Originally Posted by 1Gary
The aluminum blocks are the ones with limits of HP.In fact the aftermarket speaks to that in how they have addressed that in their design.The cast iron is a stronger part.
There is two thoughts that come to mind given you build plans.
First,the 6.0 isn't known for good gas mileage.It's better than a 383,but still isn't as good as the 5.3.So I am thinking if your plan is because you think your going to gain in that department,you might be disappointed.
Second,I know the LSx's have been turbo'ed with good success.I don't recall one with a roots type blower.I do know crank companies in the first Gen's offering a bigger snout to address the problem you have,but I don't think I've seen that for the LSx's.With the turbo it wouldn't be a issue and turbo's have a solid mid and not so much so for a bottom or top end.But I would think for a boat that would be ideal for a constant run mid rpm having a power curve right where you want it and use a EFI system for throttle response.
In general I sure wish Chevy hadn't build the c.i. sizes they did in the LSx engines in a attempt to save on gas mileage and then tried to compensate with power train gear ratio's/electronics.Most of it seems they turned back the clock to the days of 327 first gens.Certainly the mod'ed first gens out shine the LX's in the bottom end range.
1 reason the 6.0 has a bad wrap for fuel economy is because a mjority of 6.0's are found in 3/4 and 1 ton trucks and use the 4l80e trans. Apples to apples comparison with a 5.3 in a 1/2 ton truck and a 6.0 in a 1/2 ton truck reveal that fuel consumption is on par for the displacement difference. Its not like the GEN 3/4 6.0's are gas hogs by design.
I agree 100%, the new 6l80e/90e and their 4.0:1 1st gears are in use to make up for the lack of low rpm torque the GEN 3/4 engines possess. The GEN 4 LY6 is a 6.0 installed in the 3/4 and 1 ton trucks and it is a dog at low rpm, even with its VVT.
In my Vortec 350 truck I can put along 1400rpm in OD with the torque converter clucth locked up. If I apply throttle will accelarate as is. Same scenario in a GEN 3/4 engine power truck results in a downshift or TCC unlock.