View Full Version : Silly's guide to reworking engines and boosting horsepower in FSX/FS9

02-10-07, 03:48 AM
Ok here is my silly little guide on reworking your engine via the aircraft.cfg file to boost horsepower. It's simple enough if you have knowledge of how piston engines work, as each parameter effects the engine power as you would expect it too.

The aircraft.cfg file is located in the given aircraft folder. Open it in notepad and look for the piston engine section. All the parameters needed to rework the engine are located here.

First of all, max_rated_hp= does nothing at all to affect horsepower, from what I can tell. If I am wrong correct me.

Now the easiest way to increase HP is to add cyliners, or displacement to those cylinders. cylinder_displacement= and number_of_cylinders= respectivly. If you double up either of these, you will have double the horsepower, or if you increase by 25%, you have 25% more power, etc.

A substantial gain in power can come from increasing your max RPM. This setting is max_rated_rpm=. An increase in this value implies all the needed engine adjustments to move the power band higher.

The other two serttings that affect power are your compression ratio, and manifold/boost pressure. These are compression_ratio= and max_design_mp=. Only if you install a turbo/supercharger to your engine with turbocharged=1, will you be able to specify a manifold/boost pressure. The higher you set the manifold pressure, the more air you are compressing into the engine with a faster supercharger or a larger turbo, hence a higher air pressure density, and more oxygen to create power with.

As an example, in order to get the Spitfire from 2050hp up to 3000hp with the same engine block, the manifold/boost pressure is simply increased from 66.8 to 72, and RPM is increased from 2790 to 3200. In the case of the Spitfire, it measures PSI of boost rather than manifold pressure. 66.8 MP is equal to +18lb boost, and 72 MP is equal to +21 boost.

Now remember, in the real world if you go upping the boost of your engine you will have to deal with detonation, possibly resulting resulting in a blown engine, so keep that incomming air as cold as possible with the best intercooler you can afford!

Enjoy, and if you have questions please ask.

EDIT: You may also have to change the max_indicated_speed and max_mach numbers, as they trigger overspeed warnings and crashes.