Naturally Aspirated
Posts: 78
Joined: Wed May 02, 2012 3:24 pm
Cars: 96 Jeep Grand Cherokee, 87 Chevy Suburban, and hopefully a 70 Plymouth Cuda one day.
Fri Mar 15, 2013 12:15 am
Some Engine Formula Help
Okay, so I am working on making my own UTV. I want it to be a ton of fun off road, but also be able to drive around town with it as well. I've designed the frame for the most part and am going to make a scale concept out of PVC pretty soon to see how it works out, BUT I'm trying to find the perfect engine to mount on it. Now I know that there are many other things that I will have to worry about that will adjust what I'm asking, this is just a way to find, theoretically, the best engine for my UTV. I really do want it to be both a commuter car and off-road fun car.
1. I want to know how to calculate the maximum weight an engine can handle: I haven't been able to find anything online referring to the torque of an engine to how much weight that the engine can move.
2. MPG change from weight: I want to say that when it comes to city mpg the percent weight you add on is the percent that the mpg goes down, double the weight half the city mpg, but would that change the highway mpg? or is highway mpg change from the engine having to rev slightly more to keep the added weight at that speed?
3. Acceleration/0-60 change from weight: Is there a way to calculate weight into the acceleration process and see what the change will be? I was thinking if the torque to weight ration decrease you can use that percentile to adjust the acceleration timing, but I'm really not sure.
EDIT: Some interesting information I found:
People have thrown the Hayabusa 1300R engine into a Smart car, here are the stats:
The Smart Car weighs 1600lbs, 0-60 in 4.5 seconds, a top speed of 132mph, and 18-25mpg.
The Hayabusa 1300R weighs 587lbs, 0-60 in 2.6 seconds, a top speed of 186mph, and 33mpg.
The 1300R has 197HP and 102.3 ft-lbs,
making the Hayabusa's HP/Weight ratio 0.336 and ft-lbs/Weight ratio 0.315
and making the Smart car's HP/Weight ratio 0.123 and ft-lbs/weight ratio 0.064
If you add their ratios together Hayabusa is .651 and the Smart car is .187
This makes the Smart Car have 71.27% less of a ratio then the Hayabusa.
Now here's what I've found, if I increase the Hayabusa's 0-60 time by 71.27% it comes out to 4.45 seconds.
Decrease the Hayabusa's mpg by 71.27% and it's 9.5mpg
Last is decrease the top speed by 71.27% and it's 53.4mph.
But if I just calculate 71.27% of the mpg it comes out to 23.5 (average of 18-25mpg=21.5)
and calculate 71.27% of the mph it comes out to 132.56mph...
Interesting that using these numbers a certain way can come up with close to the exact same number as it actually is, but to find the 0-60 time I increase it by the 71.27% and to find the mpg and mph I was decreasing the stats by 28.73%. Maybe I have found a way to look into what the best engine would be but does this even seem right?
1. I want to know how to calculate the maximum weight an engine can handle: I haven't been able to find anything online referring to the torque of an engine to how much weight that the engine can move.
2. MPG change from weight: I want to say that when it comes to city mpg the percent weight you add on is the percent that the mpg goes down, double the weight half the city mpg, but would that change the highway mpg? or is highway mpg change from the engine having to rev slightly more to keep the added weight at that speed?
3. Acceleration/0-60 change from weight: Is there a way to calculate weight into the acceleration process and see what the change will be? I was thinking if the torque to weight ration decrease you can use that percentile to adjust the acceleration timing, but I'm really not sure.
EDIT: Some interesting information I found:
People have thrown the Hayabusa 1300R engine into a Smart car, here are the stats:
The Smart Car weighs 1600lbs, 0-60 in 4.5 seconds, a top speed of 132mph, and 18-25mpg.
The Hayabusa 1300R weighs 587lbs, 0-60 in 2.6 seconds, a top speed of 186mph, and 33mpg.
The 1300R has 197HP and 102.3 ft-lbs,
making the Hayabusa's HP/Weight ratio 0.336 and ft-lbs/Weight ratio 0.315
and making the Smart car's HP/Weight ratio 0.123 and ft-lbs/weight ratio 0.064
If you add their ratios together Hayabusa is .651 and the Smart car is .187
This makes the Smart Car have 71.27% less of a ratio then the Hayabusa.
Now here's what I've found, if I increase the Hayabusa's 0-60 time by 71.27% it comes out to 4.45 seconds.
Decrease the Hayabusa's mpg by 71.27% and it's 9.5mpg
Last is decrease the top speed by 71.27% and it's 53.4mph.
But if I just calculate 71.27% of the mpg it comes out to 23.5 (average of 18-25mpg=21.5)
and calculate 71.27% of the mph it comes out to 132.56mph...
Interesting that using these numbers a certain way can come up with close to the exact same number as it actually is, but to find the 0-60 time I increase it by the 71.27% and to find the mpg and mph I was decreasing the stats by 28.73%. Maybe I have found a way to look into what the best engine would be but does this even seem right?