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Stroker kit vs. stock crank with higher compression

October 6, 201014 yr

I can go on and on, but it's a bit of a pointless argument at this point that has completely veered off topic...

If this post doesn't end this argument, nothing will. Well done.

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October 8, 201014 yr

comment_332922

It won't as HP/CI curve is not linear.And Leon-wizz off.

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October 8, 201014 yr

comment_332936

If this thread was on HybridZ I would have shedded it by now...

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October 8, 201014 yr

comment_332937

It won't as HP/CI curve is not linear.And Leon-wizz off.

A common and often used equation used to estimate HP.

HP = (AP*CR*VE)*(CID*RPM)/(5252*150.8)

HP = Horspower

AP = Air Pressure, 14.7 psi

CR = Compression Ratio, ie: 8=9:1, 10=10:1

VE = Volumetric Efficiency; ie: stock ~ 0.90; high-performance ~ 1.00; race ~ 1.10

Keep all things on the right side of the equation other than CID equal between two engines. Same CR. Same VE. Same RPM. In other words two engines in like states of tune.

No terms are raised to a power or any other funky stuff so it's linear.

10% more CID means 10% more HP.

It also does not weight either bore or stroke in the CID term.

Another that can be used is PLAN.

HP = plan/33,000

Where p = mean effective pressure (pounds per square inch), l = length of piston stroke (feet), a = net area of piston (square inches), and n = number of cycles completed per minute.

Note again that it's linear and the result of a 10% increase in CID is a 10% increase in HP.

These equations are simplifications of the many variables that determine HP. And obviously crazy extremes in the values of the variables would make the equations less accurate.

The point is, controlling for all the variables between engines (like builds or state of tune if you prefer), if you build one with 10% more CID you will have 10% more HP.

So, as I have said multiple times, all things being equal (equal states of tune) a 10% increase in CID will gain you 10% increase in HP.

Steve

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October 8, 201014 yr

comment_332941

doradox, you are wrong and Ztrain is always right. The sky is purple and the sun revolves around the Earth. As soon as you accept his reality life will be better.