newb question on motors

[GottaHaveLS1]

Can someone explain to me what makes an engine a "stroker"? ....I know.... i'm very ignorant....

[Sprfstz28]

It's all good man :D

A stroker motor is a motor that has had the stroke lengthened in order to increase displacement. For example, take a Chevy 350, and throw in a small block 400 crank (i think its like .5" longer stroke) and the 350 is converted to a 383. You can buy kits to convert for 302s (5.0L) to 306, 331, 347 inch motors. Most of these stroker kits also include boring out the cylinders to increase displacement.

[mrr23]

you can do it with a larger bore as well. or do both together. both ways will increase dispalcement.

[hammertime]

Very generally speaking 'stroker' motors are known for making more torque, where 'bored-over' motors breathe better for more hp. A 350 Chevy has a 3.48" in stroke, and a 400 has a 3.75" stroke, so its really only about a 1/4" more, but its usually worth about 80-90 lb-ft of torque. A 402 ci LSx motor jumps from a 3.62" stroke up to 4.00" -- .38 inches!

Now, not too many people bore LS1 motors much because of the sleeve arangement in the stock block, but it can be done to a certain extent. Or you can get a C5R block for a bore up into the 4.125 range.

[Aegnor]

It's simple mathematics.
An engine cylinder is a geometric shape. The volume is: V=pi*r^2*h where V is volume (or cylindrical displacement), pi is 3.14, r is radius of the bore (1/2 the bore measurement) and h is the height (or stroke). If you increase the stroke (h) you increase the total volume, or displacement of the motor. Total displacement is D=V*# of cylinders.

Total equation is Displacement = (pi*(Bore/2)^2)*(# of Cylinders)*Stroke

Increase Stroke, increase total displacement. You can also plug in the other numbers to find out other variables, like how much you would have to bore an engine without changing stroke to get the same displacement. It's basic algebra and geometry.

Come to think of it, has anyone done a 383 by boring, with a stock stroke? And if so, what was the difference in the power bands?

[Sarge]

Only good looking people run Stroker motors....torque monsters.....

[hammertime]

Come to think of it, has anyone done a 383 by boring, with a stock stroke? And if so, what was the difference in the power bands?

Using 4.100" bore and 3.62" stroke should yield a 383, but I don't think you can do it without siamese bores ~ basically you gotta get a C5R block to do it. Seems that everyone who dropsthe coin for that goes for the extra cubes of a longer stroke.