Quote: the MP 392 carb crate engine made 620 back in 2007.
It was a std. bore 6.1 with a 3.795 stroker crank and CNC 6.1 heads.
It had the predecessor to the drag pak manifold (same intake but without injector holes), 10.3:1, .584/.552 lift cam, and that was about it. It made 620 with an 870 street avenger carb.
Then two things happened: 1. Rated HP was downgraded to 540 to make the 525HP EFI version more appealiing 2. It was never pictured in any marketing materials, and was only shown at trade shows
...and that pretty much killed it....
Clone it, and you pretty much got it.
basically 550 to 600 lift, mid 9s to 10.5:1 (more would be better), try to get at least around 400CI, the good intake manifold, and....I am not going to debate which cylinder head to use because the truth is...ANY of them will work.
Just get a core engine that does not have VCT/VVT, and don't worry too much about what heads it has.
If you have 5.7 heads, get them ported and bigger valves put in. Same with 6.1 heads. Apache heads would probably do it without porting but the intake isn't going to match up very well, so you end up working on the intake instead of the heads.
If anything, I feel the combo would slightly favor Eagle heads because of the tiny chambers/alcohol/easier to make compression, and that they should match the 6.1 dp intake fairly well also.
