Supercharger Performance and Engine Performance Parts

There’s an abundance of bolt on and custom application engine performance parts available for any vehicle, and the internet is full of advice, trials, and feedback from enthusiasts, brand promoters, magazine editors, and even racers about which performance parts are best for your car. This is the triple distilled guide on engine performance parts to help you make the most power with the least effort…..

Engine performance hinges on one of THREE general factors:

1-      Raw power factors

2-      efficiency factors

3-      Power boosters

1-      Raw power factors:

There are three raw power factors that decided whether you have a good ‘platform’ to build power on or not: Displacement, RPM, Stroke. Confused? I will explain:

                A: Displacement:  The old adage: “There is no replacement for displacement”.

Displacement is the size of your engine and thus the size of your cylinders, as your engine and cylinders get larger (by swapping to a larger engine, using overbore pistons, and increasing the stroke of your cylinder) or by any other engine design (wedge or rotary or other) that gives you a larger volume engine. As you increase the volume of your engine, you have more room to fill with nice combustible air / fuel mixture, and the bigger the volume, the bigger the potential bang, the bigger your potential horsepower.

It goes without saying that if I take a 6.0 liter V8 and a 3.0 litre boxster 4 with similar design from the same manufacturer that the 6.0 liter V8 probably makes about double the horsepower of the 3.0 liter boxster 4, and so one of the oldest and most effective tricks in hotrodding (and in Reliable OEM performance packaged cars) is to stuff a BIGGER motor , in a smaller chassis.

If you’re familiar with bottom end kits including overbore pistons, stroker cranks, stroker kits, and cylinder sleeves, then all these kits work on increasing performance essencially by increasing displacement and giving you more bang (quite literally) for your block.

B: RPM (revolutions per minute):

Every time an engine fires and ignites the air fuel mixture in the cylinders, the expanding gasses of the combustion process create a force pushing back down on the piston, exerting torque on the crankshaft, and rotating the crank, the transmission and eventually the wheels giving us acceleration. Depending on weather you have a 2 stroke, or a 4 stroke (or other) the engine will fire once every 2 or 4 revolutions. So say you have a 4 stroke motor at 1000 revolutions per minute, that means that within one minute you have 250 combustion events in your motor, which delivers torque to your crank (and eventually to your wheels for acceleration) 250 times in that minute. If we go up to 2000 RPMS, the revolutions double, and so also the rate of engine firing doubles to 500 combustion events, giving you essentially double the horsepower.

So, in terms of RAW power potential, the maximum RPM that your engine can operate at, is linearly related t how much raw power you can produce.

Formula one cars (and motor cycle engines as well) have in their quest to produce the lightest yet most powerful engines they can, used engines that are smaller in size (less volume/displacement) but more than made up for the loss of displacement by revving those engines up to 18000 revolutions.

So if you’re looking at an engine swap, and you have two engines to work with of the same volume, always take the engine that has a higher safe redline, as with that car, you have more revolutions to work with and ultimately more opportunity to make power.

cams, headwork, and other such modifications work on this principal of power production by trying to shift your peak power rpm up as high as possible giving you a higher peak horsepower figure.

C- Stroke:

What I mean by stroke is not the distance travel of the piston inside the cylinder, but rather, I mean weather we are talking two stroke, or 4 stroke, or other stroke.

A 2 stroke engine fires once every 2 revolutions. A 4 stroke engine fires once every 4 revolutions. If I had two engines of similar efficiency, the same peak rpm, and the same displacement, where one was a 2 stroke, and one was a 4 stroke, the two stroke motor would produce double the horsepower of the 4 stroke motor at every rpm point, because quite literally the 2 stroke engine has double the combustion events and delivers torque to the crank (and eventually to the wheels) twice as often as a 4 stroke motor.

Now in most situations we will not be able to convert our 4 stroke engine to a 2 stroke… but If for example I had the option to use a 2.0 liter 4 stroke in my race car vs. using a 2.0 liter twin rotor rotary engine which essentially fires one time for every revolution, then using the rotary engine of the same displacement will produce FOUR times the power output (holding all else constant : displacement, peak rpm, stroke, efficiency…etc).

To summarize section 1 of this series:

If I had to choose a motor for my race car, I would open up the rule book for my racing series and look for what is allowable in terms of maximum displacement, rpm, and stroke. And I would then choose the engine where the following calculation produces the largest result:

Raw power potential = DISPLACEMENT * MAX RPM / STROKE

This simplifies comparing for example two engines that are cheaply available at a junkyard if I wanted for example to build a low buck racer:

A)     4.6 Liter ford crown Victoria V8, 4 stroke, with 6000 RPM redline.

Raw Power potential = 4.6 * 6000 / 4  = 6,900

B) 2.3 Liter Honda CRV Inline 4, 4 stroke, with 8000 RPM redline.

Raw Power potential = 2.2 * 8000 / 4  = 4,400

C) 1.3 Liter Mazda dual roter, 1 stroke , 9500 RPM redline

Raw Power potential = 1.3 * 9500 / 1 = 12,300

D ) 1.3 Liter Hyabusa Boxster 4, 2 stroke , with 13000 RPM redline.

Raw Power potential = 1.3 * 13000 / 2 = 8,450

As you can see it’s very easy to see that if allowable in the rule books, and so ranking these engines according to my preference (from highest to lowest):

Mazda Rotary >> Hayabusa Boxster >> Ford V8 >> Honda I4

Of course the gearing, gear ratios, and final drive ratios for each engine would be different to make it work for my application… but when focusing on raw power potential this is how you pick them…

Technorati Tags: Displacement, Rotary, RPM, Stroke

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