Sacrilege

iTrader: (1)

Has anyone been able to swap an LY2 crank into an L83? I know that sounds crazy but this engine is for my long distance cruiser - the car I use when I do all of my cross country and coastal drives - so I want something that gets absolutely insane gas mileage. I have other cars with bigger swaps that I use for fun, but this car is not that. This is my grand tourer, if you will.



The stock engine gets 30mpg @ 80mph but I’ve recently found out the previous owner JB Welded the #6 spark plug into the head. (N54 in a 335i). I was debating getting a new head, but with all the headaches this engine has already given me, I’ve decided it’s just coming out - but I definitely want another DI engine to go in it because the highway gas mileage is just something you can’t ignore.

dixiebandit69

Just so we're clear, you're talking about swapping a Gen V engine into a BMW, right?

There is no DI 4.8, so you're talking custom piston territory = $$$.
What you spend on custom pistons is money that could have been spent on gas; how many MPG does the average 4.8 get vs. a similar 5.3?

LS1Formulation

iTrader: (13)

In my opinion, the loss in stroke ( and therefore torque ) will only require the throttle being opened further, which will mostly negate any mileage gains. Not to mention, there's a reason GM didn't make any AFM equipped 4.8L engines - Too low of torque when operating in AFM mode. And if you're planning on deleting AFM to overcome that issue, well, you are going to most likely be back to square one, mileage-wise. Also, who swaps a V8 in place of an L6 looking for mileage? Lol. Here's the deal: You want mileage? Swap in an LS1 F-body T-56 with the .74/.50 overdrive gears and keep your rear gear in the 3.50 range. A stock L83 in a light BMW with that gearing should net you 32-35 MPG. My Formula, when stock, got 30MPG on the highway going 75 MPH. I can't imagine a DI engine with smaller displacement couldn't exceed that figure.

Sacrilege

iTrader: (1)

All that would need to be changed is use the 4.8 rods. The wrist pin height is the same, as is dia. And the Gen3/4 4.8 and 5.3 HO pistons are the same part number, and the rod length for the Gen5 and Gen3/4 92mm stroke engine is the same at 6.098. Rod and main journal diameters also the same. That means a Gen4 4.8 crank and rods will slot right in. That part is just basic math and common sense. But the real problem is the front of the crank on the Gen4 and Gen5. That’s where things get tricky and was curious if anyone has attempted it because I’ve read the Gen5 crank has some different dimensions for the oil pump.