Nissan 370Z Tech Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
2,120 Posts
Discussion Starter #1
I'm not sure of anyone has heard of a program called 'CarTest'. It's a car acceleration simulator where you can alter/punch-in most of the car specs. It takes everything from weight, dimensions, weight-distributions, gearing, tyre/specs to ground-clearance and engine specs. You can even punch in the exact data for the power curve.

You can even enter enviromental conditions, drivetrain-losses, and friction coefficients. Once it's all in there then you can plot the gearing, find the optimal shift-points and then see it's simulated time-to-speed, as well as time-to-distance.

Anyway, I've been playing with it and punched in all the data for the 350Z, including it's power curve. I taylored most of the constants (ie. coefficients) so that the numbers that it spits out apear to be in the same ball-park as local mags ... that way I have some kind of baseline for when you start playing with things like 'simulated':
- weight reduction/increase
- different tyre sizes
- extra power (and different shape power curve)
- different gearing
- etc.

Changing any of these will change the acceleration results and (to some degree), to give me (or anyone else) an idea what effect certain mods have on the acceleration of the car as well as the speed-in gears.

Anyway, back to the stock 350Z Track that I punched in (including the OME power curve). The numbers that I have the simulator returning are:
- 0-60kph = 2.7sec
- 0-100kph = 6.3sec
- 0-160kph = 14.0sec
- 0-180kph = 18.4sec
- 400m = 14.3sec @ 161.6kph
- 1000m = 25.9sec @ 207.9kph
- top-speed = 259kph

Interesting thing is that it tells me that not all the optimal shift points are at red-line for all the gears. ie:
- 1st-to-2nd gear = 6,600rpm
- 2nd-to-3rd gear = 6,600rpm
- 3rd-to-4th gear = 6,450rpm
- 4th-to-5th gear = 6,440rpm
- 5th-to-6th gear = 6,460rpm

Mind you, when I punched in the power-curve from my dyno-pull, then it's 6,600rpm for every gearchange as my dyno shows power increase in power all the way to 6,400 - 6,500rpm.

Back to the stock 350Z. Interesting thing is what happens when I take the stock 350Z, and add 50kg (ie. full fuel tank). The acceleration numbers increase noticably:
- 0-60kph = 2.7sec
- 0-100kph = 6.5sec
- 0-160kph = 14.4sec
- 0-180kph = 18.9sec
- 400m = 14.4sec @ 160.0kph
- 1000m = 26.1sec @ 206.2kph
- top-speed = 257kph

If I add another passanger (ie. extra 80kg) into the equation then this is what I get:
- 0-60kph = 2.8sec
- 0-100kph = 6.7sec
- 0-160kph = 15.1sec
- 0-180kph = 19.8sec
- 400m = 14.6sec @ 157.6kph
- 1000m = 26.5sec @ 203.6kph
- top-speed = 256kph

So according to this simulator, running with a passanger and full tank of fuel will add 0.4sec to your 0-100kph time, 1.1sec to your 0-160kph time, and 0.3sec to your 400m time.

Now if I punch in my power-curve in there (ie. Hi-tech and K&N filter), then I get these results for the car running on empty and solo:
- 0-60kph = 2.8sec
- 0-100kph = 6.1sec
- 0-160kph = 13.3sec
- 0-180kph = 16.6sec
- 400m = 14.1sec @ 164.9kph
- 1000m = 25.4sec @ 212.5kph
- top-speed = 266kph

IMHO, these numbers are a fraction to optimistic (or the stock numbers a fraction too persimistic) as it's telling me that I've cut 0.7sec from my 0-160kph time ... that sounds a bit too much. IMHO, it's 1/2sec at most. Though, the 'guess' at 0.2sec gain over 400m might be just about right, as well as 0.2sec gain to 100kph.

Still, it's a fun tool for anyone planning to do any mods as you can do it here and it will tell you a hypothetical outcome. ie. what effect will the change in tyre width/profile will have on your speed-in-gears, acceleration and top-gear. Or wehat effect will increasing the redline/cut-out have.

Anyone interested in the carTest software can download it here:

http://www.cartestsoftware.com/cartest4.5/

The download link is towards the bottom and the free dowload is a DOS program only about 400kb.

ps. Keep in mind that it can't simulate everythihg, and in particular if grip/traction calculations cannot really be tailored for different cars as much as one would like. Therefore none of the 'results' are necesarily true to life ... it's all just an approximation based on the laws of physics.
 

·
Registered
Joined
·
3,089 Posts
yeah thats true about the weight

i used to notice my Alfa feel sluggish off the line with a few passengers, but thought it wouldnt affect the Z with all that torque

but i took my mate for a spin, and stopped for a full tank and i noticed straight away it didnt pull as well down low

jump in the SL55 and u can attach a caravan and ull still have trouble breathing under hard acceleration
 

·
Registered
Joined
·
188 Posts
Originally posted by DavidM@Jun 16 2005, 08:38 PM
I'm not sure of anyone has heard of a program called 'CarTest'. It's a car acceleration simulator where you can alter/punch-in most of the car specs. It takes everything from weight, dimensions, weight-distributions, gearing, tyre/specs to ground-clearance and engine specs. You can even punch in the exact data for the power curve.

You can even enter enviromental conditions, drivetrain-losses, and friction coefficients. Once it's all in there then you can plot the gearing, find the optimal shift-points and then see it's simulated time-to-speed, as well as time-to-distance.




I've heard of a program like that - it's called "ask DavidM".
 

·
Registered
Joined
·
2,120 Posts
Discussion Starter #5
hehe. You guys are right ... it's not like it told me anything new ;-) Though, on a more serious note, it's good to see some of the 'theories' confirmed by another source ... even if it is a program.

Another interesting thing I tried is raising the rev ceiling to 7,000rpm. Doing so on a stock car has no real benefit (except for better 0-100kph number due to not needing the 3rd gear). Though, the simulator worked out that it is still better to shift as I posted before in all but the 1st two gears.

Though, raising the rev ceiling to 7,000rpm on a car like mine yeald some banefits. They are not huge, but it does shave 0.1sec to 160kph as well as over 400m, and 0.2sec from a standing 1000m run. Also the optimal shift-points would be at 7,000rpm.
 
1 - 6 of 6 Posts
Top