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How to estimate 1/4 mile, change gears for drags and other cool stuff.

JCMarshall_Law
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JCMarshall_Law Proficient

JCMarshall_Law

Posted
Posted

Hey all,

Do you want to be able to estimate (for any car):

1) 60ft time

2) 200ft time

3) 1/4 mile time

4) 1/4 mile speed

5) Wheel spin / traction graphs

6) Most efficient shift points for best ET or best terminal speed.

7) Accleleration graphs

8) Distasnce v time

9) Gradient charts

10) and see what effect varying hundreds of vehicle parameters has on all the above.

and more...

Then take a look at the Excel dyno (excell file) that can be downloaded in the following location.

http://autos.groups.yahoo.com/group/exceldyno/

It is a really cool excell file based on visual basic macros that allows you to enter data about a car and accuratly estimate heaps of performance parameters. Inputs include, engine dyno data, car parameters (CD, weight..etc), tyre setup and more. It allows you to set shift points or have it calculate the most efficient points.

All credit for its creation goes to Wez, a mate form work. He is a mechanical engineer and has had a fair bit of experence playing around with cars - he also seems to have a lot of spare time :P He has set up a Yahoo group for all things Excel dyno, if your interested take a look.

It has been tested with a number of different cars and it has proven to return supprisingly accurate results.

Of most intrest to people on this forum would be the R32 GTR data that is already entered in the program - this data was based on another workmates car and gives very accurate results when tested at the drags. Just enter your dyno chart and car details and you can start dropping those 1/4 times.

You can always add any car that is not already in the program as long as you know all the parameters.

Here is a list of car/bike data that is already entered in the database:

93 MR2 Turbo

95 200SX SE-R

Ford Falcon AUIII

Ford Telstar 92,95

MX6 - Gen II V6

Subaru WRX

VW Baja

VW drag manx

R32 GTR

Suzuki DL650

Suzuki Hayabusa

It is all free but if you want to give Wez cash I'm sure he will not refuse:) just email him on the address at the website above.

Baja Wes Newbie

Baja Wes

Posted
Posted
Ray Hall also has a similar thing.....

http://www.turbofast.com.au/Drag.html

:)

Except that is more a rule of thumb than any sort of remotely accurate calculation.

If people want to find car specs and send them to me then I will post a new version of the sheet with the new cars up on the net.

The cars that are in there are just a few that I had some good data for so entered to check the accuracy of everything. Finding the aero data is the hardest.

JCMarshall_Law Proficient

JCMarshall_Law

Posted
  • Author
Posted

Hey Wez, did not take you long to find the thread!

Ray Hall also has a similar thing.....

http://www.turbofast.com.au/Drag.html

Like Wez said, his program is in another ballpark.

I thought I'd post up the calculated best shift points for a R32 GTR, that should get things going:

For best km/h: (this gives 11.155 @ 202.7km/h)

RPM GEAR km/h

4000 stall speed 36

8500 first 77

8200 second 124.2

8010 third 179

8020 fourth 234

8500 fifth 330

For best ET: (this gives 11.144 @ 201.8 km/h)

RPM GEAR km/h

4000 stall speed 36

8500 (redline) first 77

8500 (redline) second 128.8

8500 (redline) third 190

8500 (redline) fourth 248

8500 (redline) fifth 330

Here is a bit of an explination of why the shift points are different when chasing high trap speeds or Low ET's (from the Excell dyno)

These shift points will give you the max terminal speed for the 1/4 mile. These points are essentially where the torque curves cross each other on the Traction chart. Note these points are not always exactly right as the wind slows the vehicle during gear shift making the best shift point estimation more difficult.

However, to achieve the best ET you generally need to change gears a little later. This is because shifting later means you are going faster for the during of the shift time. This means more distance will be covered. The optimum shift point is when the advantage of shifting later if offset by the loss of being too far past where the torque curves cross. These points are easily found by trial and error. Start with the best shift points for terminal speed and increase the shift rpm from there. For most engines the best ET will be achieved by revving to redline.

Baja Wes Newbie

Baja Wes

Posted
Posted

Well when the car had the 291HP dyno chart it ran the quarter and ran an 11.9. The Excel Dyno predicts that run perfectly.

With the extra 85 wheel hp it should easily push the car into the low 11's. I can't remember if he got a time slip before that engine spat the ceramic turbines through the engine.

JCMarshall_Law Proficient

JCMarshall_Law

Posted
  • Author
Posted
I had a quick look - R32 GTR with 375RWHP running 11.1@125mph? i doubt it...

Does that mean you entered your car data? Is that what the excell sheet returned?

ferni Grand Master

ferni

Posted
Posted
Well when the car had the 291HP dyno chart it ran the quarter and ran an 11.9. The Excel Dyno predicts that run perfectly.  

With the extra 85 wheel hp it should easily push the car into the low 11's. I can't remember if he got a time slip before that engine spat the ceramic turbines through the engine.

220rwkw (291rwhp) ran an 11.9? what mph? that must be a low dyno reading, what boost was he running?

GTR R32 Collaborator

GTR R32

Posted
Posted

Ferni,

That was my car. I'm pretty sure I have told you about it before.

When my car arrived from Japan it made 217 rwkw. That was on a dyno dynamics dyno (non shootout mode). I ran an 11.99 @ 115.4 mph at our drag strip here in Townsville.

I have been involved in the development of excel dyno and I can say that it is very accurate, as long as you give it accurate data. It's in a league of its own compared to most other programs out there.

I will write more later when I have more time...

JCMarshall_Law Proficient

JCMarshall_Law

Posted
  • Author
Posted

Hey Gary,

Didn't know you had a 32 GTR last time I was up on site, prolly a good thing, I would have spent more time talking about cars than getting the full "QNI experence". I have to take a look next time I'm sent up there.

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