By:

besides piston deck height the design of the piston top and combustio 300x200 Engine Calculator

It’s hard to put to words just how powerful our engine calculator really is, especially for people trying to build up an illusive ‘All motor’ power plant …

I think the shortest way to explain how well the engine calculator works is through an example of a results page from the software itself as seen below:

Basic Information:
- Displacement = 2238 cc
- Stock Engine Volumetric Efficiency = 108 %
- Maximum Safe RPM = 7951 rpm
- Expected Bolt On Power is 163 crank hp
To reach your power goals you need:
- 3020 cc total displacement
OR – 8368 RPM red-line
OR – 18 points static compression ratio
OR – 145 % total volumetric efficiency
Valves:
- Intake Valve Size   = 2 x 29 mm
- Exhaust Valve Size  = 2 x 23 mm
Cams:
- Intake Cam Duration = 230 degrees
- Intake Cam Lift  = 7.25 – 9.5 mm
- Exhaust Cam Duration = 240 degrees
- Exhaust Cam Lift  = 5.75 – 7.5 mm
Ideal Head Flow (total per cylinder):
- Intake = 165 CFM @ 28 ” H2O
- Exhaust = 132 CFM @ 28 ” H2O
That is just part (not all) of the results that you get when doing an all motor calculation using the engine calculator module in our horsepower calculator.  I basically told the calculator that I had a 2.2 liter 135 horsepower engine (like the Toyota 5sfe engine I used to own 13 years ago that got me into the performance world)… and that I wanted to make 220 horsepower from this engine.
The power calculator gave back a set of complete and very helpful information
1- I am safe to raise my red-line from 6200 to 7900 rpm with my current bottom end dimensions and still have a safe build.
2- I will never hit that 220 horsepower mark with just bolt ons… at my current compression ratio, displacement, and red-line the best I could hope to make is around 163 horsepower and anyone selling me parts claiming much more than that doesn’t know what they are talking about.
3- To hit that 220 horsepower target I will need a combination of more RPM, more displacement, or more compression and it give me the three extremes on those parameters if I chose to just change 1 and leave the other 2 stock. Obviously going out to 18:1 compression ratio is not going to work on pump gas…. but a combination of more compression, more displacement, and a higher red-line … and a re-run of the calculator can help me find a combination that I can actually source parts for, that WILL hit my power target.
For example sake I just re-ran the simulation with:
  • 8000 rpm red-line
  • 11.5:1 compression ratio
  • 2 mm overbore pistons

And the result is as follows:

- Expected Bolt On Power is 237 crank hp

So you can see that in just two iterations I have found an all motor setup that will satisfy my power goals… what’s even more interesting is this:

  • When I re-run my numbers for the modified 237 horsepower engine, the calculator automatically redoes all of the fuel, camshaft, intake, exhaust, header, cylinder head…etc calculations to give me a complete list of parts that will support the new power level …
  • This engine simulation part of the calculator is not specific to all motor buildups. If I were doing a supercharged example here, as I modify my engine parameters with a stroker kit or a higher red-line, the engine calculator will first find out the estimated new power level from the new engine combination… after that it will go back and calculate the new (lower) boost level required to reach my power goal … so things that we see in the real world, like supercharger boost level dropping when we swap from a small block to a large block engine, while keeping the same supercharger gearing … can also be modelled using the engine calculator.

Use the engine calculator to design your engine build up