Good HP/KW ratio

Hi guys,

I’m trying to create some small Opel engines from the eighties. I’m trying to make an 1.0 Litre 45HP engine with the same bore and stroke as original.
The maximum horsepower is reached at 5500 and then should go down as you make more RPM. The horsepower and NM are very similar to the real thing.
However, this is when I set max rpm at 5500, when I set it at 6000, the maximum horsepower is at 6000 rpm and so on until finally the line of max output HP goes down.

I’d like to know how I can make the HP curve going till 5500 rpm and then drop. I know how to do it for torque, but I don’t know for horsepower.

This is just an example ofcourse. I’d like to know in general how to limit the max HP and also make it more look like this:

Try decreasing top end quality (well into the negatives if need be), and increasing the cam profile to compensate for the power drop. This should get you your peak power numbers at the rpm that you want, with a drop in power immediately thereafter.

smaller the cam the lower rpm hp and torqe bigger the cam higher end power

The original poster is not having an issue understanding the relationship between cam profile and output @ rpm… they’re trying to make the power curve in the game as realistic as possible.

I’ll explain how my suggestion works:

  1. By decreasing the top end quality, it reduces the engine’s ability to rev before the valves start floating, and I’m guessing influences variables such as cylinder head flow, valve size etc.
  2. By increasing the cam profile, it compensates for the power lost at the rpm the OP wants, but will allow the power curve to fall immediately thereafter.
  3. Doing this also brings the rpm at which peak power and torque are produced closer together (so for instance: instead of 280 hp @ 6,200rpm and 285ft/lbs @ 3,200rpm – it’ll be closer to 280 hp @ 5,500 rpm and 285ft/lbs torque @ 4,500 rpm) <<<< That’s what the OP was asking. Curious if it worked for them or not.

Welcome to the forum! :mrgreen:

Moving the peak power by causing a valve float? No offence but i wouldn’t expect a beta tester to say such thing.

Make sure you are not using variable timing exhaust valves, the cam profile is less then 40, (it doesnt needs to be any higher to produce 45hp), set the ignition timing to 100 and lower the compression if needed.
Combinations between head configuration, cams profile and ignition timing are the key to manage the peak.

The thing is, in Real Life you have different Valve Size and more strange stuff going on in the Valvetrain, also stuff like a ECU Mapping.

In Automation you just have the Cam Profile that sets how mild or aggressive the cam is and the Fuel-Mixture. Thats it.
Everything else would make the game horribly complicated - the MP shows that you can make a good engine in 3-5 Minutes. Lets say that this will double or triple if you add Valve Size, ECU Mapping and other stuff to make even more realistic torque figures. Does not add very much to the game to be honest, just stretches it and makes it more complicated.

With setting the Valvetrain Quality to a negative Value you let the valves float yes - but thats the only option… and you need to do it. If i remember correctly we had a Top End Quality of -5 to 1 on engines between 1980 and 2000. But then it mostly fitted to the engines and the curves turned out fine

A ECU Mapping would make able these perfect Torque Curves, but you would sit infront of it and optimize it for hours… thats not what you want.

:unamused: Rrrrrrrright…

And that’s all that needed to be said… thank you for your feedback.

That was my observation in trying to recreate engines from the same time period (ie. my own cars that I’ve owned over the years).

Thank you all for your responses. I’m going to try it all out.

This is one of the thing that bothers me. I’ll try to use some of the suggestions. In future, I hope ECU profile is included so we can tweak HP and Torque values.

There won’t be any more detailed ECU tuning, but frankly the whole process of designing a car is going to have so many steps and choices that I don’t think it’ll be missed much.

Sorry for the late reply, but just confirming that this worked out very well. Thank you :wink: