Swap_A_Holic's 1994 BMW 5 Series

1994 BMW 553iT: Chevy 5.3L Gen 3 V8 Turbo / T56

About this Previous Vehicle:

This is a project that began in September 2007. The concept is to take a Chevy Truck motor, install it into a BMW 5 Series wagon, and turbocharge it while maintaining a stock appearance as much as possible.

The parts used in this car are from several common vehicles, with the exception of the differential, which is a large case limited slip unit from a BMW 7 series, the radiator, which is from a same year (94) 540i, and the calipers/rotors (see below).

The cooling fan is from a 95-96 Lincoln Mk 8. The computer & wiring harness are from a 1998 Camaro/Trans Am. The oil pan (worst part of the project) is from a 2008 Hummer H3 Alpha 5.3L Gen 4 motor & uses a metric oil filter. The motor is from a 2005 GMC Sierra, the accessories are from a C5 (97-04) Corvette, except for the PS pump, which is from the BMW motor, and the intake and fuel rails are from a Camaro/Trans Am (not LS6). The injectors are 42# units. The cam is from a 2004 Corvette Z06 and was number matched to verify it was the later cam. The valvesprings were replaced with LS6 units for a higher RPM range. The heads are "317" casting from a 6.0L truck motor for lower CR due to the turbo. An aftermarket oil cooler and sandwich adapter (at the oil filter boss on the pan) are in place. The intercoolers are ATI high flow (3" in/out) from a Camaro/Trans Am application.

The motor was mounted using stock BMW mounts on some angle iron brackets bolted to the BMW crossmember. I had to section and reweld the piece between the control arms for oil pan clearance, and added a small skidplate there. I also sectioned & rewelded the trans cross member with some angle iron and used a GM trans mount.

There is a used Tial branded wastegate, the ad said 10 PSI on the spring. A new OBX blow off valve is in place on the cold side.

The brake master cylinder & hydroboost are from a 1997 Mustang Cobra.

The clutch is a stock LS7 unit from a GM dealer- got in a deal at the Corvette forum- I don't know the application for replacement, but believe it like most other Gen 3 parts is universal. The clutch MC is stock BMW for the car. A SS braid hose connects the MC to the throwout, and a remote bleeder was installed when I did this.

The transmission is from a 2002 Camaro/Trans Am. The shifter is stock GM, using the BMW boots- the wagon had a MT option in Germany, and sedan parts fit here also. The driveshaft will fit a Mustang, I will have to double check the years, but think it was an early 90's V8 unit. I got it from a driveshaft place and it is aluminum. The front yoke was replaced to mate with the T56. The BMW drives the speedometer from the diff, so the T56 works fine in this regard.

The adapter to the differential is explained in detail on the LS1tech buildup on the car- it is a Spicer or Rockford standard part that another member found. I drilled & tapped the holes in it to match the BMW differential.

The fuel pump was replaced with a 255 LPH unit from a guy that I had bought two others from and I'm using them w/o issue in my other converted cars. They are fine pumps, but he shafted me on this one by not sending the filter part, and then acting like it was my fault- it was like 2 weeks to get the parts due to his screwups. It is equivalent to the Walbro GSS series. I have forgotten his name and in any event would never buy from him again. A Walbro would be a direct replacement.

The differential is identified as above. The halfshafts and outer carriers are from a BMW 540i automatic- these were needed to fit the larger diff. The brakes were recently changed to 540i rear (thicker) rotors and calipers, and early 90's 850i single piston calipers/brackets/rotors- a bolt on upgrade with larger diameter rotors. These are getting hard to find, so future work would likely be another type of caliper or sending these out to be rebuilt. The pads are EBC red stuff front & rear. The rotors were name brand, I think Brembo- I don't buy the cheap China rotors.

I think that is the gist of what was replaced from other cars.

I added a three gauge panel to the top of the dash- mech oil pressure, vac/boost, and voltmeter. I did the bulbs red to match the BMW lighting. All gauges work in the car. The cruise control works. The stock underhood unit was retained and connected to the GM throttle body via some throttle cable parts from Pegasus Auto Racing (available online).

The exhaust manifolds are a Sanderson block hugger on the driver side, and a custom log on the passenger side. The exhaust behind the turbo is a 3" single system to a single in/dual out muffler. Once the leaks up front are corrected, it would be a lot quieter and boost sooner (see below).

I have extensive diagrams for most of what I did- wiring, plumbing, etc. I am printing these to put into a notebook for the next owner, and will burn all the digital pics I have onto a DVD at full resolution for reference.

As far as daily use, these are the current problems/nags-
1) All the idiot lights are on- battery, ABS, SRS, Parking brake. I think there must be a common cause here but have not done any wiring tracing. When I had the car on stands, none of these lights were on. The alternator is putting out almost 14V @ idle on my volt gauge and also on my multimeter, so there is no reason for that light to be on. The battery was replaced with an Optima red top a few months back, the old Interstate one had died out due to age. See #3 also.

2) The windshield has a crack in it, about 8" long at the lower passenger side. Since the car is still insured, I can have this replaced for free and am going to call this in next week. I expect they will have to order the glass, so probably a couple of weeks on this.

3) When I first drove the car, there was a whirring noise at the passenger rear. I noted the rotors were worn very thin, and at that point did the brake upgrade. The noise is still there, and some believe it may be the ABS sensor, and this could be triggering the dash lamps. The part is close to $100, so I have not fooled with it.

4) The front end, really the steering wheel- needs to be aligned. the shop I take my cars to could not get it on the lift ramp to do it since the spoiler is so low. The car drives straight down the road, but the wheel is off a little. I had the steering parts off to do the oil pan fitment. The center link and tie rod ends are new, and I lined it up as best I could from under the car.

5) The body is in very good condition, no rust. A few dents and dings. The inner fender by the turbo had to be hammered in/out for clearance.

6) There is no windshield washer setup. I could not locate a bottle to fit. A universal setup could be adapted.

7) The AC when I charged it was leaking at the drier- I got the wrong one and ended up using one from an earlier BMW 3 series- like an 86. It lacks an extra port the 88-95 5 series units have. Since I replaced it and charged it, I have not seen any leaks. However, the dash controls will not cycle the clutch. I wired it to mimic the GM system, and used a GM pressure sensor. The problem must stem from the AC demand wire that went to the BMW computer. I used this to tie into the GM computer (PCM), and then all the wires from here on out are the same as the GM setup since it has a GM compressor.

8) The headliner is worn and loose in the rear. One of the overhead speaker grilles will not stay in place. The leather is in good condition and is not torn.

9) The car needs to have the exhaust from the motor to the turbo replaced or rewelded. The car does not make boost until fairly high in the RPM range- close to 4K RPM. It could be the MPT70 is too large, but I think most of it is the leaks.

10) The car needs a professional tune. I bought an LC1 wideband device and never could get it to interface with the HP Tuners software I bought. The car does not have a Mass Air Sensor, so it is running a generic Speed Density tune. It starts and runs fine, but it really needs tuning to get the most out of it.

Vehicle sold in November 2009.