340 Max HP Potential with X/J heads?

B3422w5 said
Justin knows what he is doing, is a long time racer, his stuff runs excellent, and he is a very valued poster.
He is 100% correct. Putting a tiny iron head on a 4 inch arm motor is like wearing a life jacket in ankle deep water.
Even a well done eddie head is WAY to small to support a long armed 420 inch motor. I had such a motor and it was weezing at 1100-1200 foot mark.
For that matter, even a W2/5 head is marginal for a 420 inch motor. Even they were designed long before the advent of 4+ inch cranks. Been there done that too with a 422 W5 deal thats been 140 mph at 3200 on leafs.
Your barking way up the wrong tree here. Justin knows exactly what he is talking about and is 100% on the mark.
Can you do it. Yes. Is it a tractor. Absolutely

As someone once said, it’s hard to get enough head.. on a sbm stroker. This was stated for the smaller 4.00 arm and a 4.03 - 4.07 bore engine never mind the increased stroke to 4.15, 4.18 or 4.25. Upper W heads can get what you need when we’ll ported.

But tht is also a racing venue.

The W2-5 was out when the MP stroker cranks were in, but! They (MP) limited the stroke to 3.79 and told you to use a race block with a big bore for more cubes.