Comparing Engine Performance: A Look at Volumetric Efficiency and Specific Output

When it comes to evaluating engine performance, one metric that often gets tossed around is volumetric efficiency. This refers to the percentage of air that an engine can draw in during a power stroke, with higher numbers indicating more efficient engines. However, as the speaker notes, with clever intake tuning, it's possible to extract better than 100 volumetric efficiency from certain engines.

The speaker mentions that Ferrari engineers might be able to tell you what this number is, but for most people, it's not something that can be easily measured or compared. Instead, we're left to rely on theoretical calculations and real-world data from various sources. One example mentioned is the Honda S2000, which has a surprisingly high power-to-weight ratio despite its relatively small engine size.

Another interesting comparison comes from the Devil 16, an 8.2 liter top fuel vehicle that allegedly produces 10,000 horsepower. When corrected for fuel type and boost, this puts it in the range of 94-135 horsepower per liter – a far cry from the Honda S2000's 308 horsepower per liter. However, as the speaker notes, some estimates suggest that this number could be even higher, with some sources putting the actual power output at up to ten thousand horsepower.

This highlights the challenges and complexities involved in calculating specific output for engines like these. Different factors come into play, such as fuel type, boost levels, and compression ratios, making it difficult to make a straightforward comparison between engines.

To illustrate this point further, let's take a look at an F1 vehicle that can push the boundaries of what's possible with engine performance. In 2006, Toyota released a 2.4 liter engine that produced around 740 horsepower when spinning at an astonishing 19,000 rpm – equivalent to a whopping 308 horsepower per liter.

The key factor here is the ability to spin the engine so high, which allows it to extract more power from a given volume of air. However, this requires significant tuning and engineering expertise to achieve. As a result, comparisons between different engines become complicated and nuanced, requiring careful consideration of factors beyond just specific output.

While comparing engine performance can be tricky, it's certainly an interesting exercise that can reveal some surprising insights into the capabilities of modern engines. Whether you're evaluating production cars, motorcycles, or even top fuel vehicles, understanding how to measure and compare engine efficiency is crucial for making informed decisions about your own vehicle or investment.

"WEBVTTKind: captionsLanguage: enhello everyone and welcome in this video we're going to be talking about who makes the best engine and this video has been inspired by uh people like you in the comments um who like to battle it out talking about which you know manufacturer is making the best engine um and a lot of times what i'll see people say is you know something like oh the bugatti veyron it only makes a thousand horsepower with eight liters while the koenigsegg you know one to one makes 1300 with five liters so clearly the koenigsegg is better and so what people are doing here is comparing uh specific outputs of different engines and you know that's that's kind of fine to do i mean it's interesting to think about it's not really you know meaningful uh but i thought if people are going to be comparing these you might as well try to get as close as you can as apples to apples rather than what people typically do which is apples to oranges and comparing them so we're going to be doing three things in this video first i'm going to go through some very simple math that we're going to use in order to get everything on the same playing field then we're going to look at a bunch of different cars and see how they kind of stack up against each other and then at the end i'm going to tell you why all of this is meaningless and so just getting right into it we're going to start doing the math for the koenigsegg one to one just because it's kind of a cool example to use and so the koenigsegg one to one has a five liter engine producing 1341 horsepower so what is its specific output well we take 1341 we divide that by 5 and that gives us 268.2 horsepower per liter okay great so now we know how much horsepower per liter it makes now if we were to compare that to the bugatti veyron which is a thousand horsepower we're talking the original one out of an 8 liter so 125 horsepower per liter clearly much less than this but we're going to get into some different aspects so we want to correct for the amount of boost used essentially what we're trying to figure out here is how many liters of air are going into that engine so if you have a one liter naturally aspirated engine and it has a volumetric efficiency of a hundred percent that means you're gonna have one liter of air in there now if you have boost you're adding more air on top of that so that's what we're trying to figure out so in order to find out our multiplier for the leaders of the engine we're going to take atmospheric pressure which is 14.7 psi plus the amount of boost this vehicle has and then divide that by atmospheric pressure and that'll tell us how many more times how many more times of air this has versus a naturally aspirated engine of its size so for this engine we have 14.7 plus 26.1 that's how much boost the koenigsegg one to one uses divided by 14.7 psi and this gives us 2.77 now we're going to multiply that number by the original amount of liters we have to figure out how big of an engine this would be if it were naturally aspirated and had a volumetric efficiency of 100 and that gives us 13.9 so this is the equivalent of a 13.9 liter engine if it were naturally aspirated and had a volumetric efficiency of 100 so now we can take 1341 and divide it by 13.9 and then that gives us 96.8 horsepower per liter so this doesn't now sound as impressive as 268 because you're accounting for the amount of boost that this engine has to try and kind of level the playing field so that you can compare this against naturally aspirated engines or engines that have more or less boost than it now the final thing we're going to correct for is the compression ratio so vehicles with higher compression ratios will make more power because they're more efficient vehicles with lower compression ratios will make less power because they're less efficient so what i'm going to choose to do in this video is normalize everything to having a compression ratio of 10 to 1. so the thermal efficiency of an engine with a compression ratio of 10 to 1 you get from this equation here 1 minus 1 over the compression ratio raised to k minus 1 k is going to be 1.35 now i have a whole separate video explaining where this equation comes from if you're interested and the relationship between compression ratio and thermal efficiency so i'm not going to go over it in too much detail here but we're going to normalize the data data for a compression ratio of 10 to 1 giving us a thermal efficiency of 55.33 and so if we're to do this math for the koenigsegg it will give us 1 over 1 divided by the compression ratio which is 9 to 1 and then that's going to be raised to k 1.35 minus 1. so this is going to give us an efficiency of 53 so we have our equation here the efficiency at 10 which is 55.33 divided by our efficiency which is 53.7 divide that and set that equal to rather our horsepower over here which is 96.6 horsepower per liter and that will give us our final horsepower per liter so because what we're doing here now this is going to give us 99.65 so you'll notice a slight increase and the reason being is because the compression ratio is fairly low now they did that because of knock you know if you get higher compression ratios you start to run into nut but we just want to make sure the the playing field is level and we get all these items equal for all the different cars which we're about to compare so it's going to get a slight bump in power if we were to give it a compression ratio of 10 to 1 and then some vehicles which have much higher compression ratios are going to see a slight power reduction once we tune them down to a compression ratio of 10 to 1. so now let's get into a bunch of different cases okay so here we have a bunch of data we've got 10 different vehicles here on the left and then i've broken it down we've got the number of liters of the engine the size of the engine how much horsepower it makes how much boost the engine has what the compression ratio is what it's normal horsepower per liter uh the specific output is then the specific output corrected for boost and then the specific output corrected for compression ratio and boost and so we've got these 10 different vehicles here and it's pretty interesting you know everything kind of falls into a much more normal range i mean if you look at this column it ranges quite a bit and then if you look at this column here it keeps it more in this uh same ballpark area and that's because you're kind of comparing more apples to apples so the koenigsegg one-to-one still you know more impressive from a per liter standpoint than the bugatti veyron almost 100 horsepower per liter versus 57.8 even the subaru sti getting more than that after all these corrections uh hennessey venom gt quite a powerful engine at 79. hot s2000 this is really impressive about 117 horsepower per liter and this is from a vehicle back in you know 1999 uh that's able to pump out that much power the most impressive ones as far as production cars uh that i've calculated here for i-458 and 458 special which ups the compression ratio a bit they did a few other changes and that after all the corrections gets you to 121.3 horsepower per liter obviously way higher than all of the other things out here now what this isn't showing is there's there's a couple things about why this ferrari is going to be higher even in this uh what i'm calling apples to apples comparison because it hasn't been corrected for rpm so this is obviously spinning at a much higher rpm and that gives it the ability to make more power and also i don't really believe that their volumetric efficiency is going to be at 100 i believe they're kind of kind of have a supercharging effect um you know with some clever intake tuning you can get better than 100 volumetric efficiency and as a result i haven't compensated for that i don't know what that number is um only probably ferrari engineers could tell you that and so you know this is what's i think going to give them a little bit of a boost that's probably the same case for the honda s2000 but what's really cool about these is if you compare the s2000 to the 458 i mean it's only off by one horsepower there as far as horsepower per liter so showing you know what honda did with a very affordable car is is pretty wild as far as how much power per liter they were able to extract from it so some other kind of fun examples in here the devil 16 which has a 12.3 liter engine that supposedly produces 4500 which they proved with the dyno supposedly but anyways so that would be 367 horsepower per liter but if you do the correction based on boost i don't know what the compression ratio of that vehicle is uh 106. so you know it does sound feasible it's not like this number is impossible based on how much boost they're saying and based on the leaders of the engine so it very well could be valid a top fuel vehicle this one's different because i'm correcting for fuel type and none of the other ones i've corrected for fuel type i'm just assuming they all use you know premium gas and that works for them top fuel an 8.2 liter engine producing 10 000 horsepower 1200 per liter but if you correct for fuel type and correct for how much boost it has it puts you in the 94 to 135 depending on how much power you believe it has some estimates say seven thousand some up to ten thousand uh so a much more normal range i actually have a video where i break down the math for this exactly if you're interested in that i'll include a link in the video description and then finally we'll end with an f1 vehicle just to kind of show you know what's possible and this uh very much so plays into this rpm and volumetric efficiency back in 2006 a toyota 2.4 liter producing around 740 horsepower spinning at 19 000 rpm 308 horsepower per liter from a naturally aspirated engine so that's absolutely insane and you know one of the biggest reasons for that is because it's able to spin up so high uh such a high rpm so ideally you'd want to compare things at the same rpm and say okay how much power are they making per liter at this exact rpm but everything's going to be tuned for different rpms so that's you know very challenging to do hence why i didn't do it and also that information is probably not all that available but regardless it's kind of fun you can plug in numbers for your own car or other cars out there i think another thing motorcycles would probably have some really impressive numbers and that's as a result like i mentioned of spinning up so high so you know you're hitting 15 000 rpm um you're getting so many power strokes uh in that duration of time and so the horsepower is going to go up um so that's that's something that would be interesting to check out but you can use the math i showed you uh before this segment of the video where you know you can plug in your own numbers for any different vehicle out there and kind of see where it stacks up and see what's impressive so i would be curious uh to know from people out there if they know of anything you know that's getting higher out there as a production car i'm sure there's going to be some motorcycles that can be this but i would be curious if there are production cars out there that could beat that 121 number now as promised i told you that at the end of this video the third segment was going to be telling you why all of this is pointless and indeed it is pointless and i think you know the reason you shouldn't just compare engines and say one's better than the other simply because it has a higher specific output that doesn't tell you which engine's lighter which engine is making you know more power per pound uh which engine has a lower center of gravity which engine has better structural rigidity which engine is going to last longer and you can go on forever so there's all kinds of different variables that determine um you know how good is an engine and simply comparing specific output is fairly silly if that's the dictating the driving factor of you know which one is the best but regardless it's interesting to compare them and see who's able to extract the most energy out of a certain amount of a certain volume of air so thank you guys for watching and if you have any questions or comments feel free to leave them belowhello everyone and welcome in this video we're going to be talking about who makes the best engine and this video has been inspired by uh people like you in the comments um who like to battle it out talking about which you know manufacturer is making the best engine um and a lot of times what i'll see people say is you know something like oh the bugatti veyron it only makes a thousand horsepower with eight liters while the koenigsegg you know one to one makes 1300 with five liters so clearly the koenigsegg is better and so what people are doing here is comparing uh specific outputs of different engines and you know that's that's kind of fine to do i mean it's interesting to think about it's not really you know meaningful uh but i thought if people are going to be comparing these you might as well try to get as close as you can as apples to apples rather than what people typically do which is apples to oranges and comparing them so we're going to be doing three things in this video first i'm going to go through some very simple math that we're going to use in order to get everything on the same playing field then we're going to look at a bunch of different cars and see how they kind of stack up against each other and then at the end i'm going to tell you why all of this is meaningless and so just getting right into it we're going to start doing the math for the koenigsegg one to one just because it's kind of a cool example to use and so the koenigsegg one to one has a five liter engine producing 1341 horsepower so what is its specific output well we take 1341 we divide that by 5 and that gives us 268.2 horsepower per liter okay great so now we know how much horsepower per liter it makes now if we were to compare that to the bugatti veyron which is a thousand horsepower we're talking the original one out of an 8 liter so 125 horsepower per liter clearly much less than this but we're going to get into some different aspects so we want to correct for the amount of boost used essentially what we're trying to figure out here is how many liters of air are going into that engine so if you have a one liter naturally aspirated engine and it has a volumetric efficiency of a hundred percent that means you're gonna have one liter of air in there now if you have boost you're adding more air on top of that so that's what we're trying to figure out so in order to find out our multiplier for the leaders of the engine we're going to take atmospheric pressure which is 14.7 psi plus the amount of boost this vehicle has and then divide that by atmospheric pressure and that'll tell us how many more times how many more times of air this has versus a naturally aspirated engine of its size so for this engine we have 14.7 plus 26.1 that's how much boost the koenigsegg one to one uses divided by 14.7 psi and this gives us 2.77 now we're going to multiply that number by the original amount of liters we have to figure out how big of an engine this would be if it were naturally aspirated and had a volumetric efficiency of 100 and that gives us 13.9 so this is the equivalent of a 13.9 liter engine if it were naturally aspirated and had a volumetric efficiency of 100 so now we can take 1341 and divide it by 13.9 and then that gives us 96.8 horsepower per liter so this doesn't now sound as impressive as 268 because you're accounting for the amount of boost that this engine has to try and kind of level the playing field so that you can compare this against naturally aspirated engines or engines that have more or less boost than it now the final thing we're going to correct for is the compression ratio so vehicles with higher compression ratios will make more power because they're more efficient vehicles with lower compression ratios will make less power because they're less efficient so what i'm going to choose to do in this video is normalize everything to having a compression ratio of 10 to 1. so the thermal efficiency of an engine with a compression ratio of 10 to 1 you get from this equation here 1 minus 1 over the compression ratio raised to k minus 1 k is going to be 1.35 now i have a whole separate video explaining where this equation comes from if you're interested and the relationship between compression ratio and thermal efficiency so i'm not going to go over it in too much detail here but we're going to normalize the data data for a compression ratio of 10 to 1 giving us a thermal efficiency of 55.33 and so if we're to do this math for the koenigsegg it will give us 1 over 1 divided by the compression ratio which is 9 to 1 and then that's going to be raised to k 1.35 minus 1. so this is going to give us an efficiency of 53 so we have our equation here the efficiency at 10 which is 55.33 divided by our efficiency which is 53.7 divide that and set that equal to rather our horsepower over here which is 96.6 horsepower per liter and that will give us our final horsepower per liter so because what we're doing here now this is going to give us 99.65 so you'll notice a slight increase and the reason being is because the compression ratio is fairly low now they did that because of knock you know if you get higher compression ratios you start to run into nut but we just want to make sure the the playing field is level and we get all these items equal for all the different cars which we're about to compare so it's going to get a slight bump in power if we were to give it a compression ratio of 10 to 1 and then some vehicles which have much higher compression ratios are going to see a slight power reduction once we tune them down to a compression ratio of 10 to 1. so now let's get into a bunch of different cases okay so here we have a bunch of data we've got 10 different vehicles here on the left and then i've broken it down we've got the number of liters of the engine the size of the engine how much horsepower it makes how much boost the engine has what the compression ratio is what it's normal horsepower per liter uh the specific output is then the specific output corrected for boost and then the specific output corrected for compression ratio and boost and so we've got these 10 different vehicles here and it's pretty interesting you know everything kind of falls into a much more normal range i mean if you look at this column it ranges quite a bit and then if you look at this column here it keeps it more in this uh same ballpark area and that's because you're kind of comparing more apples to apples so the koenigsegg one-to-one still you know more impressive from a per liter standpoint than the bugatti veyron almost 100 horsepower per liter versus 57.8 even the subaru sti getting more than that after all these corrections uh hennessey venom gt quite a powerful engine at 79. hot s2000 this is really impressive about 117 horsepower per liter and this is from a vehicle back in you know 1999 uh that's able to pump out that much power the most impressive ones as far as production cars uh that i've calculated here for i-458 and 458 special which ups the compression ratio a bit they did a few other changes and that after all the corrections gets you to 121.3 horsepower per liter obviously way higher than all of the other things out here now what this isn't showing is there's there's a couple things about why this ferrari is going to be higher even in this uh what i'm calling apples to apples comparison because it hasn't been corrected for rpm so this is obviously spinning at a much higher rpm and that gives it the ability to make more power and also i don't really believe that their volumetric efficiency is going to be at 100 i believe they're kind of kind of have a supercharging effect um you know with some clever intake tuning you can get better than 100 volumetric efficiency and as a result i haven't compensated for that i don't know what that number is um only probably ferrari engineers could tell you that and so you know this is what's i think going to give them a little bit of a boost that's probably the same case for the honda s2000 but what's really cool about these is if you compare the s2000 to the 458 i mean it's only off by one horsepower there as far as horsepower per liter so showing you know what honda did with a very affordable car is is pretty wild as far as how much power per liter they were able to extract from it so some other kind of fun examples in here the devil 16 which has a 12.3 liter engine that supposedly produces 4500 which they proved with the dyno supposedly but anyways so that would be 367 horsepower per liter but if you do the correction based on boost i don't know what the compression ratio of that vehicle is uh 106. so you know it does sound feasible it's not like this number is impossible based on how much boost they're saying and based on the leaders of the engine so it very well could be valid a top fuel vehicle this one's different because i'm correcting for fuel type and none of the other ones i've corrected for fuel type i'm just assuming they all use you know premium gas and that works for them top fuel an 8.2 liter engine producing 10 000 horsepower 1200 per liter but if you correct for fuel type and correct for how much boost it has it puts you in the 94 to 135 depending on how much power you believe it has some estimates say seven thousand some up to ten thousand uh so a much more normal range i actually have a video where i break down the math for this exactly if you're interested in that i'll include a link in the video description and then finally we'll end with an f1 vehicle just to kind of show you know what's possible and this uh very much so plays into this rpm and volumetric efficiency back in 2006 a toyota 2.4 liter producing around 740 horsepower spinning at 19 000 rpm 308 horsepower per liter from a naturally aspirated engine so that's absolutely insane and you know one of the biggest reasons for that is because it's able to spin up so high uh such a high rpm so ideally you'd want to compare things at the same rpm and say okay how much power are they making per liter at this exact rpm but everything's going to be tuned for different rpms so that's you know very challenging to do hence why i didn't do it and also that information is probably not all that available but regardless it's kind of fun you can plug in numbers for your own car or other cars out there i think another thing motorcycles would probably have some really impressive numbers and that's as a result like i mentioned of spinning up so high so you know you're hitting 15 000 rpm um you're getting so many power strokes uh in that duration of time and so the horsepower is going to go up um so that's that's something that would be interesting to check out but you can use the math i showed you uh before this segment of the video where you know you can plug in your own numbers for any different vehicle out there and kind of see where it stacks up and see what's impressive so i would be curious uh to know from people out there if they know of anything you know that's getting higher out there as a production car i'm sure there's going to be some motorcycles that can be this but i would be curious if there are production cars out there that could beat that 121 number now as promised i told you that at the end of this video the third segment was going to be telling you why all of this is pointless and indeed it is pointless and i think you know the reason you shouldn't just compare engines and say one's better than the other simply because it has a higher specific output that doesn't tell you which engine's lighter which engine is making you know more power per pound uh which engine has a lower center of gravity which engine has better structural rigidity which engine is going to last longer and you can go on forever so there's all kinds of different variables that determine um you know how good is an engine and simply comparing specific output is fairly silly if that's the dictating the driving factor of you know which one is the best but regardless it's interesting to compare them and see who's able to extract the most energy out of a certain amount of a certain volume of air so thank you guys for watching and if you have any questions or comments feel free to leave them below\n"