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BMW M70, M73, S70
BMW
V12 Engine Program (as
of January 2007)
This
information starts with a basic rebuild of the BMW V12 to stock specifications,
then options are listed for different horse power levels.
Each option builds on the previous.
The additional parts and labor are noted.
BMW
did not intended for the block to be bored, therefore all Power Plant rebuilds
utilize steel liners, installed, bored and honed to the final size.
Certain
detail work is performed on all engines, starting at the stock rebuild level.
Some of these details are: balancing and blue printing, high performance
3 angle valve seat cut, radius head bolt holes, chamfer and radius sharp edges
in combustion chamber and piston tops.
There
are some parts that are not included in the regular rebuild price.
These items are usually only needed on extremely high mileage engines.
These parts include : oil pump, rocker arms, hydraulic lifters, intake
valves. These parts are assessed during disassembly and inspection.
The customer is then notified as soon as possible, of the total costs
involved.
A
long block rebuild from The Power Plant is similar to what you would get from
BMW if you ordered a remanufactured engine.
It is a bare engine from oil pan to valve covers, with no ancillary
parts.
6 Liter
M70 Engine
Stock Rebuild - long block
PARTS
-
custom forged pistons w/ rings
-
clips and pins
-
main bearings
-
rod bearings
-
rod bolts
-
main cap bolts
-
crank bolt
-
water pump
-
pilot bearing
-
oil pump chain
-
timing chain
-
timing chain guide rail - upper
-
timing chain guide rail - lower
-
timing chain tension rail
-
gasket set
-
head gaskets
-
head bolts
-
intake gaskets / mounts
-
block dowel pins - oil filter
MACHINE
-
sleeve, bore and hone block
-
replace exhaust valve guides
-
micro polish crank
-
surface heads
-
balance crank
-
balance rods, end to end
-
balance pistons
-
recondition valves
-
cut seats
LABOR @ 75.00/hr
-
disassemble engine, clean and inspect parts
-
peen, paint, prep for assembly
-
pre-assemble engine, check specs
-
final assemble engine long block
-
install intakes and ancillary parts on engine
-
TOTAL ENGINE stock long block - - $ 10,589.00
OPTION A
-
5.6 liter 375hp / 405lbs/ft / 86mm bore / CSi crank - 80mm stroke / 5576cc displacement
CSi crank $4,000.00
TOTAL engine - - - - $14,589.00
OPTION B
-
5.6 liter 405hp / 415lbs/ft / 86mm bore / CSi crank - 80mm stroke / 5576cc displacement
CSi crank $4,000.00
schrick cams - 264 duration $1,490.00
port and polish cylinder heads - 24hrs $1,560.00
match port intake gaskets - 6 hrs $ 390.00
extrude hone intake manifolds $ 950.00
TOTAL engine - - - - $18,979.00
6.0
LITER CONVERSION
This kit changes the stroke
of the engine from 73mm to 86mm, the bore from 84mm to 86mm and the compression
ratio from 8.8/1 to 10/1. The
6.0 conversion on an otherwise stock rebuild makes 405h.p. & 425lbs/ft.
-
custom billet crankshaft - 86mm stroke
crank gear kit
Csi head gaskets
custom pistons, rings, pins, clips
TOTAL engine - - - $ 15,279.00
6.0 LITER UPGRADES
This package is a continuation of the complete rebuild of the engine with the upgrade to 6 liters. The 6 liter parts change the stroke of the engine from 75mm to 86mm, the bore from 84mm to 86mm and the compression ratio from 8.8/1 to 10/1.
OPTION A
-
425hp / 435lbs/ft / 86mm bore / 86mm stroke
custom billet crankshaft - 86mm stroke
add - schrick cams - 264 duration
add - extrude hone intake manifolds
add - larger fuel injectors
crank gear kit
Csi head gaskets
add - dyno tune - break in, tune, map fuel & timing, and burn custom chip set
TOTAL engine - - - $ 19,609.00
OPTION B
-
440hp / 445lbs/ft - completely civilized, stock drivability
custom billet crankshaft - 86mm stroke
schrick cams - 264 duration
larger fuel injectors
crank gear kit
Csi head gaskets
extrude hone intake manifolds
dyno - break in, tuning, map fuel & timing, burn custom chip set
add - port & polish cyl heads
add - match port intake gaskets
add - bored out stock throttles
add - custom headers w/ceramic coatings
add - lightened and balanced conrods
TOTAL engine - - - - $ 26,584.00
OPTION C
-
455hp / 445lbs/ft - completely civilized, stock drivability
You can pick up another 15 hp by adding the larger MAF sensor and air filters
TOTAL engine - - - - $ 27,534.00
The larger air filters can not use the stock air box, therefore some may not be inclined to use this additional feature.
OPTION D
-
485hp / 465lbs/ft - may not meet emission standards - rumbly idle / 7000 redline
custom billet crankshaft - 86mm stroke
add - custom steel connecting rods
re-engineered pistons 10.5 / 1 compression
change to - custom roller cams - redline of 7000 rpm
add - roller cam valve train conversion for M70
add - high performance valve springs
add - titanium valve spring retainers
port and polish cylinder heads
match port intake gaskets
change to - modified intake manifolds
change to - custom big bore throttles
custom headers w/ceramic coatings
large MAF sensor and air filter kit
fuel injectors
crank gear kit
head gaskets (Csi)
dyno - break in, tuning, map fuel & timing, burn custom chip set
TOTAL engine - - - $ 38,494.00
OPTION E
-
530hp / 465lbs/ft - will not meet emission standards - rough idle / 7500 redline
custom billet crankshaft - 86mm stroke
custom steel connecting rods
11.0/1 pistons or higher
custom roller cams - redline of 7200 rpm
roller cam conversion for M70
high performance valve springs
titanium valve spring retainers
larger intake valves (43.5 vs 42)
larger exhaust valves (37 vs 36)
port and polish cylinder heads
match port intake gaskets
custom intake system - indv. runner
Electromotive engine management system
custom headers w/ceramic coatings
fuel injectors
crank gear kit
head gaskets (Csi)
dyno - break in, tuning, map fuel & timing, burn custom chip set
TOTAL upgrade with engine rebuild - - $ 45,694.00
Current ongoing project: OPTION F
-
610 hp / 480 lbs/ft - smooth idle will meet tailpipe emissions / 7800 rpm redline
This engine is a 6 liter bottom end build, with custom 4 valve per cylinder, heads.
Their design is based on the E46 M3 engine cylinder head - (S54 designation). More
detailed information is available for serious inquires.
Complete engine $ 83,000.00
The Power Plant has an in
house engine dynamometer and a cooperative arrangement with a chassis dyno shop.
Although performance chips can help an engine produce more power, each
engine has its own characteristics that can be optimized by tuning the fuel and
ignition for that engine specifically. After-market
performance chips are usually based on a stock engine.
On modified engines, especially stroker engines, custom chips are an
absolute necessity if longevity, maximum power and low emission are desired.
With a dyno, changes in
mixture and ignition can be adjusted for peak performance and clean emissions.
The power can be measured to an accuracy of 1%.
To get it right tuning on the street, would be guess work at best.
A major benefit, is a
controlled initial run in of the engine, which can optimize performance and
longevity. This just can’t be done on the street. The engine has to be put
through load cycles. A few minutes
of running with a load on the engine, then a few minutes of idle to let parts
cool and the temperatures normalize. The length of time and amount of load is
determined by watching the oil temperature, blow by gasses and other indicators.
Then the load and rpm is increased in steps as the indicators show the
progress. With the engine properly
run in from its new condition, all the wearing and sealing parts are correctly
mated. The pistons, rings and cylinder walls will seal more completely and more
evenly. Better sealing means more power. More
evenly means longer life for the cylinder walls and rings.
Another benefit is the
ability to make a custom chip for the DME and optimize the fuel and ignition for
maximum power. The full load and part throttle parameters can be changed to
optimize power without changing the low speed and low load values required to
meet emission tests.
Another benefit is the
ability to verify that everything is working correctly, and there are no
problems. From oil leaks or cracked spark plugs to main or rod bearings, almost
anything can be detected and corrected.
CRANKSHAFT
CAMSHAFTS
With
the recent interest in performance modifications for the BMW M70 engines, I have
collaborated with a high quality and long established cam manufacturer to make
an efficient and aggressive cam package.
This
package changes the M70 valve train design from a pad follower to a roller type
design. The cams themselves are
custom units made from a steel billet.
With
the M73 engine having the components of a roller design we decided to
incorporate those into the performance package for the M70 engine.
There are several advantages to a roller type valve train.
The two main attributes are the reduced friction and the ability to have
a faster ramp design on the lobe.
These
cams are designed to have a operating range to 7500 rpm.
Idle quality is very good with just the slightest hint of lope.
Depending on other tuning modification, the cams peak hp can be between
5700 and 6800 rpm.
SPECIFICATIONS
Stock
/
Power Plant
duration
213
245 int / 255 exh
valve lift
10.4mm
11.4mm
lobe centers
112 deg.
110 deg.
ROLLER CAM CONVERSION (M70 engines)
-
roller rockers
spring retainers
spring seats - inner
spring seats - outer
intake valves
exhaust valves
TOTAL CONVERSION - - - $ 1,157.58
CONNECTING RODS
Raising the redline from 6000 to 7000 and adding 11mm to the stroke, adds the same amount of stress as turning the engine 2000 rpm over the designed redline. The stock rods are not strong enough, or long enough, so custom rods made from 4340 billet steel are used. In order to maintain a stroke to rod ratio that is correct for the longer stroke crank, the rods are 3.5mm longer than stock.
INTAKE MANIFOLDS
For
the 500hp version, the manifolds are extensively modified.
To meet the higher rpm band and additional air flow requirements, the
plenum is enlarged and the runners are shortened.
This changes the tuning of the intake system which was originally
designed for a torque peak at 4000 rpm and hp peak at 5200 rpm.
This engine has a peak torque at 4500 rpm and a hp peak at 5700 rpm.
PISTONS
These
are custom, forged, high silicone content aluminum alloy, and designed
specifically for what ever the application.
BORED OUT STOCK THROTTLES
For this option, the stock DK throttles are completely disassembled and rebuilt. While they are apart, the housing is bored to a 3mm larger diameter and a larger throttle plate of stainless steel is fitted. The final product is a stock appearing throttle with 26% increase in area around the plate for more air flow.
For the 500hp version, custom, bigger throttle housings are made from aluminum billet and the servo motor from the stock DK throttle is transferred to them. This way all the stock engine management system can be retained. The stock throttle is 57mm diameter, the custom throttle bore is 65mm, a 33% increase in area.
MANUAL THROTTLES
For engines requiring an alternative engine management system such as Electromotive or Motec, custom throttles are made from aluminum billet. The throttle size is dependent on the application. They are designed for cable actuation.
HEADERS
The headers are made specifically for the application. They are a stepped design made form mild steel and then coated with a ceramic thermal barrier coating inside and out. The coatings really cut the heat transfer and reduce under hood temperatures dramatically. The step design is the latest in “state of the art” techniques for extracting the most power from an engine.
BLOCK
From the BMW technical information system - “the block has an increased concentration of silicone crystals at the cylinder bore surface during the casting process and can not be machined.” For rebuilding purposes, we bore out the cylinders in the block to accept a steel liner. The block is then heated and the steel sleeves are slid into those bores. As the block cools it shrinks to a tight fit around the steel liners. The new steel cylinders are then honed to the final bore dimension and the block is decked. This process is also used by BMW on some of its other late model aluminum block engines.
CUSTOM BIG VALVES
These are made of the highest quality stainless steel and are made to fit with all the stock BMW hardware.
CUSTOM
INTAKE SYSTEM
To meet the air flow and rpm tuning requirements, a completely redesigned and fabricated intake system is needed. The ports on the head are enlarged so much that the stock intake manifold is not thick enough to match the cylinder head port.
CUSTOM ALUMINUM CLUTCH
The
engines making 500 or more hp also make about as much torque, and the original
BMW clutch will not hold. For these engines the custom clutch and flywheel
package is necessary. A light
weight, heavy duty, single plate disc capable of holding up to 800 ft/lbs of
torque is used.
CUSTOM ALUMINUM FLYWHEEL
To use the above clutch, a custom flywheel is made. It is machined from billet aluminum, with a steel insert for the clutch disc friction surface.
NOTES AND SPECIFICATIONS
BMW
published specifications
Engine
type
bore
stroke
disp.
hp
torque
c. r.
redline
M70B50
e31
84
75
4988
295@5200 331@4100
8.8
6000
M73B54
e31
85
79
5379
322@5000 360@3900
10.0
6000
S70
B56
e31
86
80
5576
375@5300 405@4000
9.8
6400
Connecting
rods - 28 grams in one ounce /
16 oz’s in 1 pound
stock
BMW
526 grams (1.174 lbs x 12 = 14.09 lbs)
lightened steel 480 grams
(1.071 lbs x 12 = 12.85 lbs)
Titanium
339 grams (0.756 lbs x 12 = 9.07
lbs)
L: BMW 850 engine
- close up of headers in silver thermal barrier coatings
R:
BMW
850 engine - close up of headers in black thermal barrier coatings
BMW M70 cylinder head on flow bench
L:
V12 with polished intakes on dyno
R: BMW 850i engine on dyno - dyno’ed in 2001 this engine is a 6 liter
conversion with Electromotive Tec2
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Photographs remain property of Henry Lawrence - The Power Plant
and Anthony Vanderlinden - Wet Dog Publications
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