# General Car Question

Hey guys I have a about how liters are measured in car engines like 5.7 hemi. Does it have anything to do with bore and stroke size cuz most of my engines dont fit my cars? Or does it have to do with something else?

Yep, it’s how much air (or anything really) it would take to fill all the cylinders at once.

Bore makes the cylinders wider, stroke makes them taller, and more cylinders of course also add capacity, so those 3 things determine how many liters an engine is.

[quote=“Daffyflyer”]Yep, it’s how much air (or anything really) it would take to fill all the cylinders at once.

Bore makes the cylinders wider, stroke makes them taller, and more cylinders of course also add capacity, so those 3 things determine how many liters an engine is.[/quote]

Of course the engine never actually has that capacity, as some cylinders have a piston at the top of it’s stroke while others are at the bottom, but it represents the total amount of air it sucks in.

The other thing to think about is volumetric effeciency, which is “how much air does the engine ACTUALLY suck in”. That’s one of the main differences between powerful and not very powerful engines of the same size.

A not very well designed 2.0ltr engine might only actually suck in 1.5L of air, which means it’s 75% volumetrically efficient, and so not as powerful as one with a better intake, exhaust, cam etc.

If you are having problems fitting the engines inside the cars then there are some things that can help

If you are not doing it already, you should design the car (platform) first. Then, when you get to the relevant point in the car design process you should design the engine. This way you will get arrows that indicate how big the engine can be. green means it will fit, orange means it will fit, but it approaching the size limit, and red means it wont fit.

The other major thing that can help is knowing that most of the cars in the game so far only have very short engine bays. The main thing that affects engine length is the bore and the number of cylinders in a line. I6 engines, for example, are a lot longer than I4 or V8 engines, making them very difficult to fit into the cars that are currently available. Also, engines with a very large bore will have the same problem, so if you cant fit an I4 or V8 engine in the car due to length you will need to reduce the bore (and probably increase the stroke to regain the size loss at the cost of reduced RPM)

you will be glad to hear that the developers have been working on cars with larger and longer engine bays, so hopefully you will find something to fit your big engines into with the next update