Vortec 5.7L stroked to 383

99-2door · September 29, 2003

In order to stroke a Vortec 5.7L to a 383 and still use the stock injection, what do I need to have done? Should I have the heads ported? Do I need a bigger throttle body? I just need direction in order to make it run RIGHT, and keep emissions under control. Where can I get the computer reprogrammed to match the new displacement?

Thanks for any info,

Jason

americanmuscleman · October 3, 2003

A 383 is a 350 thats had the cylinders bored .030" over, and the crankshaft has a 3.75" stroke instead of a 3.48" like a 350 has.

How many cubic inches an engine has is calculated like this:

Volume of a cylinder = 3.1416 (Pi) x radius squared x height

A 350 block has a bore of 4.00". So the radius is 2.00". The height in this equation is the stroke, which for a 350 is 3.48".

So the 350 cubic inches comes from the volume equation above, V = 3.1416 x 2.00 squared x 3.48. This gives you 43.73 cubic inches, which is the volume of one cylinder, and a 350 has eight cylinders. So 43.73 x 8 = 349.85 cu. in.

A 383 is calculated this way: The bore is now 4.030" in each cylinder (so the radius is 2.015"), and the stroke of the crankshaft is now 3.75". So V = 3.1416 x 2.015 squared x 3.75 = 47.83 cu. in. 47.83 x 8 cylinders = 382.67 cu. in.

SO to answer your question, to create a 383, you need to bore your cylinder block 0.030" over, and install a crankshaft with a 3.75" throw. In order to use a 3.75" crankshaft in a small block, you will have to 'clearance' the block. With the longer stroke crankshaft, the connecting rods will hit the side of the block where the block and oil pan come together, so the block will have to be machined to allow the connecting rods to clear. People have been putting stroker crankshafts in small blocks for 40 years, and any decent engine machinist will know how to clearance a SBC for a stroker crank.

A 383 is physically the same size as a 350, and will bolt right in place of your stock 350 block. Use your existing Vortec 350 block to create a 383 as there are quite a few differences between it and a non-vortec 350.

If I were you, and looking for a performance gain without spending a ton of money, I would have your cylinder heads and intake professionally ported (or install aftermarket aluminum ones like the aluminum Vortec fast-burn heads) and install a larger camshaft. Of course you need a free flowing intake and exhaust (headers and high flow muffler to see the best gains). You'll also need custom tuning.

As the saying goes, 'there's no replacement for displacement', which is true, but if you'll see a LOT larger gains porting the heads and installing a bigger camshaft than you will with just adding 33 cubic inches and keeping the cylinder heads and everything else stock (you will need custom tuning if you bore the block to a 383 by the way).

Hope that answers your questions! Sorry about it being so long, once you get me going, I type 200 mph.