BMW E23 turbo LPG
BMW e23 1978
current setup:
M30 engine 3.4, m30b35 head
catcams 272 degees cam
m30b35 pistons
athena headgasket
ARP head and main studs
ANSI 316 stainless steel exhaust header
K29 63mm turbo, 14 cm^2 exhaust housing
ZF GS6-53dz gearbox
dual fuel setup, 6x valtek 34 injectors with KME evaporator, 6x630cc fuel injectors, running MS3+MS3x with LPG as main fuel, gasoline as staged injection, with switch fuel thru relais option in order to switch injectors between V1-2 and MS3X in case of gasoline start, or no LPG.
The m30 lpg turbo project started out with a stock m30 engine in 2011, and a K28 turbo.
M30b35 engine with shaved pistons, stock headgasket and ARP head studs, compression ration 1:9
B34 head with 47mm intake valves and stock intake.
turbo specs
K28
59mm inducer
25cm^2 exhaust housing T6 foot
with mild steel topmount exhaust manifold. MS3+MSX control, 6x230cc gasoline injectors, and 6 valtek 34 injectors. Soon after the first upgrade included ARP headbolts with stock head gasket and a Alpina B10 E34 camshaft
dynorun resulted with a 502hp and 620Nm @ 1,1bar boost.
Datalog of the dynorun, although during street runs 1,4 bar of boost, on the dyno only 1,1 bar is reached with same boostcontrol settings.
Not just the engine has been upgraded, to match handling and breaking to the power output of the turbo setup, the e23 is equipped with Bilstein B8 dampers, H&R springs, adjustable camber an toe-in rear axle, and a brake upgrade. the e23 with its fairly large weight, and stock brakes, does stop, but with only 1 or 2 stops the breaks overheat easily and lose most of their stock braking power. the rear brake up grade is a streight forward e34 M5 upgrade to 300x20mm brakes. On the front a setup is made consisting of E38 4-pot alu brembo calipers, with 324x30 E31 brake disks. To fit these, an inner press ring is made , to ensure the disk runs concentric on the hub. the calliper is widened, to match the 30mm disk, and with a steel adapter matched to the E23 hub. with some additional performance pads, the brakes at least match the car size and engine performance. Biggest downside is the minimum rim size of 17" required on these brakes.
After 7 years of running the setup with the original engine on LPG, and pushing up to 1.5bar boost on almost daily basis, with the combo of LPG, K28 an stock drivetrain setup (sachs 765 clutch, but stock getrag 265 overdrive gearbox) the power starts a little to late to comfortably use the turbo. downshifting to wake up the turbo gets bored in a daily driver, so the idea is born to swap turbo with an more suitable one for daily use. 2 second hand K29 turbo's have been purchased, with a considerable smaller turbine housing of 14 cm^2. As the K29 with smaller turbine has a T4 footprint instead of the T6, a new manifoldis made out of 316L stainless steel, with a bottom mount orientation, to better cool the turbo, and reduce heat in the engine bay and bonnet.
with the turbo in bottom mount, the enables the wastegate to be topmount, creating much better access in order to work on it. No more requirement to get the whole wastegate out in order to swap springs!
Next item to solve is the bigger inducer of the turbo, it is a 63mm billet design, flowing much more than the previous turbo. This of course (as a experienced modifying enthousiast) requires (or enables, depending on point of view..) a complete makeover of the engine, in order to convert the inducer size to reliable power, as the old engine is still stock bottom end and stock head gasket.
a m30b34 KAT bottom end is used, with 8:1compression pistons. block is modified with oil spray nozzles to cool the pistons, and the main bearing cap bolts are switched to ARP studs.
as it has been for 7 years of running the Megasquirt MS3 out of 2011, it should be time for a firmware update, which seemed straightforward. In the end however it resulted in 6 broken piston ringlands, as the new firmware moved the ignition about 14 degrees more advance which I did not check properly...
so combined with stock pistons,1,7bar boost and 17 degrees advance@ 5000 rpm (which then was 31 degees advance in reality) quickly destroyed the ringlands, especially in cilinder nr2, which lost compression but fortunately was noticed immiatedly, so no further damage to the rest of the engine.
swapped the pistons out for a set of full stock b35 1:9,3 compression pistons, moved to a catcams 272 degrees camshaft as the engine was out anyway, and run a maximum of 1.5 bar of boost.
new setup dyno'd at 0,7 bar boost resulting in 380 whp and 501 Nm, with the next run @ 1,4bar resulting in 549 whp and 721 Nm. for some reason the dyno was not able to measure losses during the down-slope (due to to high resistance) and was unwilling to give corrected hp and Nm, although this is not to bad anyway especially regarding high dyno room temperature's of 34 degrees C.
most annoying part of the whole setup is the horrible shift quality of the old Getrag 265 with the sachs 765clutch. probably mostly due to some worn synchro's, but not user friendly. Using the internet for inspiration and encountering the gs6-53dz swap somewhere, I found 2 gearboxes at a local demolition company, and attempted the swap, not knowing of the gearbox would fit the e23 tunnel or not.
wanting to use the sachs 765 clutch,and stock (licht m30b28) flywheel, the gearbox is modified to fit with a stock m30 clutch kit (although slightly modified fork to create a little more space inside the bellhouse).
using an old getrag 260 bellhousing cut of a broken gearbox a a special tool milled to fit the GS6-53dz onto an M30 engine without bellhousing but directly onto the input shaft axle cover bolt pattern. This enables proper alignment of the gearbox onto a mock up engine, in order to weld the 260 bellhousing and gs6-53dz gearbox. together with a low profile 6 fuck plate the improvement in gearbox is huge!
short first gear enables running long diff and stiff clutch without stalling issues in daily driving
6 speed gear ratios feel similar to the dogleg 265 which I ran, but which clearly missed the overdrive in daily traffic. giving perfect match with the turbo and powerband.
overdrive combined with 3,07 rear end alows for low revs on the highway
gearbox is massively more robust then the getrag 265, which in the end also held all the power (in the e28/e24 even 1000+ Nm)
downside of the gearbox is a rattle of gears at low revs, high load, with warmed up gearbox. not sure if that is due to the age of this particular box, or the significantly different setup of the system (single-mass flywheel, solid disc no springs, solid 6 puck, and direct driveshaft (no guibo)
