Ls swap

[livingez123]

Hi everyone, I have been reading just about every thread about the ls swaps. It seems everyone has their​ own preference in vehicle of choice. The I6 cars with rack and pinion steering seem to be favored while the 540 gets the nod for the bigger rear diff. What about the 528,530 or even the 740. I plan on a 6.0 and a auto for a mild daily driver. No track days or drags, I have a car for that. I just want a nice driver. I have done my fair share of engine swaps in other makes. So a BMW is next on the list. I might buy my mounts or depending on my mood just make them. I not afraid of some fab work or wiring... I actually like wiring!
So what do all of the experts think.

[waters17]

I'm no expert, but I've been researching the hell out of which engine and chassis to go with for my someday swap. I daily drive a e39 540i and the heavy steering was noticeable when I first got the car, but now it's just business as usual. -I believe you can install the M5 box with the servo assisted steering though. I've read that the ball steering box can get in the way of turbo piping. -I dunno. rack and pinion sounds nice, but I think it should be easy enough to swap out the subframes and associated parts if need be. Chances are, the suspension would get upgraded anyway. What's another couple hundred on a new subframe?

Engine choices are a nightmare for me. Doing a swap with a motor with similar specs to the M62 or S62 seems like a waste of time. Why'd you decide on a 6.0? To keep the equation simple, I want to go NA. I think I've decided on a LQ4/9 stroked and bored to a 408. Seems like it should be capable of decent numbers and maintain reliability. -building it for a reasonable amount of money is another story. I'm hoping for somewhere around 450-500whp with decent low end tq. Seems like every route I go down, I'm looking at $10k for a motor that meets my specifications.

The 540 has like a 2.81 or something open diff, so it'll need to be swapped or modified. Seems like the common route is the 3.15 LSD from the M5. -but I think that is due to the convenience factor. Then I end up thinking about the gear ratios in the GM trans vs the BMW trans. How's that going to work out? Ideally, I'd like to mate a 3.64 diff to the GM trans. That way I get decent power and good driveability. -easy to achieve with a $4,000 custom diff, but it sure would be nice to be able to retrofit something into the e39 diff.

A big 7 series swap would be an awesome daily driver. I think with that one, you'd want to start with a V12 platform so you don't have to worry so much about drivetrain strength. I really like the idea of a e32 LS swap.

[livingez123]

I'm going with a LQ4 short block with some LS3 heads, why? Because I have 3 of them sitting in my shop! This will make 500hp at the crank I all day long. All engine parts I have along with a 4l60e and 2, 4l80e transmission's​. I have my choice of cars to use, there are no shortages of them up in the PDX area. I did find a real nice ultra low mile black on black 740 (68k) and several 528, 530 and a 540 with the M package. I also found a sweet touring in red. Making the mounts are a non issue for me but I will price them out anyhow. Headers I might build but for the price to repair my tig I might just buy them. Right now I'm just shopping for the right car. This will probably be my last build because I've gone through 7 spinal surgeries and I just want a nice driver.

[waters17]

I looked up that 99 740iL. Seems like a good candidate, and a really good price too. That 95 740 with the dinan stuff looked pretty nice. I had no idea the 740's were so inexpensive. With spinal issues, I'd definitely go for a 7 series. I feel like i'm climbing out of my 540 sometimes.

[734i]

For those unfamiliar with the GM automatics, there's no arguing the brute strength of the 4L80E / 4L85E, they can be built to hold 1500+ HP, but the ratios are manure if you're street-driving 600 HP or less, which happens to be the upper limit of what the 4L60E /4L65E / 4L70E / 4L75E can be built to survive. And on paper, the 4L60E's 1-2 ratio spacing seems bad, but in daily driving, it's very very good. The torque converter mostly covers it, the torquey V8s do the rest.
With builds like these, you should choose your differential gearing based on your tire size and what cruise RPM the engine likes. Any of the LS V8s will be happy with a cruise RPM of 1800 at 65 MPH, and will give MPG in the upper 20s. If you're going to fudge, fudge high. I suggest keeping it under 2200, but that's better than fudging low, like 1700.
A stock LQ4 can easily pull 1700, some stock LS combos have come from the factory geared as low as 1400, but that just results in a lot of downshifting, all the time. That was just to satisfy the EPA's CAFE. Do yourself a favor and don't try it.
If you insist on daily-driving a 4L80E, then try for a cruise RPM between 2100-2300 at 65 MPH.
Here's the math: axle ratio times OD ratio times 336 times mph, divided by loaded tire diameter, which is 97% of advertised.
As supporting evidence, if you look up your tires on tirerack dot com, you'll see revs per mile listed right after the advertised diameter. If you do the math, they don't match. Here's how that works: 20168.067 divided by 97% of the measured diameter.