AzCoupe":1aacyik8 said:
On a stock motor with headers, your probably looking at 40 HP or so. Not really sure, as no one has dyno'd their motor before and after the head swap? At least, not that I am aware of....
I can affirm that 40 hp is net flywheel hp increase, or 28 to 42% depending on what you would have had stock. Ball park rear wheel hp is 67 rear wheel hp. Figures for a reworked alloy head 2-bbl without headers are about 85 to 95 rear wheel hp.
There have been some historic early iron head 2V verses stock 200 log comparisions, and 40 flywheel hp is certain on an engine with no cam, ignition, compression and exhast changes asside from optimisation. You get a 2-bbl carb right off, great flow rates and sensational cylinder to cylinder flow efficiency.
Benchmark is the early Cross flow alloy head engines in Australia, where the 2-bbl versions put out 121 hp net, compared to the 85 to 94 net flywheel Hp of the US 1-bbl log head. 24 to 34 hp up on stock without anything but one alloy bolt on and a better carb. A set of headers brings that up to 143 hp, generally an 18% increase, and so with Mikes head, 2-bbl and headers, you'll see a 49 to 55 hp flywheel increase with reasonable certainty.
The real delight is that all the hard work has been done by Mike, and it exceeds what was done on the Aussie Iron 2V and alloy 2-bbl X-flow heads, without all the hassels that go with an imported head.