Lotus engine simulation

[deuxsanscinqgti]

Hi everybody,

I want to know if there are some people who use the interesting Lotus Engine Simulation software here ?

I have tested the freeware version (only a single cylinder model) and now I think it would be nice to work with a multi-cylinder model.

Have you ever compared simulating result of this software with dyno test ?

regards

julien

[Carlos]

Can't you just multiply by the number of cylinders and make adjustments?

[Callum]

sorry deuxsanscinqgti, i can't help you.

[axle]

A report to the mods too as asking for hooky software on a forum is a no-no.

[F1_eng]

I have never used the Lotus software because I don't believe its the best. I have done a tromendous ammount of work with another simulation software called GT Power, made by Gamma Technologies.

Models that I correlate are generaly within 2% from measured dyno results. The only issue for someone messing around is, you need a huge ammount of data to correlate a model. Without some form of correlation most of the simulation is useless.

[Belatti]

I have used the freeware 1 cyl version to simulate a one of the 6 cylinders of a
TC engine.

The valvetrain concept cant be simulated well because the tool is not allowed to use. The combustion chamber cant be modelled. The intake and exhaust pipes, due to the 1 cyl model are another problem, too. The model is only a unidimentional gas model.

Still I could have fun, play a little and learn about exhaust pressure waves.

The engine has carburettor, an air box (check the hood) and the block design is from the 50s..... something similar to NASCAR. If you want to know more about TC just ask Ken Shrader who was doing some laps last weekend here with his NASCAR

http://www.turismocarretera.com/



I would said that the power/torque vs rpm curves that the program generates are not that far away from dyno results.

[F1_eng]

Belatti, how are you generating this model or whichever engine you are simulating?

[Belatti]

Belatti, how are you generating this model or whichever engine you are simulating?

Here a printscreen from the model I did:



Its a Ford Falcon, 188 cu.in. 6 cylinders, OHV (2 per cyl.) and Weber 48-48 carb.

[F1_eng]

How do you know discharge coefficients for each element?

[Belatti]

How do you know discharge coefficients for each element?

You dont.

[F1_eng]

How do you expect the 1D simulation software to predict airflow through each component, which is essentialy what governs torque.

This is a problem with models that people set-up for a guess, they are more or less worthless. A decent model needs to have 1D-3D coupling where more complex flow situations would be solved in 3D. This is because orifices have different Cd at different air and therefore engine speeds.

Anyone that knows what they are doing with engine simulation does not correlate to power figures, correlation of most models is done to volumetric air flow. The simulation software also predicts frictional power loss which is very in depth, it is more or less a whole different model. This friction model also needs to be correlated from a motoring rig for it to be of any worth in predicting power loss.
Also the valvetrain dynamic simulation would need to be correlated for a decent model.

My point being that a quick model is worthless. Unless you know very basic stuff like discharge coefficients of orifices, any change you want to predic are worthless. For example, you want to predict optimal inlet cam timing but if you are slightly out on your Cd for an orifice, the flow behaviour will be wrong and all corresponding results are way off.

[machin]

I've had a go at making my own engine simulation program which draws power and torque curves from a selection of parameters and find that correlation to real engines is pretty good; Peak Torque and Power figures and the RPM at which they occur are accurate to known engines to about +/-5%. However, as a "design" tool its absolutely useless as it doesn't go into enough detail; e.g what's the affect of adding bends into the exhaust system? It can't tell you this.... or the affect of changing valve angles by 1 degree?.... it can't tell you this either.... but it is interesting to play around with different engine architectures to see the general effect. I guess the Lotus program is similar (although I also guess its A LOT better!!!!); i.e. interesting to play with, but you couldn't really design anything from it...

[Belatti]

How do you expect the 1D simulation software to predict airflow through each component, which is essentialy what governs torque.

I do not expect any prediction. Read carefully again for what do I use the soft. Just play a little bit...

This is a problem with models that people set-up for a guess, they are more or less worthless. A decent model needs to have 1D-3D coupling where more complex flow situations would be solved in 3D. This is because orifices have different Cd at different air and therefore engine speeds.

Anyone that knows what they are doing with engine simulation does not correlate to power figures, correlation of most models is done to volumetric air flow. The simulation software also predicts frictional power loss which is very in depth, it is more or less a whole different model. This friction model also needs to be correlated from a motoring rig for it to be of any worth in predicting power loss.
Also the valvetrain dynamic simulation would need to be correlated for a decent model.

Agree. And I will quote myself:

The valvetrain concept cant be simulated well because the tool is not allowed to use. The combustion chamber cant be modelled. The intake and exhaust pipes, due to the 1 cyl model are another problem, too.

You know, when you are millions miles away from the developed motorsport world, you dont have access to any team or technology, you have never ever seen a modern engine dismantled and all you have is a misc soft, an old dyno graphic from an old racing engine, the technical rulebook, your Uni books, imagination, time and this website... well... you may end up thinking that the thing I did is pretty well... at least in a qualitative way.

Sometimes I think what would I do if find myself working in an F1 or world class motorsport team, as I never take status quo as an option. Besides, I can hardly work 8 hours a day in my present job, still I would work 14 hours there and be happy...

My point being that a quick model is worthless. Unless you know very basic stuff like discharge coefficients of orifices, any change you want to predic are worthless. For example, you want to predict optimal inlet cam timing but if you are slightly out on your Cd for an orifice, the flow behaviour will be wrong and all corresponding results are way off.

I guess its worthless for a world class engine manufacturer, yes. For an eng student still its pretty cool.

[Belatti]

I've had a go at making my own engine simulation program which draws power and torque curves from a selection of parameters and find that correlation to real engines is pretty good; Peak Torque and Power figures and the RPM at which they occur are accurate to known engines to about +/-5%. However, as a "design" tool its absolutely useless as it doesn't go into enough detail; e.g what's the affect of adding bends into the exhaust system? It can't tell you this.... or the affect of changing valve angles by 1 degree?.... it can't tell you this either.... but it is interesting to play around with different engine architectures to see the general effect. I guess the Lotus program is similar (although I also guess its A LOT better!!!!); i.e. interesting to play with, but you couldn't really design anything from it...

Thats interesting machin

I made some excel files for plotting curves, gases p-v diagrams, for dynamic forces and part sizing in order to do Uni excersices faster

[saad7868]

I've had a go at making my own engine simulation program which draws power and torque curves from a selection of parameters and find that correlation to real engines is pretty good; Peak Torque and Power figures and the RPM at which they occur are accurate to known engines to about +/-5%. However, as a "design" tool its absolutely useless as it doesn't go into enough detail; e.g what's the affect of adding bends into the exhaust system? It can't tell you this.... or the affect of changing valve angles by 1 degree?.... it can't tell you this either.... but it is interesting to play around with different engine architectures to see the general effect. I guess the Lotus program is similar (although I also guess its A LOT better!!!!); i.e. interesting to play with, but you couldn't really design anything from it...

F1_eng: I need help regarding GT Power software.as i am new user and i have FYP to do related to it...Please reply.