-6 engine used in the Mustang and the F-150 pick up truck. It has 302 bhp which I would de-rate to 200 hp at approximately 4,000 rpm (based upon the various dyno tests I have reviewed for this engine). A precise weight is hard to come by, but it appears that this engine would be approximately 340 pounds.
Ford 3.7L V6 Specifications
Type: 3.7L DOHC 24-valve V-6
Manufacturing Location: Lima Engine Plant, Ohio
Configuration: 60-degree V-6, aluminum block and heads
Intake Manifold: Composite, slit plenum
Exhaust Manifold: Cast iron
Crankshaft: Forged steel
Redline: 6700 rpm
Throttle Body: 65 mm, electronic
Valve train: DAMB, 4 valves per cylinder, intake variable camshaft timing
Valve Diameter: Intake: 37mm
Exhaust: 31 mm
Pistons: High temperature cast aluminum alloy with low-friction coated skirts, low-tension rings
Connecting Rods: Cracked-powder metal
Ignition: Pencil coil
Bore x Stroke: 3.7 x 3.4 in/96.5 x 86.7 mm
Displacement: 224 cu in/3.696 cc
Compression Ratio: 10:5:01
Horsepower: 302 @ 6250 rpm
Horsepower per Liter: 71.5 (estimated)
Torque: 280 lb-ft @ 4500 rpm
Recommended Fuel: 87 Octane
Fuel Injection: Sequential multiport fuel injection
Oil Capacity: 5.5 quarts, with filter
* table from an earlier post by J3cubav8R re this engine, but it matches what I have seen elsewhere as provided by Ford (at least I tried to put it in table form)
The re-drive would be the Ballistic Gear Reduction unit Ballistic Gear Drives Gear Reduction Units for Airboat Applications . This unit has a long and reliable history in airboats and has also been used successfully by the developers of the (now awarded) STC permitting use of a Corvette engine in a Cessna 172. The re-drive would turn a four bladed 9 ½ foot diameter propeller using a 2.1:1 or 2.3:1 reduction ratio. The choice of gear ratio would depend on actual engine output as measured on a dynamometer. Original rpm with this size prop was approximately 1750 to 1800 rpm. The above reduction ratios should produce slightly lower rpm, but it will be fairly close. Use of a 1.8:1 ratio would let the prop spin too fast at approximately 2222 rpm at which point the blade tips would either be supersonic or very close to it. The original Hisso powered SE used a four bladed wooden prop and I would like to have the same, but that is not crucial by any means.
Ready for the questions? The most obvious one is whether there is anything about this engine or drive or the combination of the two (or the prop either for that matter) that raise any red flags? I have tried to think through these selections, but I am not an engineer, nor am I a mechanic nor have I ever done this before. My idea of fixing my car is to drive it to Christian Brothers Garage (whereupon I congratulate myself for getting there without having lost anything along the way). To say I am mechanically gifted would be an overstatement. The Airdrome SE, however, is a very simple design, as airplanes go, and it has good support from its designer. Also, I do pick up on the basics pretty quickly and after reviewing this site and others in some detail, and having reviewed information about the original design, having talked to the designer about his version of the SE and his views on engine options, weight and balance, etc., this seems to work. Frankly, the prop is the item I have done the least thinking about. Rightly or wrongly, I figure if it worked in 1917, it will probably work now. Am I missing anything obvious on my basic selections?
The next question may be a real hoot to you all, but it is one that has worried me considerably. In view of the heavy computerization of modern automobile engines, how do I go about modifying the computer to work properly in an airplane, or do I even try? Do I just throw it away and go with an iron, or in this case aluminum, dumb engine? Can you even do that nowadays? My automobile’s mechanic says I can, although you will obviously lose a lot of the efficiencies made possible by the computer systems. While he says that can be done, he has never actually done it himself and I tend to prefer experience to theory. My particular concern is with some of the “safety” designs of a modern automobile engine, like the protective measures that will shut the engine down rather than letting it significantly overheat. Bad idea in an airplane. An automatic engine shut off in order to protect the engine has the real potential to reverse my required priority (people first, engine last). That outcome would be reminiscent of a similar reordering of priorities in the F-16 some years ago. It resulted in the death of an excellent pilot, a previous ANG winner of the USAF Gunsmoke competition, when his attempts to pull out at low altitude were overruled by the aircraft’s flight controller in order to help extend the wing spars’ life span. So, how do you rework the computer in an automotive engine? Are there kits or programs that will take care of that? Are there people who do that? Do you just gut it? I am not averse to finding experts and paying them do their stuff. (Which, ultimately, is why I’m here in the first place, but without the paying part.)
Before I go further I should mention that I watched Stol’s superb review and explanation of his engine installation in his own airplane. It was extremely instructive and, to a novice like myself, incredibly intimidating. He points out so many issues that have to be considered and, while some of them won’t necessarily apply to my airplane (for instance, the cooling issue in my airplane is much simpler as my radiators are right there on the nose), others very clearly will apply. He pointed out how his mixture control was installed, but he did not say anything about mags, presumably because he retained the engine’s electronic ignition. Can mags be installed into an auto engine at an almost reasonable cost? I know electronic ignition is far more efficient, but I am still a bit leery of it in an airplane. I like the redundancy and mechanical reliability of mags vs. electronic ignition. Having been struck by lightning while driving my electronically dependent car a number of years ago (a convertible no less), I found it was very nearly totaled by that encounter and crazy unexplained electrical problems continued to pop up for years afterward despite the best efforts of an exceptionally good mechanic. Those problems eventually forced me to get rid of the car when its engine began shutting down spontaneously at inopportune moments, typically refusing any offers to restart for at least 45 minutes to an hour. Obviously not what you want to be worried about in an airplane and that was twenty years ago when engines were far less dependent on computers than they are now. So I am not a big fan of electronics over mechanical functions on the real backbone issues. I know mags are doable with enough money (as is almost everything), but are mags a bad idea in a modern auto engine? Why?
What about carb heat? I have read some articles asserting that carb heat wasn’t needed in current auto engine conversions because you won’t get carb ice, presumably because they are fuel injected, but Stol pretty well put that suggestion to rest by describing in detail how his system allows him to identify potential carb icing. Yet he didn’t mention actually having carb heat himself. Why? I assume Stol was talking about carb icing in a throttle body injector, correct? Would a throttle body injector be a good idea versus the multiport fuel injectors on this engine? Can you change from multiport injectors to a throttle body injector? Can you even have a mixture control in an injected engine without a throttle body injector system? Do throttle body injectors require carb heat? Once again, just to establish my card carrying Luddite status, could you use a carb on this engine? This once again harkens back to my distrust of an electronic system. (Do you see an emerging pattern?) Carbs are much simpler than is fuel injection, even than a throttle body injector, and more reliable, but are they even minimally functional in an application like this? Would there be a loss (or gain?) of horsepower if you converted to a carb? (I told you these questions were basic.)
I will stop for now as I don’t want anyone to hurt themselves by laughing so hard that they fall out of their chairs. That may be too late, but I will save my next questions until after you all have regained your composure.
Thanks. And please be gentle.
Matt
I know from reading this forum that some folks get a bit testy when they see others making technically inaccurate statements about engine or accessory design, installation, or function. That will not be a problem with this post. I say that because I am equipped with a nearly universal lack of knowledge about any of the above issues and will make no claim of knowing exactly how just about anything works. What little I do know is just enough to get myself in trouble. Indeed, it is my hope to stay out of trouble by getting your input on some very basic questions. Although the engine I am interested in is a Ford, my questions are not specific to that engine, so I have placed this question here in the general discussion.
To start with, my goal is to build an Airdrome Airplanes SE-5a. This actually avoids a lot of the preliminary arguments you sometimes see about whether an automotive engine is or is not a good choice for the airplane in the first place as the Hispano Suiza engine used in the original design was largely derivative of pre WW1 automobile racing engines. The arguments that are often raised about weight and power ratios for an automobile engine vs. a certificated engine don’t apply either because the original 200 hp Hisso was about 450 pounds, far heavier than the engine I am hoping to use, yet the new engine will deliver the same power as did the original Hisso. The debate over whether a re-drive should or should not be used, it’s weight, etc., also doesn’t have much impact as the original design used a re-drive, but one considerably heavier and less reliable than what is available today (it had the occasional, and rather unpleasant, habit of leaving the airplane and taking the propeller with it). In short, all the arguments you hear about whether an automotive engine is or is not a good idea have pretty much been pre-empted by the history of this design and the fact that I am not trying to maximize performance, but to duplicate it (at least to some degree).
The engine I am looking at is the normally aspirated Ford Duratec 37, the V-6 engine used in the Mustang and the F-150 pick up truck. It has 302 bhp which I would de-rate to 200 hp at approximately 4,000 rpm (based upon the various dyno tests I have reviewed for this engine). A precise weight is hard to come by, but it appears that this engine would be approximately 340 pounds.
Ford 3.7L V6 Specifications
Type: 3.7L DOHC 24-valve V-6
Manufacturing Location: Lima Engine Plant, Ohio
Configuration: 60-degree V-6, aluminum block and heads
Intake Manifold: Composite, slit plenum
Exhaust Manifold: Cast iron
Crankshaft: Forged steel
Redline: 6700 rpm
Throttle Body: 65 mm, electronic
Valve train: DAMB, 4 valves per cylinder, intake variable camshaft timing
Valve Diameter: Intake: 37mm
Exhaust: 31 mm
Pistons: High temperature cast aluminum alloy with low-friction coated skirts, low-tension rings
Connecting Rods: Cracked-powder metal
Ignition: Pencil coil
Bore x Stroke: 3.7 x 3.4 in/96.5 x 86.7 mm
Displacement: 224 cu in/3.696 cc
Compression Ratio: 10:5:01
Horsepower: 302 @ 6250 rpm
Horsepower per Liter: 71.5 (estimated)
Torque: 280 lb-ft @ 4500 rpm
Recommended Fuel: 87 Octane
Fuel Injection: Sequential multiport fuel injection
Oil Capacity: 5.5 quarts, with filter
* table from an earlier post by J3cubav8R re this engine, but it matches what I have seen elsewhere as provided by Ford (at least I tried to put it in table form)
The re-drive would be the Ballistic Gear Reduction unit Ballistic Gear Drives Gear Reduction Units for Airboat Applications . This unit has a long and reliable history in airboats and has also been used successfully by the developers of the (now awarded) STC permitting use of a Corvette engine in a Cessna 172. The re-drive would turn a four bladed 9 ½ foot diameter propeller using a 2.1:1 or 2.3:1 reduction ratio. The choice of gear ratio would depend on actual engine output as measured on a dynamometer. Original rpm with this size prop was approximately 1750 to 1800 rpm. The above reduction ratios should produce slightly lower rpm, but it will be fairly close. Use of a 1.8:1 ratio would let the prop spin too fast at approximately 2222 rpm at which point the blade tips would either be supersonic or very close to it. The original Hisso powered SE used a four bladed wooden prop and I would like to have the same, but that is not crucial by any means.
Ready for the questions? The most obvious one is whether there is anything about this engine or drive or the combination of the two (or the prop either for that matter) that raise any red flags? I have tried to think through these selections, but I am not an engineer, nor am I a mechanic nor have I ever done this before. My idea of fixing my car is to drive it to Christian Brothers Garage (whereupon I congratulate myself for getting there without having lost anything along the way). To say I am mechanically gifted would be an overstatement. The Airdrome SE, however, is a very simple design, as airplanes go, and it has good support from its designer. Also, I do pick up on the basics pretty quickly and after reviewing this site and others in some detail, and having reviewed information about the original design, having talked to the designer about his version of the SE and his views on engine options, weight and balance, etc., this seems to work. Frankly, the prop is the item I have done the least thinking about. Rightly or wrongly, I figure if it worked in 1917, it will probably work now. Am I missing anything obvious on my basic selections?
The next question may be a real hoot to you all, but it is one that has worried me considerably. In view of the heavy computerization of modern automobile engines, how do I go about modifying the computer to work properly in an airplane, or do I even try? Do I just throw it away and go with an iron, or in this case aluminum, dumb engine? Can you even do that nowadays? My automobile’s mechanic says I can, although you will obviously lose a lot of the efficiencies made possible by the computer systems. While he says that can be done, he has never actually done it himself and I tend to prefer experience to theory. My particular concern is with some of the “safety” designs of a modern automobile engine, like the protective measures that will shut the engine down rather than letting it significantly overheat. Bad idea in an airplane. An automatic engine shut off in order to protect the engine has the real potential to reverse my required priority (people first, engine last). That outcome would be reminiscent of a similar reordering of priorities in the F-16 some years ago. It resulted in the death of an excellent pilot, a previous ANG winner of the USAF Gunsmoke competition, when his attempts to pull out at low altitude were overruled by the aircraft’s flight controller in order to help extend the wing spars’ life span. So, how do you rework the computer in an automotive engine? Are there kits or programs that will take care of that? Are there people who do that? Do you just gut it? I am not averse to finding experts and paying them do their stuff. (Which, ultimately, is why I’m here in the first place, but without the paying part.)
Before I go further I should mention that I watched Stol’s superb review and explanation of his engine installation in his own airplane. It was extremely instructive and, to a novice like myself, incredibly intimidating. He points out so many issues that have to be considered and, while some of them won’t necessarily apply to my airplane (for instance, the cooling issue in my airplane is much simpler as my radiators are right there on the nose), others very clearly will apply. He pointed out how his mixture control was installed, but he did not say anything about mags, presumably because he retained the engine’s electronic ignition. Can mags be installed into an auto engine at an almost reasonable cost? I know electronic ignition is far more efficient, but I am still a bit leery of it in an airplane. I like the redundancy and mechanical reliability of mags vs. electronic ignition. Having been struck by lightning while driving my electronically dependent car a number of years ago (a convertible no less), I found it was very nearly totaled by that encounter and crazy unexplained electrical problems continued to pop up for years afterward despite the best efforts of an exceptionally good mechanic. Those problems eventually forced me to get rid of the car when its engine began shutting down spontaneously at inopportune moments, typically refusing any offers to restart for at least 45 minutes to an hour. Obviously not what you want to be worried about in an airplane and that was twenty years ago when engines were far less dependent on computers than they are now. So I am not a big fan of electronics over mechanical functions on the real backbone issues. I know mags are doable with enough money (as is almost everything), but are mags a bad idea in a modern auto engine? Why?
What about carb heat? I have read some articles asserting that carb heat wasn’t needed in current auto engine conversions because you won’t get carb ice, presumably because they are fuel injected, but Stol pretty well put that suggestion to rest by describing in detail how his system allows him to identify potential carb icing. Yet he didn’t mention actually having carb heat himself. Why? I assume Stol was talking about carb icing in a throttle body injector, correct? Would a throttle body injector be a good idea versus the multiport fuel injectors on this engine? Can you change from multiport injectors to a throttle body injector? Can you even have a mixture control in an injected engine without a throttle body injector system? Do throttle body injectors require carb heat? Once again, just to establish my card carrying Luddite status, could you use a carb on this engine? This once again harkens back to my distrust of an electronic system. (Do you see an emerging pattern?) Carbs are much simpler than is fuel injection, even than a throttle body injector, and more reliable, but are they even minimally functional in an application like this? Would there be a loss (or gain?) of horsepower if you converted to a carb? (I told you these questions were basic.)
I will stop for now as I don’t want anyone to hurt themselves by laughing so hard that they fall out of their chairs. That may be too late, but I will save my next questions until after you all have regained your composure.
Thanks. And please be gentle.
Matt
