When does an engine become a performance engine?

[KwS 2372]

12 minutes ago, Herbmiester said:

Yes torque is what road cars need, always has been. 

Bugger that, nothing like driving a high revving (car) engine hard, like a B18CR. Torque is great and all, but there is still something about an engine that makes all its power way way way up in the rev range. Same with the S50B30 TBH, not much down low, but my god it pulls like a freight train up high.

[Herbmiester 908]

2 hours ago, KwS said:

Bugger that, nothing like driving a high revving (car) engine hard, like a B18CR. Torque is great and all, but there is still something about an engine that makes all its power way way way up in the rev range. Same with the S50B30 TBH, not much down low, but my god it pulls like a freight train up high.

Sure but why not have the best of both worlds, an LS screaming at 6700 RPM while still giving massive amounts of torque. Just look at BMW the evolution from M50 to M54 was all about torque. Vanos is a torque increasing technology. BTW I dont know how many VTEC engined Hondas I have beaten at the traffic light drag strip because they take to long to get into the groove.   

[Herbmiester 908]

1 hour ago, 3pedals said:

n contrast the old LS1 makes a fair amount of torque but is RPM constrained - Screaming at 6,700 RPM is an oxymoron - decent road going 6's V8 & 12's have been able to pull north of 8,000 RPM for the last 50 years.

You can gather I'm not a fan of the LS engine - it is mediocre when OBJECTIVELY measured and long past it's use by date.

Actually no. Only a few really high performance engines mostly from the elite manufacturers can make power at or past 8000 RPM.That trend is now over the high revving NA engine is in decline. Forced induction is taking over. 

Yes Ron we know you dont like the LS too few valves and made in the wrong country but when an LS engine (Read Camaro) can hang with an M4 and a Camaro Z28 can lap Willow Springs quicker than a Nissan GTR then I fail to see how the engine is past the use by date. Car designers call it packaging and the LS packages very very well. Anyway it would seem that screaming NA engines are the ones that are past their use by date. BMW has abandoned them and even Honda has finally given in to Turbocharging, Audi are persevering with the V10 but these are hardly everyday engines. Looks like high revving NA engines are actually the ones past their use by date, Now I dont say that with any glee as I appreciate the sound they make and the engineering involved. The S54 would still be one of my favourite engines right up there with the 4 inch bore alloy LS engines. 

[Herbmiester 908]

Drive an LS powered E36 and you will understand. KW/KG is the real measure. 

[Herbmiester 908]

On 12/14/2016 at 2:21 PM, gjm said:

What thoughts do folks have? When does an engine become a performance engine? Is the absolute power produced (or torque) make any engine a performance one, or is it the case that specific power output - hp per litre - is the yardstick? Does forced induction move the line?

Yet again Ron this was the question and the answer yet again is yes because it increases the KW/KG ratio so any engine that increases the first and does not increase the latter can be considered a performance engine, why because it increases performance, sorry Ron I am trying to make this simple for you.  I find your statement about the E36 not being interesting when you own one rather contrary. It's a very well regarded chassis and with a jump from 190 to 400 Hp I would think that would make it very interesting indeed. I certainly thought so when I drove it. 

BTW M50 198 kg M52 177 LS1 181 Kg. The V8 sits further back in the chassis help front to rear balance. So why is an engine that is as light as the engine it replaces but doubles the horsepower not a performance engine? 

You're not the only one here who has driven fast cars Ron, but I suspect your scope is limited if you haven't spent time with one of the modern big CC NA engines. It's not the same as an Alfa let me tell you that much.

[Herbmiester 908]

4 hours ago, 3pedals said:

If either the M4 or the GTR were the same capacity they would slaughter the Camaro - and they would not sound like a tin can factory in an earthquake.

Ron the fact is they aren't but they use forced induction so it's a moot point. And as for sound the M4 is widely panned for having a crap sounding exhaust note, they even pipe it through the speakers to try and enhance it while the Camaro is praised for sounding great. Your swimming against the tide yet again Ron. 

[Herbmiester 908]

3 minutes ago, 3pedals said:

Normally aspirated  E(0 M3 v8 4 litre 309kW  = 77.25 kW/l

Latest LS engine 319kW from 6.2 litres = 51.45 kW/l

Scale the M3 engine up and it would be about 478kW  outcome =no contest  the M3 is a performance engine and the LS is just a cooking variety

The thing is this is fantasy not reality, the reality is this what you can buy not what you dream up. Also care to estimate the size of a DOHC engine at that CC? Well let me share something with you Ford went DOHC for the falcon range and the the engine was so physically big it had to sit high in the engine bag just to clear the strut towers this had a very negative effect on handling. Big CC DOHC V8s are TALL and WIDE, you need big engine bays to accommodate them. Click click starting to get it yet Ron? Ever wonder why the S65 has such a short stroke, well a good part of that is deck height. Short stroke engines have lower deck heights, lower deck heights keep the engine narrower. Oh and dont tell me the short stroke was to make it rev the s54 was under square and it revved quite well. 

BTW WTF Trump what's that got to do with anything. 

As to not getting it I get it perfectly it's you who doesn't get it. All you care about is KW/L and its a flawed metric, only useful in racing. Like I said earlier no one cares if you have a better KW/L ratio  what matters is power to weight. 

[M3AN 4015]

I never imagined this thread would end up like this... 

Oh, and this forum software sucks hard. Give us a basic bbcode editor so we can actually post the sh*t we want!

[coop 261]

11 hours ago, 3pedals said:

Under the kW/litre metric the LS series engines crank out somewhere round the 50kw / litre , they get to about 6,700 Rpm

That's about the same as any off the yard sedan these days  and for about the last 20 years? - that's why I don't rate the LS engine - cos it fails the basic tests. and it fails them because it is obsolete technology that has been long since surpassed  DOHC's came out in production cars in the 50's , 3&4 valve/ cylinder engines were the norm in the 80's.  

If either the M4 or the GTR were the same capacity they would slaughter the Camaro - and they would not sound like a tin can factory in an earthquake.

Accept the dinosaur in the room - the LS is not a performance engine , it is just a big engine.

As for the rest of the comments - they are essentially what I said: hairdryers on performance engines make awesome high power , dynamic engines - Power,  Torque  and RPM all with good fuel economy.

 

So back to the original question the thread poses, when does an engine become a performance engine?

A performance engine today:  Somewhere north of 80kW/ litre with a decent rev range and  broad power/torque spread

1990's performance engine : Somewhere north of 70kW/ litre with a decent rev range and  broad power/torque spread

 

You are missing the point in that physical size and weight are also factors in determining a performance engine. As pointed out, by your reasoning the Ford 5.4 quad cam (you could also add in BMW M62TU) are more of a performance engine than the LS1 for their irrelevant kW/litre figures. When the LS1 sh*t all over both of them in the real world back in the day! 

 

The success GM are having with their ohv small block, and Chrysler with theirs cproves you wrong re obsolete. If you are going to claim that of them, you may as well say it for all ICE, the current crop of small displacement turbo motors are simply giving them an extra lifeline. 

Consider the S62 and LS1 Callaway from the same era. Identical power and torque figures, and torque curves. From a performance view point which one excells more. The S62 that achieves the same from 700cc less, or the LS1 which is 30ish kg lighter and significantly, physically smaller - packaging, engine placement, COG.

No doubt the E39 is a superior car, I'd say it's most likely a better car than the current FPV/HSV, but as far as a crate engine for a project track, targa car etc, the LS1 would be a decision from the head, a no brainer. The fact the LS1 doesn't rev as high, and uses 700cc to achieve the same doesn't take away any of its performance credentials. 

 

re obsolete ohv motors, my mate has the latest Dodge Ram with the 5.7 Hemi. Cylinder de activation and 8 speed auto.

105 litre tank which returns 900km mixture urban and motorway. You can't complain with that, just goes to show how versatile the small block push rod motors are. From towing 6 tonne in a pick up or run 12 second 1/4 mile or pull 600,000+ km in a taxi/limo no dramas! A while to go before they are obsolete.

 

 

 

 

[Michael. 2312]

Ugh, this thread became so painful to read (mostly because of a certain someone) 

[Herbmiester 908]

Yeah my apologies I should have just let it go.

 

[huff3r 347]

6 minutes ago, Herbmiester said:

Yeah my apologies I should have just let it go.

 

Consider it a lesson learned, I did when it was my turn

[Michael. 2312]

Jesus Christ, this is a public BMW forum that is supposed to be enjoyable & and open discussion

You make it sound like this is a A level exam question that can only be answered by arguing one point of view. 

 

 

[BreakMyWindow 1870]

2 hours ago, 3pedals said:

It's pretty simple Michael, read the questions and answer / comment on them - paraphrased from above ( reproduced & paraphrased without the permission of the Graham) :

Questions

1. Is less than 74.5kW/ litre just a cooking engine
2. its is only recently that NA  engines producing over 74.5kW/l have been sold in production cars - is this true?
3. Is it the case that specific output kW/litre is the metric
4. Does forced induction move the line

Answers (IMO)

1. No- less than 55kW/ litre is a cooking N.A engine,  55-75 is a mild performance N.A engine,  75 + is a high performance NA engine  and 100kW/l is a good boosted performance metric.
2. No, production and semi production / specials back to the  mid to late 60's achieved this,
3. Yes,
4. Yes.

Excuse my conversion of a "mixed metric"  into a "unit consistent"  metric some of us ARE sticklers for detail.  

 

 

[Neal 509]

Anything that's been ported and polished, balanced and blueprinted, has bigger carbs, headers or extractors, raised compression ratio with 1/2 race cam or better.

or modern stuff where most of this is in base build... 

or anything with a Honda badge

simple !

Edited December 19, 2016 by Neal

[M3AN 4015]

I have a 4.5 turn brushless in my TRF511, now that's a performance engine motor. 

[richard 384]

Engine blueprinting

What blueprinting REALLY is.

Contributed By: Enginebasics.com

I would argue that the most abused word in the engine building world is the word Blueprinting. This word is now tossed around with anyone who has a high-performance motor built these days. In-fact, it appears that EVERYONE seems to have a blueprinted race motor if you look at for sale ads on classic trader. Are this many people paying the $10-$20 THOUSAND DOLLARS to have a blueprinted motor built, or do people not really understand what a fully blueprinted motor really is?

I would argue that it’s the later in that question. Most people assume that if their machinist measured and bored the motor to match the pistons. And if the machinist measured and matched the rod and crank bearings then BOOM, you have a fully blueprinted motor. The reality is this is FAR FROM the case. Some people say the machinists are to blame since they “SELL” their customers on this idea that there motor is blueprinted to increase sales. Some people say the customers are to blame since everyone wants to say they have a “blueprinted” motor these days. Whoever it was….. who really cares. Everything described above is things that your SHOULD BE doing any time you assemble a motor. Lets clear things up then.

To really blueprint a motor requires an INSANE amount of time, and an INSANE amount of parts. Every part of the motor will be measured and balanced to each-other in a manner that will require going through dozens of pistons, rods, bearings….it’s incredible. In the last fully blueprinted motor build I was involved in, we had to order three sets of pistons from the manufacturer before we came up with eight that were all within a thousands of spec. We ordered four sets of rods before we came up with four that were all within spec of each-other. The manufactures are not to blame. Technically each set could have been used to build a motor that would have run for 200k miles, and could have been balanced to work just like any other motor with some machining on the crank. A true blueprinted motor though, is one were every single part has been measured and matched exactly to a tolerance that FAR EXCEDES the manufacturers original tolerances. On a blueprinted motor one could say there “are no tolerances”, since everything is matched at times to a hundred thousands of an inch. The amount of balancing a blueprinted motor needs is so low its off the scale. All bearing and races are measured to be with-in thousands of each-other.

Hopefully you see there is a lot more to a blueprinted motor than just having some things measured and machined to fit. Blueprinting is a long process requiring LOTS of parts to find them within spec of each other, and LOTS of machinist time in measuring and scoping everything. The actual motor is measured and put into tolerance instead of machining components to balance at the crank.

So does all this really mater? For a street motor I would argue no. In reality blueprinting a motor is all about getting every last inch of performance out of it, no matter what the cost. While a blueprinted motor will rev faster, have less rotational power losses, and harmonically be stronger, its not worth the money for a street application. Are there such a thing as blueprinted motors out there….. absolutely. But are the thousands of blueprinted motors you see advertised on ebay really blueprinted? Well, I’ll let you be the judge.

  

[Neal 509]

Interesting view on blue printing 

in my car I'm picturing  a series engine where the manufacturing process leaves plenty of room for improvement in pistons, rods and crank and breathing comes via porting.

i guessing manufacturing tolerances these days are so close it's not needed unless you want that 10000 rpm plus s14 

 

 

[coop 261]

On 19 December 2016 at 1:12 PM, 3pedals said:

It's pretty simple Michael, read the questions and answer / comment on them - paraphrased from above ( reproduced & paraphrased without the permission of Graham) :

Questions

1. Is less than 74.5kW/ litre just a cooking engine
2. its is only recently that NA  engines producing over 74.5kW/l have been sold in production cars - is this true?
3. Is it the case that specific output kW/litre is the metric
4. Does forced induction move the line

Answers (IMO)

1. No- less than 55kW/ litre is a cooking N.A engine,  55-75 is a mild performance N.A engine,  75 + is a high performance NA engine  and 100kW/l is a good boosted performance metric.
2. No, production and semi production / specials back to the  mid to late 60's achieved this,
3. Yes,
4. Yes.

Excuse my conversion of a "mixed metric"  into a "unit consistent"  metric some of us are sticklers for detail.  

 

Ok, so is it you who sets this criteria that a performance motor is determined by kw per litre figures and only that?  

 

This maybe going around in circles but you consider the Chev LS7 to be in the same league as the engines in the Camry 4cyl, or Primera, or a 318i etc ie not a performance motor. 

Same deal with Chrysler Hemi 6.4 v8 at  355kw 55kw/litre

MB 6.2 AMG at 376kw 60kw/litre

LS7 roughly 53kw/litre. 7.0 litres and 373kw, 637nm torque and a flat torque curve from about 3000rpm. Red line at 7100rpm. Lightened internals. Larger exhaust and intake. Larger valves. Dry sump. Without sampling it I'd put money down on that engine being one of the most premium n/a performance motors of the past ten years (maybe of all time). Up there with M3 4.0, MB 6.2 V8 etc. 

By your reasoning the latest Ducati 1299 or KTM 1290 is less of a performance motor than the jappa multis for having similar power figures but using 300cc more?! 

Take both types for a spin the big twins are ten times as brutal down low and the same if not more up top as the (relatively) torque less jappas!! 

 

Anyway, long live high revving n/a motors of all capacities regardless of irrelevant kw/ litre figures! 

 

[Herbmiester 908]

On 12/19/2016 at 1:12 PM, 3pedals said:

It's pretty simple Michael, read the questions and answer / comment on them - paraphrased from above ( reproduced & paraphrased without the permission of the Graham) :

Questions

1. Is less than 74.5kW/ litre just a cooking engine
2. its is only recently that NA  engines producing over 74.5kW/l have been sold in production cars - is this true?
3. Is it the case that specific output kW/litre is the metric
4. Does forced induction move the line

Answers (IMO)

1. No- less than 55kW/ litre is a cooking N.A engine,  55-75 is a mild performance N.A engine,  75 + is a high performance NA engine  and 100kW/l is a good boosted performance metric.
2. No, production and semi production / specials back to the  mid to late 60's achieved this,
3. Yes,
4. Yes.

Excuse my conversion of a "mixed metric"  into a "unit consistent"  metric some of us a sticklers for detail.  

 

This is not the real world, its a just a calculation. As I mentioned earlier many so called performance engines do it through revs. Just like the old NA F1 engines each year the revs got higher as there were no other ways to make the HP. So Ron your criteria is really all about engines that rev to high RPM. Therefore a rotary engine trumps all those DOHC engines. 

Finally let's look at a classic BMW engines that many of us like; the the M54 B30 56 kW/L compare that to a so called Dinosaur LS that make similar numbers, they make peak power at similar RPM and have similar KW/L. By default the valve train arrangement in a road car has less of an impact than the rev limit. But its all a moot point when an LS (Any one from 4.8 to 7L) fits where a DOHC V8 wont. We get back to the metric that matters KW/KG. Its no wonder BMW went to forced induction and soon it will be going 4wd as well as the power these engines produce make it hard for them to get to the ground. But that's another discussion.

[richard 384]

Going on your answer Ron, if blueprinting is obsolete then so is engine balancing as the manufacture of parts can get it prefect.

This is small write up ( better than I can do ).

Engine Balance

Due to the presence of the number of reciprocating parts, like piston, connecting rod, etc.
which move once in one direction and then in other direction, vibration develops during
operation of the engine. Excessive vibration occurs if the engine is unbalanced. It is, therefore,
necessary to balance the engine for its smooth running. The vibration may be caused due to
design factors or may result from poor maintenance of the engine. In order to minimize the
vibration, attention must be given to the following parameters :
(£) Primary balance
(«) Component balance
(Hi) Firing interval
(iv) Secondary balance.
2.8.1.

Primary Balance

When a piston passes through TDC and BDC, the change of direction produces an inertia
force due to which the piston tends to move in the direction in which it was moving before the
change. This force, called the primary force, increases with the rise of the engine speed, and
unless counteracted produces a severe oscillation in the vertical plane, i.e., in line with the

Fig. 2.40. Direction of primary force for single cylinder.
Single-cylinder. Figure 2.40 illustrates the primary inertia forces developed in a single-
cylinder engine. The diagram shows the direction and magnitude of the force for one revolution
of the crankshaft, in which the upward direction has been considered as positive. Thus at TDC,
the deceleration of the reciprocating masses (piston assembly and one-third of the connecting
rod) produces an upward force on the engine.
At BDC a similar force is also generated but the direction of the force is downwards. The
effect of these two forces is such that when the engine is running it oscillates up and down at a
frequency equal to the engine speed, causing vibration.
This vibration of the engine can be reduced by
adding counter-balance masses at A and B to exert
an outward force with the rotation of the crankshaft.
Also by varying these two masses, the outward force
can be made to equalize the inertia forces Fi and
F2. It may be noted that in positions other than the
dead centers the counter-balance masses themsel-
ves produce an out-of-balance force. This is un-
desirable because it only shifts the plane of
vibration from the vertical to the horizontal. There-
fore, the counter-balance mass used on a single-
cylinder engine is set to balance only half the
reciprocating mass. As a result, vibration in the
vertical and horizontal planes is expected in a single
cylinder engine. To withstand this vibration all nuts
and bolts used on vehicles propelled by single-
cylinder engines should be adequately locked.
Four-cylinder. The crank throw layout on a four-cylinder in-line engine and the direction
of the primary forces are shown in Fig. 2.41. Primary balance is achieved in this arrangement,
because the forces on the two pistons at TDC equal the forces on the pistons at BDC.
The crankshaft throws (as shown in Fig. 2.41) are arranged so that forces acting on pistons
1 and 2 develop the opposite turning moment (couple) on the shaft axis to that produced by the
forces on pistons 3 and 4. The opposing couples introduced by this crankshaft layout prevent
the rocking action of the engine and consequently minimize fore and aft vibration of the engine.
Counter-balance masses are added to the crankshaft to reduce the bending action on the
crankshaft produced by the couples, and the high load on the center main bearing. Also, five
main bearings are used to support the crankshaft, instead of the three commonly used in the
past, so that a stiffer construction is obtained which is essential for the high-speed operations
of modern engines.
Three-cylinder. Consideration of balancing of a three-cylinder in-line unit is useful
because it is used as a ‘straight’ in-line engine and also it forms the back unit for both the in-line
six and V-six cylinder engines. Figure 2.42 illustrates the crankshaft layout and the primary
forces when piston 1 is at TDC. In this case the crank throws are set at 120 degrees; therefore
the large force at each of the dead centers is balanced by the two smaller forces on the other two
pistons. These smaller forces are caused due to acceleration or deceleration of the piston as it
approaches or leaves the end of the stroke.

Fig. 2.41. Primary forces for four cylinders.

Fig. 2.42. Primary forces for three cylinders.
2.8.2.

 

Component Balance

To minimize vibration, all components that rotate at high speeds must be balanced. This is
specifically important for large heavy components such as a flywheel and clutch assembly. Even
though these two parts are balanced individually within allowable limits, the mating of each
part with the crankshaft axis is essential so that they ‘run true’. Various location devices such
as spigots, registers and dowels are used to obtain mating of these components.
Ideally the balancing of both the crankshaft and flywheel assembly as one unit is desirable
because it avoids the ‘build-up of tolerances’. Vibration occurs when ‘heavy spots’ of each part
are positioned so that they all act in the same direction. High cost associated with during
manufacturing as well as repair generally rules out the use of this one-piece balancing method
on mass-produced vehicles. Reciprocating masses should also be balanced to achieve good
primary balance. All parts that move in this manner should have nearly equal weight.
Balance of components should cover both static balance and dynamic balance. The static
balance can be carried out by placing the shaft and/or component on two horizontal ‘knife-edges’,
so that when released the heaviest part moves to the bottom. Dynamic balance requires
expensive equipment, which rotates the part at high speed and indicates the extent and location
of the heavy spots. Imbalance is normally corrected by removing metal by drilling one or more
holes in the component at the heavy point.
2.8.3.

 

Firing Interval

The angle turned by the crankshaft between power strokes of a multi-cylinder engine should
be regular to achieve maximum smoothness. Also if the more cylinders are fired during the 720
degrees period of the four-stroke cycle, the lower is the variation in the output torque, and the
smoother is the flow of power to the road wheels (for details refer sections 2.4.2 and 2.6).
2.8.4.

Secondary Balance

The inertia forces considered during the study of primary balance are based on a piston
movement, called simple harmonic motion (SHM). This type of reciprocating movement is
illustrated in Fig. 2.43A. Let a point P travels at a constant speed around a circle of diameter
AB, and another point N moves in a straight path from A to B. The point N is said to move in
simple harmonic motion if it always keeps at the foot of the perpendicular NP. The velocity of
point N varies as it travels across AB and this is represented by the graph (Fig. 2.43B).
When the movement of an engine piston is compared with SHM, it can be seen that during
the first 90 degrees rotation of the crank from TDC, the piston covers a greater distance and
within the range 90-180 degrees it covers a smaller distance in the given time (Fig. 2.43C). This
causes the following situations.
(a) The piston travels more than half the stroke during movement of the crank from TDC
to the 90 degrees position.
(b) Considering the piston initially at TDC, the relative piston velocity for each 90 degrees
of crank movement is fast, slow, slow, and fast.
(c) The piston dwell, which is the angular period where piston movement is small in
relation to crankshaft motion, at BDC is much greater than at TDC.
id) The inertia force at TDC is much greater than at BDC.

This last point demands for the engine balance if vibration is to be reduced. The study of
engine balance requires the analysis of secondary balance, which involves the difference
between actual piston movement and the ideal SHM.

Fig. 2.43. SHM and actual piston motion.
Figure 2.44 presents the primary force produced by SHM, and also the secondary force
required to be added or subtracted to correspond the actual motion. It is observed that the
frequency of the secondary force is twice the speed of the crankshaft. The information provided
by this graph can be used to obtain the direction of the secondary force and this has been added
to the diagram of the engine’shown in Fig. 2.45. The result indicates a four-cylinder in-line
engine has very good primary balance but has poor secondary balance. This imbalance produces
a vibration in the vertical plane at a frequency twice the speed of the crankshaft. In the past
this vibration has been tolerated and soft rubber engine mountings have been used to prevent
transmission of the engine vibration to the remainder of the vehicle.

Fig. 2.44. Graph of secondary force.

Fig. 2.45. Direction of primary and secondary forces.
In the three- and six-cylinder in-line units, and V-six, the secondary forces balance out, and
this is one reason why the six-cylinder in-line engine was used extensively in the past. Nowadays
four-cylinder in-line units for engines up to about 2 liters capacity are preferred, because of
promising economy resulting from lower frictional losses. When it is combined with the use of
simpler engine management systems, a higher power to weight ratio can be obtained. In
addition, the short and stubby crankshaft used on a four-cylinder unit does not produce severe
torsional vibration problems associated with longer shafts.

Secondary Harmonic Balancer.

The use of a secondary harmonic balance is an effective method of eliminating secondary
forces. Frederick Lanchester used this method first time in 1911 to balance four-cylinder
engines. Even though this device was very effective, the use of soft rubber mountings instead
of a damper continued for cost reasons. In 1975 Mitsubishi of Japan produced a secondary
balancer, in several ways similar in principle to the Lanchester type. The engines using this
arrangement are much smoother in operation.
The principle of a secondary balancer is illustrated in Fig. 2.46. Two counter-balance shafts
having offset masses are driven by the crankshaft at twice crankshaft speed. One counter-
balance shaft is rotated clockwise and the other anti-clockwise. Both shafts are timed to the
crankshaft so that when the piston is at TDC both masses exert a downward force.

Fig. 2.46. Principle of secondary balancer.
To counteract the secondary force on the engine, the balancer exerts an opposing force only
when it is necessary. For four-cylinder in-line engines this is a maximum when at 0, 90, 180,
and 270 degrees rotation of the crankshaft. In Fig. 2.46A and C, this balancing force is
downwards and upwards respectively. In Fig. 2.46B and D, the two masses of the balancer
oppose each other causing a neutral effect. The engine attains a state of balance in these neutral
positions.
Mitsubishi Motors ‘Silent Shafts’ arrangement incorporates twin counter-balancing shafts
with one shaft higher up the engine than the other (Fig. 2.47). This shaft arrangement damps
the vertical vibration and also the secondary rolling couple, produced when the crankshaft is
rotated by the force of combustion.
The upper shaft rotates in the same direction as the crankshaft and the vertical spacing of
the shafts is 0.7 times the length of the connecting rod. This arrangement of the counter-balance
masses sets up a couple, which opposes the rolling couple. Balance of the rolling couple
throughout the complete engine load range is not possible. Therefore a shaft position is
optimised to minimize the unabalnced couple during the most frequently encountered road load
conditions. The rolling couple of a balanced four-cylinder engine, with this arrangement provides
a better result than that of a six-cylinder unit.

Fig. 2.47. Secondary balancer (Mitsubishi Motors).

Fig. 2.48. Secondary balancer as fitted to Porsche engine.
The Porsche 944 engine (Fig. 2.48) installs a double-sided toothed belt, to drive the
counter-balance shafts. The balancer system on this engine reduces the noise level by 20 dB.
When the secondary vibration, especially at high engine speed is minimized, it provides a
reduction of the ‘boom’, which is felt and heard in the passenger compartment. In addition, a
decrease in secondary vibration lengthens the life of engine auxiliaries such as emission control
equipment, electrical and fuel supply components and management systems, which incorporate
electronic devices.

[huff3r 347]

57 minutes ago, 3pedals said:

BMW S1000RR compared to Ducati 1299 - data sourced from internet --   then SS1000RR scaled  to equivalent capacity  of Ducati 1299  and labelled S1300RR

Except this is a huge waste of time, because engines do not "scale" like that. If they did, then every manufacturer would build a hot little motor and upsize it, and they would all be based off motorcycle engines.

 

But anyway, this thread has been done to death, you are flogging a dead horse. Just agree to disagree already! You don't have to always prove everyone wrong, you can just let them be wrong and take comfort that you are right (in your own opinion at least).

[Herbmiester 908]

Perhaps I will put an LS into my 318i and call it Ron.

[Herbmiester 908]

Brakes are easy, e46 brakes and better pads. 

[M3AN 4015]

On 14/12/2016 at 9:37 PM, gjm said: