[DavidBoren]

Crankshafts have nothing to do with redline if we are only referring to the stroke of a crankshaft. With light enough, more specifically less massive, moving parts, stroke plays absolutely no limits on redline. The only limiting factor is heat through friction and vibration issues caused by large amounts of mass spinning really fast. Natural frequencies and the efficiency of the cooling system play a larger role than just the length of stroke.

I determine my redline based on cylinder head flow. I used online calculator(s) to see what the head flow numbers I had available could support. The Wallace racing online calculator said that the TEA stage two ported heads could flow enough to support six liters of displacement up to 8000rpms.

General Motors spun the LS7 to 8k during testing. So I knew the 4" crank (combined with lightweight parts) would not be an issue. Especially considering I will have smaller, less massive, pistons which is reducing weight/ mass out on the important end (so it doesn't matter as much if my non-titanium rods weigh more because that weight/ mass is closer to the axis of rotation).

Once I saw that the 5.3 heads could be ported enough to support six liters of displacement spinning at 8k, I honestly stopped worrying or even thinking about the redline.

Whatever the end of the powerband to the aggressive vvt comp cam is will be my redline. People on the interwebs talk about revving the vvt LS motors to over 6600rpms once the afm/dod is eliminated and new lifters are installed. And I'm sure +/- 6500rpms will be plenty for me.

But anyways, to answer your question, yes a 4" crank will fit in the standard block. I am not a pioneer in this effort. Wiseco makes forged pistons specifically for use with a 4" stroke and 6.125" rods in the 3.78" bore block. I believe K1 offers a complete forged rotating assembly using these pistons.

For reference:
LS2 cam is something like 204°/218° .551"/.547" 117° lsa

The aggressive vvt cam is 218°/222° .566"/.578" 114° lsa

Take whatever conclusions from that as you will. But, to me personally, it would appear that the aggressive vvt cam would favor a higher redline than the stock LS2 cam. And that's why I have stated that my redline would be higher than a stock LS2.