CAE Tools for Car Performance Modifications?

RevHead asks: "Although after-market performance modification of cars is a discipline which claims a significant following all over the world, most of the information available on the topic tends to be more of anecdotal nature. To add to this and the plethora of conflicting information out there, most of the tips and techniques tend to be of 'do it and see if it works' type of experimentation. I am interested in the simulation approach prior to actual experimentation to get a decent picture of what to expect during the experimentation phase, which IMHO should be safer and more cost-effective. Has anyone resorted to this approach (successfully) when it comes to engine modification, suspension design, aerodynamic performance and emission control? If so what software is available for these tasks? Which are the most popular/most effective? Does anyone know of any public-domain automotive engine models available for CAE applications such as Catia and ADAMS?"

Comments

sale modification

[alan_d_post]

Instead of fixing up the car, modify your life by getting rid of it entirely. You will learn patience and calm as you wait for the bus. Seriously! You will also be able to read more. Less stress, more thought, all good! No simulation needed!

Re:sale modification

[xinu]

"Instead of fixing up the car, modify your life by getting rid of it entirely. " The problem with your logic is that you don't gain any new knowledge or experience by 'waiting for the bus'. You don't modify your car to get from Point A to point B faster, you modify your car to get the most out of it that you can. It's called a hobby. If you were to take up one or two of those, you might avoid making such embarrasing comments.

Ah but you do gain knowledge reading a book while waiting for a bus, opposed to concentrating on driving.

"Getting the most out of your car" isn't going to be gas mileage, it's handling and speed.

Embarrasing comments? I think he made a valid point. I'd reasses who made the silly comment.

Nor do I see how having a hobby or multiple hobbies prevents one from saying stupid stuff...

I can't believe you got modded up for such a troll.

Re:Computerized Car Mods

[gerardrj]

I guess one really needs to look at the problem and figure out if your really need all those and other variables in the model.
There was a great example of this in economics, matmaticians spent years attempting to model market performance, so they could properly price options. The equation took everything in to account, and was pages long.
Finally a few guys figured out that most of the variables effectively cancelled each other out, and came up with a five variable or su equation that could accurately plot market performance and stock option prices in real time at any resolution (continuous time).

The auto manufacturers do use super computers to model the fluid dynamics through the intake, compustion and exaust systems, but starting with the basic functioning and building a rough model would probably allow an modder to determing if putting a larger turbo on would add any torque, or if a larger intake and exaust system would be necessary first.

What I do find humourous many times is all these tweeked Toyotas with all the laughable stickersand emblems that smoke their tires off the line. They whole point of the engine mods is to get the powet to the pavement to move the car, or so I thought. Making pretty white smoke and noise I could do with a small windshield pump and brake fluid installed on the drive wheels of any vehicle.

Here's the biggest problem:

[UserChrisCanter4]

Simulation is nothing in the autmotive world, particularly the aftermarket. You have to test and test and re-test. Sure, I suppose a competent mechanical engineer could come up with some formulas to reasonably estimate what modification X might produce. In fact, a lot of drag guys will run simulations that reasonably calculate, based on their current weight, what kind of power they need to do a 1/4 mile at a certain time. That's a reasonably simple calculation.

The catch is going to be getting the actual specs for a given car.

Let's say I want to bolt on a simple turbocharger and intercooler setup. It's a reasonably good quality turbo with minimal lag. Now let's say I bolt the same turbocharger onto the following three cars:

Older model Honda ('98) Honda Civic LX: My turbo and the accompanying modifications make, say, 400 hp at the wheels. My car is now close to undriveable because torque steer is ridiculous when the turbo starts to pull, and the necessary suspension mods will either make the car fast but unable to steer (too stiff a rear) or negate most of the power gain (rear is too soft and the front wheels hop).

97' Camaro SS: My turbo add-in is basically worthless unless I do a lot of engine work. The higher compression pistons on the Camaro mean that unless I knock the boost down to about 6 PSI, I'm going to be knocking my engine apart with detonation. For the same $5,000, I could've stroked the engine, ported and milled the heads, and upgraded the intake and exhaust.

'97 Toyota Supra: My intercooler is too big to work with the factory radiator, and thus, the car constantly overheats (not good). Either I need to get a bigger radiator or a smaller intercooler.

Now, I could probably have predicted that the Honda would torque-steer like a mother, given a basic knowledge of its drivetrain. I would have selected a supercharger and been content to put 250 or 300 horsepower to the wheels and call it a day. Any reasonably well-written program would predict the same torque-steer. But it might not have been able to tell you about the suspension issues, as it would likely assume a purely physics approach to the suspension, while I would recognize that things like gravel on the road, short inclined exits from fast-food places, and crappy roads would mean that my car would lose traction all the time.

As for the Camaro, any reasonably intelligent program could tell you that the compression ratio was too high too feed heavy boost to. It would likely recommend the same Natural Aspiration tuning.

Now for the Supra, that would be the hardest to predict. Without a lot of raw data on engine bay heat buildup in various areas, I couldn't see any program reasonably predicting such an occurence. So, while the '97 Supra would've been the ideal recipient for such an upgrade, the computer would probably fail to recognize the terrible amounts of heat such an upgrade might generate.

Blah Blah... let me shorten the long story: Tuning a car is not an easy process, and it certainly isn't like a lot of tuning mags will have you believe ("Joe had this and this and this done. He rolls on these type of tires and posts this timeslip. Joe hopes to add these modifications in order to acheive this lower time"). There's a reason professional shops charge about 3X what reasonable part and labor costs for a given complete upgrade might be. If you're running straight lines all day long and rebuilding at the end of the day (as in drag), a pick-a-part approach is somewhat suitable as long as you have a good idea of what you're doing. For turning a reliable, daily-driven car into a much faster, reliable, daily-driven car, it's a hell of a lot harder. Open source or no, there's a lot more that a computer needs to know beyond basic physics and math calculations in order to accurately predict what a given upgrade might do.