Dyno Maths Library

[Lowell Foo]

This was a decent 3rd gear pull, but a vacuum cap blew off at 7500rpm

Pump gas + methanol = 80-100mph in 1.55s    60-100mph in 2.96s including a granny like 0.4s 2-3 shift. 

[Mike J]

Does anyone have the proper inputs for a 98 Talon AWD?  I looked at yours Erich (2G Eclipse) but I see you have not modified the gear ratio, coeff drag etc.

My wheel size inputs get the vehicle speed and vehicle speed MPH to within 2 mph.  So that seems to tell me the gear ratio is quite close already.

This only seems to work on my internal logs due to the sampling rate.  Unfortunately my internal logging is down at the moment.

I took a PC log today of a long 3rd gear pull with the engine speed set to fastest rate but the hp and tq fall off half way through the run.  I mucked with the specified filter values and if I reduce them by about a factor of 10 each I seem to get a graph that looks closer to what it should look like but it still starts late and ends early.

The HP values are about what I was expecting, but the car hasn't been on a dyno in ages.

So if anyone can reply with the correct values for a 98 Talon it would be greatly appreciated.

[Mike J]

Okay I have been able to find some of the info online:

2G Talon AWD MT (from the VFAQ):
3rd Gear Ratio: 1.115
Final Drive Ratio: 4.929

But putting these values in killed my vehicle speed to vehicle speed MPH... seperating them by 42 MPH at 6500 rpm!!!  It also brought my HP and TQ numbers down more then I think is warranted.  What went wrong here?

I also still need the coef of drag and the frontal area for my car.  If anyone has these please let me know. 

Thanks.

[Mike J]

Oops, clicked the wrong overlays.

Guess I want to compare vehicle_speed_MPH and vehicle speed.... not vehicle_speed.

However, this still gives me a little over 3 mph difference by 6800rpm with the gearing data from the VFAQ when looking at my PC logs with low filter values.   On my older internal logs where I kept the filter values unchanged there is about a 6mph difference by 6800rpm.

[Lowell Foo]

Can you post up your datalog along with the math file?

[Mike J]

Here is the raw unmodified PC log from today and the modified math file.

It's not in the attached math file file but I did also try adjusting the final drive ratio to 4.779 which gets the vehicle speed and vehicle_speed_MPH to within 1mph at 6800 (just for reference).  This netted my +20hp.  So it appears that having the inputs off can make a rather large difference.  So if we can figure out why my vehicle speed and vehicle_speed_MPH don't match it would help a bunch.

I will also be doing another PC log on the way home from here to compare.  I will start the run at a lower rpm and try to run it higher.

Edit:  Wait!!!  It somehow saved my change to the DRIVE_RATIO value.  So make sure you set it back to 4.929 in the attached math file.

[Lowell Foo]

Your results look fine to me, but I wouldn't trust the stock VSS to be accurate.  You're better off to measure tire size by rolling the car beside a 100ft tape measure, do the math, and then input Wheel_Radius directly. 

60-90mph in 3.22 seconds should put you around 120mph trap speeds.  Put some methanol spray on that setup and turn up the boost...  I just checked one of my datalogs, and 60-90mph rolls up in 2.13s including a 2-3 shift.  Probably would be quicker if I only used 3rd gear. 

[Mike J]

So you think ~330hp at the wheels as the maths state is good for 120mph trap speeds? 

[Lowell Foo]

330whp on a Mustang AWD dyno is probably enough.   I was just going by your 60-90mph time and comparing it to times of cars with tested 1/4 mile trap speeds.  If you want to try something interesting, plug some magazine time-to-speed data into Excel, and then plot your own cars data to see how it compares.

http://www.corvetteactioncenter.com/specs/c6/2006/z06/2006z06perf.html

[Mike J]

Just for reference I dug up some old logs. 

My 122mph run did 70 to 90 in 1.51sec. -> maths say 460ish at the wheels.

My 116mph run did 70 to 90 in 1.772sec. -> maths say 400ish at the wheels.

This mornings run did 70 to 90 in 1.96sec -> maths say 355ish at the wheels.

Seems a bit high, but meh .  Still should be a very useful tool for tuning.

[turbotito121079]

ok i have a sc300 running a 2jz. i have a t76 bb turbo and 264 cams and meth. im running 16lbs. my hp that im getting is 260whp and 240 trq. i know for a fact that i have alot more then that. i think that i need to setup mCD_DRAG:  Coefficient of drag for your car. 
CD_AREA:  Frontal area of your car, in square feety
does anybody know what numbers to put into this.

[Lowell Foo]

Just for reference I dug up some old logs. 

My 122mph run did 70 to 90 in 1.51sec. -> maths say 460ish at the wheels.

My 116mph run did 70 to 90 in 1.772sec. -> maths say 400ish at the wheels.

This mornings run did 70 to 90 in 1.96sec -> maths say 355ish at the wheels.

Seems a bit high, but meh .  Still should be a very useful tool for tuning.

Darn, my 3rd gear starts above 80mph.  82-108mph in 3rd gear takes me 2.18s and maths say 510whp or so.  70-90 = 1.47s including having the clutch depressed for 0.376s.

[Talongt]

Just for reference I dug up some old logs. 

My 122mph run did 70 to 90 in 1.51sec. -> maths say 460ish at the wheels.

My 116mph run did 70 to 90 in 1.772sec. -> maths say 400ish at the wheels.

This mornings run did 70 to 90 in 1.96sec -> maths say 355ish at the wheels.

Seems a bit high, but meh .  Still should be a very useful tool for tuning.

Darn, my 3rd gear starts above 80mph.  82-108mph in 3rd gear takes me 2.18s and maths say 510whp or so.  70-90 = 1.47s including having the clutch depressed for 0.376s.

Those numbers seem pretty close to me!  I check a log today and report back my findings.

[fre24]

Here is the information for an 03 and 04 5 speed evolution 8:

1st: 2.928:1
2nd: 1.950:1
3rd: 1.407:1
4th: 1.031:1
5th: 0.720:1
Final drive: 4.529:1

cd: .36
frontal area: 24.92

Attached is my dyno log which came out pretty well.  I estimate this is fairly accurate, because I used a somewhat conservative weight: 3300lbs.  I did a trap speed calculation from my 127 and that comes out to about 540whp, but I have retuned it a bit since then.  I would say this is definitely pretty close.  The log had 1-3rd gear but I just zoomed in on 3rd, since that is the ratio I used.

[Kurt]

Thanks for your work on this, FWombat!     I made a couple of pulls to compare boost levels and this is what I came up with.  I used the XY Plot Option with Engine Speed as X and the overlays option with HP and TQ for Y.  Also, I edited the max and min RPM to 7000 and 3000 so it wouldn't look all squished.  I used photoshop to overlay the two files.  The Y axis starts at zero=100HP/TQ, 25=200, 50=300, 75=400, 100=500.





Here's another that I've been wanting to compare for a while.  My engine, Toyota 2JZ-GE (n/a Supra), has a valve which effectively varies the length of the intake runners to give more torque below 4500rpm.  I don't think anyone's tried with and without until now.  It gives a nice 30ft-lbs extra in my situation.