Engine Simulator

Posts related to specific vehicles, or any other general tuning info.

Engine Simulator

Postby Relic » Wed Aug 08, 2012 5:00 pm

My donation to this site.
I hope some of you will be able to put it to use.
OpenOffice required for the spreadsheet.
http://www.openoffice.org/

This is a simulator I created to tell me the air flow, fuel flow, power and torque.
You give Atmospheric condition, eficiency of turbo, intercooler and engine...lambda and boost to use.
[you can view the results of modding these variable in the charts or in the model]
The simulator spits out everything else.
Its designed for 4 cylinder turbo diesel engines.
It wont be bang on....but should be pretty damn close.

For reference UK atmsopheric varies from 960-1060 mbar summer-winter and 30-0c air temps.
You should make sure your boost sits nice on the compressor map at all these extremes.
This should protect against surge, overspeed and choke in the UK.
Garrett uses 85f and 13.95psi absolute as correction for MAF readings to protect against surge.
86f(30c) and 13.92psi(960mbar) has even less air density than this and is a little safer.



Variables to Enter....


Air Temp [atmospheric temp to use for this simulation Farenheit]
Air Pressure [atmospheric pressure to use for this simulation psiA]
Intercooler Pressure Loss Ratio [assuming upto 3psi loss and peak MAP of 37 psi = 37/40]
Induction Pressure Loss Ratio [assuming upto 0.5psi loss and atmospheric is 14.5 = 14/14.5]
No. Cylinders [not used..only for 4 cylinder engines...adventurous could modify the the model using this to allow for more cylinders...I never got round to it]
Displacement 2 [engine cc value here]
Min RPM [idle speed]
Max RPM [redline limit or map limit]


Volumetric Efficiency Control (descibes the ramp leading to the spike and slope after the spike).

Peak Volumetric Efficiency RPM [this is the rpm the VE spike occurs]
Start VE RPM [rpm you want to start the ve slope]
End VE RPM [rpm you want to end the ve slope]
Max VE% [this is the peak ve value where 1=100%]
Start VE% [the start ve value @ the start rpm]
End VE% [the end ve value @ the end rpm]
Volumetric Shape Start [not used]
Volumetric Shape End [not used]
http://www.turbobygarrett.com/turbobyga ... elTech.pdf
If you datalog rpm iat map and maf you can use the formula in the pdf to calculate VE vs RPM


Compressor Efficiency Control (models the path the boost takes through the efficiency islands on the turbo compressor map).

Values as above...plus...
Volumetric Shape Start [The curve is cut into two part before and after peak. This is the curve before peak]
Volumetric Shape End [This is the curve after peak]
The values are an angle in degrees.
Based on a quarter circle that is cut by a chord to use less and less of the curve.
An angle of 0 used the whole 90 degrees of the curve (very fat and full).
A value of 89.999 uses only 0.001 degrees of the very top of the curve (more of a slope with curved end).
The two quarter circle segment join together at the peak and are always tangent to each other.


Intercooler Efficiency control (models the curve for the intercooler efficiency).

Values used as above.
You need to datlog your own car to work out you intercooler efficiency.
http://www.not2fast.com/turbo/glossary/ ... tyCycle=85
This site will help you work out the efficiency.

Lambda control (lets you use a curve to define the AFR based on 14.6:1=lambda [editable]).

Values used as above


Stoichimetric ratio (used for the Lambda calcs above...arguments exist over 14.5 or 14.6 so now you can change it).


Brake Specific Fuel Consumption Control (models the curve for BSFC in lb hp hr)

Values used as above
You need to hunt for your own values....datalog to work it out if needs must.
bhp x afr x (bsfc/60) = MAF lb/min ...use a dyno and measure MAF BHP RPM at the same time to work out BSFC vs rpm.
You know the AFR vs RPM....you entered it above and its in the model tab ;)
Require the fuel to be calibrated correctly.


Manifold Absolute Pressure Control (models the boost curve you intend to use).

Values used as above.
you should keep an eye on the compressor map when adjusting.
Make sure you are not in surge, over revving or in choke at any Atmospheric temp or pressure.

Variables & Charts displayed (the model tab is a complete spreadsheet with all values that you can copy or reference into ECU table)

RPM vs VE%
RPM vs IE%
RPM vs CE%
RPM vs LAMBDA
RPM vs AFR
RPM vs MAP (mbar)
RPM vs MAP (psi)
RPM vs IAT (F)
RPM vs IAT (C)
RPM vs MAP (mbar)
RPM vs MAF (lb/min)
RPM vs MAF (g/s)
RPM vs MAF (mg/str)
RPM vs MFF (mg/str)
RPM vs TORQUE (NM)
RPM vs TORQUE (lf.ft)
RPM vs POWER (BHP)
RPM vs POWER (PS)
CURRENT BOOST ON COMPRESSOR MAP (uses the GT1752 tab for the compressor map limits..you should use your own turbos map)
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Re: Engine Simulator

Postby Relic » Wed Aug 08, 2012 5:19 pm

For DIN correction you should set air temp and pressure to 68f (20c) & 14.7psi (1013.25mbar)

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Re: Engine Simulator

Postby OdinEidolon » Wed Aug 08, 2012 9:21 pm

Wow! You ut lots of work into it, well done!

I'll take a look at it more closely soon, seems very interesting.

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Re: Engine Simulator

Postby Relic » Wed Aug 08, 2012 9:33 pm

Having to do and learn everything from scratch on my own....yes a lot of painful hours, days, weeks and months :cry:
Still....hopefully useful and worth it to members here.
Perhaps I'll even see others develop it and improve it :D
Last edited by Relic on Wed Aug 08, 2012 9:34 pm, edited 1 time in total.

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Re: Engine Simulator

Postby ecuedit » Wed Aug 08, 2012 9:34 pm

That's a lot of effort in this one.

Have looked at the pdf, I have to take some time to look closely.
Well done, nice work.

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Re: Engine Simulator

Postby Relic » Wed Aug 08, 2012 9:43 pm

Thanks.

Would be better if it could do SOI rail pressure and duration too.
But thats way way beyond me at the moment.
:?

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Re: Engine Simulator

Postby RPM freak » Wed Aug 08, 2012 10:38 pm

Nice work i must say.

There are only 2 products to make the universe work properly - Duct tape and WD40. If it moves and it shouldn't - Duct tape. If it doesn’t move and it should - WD40. Everything else is just stuff.
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Re: Engine Simulator

Postby hinkxx » Wed Aug 08, 2012 10:56 pm

Wow. A lot of info that I do not really understand :) I'll need to come back later ...

How much of this stuff is empirical? Can this 'model' be generalized for other turbo diesel engines, too? If so, what would the implications be? Do I need to make measurement of the data you provide, or did it pop out of model for you? Sorry if this are n00b questions, but it looks very interesting!! Great job!

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Re: Engine Simulator

Postby Relic » Thu Aug 09, 2012 1:27 am

Yes it can be used with other 4 cylinder diesel engines.
You'll have to change the turbo compressor map data to suit whatever is in your car and adjust the compressor efficiency curve to suit where your boost lies on that compressor map.
You have to datalog you car to work out VE, and intercooler efficiency.
You'll need dyno + datalogging to work out your BSFC.
You'll need to change the engine capacity and rpm limits.

Thats the background stuff you only need to do once really unless you change intercooler or turbo.

With that stuff out the way all you do is change the desired boost curve and the desired lambda curve.
Everything else is auto filled.

You can change the weather conditions too.
Theres a 30hp difference between winter and summer extremes in mine due to the air density change (Mass Air flow is much higher in winter and fueling/power is locked to MAF with the lambda or AFR).

I am using it to model the optimum boost curve for my turbo and the maximum fueling for worst case weather extremes.
If I fuel it for max power in winter...mass air flow will drop in the summer and the smoke limiter will cut the fueling to suit.
I tried 5 different boost profiles using the same lambda to see the power and torque for each.
Using curves like this it pays to lower max torque a little if you wish to gain more max power.
The profiles contain where they sit on the compressor map at the 4 weather extremes
30c 960mbar
0c 960mbar
0c 1060mbar
30c 1060mbar
and a nominal 15c 1010mbar which is the general average where it will be mostly.
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Re: Engine Simulator

Postby Relic » Thu Aug 09, 2012 1:55 am

Come to think of it I dont see why you couldnt use it for 4 cylinder petrol turbo too :?

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