Originally Posted by ThirdDegree
Does anyone know how much they flow? How alike they are to their 350 counter parts? I have found very few reviews. Mostly bad.
Where have you been? The magazines and books are full of Vortec reviews though we're 15 years past their introduction so they don't capture headlines like they used to.
In test after test compared to other production Chevy heads they deliver a 20 to 60 horse improvement by just bolting them on. 20 horses against older small chamber heads like the 462 or L98 when ported and 40 horses against these heads unported. 40 horses against large chamber heads like the 441 or 882 ported and a solid 60 against these heads unported. Plus the Vortec doesn't give up much bottom end torque, not enough to be felt. There are heads like the GMPP Fastburn which is essentially an LT4 head made for conventional coolant flow which will out flow the Vortec and certainly many aftermarket heads that will but they all give up a lot of bottom end to do it and cost a lot more. Then again the GM Vortec does require a Vortec specific intake and whether you get one from GM or off the aftermarket they are a bit pricey.
With Vortec heads and a cam like the Comp 262 to 268 with a 650 to 750 Holley and full length headers, the engine will make around 400 horses with an otherwise production bottom end. With changes to the piston to a D dish to improve the squish/quench characteristics and get the compression up around 9.25:1; it is possible to move that number toward 425 from 350 inches and have a very streetable motor that will take an automatic without having to up the converter stall.