Project LSX 4.6is

[Don Nguyen]

Originally Posted by bmwman528e

Nothing other than the sway bar may be an issue and will need to be modified. The oilpan clears and the front dress clears. I will be running A/C so I wanted the mounts to work with the most generic cheap front dress. Its no fun spending $500-1000 just on a corvette/camaro/CTSV front dress. These were all issues I ran into with the smaller shorter tighter E39 chassis. We are fortunate our X5's have an enormous bay. I will also be finding a way to use the factory automatic shifter with my setup.

That's good to hear. On my E36 swap, I had to move the ABS out of the way and use a different steering piece to get it to work with the LS swap headers.

Are the diffs on the v8 E53s an LSD? I don't think so right? I still need to look into what diffs from other cars would be a bolt in swap for the E53 rear subframe.

[bmwman528e]

Originally Posted by Don Nguyen

That's good to hear. On my E36 swap, I had to move the ABS out of the way and use a different steering piece to get it to work with the LS swap headers.

Are the diffs on the v8 E53s an LSD? I don't think so right? I still need to look into what diffs from other cars would be a bolt in swap for the E53 rear subframe.

None that Im aware of unfortunately. Maybe Thayer Motorsports could build a stock one to your spec. I should call them next week.

[bcredliner]

Originally Posted by bmwman528e

600-650RWHP on 15-17lbs of boost and 500's on a lower waste gate spring. More power could be had with E85 and higher boost but with a gen 3 LS engine the rods are only so good. I don't feel like pushing it past its limits all day every day. Rear subframe will be removed and boxed in and reinforced. All new Poly bushings and will most likely be putting a 4.4i 3.64 rear end instead of the 3.91 4.6is diff. If I could get a E39 M5 3.15 diff to work and make mounts and modify to run I would. Driveshaft will be a one piece. If that doesn't end up working out a modified 9" will be put in but Im hoping to avoid that due to the $4-5000 conversion cost. Do you have any recommendations for the rear subframe on what you think the weak link is? I know your X5 has had a decent amount of power thrown at it over the years.

Manual or Automatic? Retain all wheel drive? Torque goal?

[bmwman528e]

Originally Posted by bcredliner

Manual or Automatic? Retain all wheel drive? Torque goal?

Automatic 4l80e, RWD, 575-600tq

[lo_jack]

Originally Posted by bmwman528e

None that Im aware of unfortunately. Maybe Thayer Motorsports could build a stock one to your spec. I should call them next week.

This is true, and the only difference between all of the differentials in E53 is ratio only (depending on the engine).

But L332 Rover (BMW owned them at the time) rear suspension will bolt up with a little modification, and I THINK they had options for some kind of locker, and possibly different torque splitting from the transfer case, which was not an NV125.

Sarek on this board put an L332 rear subframe on his E53. Search up his off-road thread. He said that subframe was more robust and had better articulation as well...neither would be bad with your torque goals.

[bcredliner]

Not all E53 diffs are plug and play.

Why do you plan to go from 3.91 to 3.64 or 3.15 diff ratios?

[bmwman528e]

Originally Posted by bcredliner

Not all E53 diffs are plug and play.

Why do you plan to go from 3.91 to 3.64 or 3.15 diff ratios?

For a boosted application the longer the gear the better within reason. With a 3.91 and a 4 speed 4l80e the rpms will be relatively high at freeway speeds etc. If this was a 6l80e trans maybe the 3.91 would be a good setup. At 80mph in overdrive with a 3.91/4l80e you will be turning 2700RPM. With a 3.15 you are at 2200RPM.

[bcredliner]

Unless your goal is top speed, going to a 3.15 ratio is going to decrease 0-60-100 time. You might get better mileage cruising at 2200 RPMs if that is your goal. Isn't there a 5-8 gear GM transmission that would be better for both acceleration and cruising?

[bmwman528e]

Not sure on the 8 speed front but the 6l80e has 6th gear at 0.67 4l80e is at 0.75 so not a huge improvement there. Traction is going to be an issue plain and simple and a 3.15 gear or atleast a lower gear than a 3.91 will be a huge help. As well as LSD.

Here are some updated pics from today. This will be the final home for the engine. There are no modifications needed at all for the swaybar or the oilpan which will help keep costs down for whoever wants to swap their SAV in the future. Stock Front Dress and Stock Truck Intake Manifold have all sorts of clearance. The engine mounts will be a tubular design. As you can see there is a ton of space on the drivers side for off the shelf performance headers. Ill update the thread once I know which headers will work.

[bcredliner]

Might want to address any traction issues from higher gear ratio with choice of tires. Or, see what happens before going to lower ratio. That is, unless top speed is your goal rather than A to B time. With lower gear ratio it will take longer for turbo to spool up and torque is your best friend when trying to get a heavy vehicle going. You should be able to put 600 ft/lbs to the ground with 3.91 ratio. Worst case you just adjust throttle input until you get rolling a few feet.