Question about engine boost parameters

Roadblock

I was looking for information about how to set up engines, and was going through some of the mods I have looking at what was done, and the iDT ChampCar2005-2006 mod has left me a bit confused.

Does anyone know what the formula is for the BoostPower parameter in the engine.ini? The closest to an answer I've found is the following (and it explains the BoostTorque parameter nicely)

BoostEffects=(15.0, 0.005, 0.052) // RPM increase per setting, fuel increase (1%) per setting, engine wear rate (5.2%) per setting
BoostTorque=-0.0043 // 0.4% less torque per setting (applies to all RPMs)
BoostPower=0.000150 // % more horsepower per setting

The order that rFactor applies these setting is important:

The BoostTorque change is applied uniformly across the entire torque curve, from 0 to peak rpm. The change applied is multiplied by the garage setting - as with all rF settings you can have as wide a range as you choose to declare; if you are implementing P2P then just have two settings and map rF's temporary boost button.

After the torque curve has been modified, the power change is applied. This is not only multiplied by the garage setting, it is also multiplied by rpm - in this way you can make the engine curve more (or less) peaky.
Click to expand...

This says the Boostpower is applied after BoostTorque, and that it is not only a function of the garage setting (and presumably the base horsepower), but also RPM. I just can't find anything that spells out the formula. Moreover, the numbers in the ChampCarLola_engine.ini file don't seem to match with the comments:

BoostTorque=0.0031 // 28 ft-lb increased torque at peek with PTP
BoostPower=0.0033 // 75 hp increased power at peak with PTP

The peak torque in this file is this line:

RPMTorque=( 11000.0, -133.6, 475.0)
so, 475Nm = 350.34 ft-lbs * 0.0031 = 1.086 ft-lbs of additional torque with their Push-To-Pass setup. I'm not sure where they are getting 28 ft-lbs, but perhaps I am missing something.

Anyone able to shed some light on this?

Thanks!
 
I may have answered my own question. It took quite a lot of digging, but I finally found some old posts from the RaceSimCentral forums that have long been deleted that shed some light. Supposedly this came from someone at ISI:


NewTorque = (torque in the .ini file)*(1 + (boost_setting * BoostTorque))

Then, to add in BoostPower, the equation should be (note that the comment in the INI file is not correct) ...

NewTorque = NewTorque + (RPM * boost_setting * BoostPower)
Click to expand...

Using these formula, I do compute approximately a 75hp gain at 13000 RPM using the above example from the ChampCar2006 mod. The 28 ft-lbs of torque isn't accurate though, so that comment threw me off a bit.

So, if anyone else was wondering about this, there you go!
 
Is it me or is there something strange with the second formula?
The first one makes sense.
But then NewTorque = NewTorque + (RPM * boost_setting * BoostPower).
Again NewTorque=?
And wherefrom do you get the increasing of the power?
 
Since horsepower is a function of torque and rpm, increasing torque will result in an increase in horsepower. In the case of this formula, it's quite a bit more HP as you get to higher RPM.
 
You must log in or register to reply here.

Back
Top