Understanding the BMW E30 Engine: Performance Upgrades and Analysis

6/5/2019
[Document title]
[Document subtitle]
AGRIPPINA
[company name]

INTRODUCTION
The BMW E30 is a modern car developed to ensure proper transport and safety while at high
speeds. The performance upgrade is based on the stroker version of the M20 with a 6-part
engine. There are many original components where the vehicle’s capacity at 2 liter to 2.7 liter.
The vehicle’s engine is built on the oil crisis period in the early years with a focus on fuel
efficiency. The vehicle provides high torque engine with efficient levels of general driving. The
vehicle needs a higher revving and large capacity engine that provides more power. The M20,
like the M10, is fairly well tuned from the factory. There is not a lot of hidden horsepower just
waiting for you to tease out. There are a few things that can be done to make the engine run
better and make a little more power, on the order of 5 to 10 percent at the wheels.
A good-running, stock M20B25 can put out up to 145 or so horse power at the rear wheels,
depending on many factors. The best thing to do is to reduce the intake restriction by replacing
the air box with a cone filter and heat shield for a small increase in airflow and power. For even
more gains you can swap out the air/fuel meter (AFM) for a larger one from a 535 or 735 with
the 3.5-liter engine. You may have to swap circuit boards from your AFM to get the idle to
smooth out.
The M20 Stroker is based on the crank centerline,
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The relevant parameters for the M20 stroker are as follows,
The piston is the cylindrical piece of metal that rides up and down the inside of the cylinder. The
piston rings provide the sliding seal between the outer edge of the piston and the inner section.
The piston rings function to prevent the fuel/air mixture such that the exhaust in the combustion
chamber from the leaking obtains the compression and combustion. They keep oil in the sumps
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so as to make sure that there is no leakage into the combustion area where the oil may be burnt
and lost. The connecting rod, on the other hand, connects the piston to the crankshaft. It can
rotate at both ends such that the angle can change so as to move the piston while the crankshaft
rotates. The crankshaft is the section that controls the piston movement. It moves the piston up
and down into circular motion as on the crank. The piston can be divided up into the following
distinct areas: crown, ring zone, body or skirt and gudgeon pin bushings. The piston crown can
be fiat or slightly convex or concave. On high-performance engines, a recess acting as part or all
of the combustion chamber is often formed in the piston crown. The piston in some auto motives
is a sliding plug that fits directly into the bore of the cylinder. The piston seeks to vary the
volume enclosed by the cylinder by exerting a force on the fluid inside the cylinder.
PROBLEM STATEMENT
(I) To determine the choice of connecting rod length by changing the maximum side
loading between piston and cylinder wall.
(II) To determine how the choice of connecting the rod length affect the forces
experienced by the gudgeon pin and the journal bearing.
(III) To determine if the velocity- acceleration is significantly dependent on the choice of
the connecting rod.
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(IV) To determine the rpm of the 2.5i and M3 as compared to the 7000 rpm of the eta
engine.
ENGINEERING ANALYSIS
There are several assumptions made in regards to the design and dynamics of the machines:
(I) The combustion chamber does not produce force using gas.
(II) The angular velocity of the engine is set to 7000 rpm and the acceleration of the
engine is set to zero.
(III) The acceleration of the engine does not produce force.
(IV) The cylinder and the piston are not required to have any form of friction between
them.
SYSTEM MODELLING & IMPLEMENTATION
The M20 stroker for the BMW E30 is comprised of piston and the connecting rod. The piston
and the crack is connected using a con-rod.
Studying the kinematic dynamics of the system,
V B =V A + V B
A
The piston is the main part of the engine which transfers the force from the gas which expands in
the cylinder to the crankshaft and links to the connecting rod. The position of the piston using the
vector loop is obtained as,
x= ( l+r ) −s
The schematic diagram for the crank mechanism components relationship illustrates the
connecting rod length, crank radius, and the instantaneous piston position from the piston pin.
The mean piston velocity for the 6 stroke engine is computed as,
vp = 2 ln
60
The relationship between the crank radius and the connecting rod length and distance from the
piston axis for the pin to the crank axis such that the variables of the crank mechanism are
formulated as,
s=lcos φ+r cos θ
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¿ l sin φ=r sin θ
The values are rearranged to obtain the relationship with the angles as,
The values are factorized with a focus on the higher approaches such that,
The kinematics are used to formulate the piston instantaneous displacement in the crank
mechanism such that,
The system is able to manipulate the kinematics by expressing the equation by easily estimating
the variable based on the angle phi. The system is able to determine the angle theta which is the
crank angle,
The piston instantaneous velocity is obtained from the piston on the crank mechanism,
Performing the first derivation of the equation with respect to the crank angle in the equation,
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