what exactly is a 383 stroker? How much are they and do you buy them or make them. any info would be helpful. How much HP and also are they worth it? Thank You Mike

 

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New crank/rods/pistons with a larger bore and longer stroke increase your engine's cubic inches of displacement.

I'd say at least 5 grand, starting. Including labor of taking your motor out, machine work, and parts.

Without heads and cam, not much more power, unless you increase you're compression ratio.

 

Stroking an engine refers to increasing the stroke of the crankshaft, with or without an increase in bore size, to increase displacement and produce more torque by increasing the mechanical leverage of the pistons on the crankshaft. In essence, you're giving the pistons a longer "lever" to push on the crankshaft with.

The stroke of the crankshaft is the distance from the centerline of the main journals to the centerline of the rod journals.

One formula for calculating engine displacement is:
bore x bore x stroke x # cylinders x 0.7854 = CID

For a 350 (5.7 liter)...
4.0" x 4.0" x 3.48" x 8 x 0.7854 = 349.85 (350) CID

The stroke of the 350 crankshaft is 3.48". If we increase stroke to 3.75", you can see the effect on displacment...

4.0" x 4.0" x 3.75" x 8 x 0.7854 = 376.99 (377) CID

If we increase both the stroke and the bore, we get even more displacement. Increasing stroke to 3.75" and increase the bore (cylinder) diameter by 0.030" ("30 over"), you get...

4.03" x 4.03" x 3.75" x 8 x 0.7854 = 382.67 (383) CID

Any time you increase the stroke of the crankshaft, you'll have to buy new pistons at the very least. You could stay with a 5.7" long connecting rod (stock length), but most go with 5.85" or 6.0" rods to increase dwell time (the time the piston spends at TDC and BDC before changing direction).

If you buy a 3.75" crankshaft, you have the option of cast or forged. 3.875" and larger crankshafts are only available forged, and that increases the cost, but forged crankshafts are also stronger. You can also buy a complete 383 rotating assembly (crankshaft, rods, pistons, rings, etc.) from several vendors now.

While it's not set in stone, with all other factors remaining the same (heads, cam profile, compression ratio), the increase in power should be roughly equal to the increase in displacement. In other words, a 383 would make about 9-10% more power than a 350, since you've increased displacement by that percentage, and power is a function of how much air and fuel you can burn in a given period of time.

The benefit of the 383, however, is that it will make significantly more low end torque than a 350, and therefore more low end power. It should also have a flatter, more powerful torque curve. You are increasing the area "under the curve", and therefore increasing the average output of the engine as well, which means it should accelerate more strongly over a greater rpm range when compared to the original 350.

At least that's my understanding...

Hope that helps.