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Stroker, what is a stroker and how it works.
A stroker is just what is says it is. Stroke. I'm not getting into understanding how an engine works but I am going to talk a little bit about the bottom end. In the bottom end you have a crankshaft (crank) it has main journals and rod journals. The main journals is where the crank sits in the block and is retained by the main caps. These journals are in a straight line, otherwise the crank would wobble around crazy and destroy your engine. The rod journals are where the ends of your rods are connected to the crank. To determine the stroke of the crank you measure from the centerline to the centerline of the rod journals. This is known as your stroke. To determine piston travel, take the stroke and times it by 2. A stock LT1 has a crank with a stroke of 3.48", with a stock rod length of 5.7", and a stock bore of 4.00". Using these three numbers we can determine the cubic inches and liters of the engine.
Here is the formula for this:
So lets say you drop a 3.75" crank into a stock bore LT1.
So as you can see just by changing the stroke of your engine can net you extra cubic inches, by changing the piston travel.
Bore Over explained:
Ever heard someone go "I have bored my engine 30 over." Did you ever wonder what that means? When someone bores their engine over they mean they bored the stock bore bigger. Now we are talking tiny amount being removed. A 30 bore over is .030" thats 3 hundredths of an inch bigger than the stock bore. A 40 over is .040" and so on. Now that doesn't sound like much but using the formula above, boring a 350 .030" over can net you extra ci.
Stroker + Over bore = Power:
Adding a stroker crank and boring over will net you even more cubic inches. Remember adding a 3.75" crank to a stock bore 350 increased the ci to 377? Well now bore it 30 over (.030") and add 5 more ci to that. That gives you a total of 383 ci. Obviously engines work by the more air and fuel you can fit in, the more power you can make. Well a 383 will fit 33 more ci then a 350, thats a .54 liter difference! Now different sized cranks and bores will give you different ci. Here are the common ones.
A 3.75" crank with a 40 over (.040")
A stroker is just what is says it is. Stroke. I'm not getting into understanding how an engine works but I am going to talk a little bit about the bottom end. In the bottom end you have a crankshaft (crank) it has main journals and rod journals. The main journals is where the crank sits in the block and is retained by the main caps. These journals are in a straight line, otherwise the crank would wobble around crazy and destroy your engine. The rod journals are where the ends of your rods are connected to the crank. To determine the stroke of the crank you measure from the centerline to the centerline of the rod journals. This is known as your stroke. To determine piston travel, take the stroke and times it by 2. A stock LT1 has a crank with a stroke of 3.48", with a stock rod length of 5.7", and a stock bore of 4.00". Using these three numbers we can determine the cubic inches and liters of the engine.
Here is the formula for this:
3.1416/4 x bore(squared) x stroke x cylinders
3.1416/4 x 4.00^2 x 3.48 x 8 = 349.88 cubic inches (rounded to 350)
To convert from ci to liters is: ci / 61 = liters3.1416/4 x 4.00^2 x 3.48 x 8 = 349.88 cubic inches (rounded to 350)
350 / 61 = 5.73 liters (rounded down to 5.7 liters)
So to increase the ci or liters of and engine you can increase the stroke making the piston travel farther. The piston travel on a stock LT1 is 6.96". You increase the stroke by putting in a stroker crank. Which means the measure from the centerline to the center of the rod journals is longer. Longer rods must be used to compensate for the extra travel. So lets say you drop a 3.75" crank into a stock bore LT1.
3.1416/4 x 4.00^2 x 3.75 x 8 = 376.99 (rounded up to 377 or 6.18 or 6.2 liters)
By adding a 3.75" crank, you have added roughly 27ci or .44 liters to your engine. Piston travel now went from 6.96" to 7.5" which is where the extra cubic inches came from. So as you can see just by changing the stroke of your engine can net you extra cubic inches, by changing the piston travel.
Bore Over explained:
Ever heard someone go "I have bored my engine 30 over." Did you ever wonder what that means? When someone bores their engine over they mean they bored the stock bore bigger. Now we are talking tiny amount being removed. A 30 bore over is .030" thats 3 hundredths of an inch bigger than the stock bore. A 40 over is .040" and so on. Now that doesn't sound like much but using the formula above, boring a 350 .030" over can net you extra ci.
3.1416/4 x 4.030^2 x 3.48 x 8 = 355.11 or 355ci
Just boring your stock bore .030 over, you gained and extra 5 cubic inches. You have to be careful when boring over. Since you are removing material you are thinning the cylinder walls, removing strength from them. A 350 should not be bored more than .060 (60 over). Even this is getting right on the edge which I don't recommend. The fun part is now joining a stroker crank and a over bore.Stroker + Over bore = Power:
Adding a stroker crank and boring over will net you even more cubic inches. Remember adding a 3.75" crank to a stock bore 350 increased the ci to 377? Well now bore it 30 over (.030") and add 5 more ci to that. That gives you a total of 383 ci. Obviously engines work by the more air and fuel you can fit in, the more power you can make. Well a 383 will fit 33 more ci then a 350, thats a .54 liter difference! Now different sized cranks and bores will give you different ci. Here are the common ones.
A 3.75" crank with a 40 over (.040")
3.1416/4 x 4.040^2 x 3.75 x 8 = 384.56 or 385ci
A 3.875" crank with a 30 over (.030")3.1416/4 x 4.030^2 x 3.875 x 8 = 395.42 or 395ci
Well I have done enough math for you. To see what your engine cubic inches or liters would be pick your crank and bore and just plug it into the formulas I provided and presto you have your new cubic inches.