Physics Based Performance Modeling/Simulation - 0-60, 1/4 mi, Top Speed

[swamp2]

Physics based simulators can be quite accurate and useful in understanding how a vehicle will perform. They can also help debunk ideas such as that changing a final drive ratio will make a vehicle overall faster.

There are a couple other threads here on the top speed of the Bronco and Raptor (if delimited). Those have been full of nervous nellies, to say the least. Due to not being able to find the trucks frontal area online, I calculated it. This number is required for such simulation to calculate drag force. The vehicles frontal area is 35 ft^2 (calculation below, and notes as to why numbers shown in this image do not quite match the 35 figure are here).

With this in hand, I updated my full vehicle performance simulations. Overall numbers compare well with MotorTrend results (also shown below). 0-100 vs. Car and Driver is nowhere close though. Looks like they may have got a "purposeful outlier" from FMC based on that number. Maybe they had the (not yet available to us) Ford Performance Tune already installed...

Here are the basic inputs:

Power losses typically have to be tweaked a bit on a second screen of real geeky details. I'm using about a 17% total drive train loss.

Power losses are shown vs. vehicle speed and demonstrate my prior comments about aero losses being insignificant below ~50 mph and dominating above ~80.

Hopefully a bit better than the BeamNG "physics" shown here, although that is good for a load of laughs and certainly does capture some "physics" (phenomenology, really I guess).

Sponsored

 

[raptorusmaximus]

Very interesting....... it is a flying brick after all...

 

[mpeugeot]

Very interesting....... it is a flying brick after all...

All I know is that my Bronco will run a low-mid 6 second 0-60 and a sub 14.5 second 1/4 mile.

Didn't use a simulator, just used a Bronco.

I really like what he did with presenting all the data above. It's good work.

 

[bcool2525]

I wonder what software created this? I would love to see how other vehicles perform.

 

[swamp2]

I wonder what software created this? I would love to see how other vehicles perform.

It is called CarTest. It's decent out of the box, but needs some significant adjustments beyond the main input screen to be accurate.

One of it's most significant shortcomings (likely bug) is how it deals with drivetrain losses, which are absolutely critical to get good results. The inputs here do not appear to sum to match the output loss graphs. Thus, after discussion with the developer, I somewhat arbitrarily adjust the individual drivetrain loss numbers to get a graph with the total desired loss at peak rpm in 1st gear.

I also wrote my own huge/complex spreadsheet based version of such a tool. It generally agrees with CarTest but it's very difficult for me to implement a tire slip/spin capability inside Excel. CarTest includes this phenomena.

 

[bcool2525]

It is called CarTest. It's decent out of the box, but needs some significant adjustments beyond the main input screen to be accurate.

One of it's most significant shortcomings (likely bug) is how it deals with drivetrain losses, which are absolutely critical to get good results. The inputs here do not appear to sum to match the output loss graphs. Thus, after discussion with the developer, I somewhat arbitrarily adjust the individual drivetrain loss numbers to get a graph with the total desired loss at peak rpm in 1st gear.

I also wrote my own huge/complex spreadsheet based version of such a tool. It generally agrees with CarTest but it's very difficult for me to implement a tire slip/spin capability inside Excel. CarTest includes this phenomena.

Wow thanks, I found the write up fascinating. Maybe this weekend I will purchase the software and mess around a bit.

 

[swamp2]

Wow thanks, I found the write up fascinating. Maybe this weekend I will purchase the software and mess around a bit.

DM me if you have any questions. I've got a great vehicle dynamics text book recommendation as well.

 

[HeHateMe]

Damn good stuff... And this is why he's got a Raptor and I don't...

 

[swamp2]

Damn good stuff... And this is why he's got a Raptor and I don't...

Ha, thanks. I'm definitely a bit of car nerd (car, truck, aircraft, whatever). Unfortunately, I don't have a Raptor yet, but my dealer said he thinks he'll have an allocation for me this month. It will be tight with end of '23s approaching.

(It seems on one's profile you must choose a Bronco model, whether you own one or not...)

 

[BigMeatsBronco]

It is called CarTest. It's decent out of the box, but needs some significant adjustments beyond the main input screen to be accurate.

One of it's most significant shortcomings (likely bug) is how it deals with drivetrain losses, which are absolutely critical to get good results. The inputs here do not appear to sum to match the output loss graphs. Thus, after discussion with the developer, I somewhat arbitrarily adjust the individual drivetrain loss numbers to get a graph with the total desired loss at peak rpm in 1st gear.

I also wrote my own huge/complex spreadsheet based version of such a tool. It generally agrees with CarTest but it's very difficult for me to implement a tire slip/spin capability inside Excel. CarTest includes this phenomena.

yeah especially the gear ratio results. lower gears equals quicker acceleration!

 

[BigMeatsBronco]

All I know is that my Bronco will run a low-mid 6 second 0-60 and a sub 14.5 second 1/4 mile.

Didn't use a simulator, just used a Bronco.

I really like what he did with presenting all the data above. It's good work.

exept he thinks tall gearing is superior for acceleration...ROFL

 

[BigMeatsBronco]

this program/technology is as old as Grand Torismo video games, ROFL...only slightly better and improved.

 

[swamp2]

yeah especially the gear ratio results. lower gears equals quicker acceleration!

Absolutely not more acceleration across multiple gears. This is a common misconception. Will get some improved single gear results which get offset by needing to shift earlier. The shift times themselves along with the longer duration in a rpm/gear with less gear multiplcation/power also disadvantages a re-gear to lower gearing/FD.

 

[BigMeatsBronco]

Absolutely not more acceleration across multiple gears. This is a common misconception. Will get some improved single gear results which get offset by needing to shift earlier. The shift times themselves along with the longer duration in a rpm/gear with less gear multiplcation/power also disadvantages a re-gear to lower gearing/FD.

hop on yer bicycle and put er in the tallest gear you got....then "accelerate " up to only 1/4 top speed.

now try the same in a much lower gear "accelerate " to the SAME speed...

Now tell us all which gear is quicker accelerating again?

 

[swamp2]

exept he thinks tall gearing is superior for acceleration...ROFL

Nope, I never said that and do not believe it. Pure rubbish, prove it or cork it.

hop on yer bicycle and put er in the tallest gear you got....then "accelerate " up to only 1/4 top speed.

now try the same in a much lower gear "accelerate " to the SAME speed...

Now tell us all which gear is quicker accelerating again?

We already hashed out this debate somewhat thoroughly here in your thread.

In this "wonderfully elucidating" bicycle example above, choosing the incorrect gear for an acceleration contest (essentially forcing the "engine" to output way less than its peak power) and then not permitting shifting "proves" something about which gear(s) is better for acceleration? Hardly. It's really simple, get your engine (or body) at/near peak power and keep it there as long as possible, this is obviously done by gear choice and shift points. What you are doing is maximizing the time integrated power.

As, I demonstrated, conclusively, in the other thread, a regeared FD does not provide performance benefits across the board and across gears, it helps here and hurts there and is highly dependent on the contest. I showed you a 5.38 and then a 6 and surprise, surprise, no overall improvements. Also, over in that thread you first claimed, essentially that physics is wrong and then went on to accept the physics and completely misinterpret the results as opposite as possible.

Again, across multiple gears, regearing provides NOTHING for overall performance. Why of course, simple, the engine power output is all that matters.

Sponsored