BMW Z4 (2007, E85) engine swap to 6.2L V8
Discussion
Hi all - I think I'm now at the stage of being happy to share the build of my new project as I've been driving it all week and so far, no major issues!
To start off, I previously built a project that had a new 6.2L V8, (LS3) that I was finding was becoming more frustrating than fun. After keeping the car for a few year, and tinkering with it to get rid of some fairly rough work/ solutions, I decided that I wanted rid. I loved the drive-train though so I eventually came upon the idea of keeping that, binning everything else apart from a few momentos and putting it all into something a lot more modern.
So, bye bye Rolls Royce...
... hello BMW Z4 2L.
Before you think I was just throwing the Roller away, it was little more than 80% of a shell! I'd had to cut a lot of the steelwork out to fit the new engine and the brakes, suspension, steering, etc. were all bespoke to my project. I saved the grill for my wall in the garage but there was nothing really left in there worth saving.
The Z4 was a non runner as the previous owner had fallen out with their mechanic. The engine was not running and there were deeper, hidden problems with it.
Anyway, I pulled out the 2L BMW lump and loaded in the V8. A quick note here though: as some Z4's in the states have been converted I did some research before I attempted the installation but what I found was that the forums said my unmodified LS3 V8 wouldn't fit. The oil pan fouls against the subframe brace. So, I did my measurements, thought it'd be close but do-able, and managed to get it in there with a bit of a thump. Doubt it'll come out easily but there is about 10mm between the sump and the brace so I feel that's close but not a problem.
Easy I thought, a weekends work so far. Now to make up the engine mounts, propshaft and exhaust.
Engine mounts 3 weeks work: I thought at first that I could re-use the BMW mounts and adapt them to the LS3 mounting plates I had from the previous project but after two failed attempts I realised that a combination of the weird metal alloy BMW had used plus my frankly terrible welding wasn't going to do it. I made a third set using seriously heavy duty C beam and massive amounts of welding glue which so far have held up just fine.
Exhaust 2 weeks for the Mk1: I bought a load of new stainless steel pipework plus cats, silencer/ back box and joints and welded it all together, badly. Only a few weeks to get the first version on but it was far too low and also clashed with the steering and suspension. Plus was technically what you'd call a bit loud (98dB on tickover). So over about another 4 months I took it off, tweaked, re-mounted, cursed, took off, etc. After the 2nd MOT (see below), I also decided the noise was probably a little much so added two short silencers into the pipework and came up with the Mk2 (85dB):
Also worth mentioning that one of the US naysayers stated that the reason the LS3 wouldn't work in the right hand drive Z4 is that it clashes with the steering and bodywork. And they're right, it would have. Never one to give in to steelwork, I decided to turn the manifold upside down and loop the exhaust pipe upwards and then down to get a better angle through the steering. It was all a bit close, mm's to spare, so another tweak to the Mk2 had me scalloping the pipe so the steering shaft runs through the pipe.
Propshaft 1 week for the Mk1: I took the end flange from the old project and the propshaft from the BMW then outsourced the shortening to a local propshaft specialist company. Fitted it and found that it wobbled about like me on 10 pints. I tried all sorts of tweaks like playing with the engine alignment, revising support brackets, etc. but it was too bad. On a 10mph test drive it felt like the car was tearing itself apart so I eventually called a tow truck and took the car to a local car restoration company as they offered to put it on a ramp and rotate the shaft by hand to see the extent of the problem (there's only so much you can do on your back on your driveway!). The wobble was obvious and it wasn't the alignment. So onto the Mk2 propshaft by a different specialist and that was for some reason too short. So onto the Mk3 and the wobble was still there! Mk3 gave way to Mk4 and we also swapped out the aluminium shaft coupling I had in there with a standard rubber one, which is what it's now running. There is still a wobble but its very minor. We looked at a Mk5 but the racing company roped in to help said the shaft was so short it was literally as good as it'll get as a cheapo bespoke unit. All in, the propshaft has taken over 6 months to sort including 2 months on and off a ramp in the restoration company.
But there was more work in between all that:
Fuel system 2 weeks: When I took a few steps back and thought of other jobs to sort I looked up the fuel pump spec for the 2L Z4 and found that all Z4's apart from the 2L had sufficient flow and pressure for the LS3. Typical. So, ordered the larger spec one from ebay and it arrived in days. But, and it's a big but, the fuel pump is inside the tank and the only access is a circular bolted flange on the bottom on the underside of the car. To replace the pump you have to drain the fuel then stick your arm into the tank up to your elbow (bearing in mind you're still working on your driveway the this point), disconnect the connections by finger tip as you can't see anything, pull the old pump out then reverse the process for the new one.
Steering 3 weeks: In a similar vein to the pump issue, the E85 Z4 was the first BMW to have electric steering across the full range. Some research and I find that the BMW electric steering system requires over 20 inputs from the control system, including some derived from the engine. As I'm no longer running the old 2L ECU that was a bit of a show stopper. I had the idea of an interface module (see below) but I felt that having something as important as steering subject to something I was adding which was made in someone's bedroom was going to end in tears. Some more research led me to Z4 tuning forums and found that apparently the electric steering is a common failing of the E85 Z4 and a lot of modders swap it out for hydraulic steering. As I had a power steering pump on the LS3 that's the route I went. As advised I went for the purple labelled one (eBay) which is the fast rack and plumbed it all in including new high pressure hoses I had made locally. I had to interface the steering shaft with the new rack as (wouldn't you know it) the Z4 end connection is about 1mm too large for the new unit. The advise was to replace the full shaft with one from a 3 series but I found that the universal joint was the same dimensions so swapped the end fitting only. All good, seems to work a treat.
Cooling system 2 months: Obviously the BMW cooling system is a spiders web of efficiency so that needed some adaptation. I also managed to blow the whole thing up during MOT 2nd attempt (see below) so after that I replaced the radiator with an aluminium one and also the blown to smithereens overflow canister.
Warning codes 4 months: With everything kinda sorta in and the engine not overheating I started looking at the warning codes given the MOT station I spoke to for attempt 1 said if there were any codes it'd fail immediately. I assumed that the warning codes were all simple fixes but how wrong I was! 1st big issue was that as the Z4 was a non runner when bought it had issues I had to fix first. For example, the DCS pump was a replacement but the mechanic hadn't set the VIN number in the pump so it threw up all sorts of seemingly unrelated codes such as ABS and steering faults. The brake pads wear sensors were all worn. The steering 'zero' position needed resetting. Etc. I ended up buying the BMW programming software and fixed the coding issues and replaced the parts that needed physically replacing. That was 'fun'!
Control system 6 months: In parallel to the warning codes it became obvious that I'd need to resolve the speed, temp and revs which on a BMW all comes from the engine. I had lots of ideas about bypassing them but it became so complex I looked for another solution. Luckily, there is a small company run by some students who make a CAN bus module that adapts an LS3 ECU to BMW control system. Ordered one which dutifully turned up a month later and it simply sorted all the problems! Very impressed with this little piece of kit! Fun fact, BMW said there was no way you can code a Z4 without the engine present; glad I didn't pay for that gem of wisdom!
I also needed to reset a code on the LS3 which was eluding me. I asked garages who had similar engined cars such as the Monaro (Vauxhall) but no-one would touch it without extortionate fees. Again, some research later lead me to the Tech II unit that GM uses in the states. It's made in China (!) so I ordered one and waited a month for it to arrive. Of course, it arrived with the card for a SAAB. Another few weeks and I got the one for Chevy. 10 mins with the unit and my code was gone.
And then you have the MOT!
1st attempt (a & b): I knew the car would fail as I was still working on resolving the codes but I wanted to know what else it'd fail on. I ran it to the local Halfords as they've been unnervingly helpful in the past on the Rolls project. They couldn't get the car on the ramp as the exhaust was too low. Took the car back home, strapped the exhaust up as far as it'd go and... still couldn't get it on the Halfords ramp.
2nd attempt: I rang around the local modders and asked who they'd recommend for really low cars. They recommended a local Kwik Fit which was brand new so had really low ramps. All was going ok, apart from the windows in the waiting area shaking when they did the emissions run, until the cooling system exploded. I'd made a mistake in the way I'd plumbed the expansion tank so that let go spectacularly spraying coolant all over a hot V8. Much steam, swearing, etc. followed as it was quickly removed from the test area. One good thing that came from it was that they got some readings indicating that it would fail the emissions test anyway.
3rd attempt: After we sorted the propshaft, I asked the garage to take the car to a more specialist MOT station rather than the run-of-the-mill ones I'd used previously. Again it failed but on brake lines (corroded), bushes (goosed) and emissions. The garage sorted the mechanical bits while I researched the emissions side (see PH thread here: https://www.pistonheads.com/gassing/topic.asp?h=0&... ). We ended up slathering exhaust gum on literally every joint and had another go.
4th attempt: And it passed!
And that's where we are today. About 18 months, around £2K in parts and £1K of garage parts/ fees. There are still some tweaks to make such as better exhaust routing and welding to replace the gum but really its a runner now. In about 6 months or so I'll look at the next stage which will see better brakes, a retrim of the interior and a respray.
To start off, I previously built a project that had a new 6.2L V8, (LS3) that I was finding was becoming more frustrating than fun. After keeping the car for a few year, and tinkering with it to get rid of some fairly rough work/ solutions, I decided that I wanted rid. I loved the drive-train though so I eventually came upon the idea of keeping that, binning everything else apart from a few momentos and putting it all into something a lot more modern.
So, bye bye Rolls Royce...
... hello BMW Z4 2L.
Before you think I was just throwing the Roller away, it was little more than 80% of a shell! I'd had to cut a lot of the steelwork out to fit the new engine and the brakes, suspension, steering, etc. were all bespoke to my project. I saved the grill for my wall in the garage but there was nothing really left in there worth saving.
The Z4 was a non runner as the previous owner had fallen out with their mechanic. The engine was not running and there were deeper, hidden problems with it.
Anyway, I pulled out the 2L BMW lump and loaded in the V8. A quick note here though: as some Z4's in the states have been converted I did some research before I attempted the installation but what I found was that the forums said my unmodified LS3 V8 wouldn't fit. The oil pan fouls against the subframe brace. So, I did my measurements, thought it'd be close but do-able, and managed to get it in there with a bit of a thump. Doubt it'll come out easily but there is about 10mm between the sump and the brace so I feel that's close but not a problem.
Easy I thought, a weekends work so far. Now to make up the engine mounts, propshaft and exhaust.
Engine mounts 3 weeks work: I thought at first that I could re-use the BMW mounts and adapt them to the LS3 mounting plates I had from the previous project but after two failed attempts I realised that a combination of the weird metal alloy BMW had used plus my frankly terrible welding wasn't going to do it. I made a third set using seriously heavy duty C beam and massive amounts of welding glue which so far have held up just fine.
Exhaust 2 weeks for the Mk1: I bought a load of new stainless steel pipework plus cats, silencer/ back box and joints and welded it all together, badly. Only a few weeks to get the first version on but it was far too low and also clashed with the steering and suspension. Plus was technically what you'd call a bit loud (98dB on tickover). So over about another 4 months I took it off, tweaked, re-mounted, cursed, took off, etc. After the 2nd MOT (see below), I also decided the noise was probably a little much so added two short silencers into the pipework and came up with the Mk2 (85dB):
Also worth mentioning that one of the US naysayers stated that the reason the LS3 wouldn't work in the right hand drive Z4 is that it clashes with the steering and bodywork. And they're right, it would have. Never one to give in to steelwork, I decided to turn the manifold upside down and loop the exhaust pipe upwards and then down to get a better angle through the steering. It was all a bit close, mm's to spare, so another tweak to the Mk2 had me scalloping the pipe so the steering shaft runs through the pipe.
Propshaft 1 week for the Mk1: I took the end flange from the old project and the propshaft from the BMW then outsourced the shortening to a local propshaft specialist company. Fitted it and found that it wobbled about like me on 10 pints. I tried all sorts of tweaks like playing with the engine alignment, revising support brackets, etc. but it was too bad. On a 10mph test drive it felt like the car was tearing itself apart so I eventually called a tow truck and took the car to a local car restoration company as they offered to put it on a ramp and rotate the shaft by hand to see the extent of the problem (there's only so much you can do on your back on your driveway!). The wobble was obvious and it wasn't the alignment. So onto the Mk2 propshaft by a different specialist and that was for some reason too short. So onto the Mk3 and the wobble was still there! Mk3 gave way to Mk4 and we also swapped out the aluminium shaft coupling I had in there with a standard rubber one, which is what it's now running. There is still a wobble but its very minor. We looked at a Mk5 but the racing company roped in to help said the shaft was so short it was literally as good as it'll get as a cheapo bespoke unit. All in, the propshaft has taken over 6 months to sort including 2 months on and off a ramp in the restoration company.
But there was more work in between all that:
Fuel system 2 weeks: When I took a few steps back and thought of other jobs to sort I looked up the fuel pump spec for the 2L Z4 and found that all Z4's apart from the 2L had sufficient flow and pressure for the LS3. Typical. So, ordered the larger spec one from ebay and it arrived in days. But, and it's a big but, the fuel pump is inside the tank and the only access is a circular bolted flange on the bottom on the underside of the car. To replace the pump you have to drain the fuel then stick your arm into the tank up to your elbow (bearing in mind you're still working on your driveway the this point), disconnect the connections by finger tip as you can't see anything, pull the old pump out then reverse the process for the new one.
Steering 3 weeks: In a similar vein to the pump issue, the E85 Z4 was the first BMW to have electric steering across the full range. Some research and I find that the BMW electric steering system requires over 20 inputs from the control system, including some derived from the engine. As I'm no longer running the old 2L ECU that was a bit of a show stopper. I had the idea of an interface module (see below) but I felt that having something as important as steering subject to something I was adding which was made in someone's bedroom was going to end in tears. Some more research led me to Z4 tuning forums and found that apparently the electric steering is a common failing of the E85 Z4 and a lot of modders swap it out for hydraulic steering. As I had a power steering pump on the LS3 that's the route I went. As advised I went for the purple labelled one (eBay) which is the fast rack and plumbed it all in including new high pressure hoses I had made locally. I had to interface the steering shaft with the new rack as (wouldn't you know it) the Z4 end connection is about 1mm too large for the new unit. The advise was to replace the full shaft with one from a 3 series but I found that the universal joint was the same dimensions so swapped the end fitting only. All good, seems to work a treat.
Cooling system 2 months: Obviously the BMW cooling system is a spiders web of efficiency so that needed some adaptation. I also managed to blow the whole thing up during MOT 2nd attempt (see below) so after that I replaced the radiator with an aluminium one and also the blown to smithereens overflow canister.
Warning codes 4 months: With everything kinda sorta in and the engine not overheating I started looking at the warning codes given the MOT station I spoke to for attempt 1 said if there were any codes it'd fail immediately. I assumed that the warning codes were all simple fixes but how wrong I was! 1st big issue was that as the Z4 was a non runner when bought it had issues I had to fix first. For example, the DCS pump was a replacement but the mechanic hadn't set the VIN number in the pump so it threw up all sorts of seemingly unrelated codes such as ABS and steering faults. The brake pads wear sensors were all worn. The steering 'zero' position needed resetting. Etc. I ended up buying the BMW programming software and fixed the coding issues and replaced the parts that needed physically replacing. That was 'fun'!
Control system 6 months: In parallel to the warning codes it became obvious that I'd need to resolve the speed, temp and revs which on a BMW all comes from the engine. I had lots of ideas about bypassing them but it became so complex I looked for another solution. Luckily, there is a small company run by some students who make a CAN bus module that adapts an LS3 ECU to BMW control system. Ordered one which dutifully turned up a month later and it simply sorted all the problems! Very impressed with this little piece of kit! Fun fact, BMW said there was no way you can code a Z4 without the engine present; glad I didn't pay for that gem of wisdom!
I also needed to reset a code on the LS3 which was eluding me. I asked garages who had similar engined cars such as the Monaro (Vauxhall) but no-one would touch it without extortionate fees. Again, some research later lead me to the Tech II unit that GM uses in the states. It's made in China (!) so I ordered one and waited a month for it to arrive. Of course, it arrived with the card for a SAAB. Another few weeks and I got the one for Chevy. 10 mins with the unit and my code was gone.
And then you have the MOT!
1st attempt (a & b): I knew the car would fail as I was still working on resolving the codes but I wanted to know what else it'd fail on. I ran it to the local Halfords as they've been unnervingly helpful in the past on the Rolls project. They couldn't get the car on the ramp as the exhaust was too low. Took the car back home, strapped the exhaust up as far as it'd go and... still couldn't get it on the Halfords ramp.
2nd attempt: I rang around the local modders and asked who they'd recommend for really low cars. They recommended a local Kwik Fit which was brand new so had really low ramps. All was going ok, apart from the windows in the waiting area shaking when they did the emissions run, until the cooling system exploded. I'd made a mistake in the way I'd plumbed the expansion tank so that let go spectacularly spraying coolant all over a hot V8. Much steam, swearing, etc. followed as it was quickly removed from the test area. One good thing that came from it was that they got some readings indicating that it would fail the emissions test anyway.
3rd attempt: After we sorted the propshaft, I asked the garage to take the car to a more specialist MOT station rather than the run-of-the-mill ones I'd used previously. Again it failed but on brake lines (corroded), bushes (goosed) and emissions. The garage sorted the mechanical bits while I researched the emissions side (see PH thread here: https://www.pistonheads.com/gassing/topic.asp?h=0&... ). We ended up slathering exhaust gum on literally every joint and had another go.
4th attempt: And it passed!
And that's where we are today. About 18 months, around £2K in parts and £1K of garage parts/ fees. There are still some tweaks to make such as better exhaust routing and welding to replace the gum but really its a runner now. In about 6 months or so I'll look at the next stage which will see better brakes, a retrim of the interior and a respray.
Edited by anonymous-user on Saturday 15th February 16:29
king mental. I love it. 
Cheers all. Right now I'm trying to not be too mad with the throttle. Its all suprisingly solid. The garage drove it and said that apart from the mad noise you'd not know it wasn't BMW (which I take as high praise!). Of course its daft powerful and has mountains of torque but what I'm really liking is that you can stick it in 6th gear at 70mph and its only doing 1800RPM.
It should be as fast as a base corvette as its the same engine and roughly the same power-to-weight ratio. Shorter wheelbase so it'll be a bit more lively but I see it as my version of a modern TVR.
It should be as fast as a base corvette as its the same engine and roughly the same power-to-weight ratio. Shorter wheelbase so it'll be a bit more lively but I see it as my version of a modern TVR.
Jakg said:
I didn't want to open this thread as like all silly engine swaps you get some pictures of an engine, the patient car without an engine, and some pictures of welded metal and then nothing. But it works! I'm impressed.
Yeah, I've followed a lot of build threads over the years and a distressing number just seem to run out of momentum. i didn't want to put anything up until it was my daily driver.gregs656 said:
Superb. I love it. Keep the red!
Yes, it'll still be red. Maybe a tad darker red. The problem that you don't see on the pics is that the plastic and metal panels are aging at different ratesso you can see marginally different shades of red as you walk round it. I also need to put some vents in the bonnet as the exhaust runs so close to it. If I do that it'll need some paint anyway.
fatbutt said:
Yes, it'll still be red. Maybe a tad darker red. The problem that you don't see on the pics is that the plastic and metal panels are aging at different ratesso you can see marginally different shades of red as you walk round it.
I also need to put some vents in the bonnet as the exhaust runs so close to it. If I do that it'll need some paint anyway.
Fantastic thread OP - it's great to see a project like this get finished. I also need to put some vents in the bonnet as the exhaust runs so close to it. If I do that it'll need some paint anyway.
But you probably really do need to do something with the 2.0 litre Z4 brakes now it has an LS3 fitted!
Mr Tidy said:
Fantastic thread OP - it's great to see a project like this get finished.
But you probably really do need to do something with the 2.0 litre Z4 brakes now it has an LS3 fitted!
Brakes are phase 2 But you probably really do need to do something with the 2.0 litre Z4 brakes now it has an LS3 fitted!
I plan to follow something along the lines outlined here: https://z4-forum.com/forum/viewtopic.php?f=24&...
Thanks for sharing. Looking forward to more updates. 
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