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The engine is the size of a push mower. > XTS-210 is about the size of a basketball, weighs in at 19 kg (42 lb), and displaces 210 cc. So you are talking abou

The engine is the size of a push mower. > XTS-210 is about the size of a basketball, weighs in at 19 kg (42 lb), and displaces 210 cc. So you are talking about a 26HP lawn mower. While the Camry might make more power at its normal size. It would not if you scaled it down to the size of a basketball. I'm guessing it would make 1-3HP at that size.

93po 3y ago
A Traxxas 5407 TRX 3.3 engine used in RC cars makes 1.42 horsepower, weighs 305 grams, and fits in the palm of your hand. This is 1hp per 0.46 pounds of engine weight, nearly three times better than the camry engine. Granted an RC engine runs on a mixture of fuel and nitromethane, and doesn't have any reasonable durability compare to a Camry engine. But it also only costs $200.
- seabird 3y ago
  You can't just make the Traxxas 18x bigger and get linear performance improvement. Trying to compare power/weight between engines with radically different weight constraints is silly.
  - 93po 3y ago
    Ok, a Kawasaki H2R engine makes 326 horsepower and weighs about 160 pounds running regular fuel. That's almost identical to the Traxxas - 1hp for 0.49 pounds.
    - seabird 3y ago
      That engine is 4x heavier and supercharged. You're not comparing apples to apples.
      - 93po 3y ago
        my point is that this ratio exists both much smaller and also somewhat larger. it makes sense this same ratio would be possible in the middle of the two as well. also diesels have super/turbo chargers all the time on production engines, why is that cheating?
  - syrrim 3y ago
    If you had 18 such engines it would get you precisely 18x the performance, at precisely 18x the weight.
    - aidenn0 3y ago
      And precisely 1/18 the MTBF
      - pas 3y ago
        but it fails gracefully, right? (only one engine fails at a time) it's like RAID, great until the RAID card itself fails
        aidenn0 3y ago
        It's probably most like losing power in a single cylinder; the effects vary from engine to engine.
        jacquesm 3y ago
        They tend to seize and when they do and you gang them they'll likely break stuff in the other ones unless you add a freewheel or some other luxury like that.
      - 93po 3y ago
        In a way, sure. Often when a car engine fails people just replace it. If you were to replace all 18 when the first one failed, the same way you would with a regular car engine, it's not 1/18 the MTBF. And if it was just 1 failing prematurely and you replaced only that one, you also see that same dynamic with car engines when a single component of it fails that's worth fixing.
    - Retric 3y ago
      No, because you would need to add structural elements, some way of combining power output, and cooling if you’re aiming for a similar form factor.
- cjbgkagh 3y ago
  I've read about a lot of people complaining about the difficulty of getting the mixture right, perhaps that might be a show stopper for a UAV that must reliably work unattended for a long time. Though the military should also be able to get such mixtures down to a science - so I don't know.
- kortex 3y ago
  > Granted an RC engine runs on a mixture of fuel and nitromethane That's a huge difference. The main limiting factor in engine power is mass air flow, not fuel. Engines are as much air pumps as they are containers for extracting expansion from explosions. Nitromethane provides extra oxidizer in liquid form, putting nitro engines in some ways closer to rocket engines in terms of power-to-weight ratio.
- m463 3y ago
  I'm not familiar with that engine, but I remember having little glow-plug engines and they didn't even have piston rings. (and were not efficient)
ww520 3y ago
The Camry engine has 4-6 cylinders for its size. A single cylinder is not much bigger than a basket ball.
bluGill 3y ago
Every motorcycle mechanic I've seen has a sign in the shop: speed costs money, how fast do you want to go. That sign isn't referring to the costs to modify an engine to go faster so much as the cost to constantly rebuild the engine after they modify it to go fast. I've seen two identical engines, one rebuilt to stock and one rebuilt to max speed - the cost for both rebuild jobs was about the same (the parts for speed were more - but not much more compared to the labor which was the same), but the engine rebuilt to stock ran for thousands more hours, while the one rebuilt for speed has the mechanic bragging that it lasted a whole 80 hours!
- sliken 3y ago
  My dad used to say the perfect race car would explode into a million pieces just after it crossed the finish line. Anything more robust is wasted weight.
- 0cf8612b2e1e 3y ago
  What is done to modify an engine for speed? What kind of improvement can be seen for speed (accelerates XX faster? YY higher top speed)?
  - sliken 3y ago
    Normal cars are designed from wide temperature ranges (something like -30F to 130F), -100 to 14k feet altitude, with a wide range of sand, dirt, snow, ice, hail and a wide variety of roads surfaces and steepness. Generally they seem designed to last 100k miles under normal use and terrible things don't happen if you forget an oil change. You can do a chip tune that might get you more HP across a wide range of RPMs, but you won't be as robust, will need maintenance more often, and will likely wear through oil, gas, differentials, clutches, and related more quickly. There's MANY things you can do that all basically come down to burning more gas+o2 in less time. Higher intake airflow (turbo, supercharger, better/missing air filters, scoops, etc), bored out cylinders for more engine displacement, more gas (increased fuel pressure/pumps), increased RPMs, and decreased exhaust pressure (better pipes, decreased or missing cats). Trick is, more gas+o2 burned = more heat, more wear, more stress, hotter oil, faster clutch wearing, faster tire wearing, and generally faster brake wearing. Turbos are driven by exhaust, spin at crazy RPMs, increase air intake pressure, and generally are harder on the engine and oil and make cooling more of an issue. Higher RPMs require more precise timing, better valves+springs, better balanced cam shafts, etc. So what might seem like a cheap/easy change like increasing turbo boost from 10psi to 15psi might like a good idea, but have major impact on engine life and maintenance costs. A single blown head gasket from the increased temp, increased vibration, and increased pressure can be very expensive. Much like CPUs of today, cars are generally designed carefully for their performance level and there's less spare performance left to be easily tweaked. Much like how older CPUs could be overclocked for substantial performance gains. Now both cars and CPUs will throttle if they don't have enough cooling or any of numerous other sensors detect potential problems. It's pretty common these days to see a car with 300hp, but 350hp for up to 10 seconds before the sensors reel you back in.

93po 3y ago

A Traxxas 5407 TRX 3.3 engine used in RC cars makes 1.42 horsepower, weighs 305 grams, and fits in the palm of your hand. This is 1hp per 0.46 pounds of engine weight, nearly three times better than the camry engine. Granted an RC engine runs on a mixture of fuel and nitromethane, and doesn't have any reasonable durability compare to a Camry engine. But it also only costs $200.

seabird 3y ago
You can't just make the Traxxas 18x bigger and get linear performance improvement. Trying to compare power/weight between engines with radically different weight constraints is silly.
- 93po 3y ago
  Ok, a Kawasaki H2R engine makes 326 horsepower and weighs about 160 pounds running regular fuel. That's almost identical to the Traxxas - 1hp for 0.49 pounds.
  - seabird 3y ago
    That engine is 4x heavier and supercharged. You're not comparing apples to apples.
    - 93po 3y ago
      my point is that this ratio exists both much smaller and also somewhat larger. it makes sense this same ratio would be possible in the middle of the two as well. also diesels have super/turbo chargers all the time on production engines, why is that cheating?
- syrrim 3y ago
  If you had 18 such engines it would get you precisely 18x the performance, at precisely 18x the weight.
  - aidenn0 3y ago
    And precisely 1/18 the MTBF
    - pas 3y ago
      but it fails gracefully, right? (only one engine fails at a time) it's like RAID, great until the RAID card itself fails
      - aidenn0 3y ago
        It's probably most like losing power in a single cylinder; the effects vary from engine to engine.
        jacquesm 3y ago
        They tend to seize and when they do and you gang them they'll likely break stuff in the other ones unless you add a freewheel or some other luxury like that.
    - 93po 3y ago
      In a way, sure. Often when a car engine fails people just replace it. If you were to replace all 18 when the first one failed, the same way you would with a regular car engine, it's not 1/18 the MTBF. And if it was just 1 failing prematurely and you replaced only that one, you also see that same dynamic with car engines when a single component of it fails that's worth fixing.
  - Retric 3y ago
    No, because you would need to add structural elements, some way of combining power output, and cooling if you’re aiming for a similar form factor.
cjbgkagh 3y ago
I've read about a lot of people complaining about the difficulty of getting the mixture right, perhaps that might be a show stopper for a UAV that must reliably work unattended for a long time. Though the military should also be able to get such mixtures down to a science - so I don't know.
kortex 3y ago
> Granted an RC engine runs on a mixture of fuel and nitromethane That's a huge difference. The main limiting factor in engine power is mass air flow, not fuel. Engines are as much air pumps as they are containers for extracting expansion from explosions. Nitromethane provides extra oxidizer in liquid form, putting nitro engines in some ways closer to rocket engines in terms of power-to-weight ratio.
m463 3y ago
I'm not familiar with that engine, but I remember having little glow-plug engines and they didn't even have piston rings. (and were not efficient)

ww520 3y ago

The Camry engine has 4-6 cylinders for its size. A single cylinder is not much bigger than a basket ball.

bluGill 3y ago

Every motorcycle mechanic I've seen has a sign in the shop: speed costs money, how fast do you want to go. That sign isn't referring to the costs to modify an engine to go faster so much as the cost to constantly rebuild the engine after they modify it to go fast. I've seen two identical engines, one rebuilt to stock and one rebuilt to max speed - the cost for both rebuild jobs was about the same (the parts for speed were more - but not much more compared to the labor which was the same), but the engine rebuilt to stock ran for thousands more hours, while the one rebuilt for speed has the mechanic bragging that it lasted a whole 80 hours!

sliken 3y ago
My dad used to say the perfect race car would explode into a million pieces just after it crossed the finish line. Anything more robust is wasted weight.
0cf8612b2e1e 3y ago
What is done to modify an engine for speed? What kind of improvement can be seen for speed (accelerates XX faster? YY higher top speed)?
- sliken 3y ago
  Normal cars are designed from wide temperature ranges (something like -30F to 130F), -100 to 14k feet altitude, with a wide range of sand, dirt, snow, ice, hail and a wide variety of roads surfaces and steepness. Generally they seem designed to last 100k miles under normal use and terrible things don't happen if you forget an oil change. You can do a chip tune that might get you more HP across a wide range of RPMs, but you won't be as robust, will need maintenance more often, and will likely wear through oil, gas, differentials, clutches, and related more quickly. There's MANY things you can do that all basically come down to burning more gas+o2 in less time. Higher intake airflow (turbo, supercharger, better/missing air filters, scoops, etc), bored out cylinders for more engine displacement, more gas (increased fuel pressure/pumps), increased RPMs, and decreased exhaust pressure (better pipes, decreased or missing cats). Trick is, more gas+o2 burned = more heat, more wear, more stress, hotter oil, faster clutch wearing, faster tire wearing, and generally faster brake wearing. Turbos are driven by exhaust, spin at crazy RPMs, increase air intake pressure, and generally are harder on the engine and oil and make cooling more of an issue. Higher RPMs require more precise timing, better valves+springs, better balanced cam shafts, etc. So what might seem like a cheap/easy change like increasing turbo boost from 10psi to 15psi might like a good idea, but have major impact on engine life and maintenance costs. A single blown head gasket from the increased temp, increased vibration, and increased pressure can be very expensive. Much like CPUs of today, cars are generally designed carefully for their performance level and there's less spare performance left to be easily tweaked. Much like how older CPUs could be overclocked for substantial performance gains. Now both cars and CPUs will throttle if they don't have enough cooling or any of numerous other sensors detect potential problems. It's pretty common these days to see a car with 300hp, but 350hp for up to 10 seconds before the sensors reel you back in.