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Seeking advice in engine design process!

Hi guys,

So I’m really enjoying the game but I noticed I tend to get stuck in a familiar hole when designing engines, and I’m having real trouble making fuel efficient engines in the start / mid game.

I don’t know much at all about real engines, so I might be doing things totally wrong!

So what I usually do is choose a fairly sensible size and layout, usually an inline 4 between 1400cc and 2000cc.

I pick the most basic forged components, usually single barrell eco twin carburettor (for the first few decades at least) and don’t touch the sliders, except to make the exhaust a couple of clicks smaller, before I then test the engine.

Usually the engine is knocking, so I go back and cut the compression until it works. I find if I optimise this to performance or economy it’s in the same general neighborhood, a couple of clicks apart.

Then I go to the cam profile. On this one there seems to be two peaks with a trough in between - so sliding it towards “race” will improve performance to a point, then it will fall slightly, then it will raise again to a higher peak than before, then drop off permanently.

I usually choose the lower of these two peaks because I want a bit more low end torque.

Then I go through the remaining sliders maximising economy.

I never seem to end up with anything better than about 18mpg in the finished car! And I’ve found that some weird engines, like a tiny V6 I made, give a figure lower (better - 0.650-ish?) than some inline 3 or 4 cylinder engines.

Am I misunderstanding what the economy / efficiency meter in the engine designer part means?

Should I be using a different process of sliders maximising different attributes?

The ‘help’ box suggests higher compression, leaner fuel mix and more advanced combustion should result in better fuel efficiency, but this never seems to work out for me.

Thanks!!

1 Like

The efficiency rating in the engine designer is consumption per HP (or whatever unit you’re using). That’s half of the equation. Sometimes a bigger engine is more efficient, particularly in a larger car. While you may have a good per-HP rating in a 4 cylinder, the overall lack of power produced may be setting it back.

Also you have to consider gearing. In a lot of cases, you have to gear the transmission REALLY long to get optimal fuel economy. In CSR67, I had a contestant complain that he was having problems making economical engines. I took a look at his design, made a couple minor tweaks (made it run richer, with a more eco profile cam) and then lengthened the gearing, and squeezed out another 20% (raised from 14 to 17 MPG).

There are guys here who can make just ridiculously efficient yet sufficiently powerful engines. guys like NormanVaxhall come to mind. You might want to ask advice of/emulate someone like that.

5 Likes

Thanks for your help! That’s very useful. I hadn’t given the tranission much thought up until now.