h22a balance shaft removal

lilskater519

Bronze!?
Registered VIP
5+ Year Member
whats the posi's/negi's of this?
ive herd some pretty bad stories about it but ive also herd some good..
thanks.
 

Wax Hands

Smell my finger
Registered VIP
Positive: a couple of extra horsepower will be freed up.

Negative: 4 cylinders are already inherently unbalanced and removing the balance shafts on a larger displacement 4cyl is going to accelerate engine wear. Which in turn shortens the life of your engines components.

So are you willing to trade a little bit of power for engine life.
 


PhntmSk8r

H23VTEC
Registered VIP
5+ Year Member
Positive: a couple of extra horsepower will be freed up.

Negative: 4 cylinders are already inherently unbalanced and removing the balance shafts on a larger displacement 4cyl is going to accelerate engine wear. Which in turn shortens the life of your engines components.

So are you willing to trade a little bit of power for engine life.
Can you prove that with documentation? :roll:

It's blown up to make people think it's worse than it actually is, just like the whole 'omg h swaps are sooooo heavy' crap.

You might lose 10k miles off the life of the motor, if you have a swapped car chances are it's not going to see 100k+ on the same motor before blowing up anyway. Makes no difference. If it was your stock commuter car that you drove every day just to get the job done, I'd say not worth it; since this is not the case, i say go for it. Do the water pump/timing belt while you're at it.

I still have mine within my block, but no belt on them/running them. Fully built bottom end but also not my daily driver. It's only had maybe 2500 miles put on it since September and i've had zero issues with it.
 

lilskater519

Bronze!?
Registered VIP
5+ Year Member
Can you prove that with documentation? :roll:

It's blown up to make people think it's worse than it actually is, just like the whole 'omg h swaps are sooooo heavy' crap.

You might lose 10k miles off the life of the motor, if you have a swapped car chances are it's not going to see 100k+ on the same motor before blowing up anyway. Makes no difference. If it was your stock commuter car that you drove every day just to get the job done, I'd say not worth it; since this is not the case, i say go for it. Do the water pump/timing belt while you're at it.

I still have mine within my block, but no belt on them/running them. Fully built bottom end but also not my daily driver. It's only had maybe 2500 miles put on it since September and i've had zero issues with it.
lol f**k the heavy rumor, the tq makes up for it..

so i dont have to get the f**king mount blah blah kit? i can just rip the belt off? the shaft wont rattle around or anything?
yea my engines only got like 40k i just want some more power since im going n/a and its hard to make big numbers.
 


PhntmSk8r

H23VTEC
Registered VIP
5+ Year Member
dont expect anything major. 4whp will be likely, some have seen 12, some have seen 1, depends on the motor really.

the shafts wont rattle around, no. They're held in, and you need to keep them in there or you'll lose a ridiculous amount of oil pressure. The "block off kit" just gives you 2 solid chunks of aluminum to slide into the holes where the balance shafts came out, and a fancy aluminum polished block off plate you'll never see if you run timing covers.

Save yourself the $$$ and just take the belt off, leave the rest of it alone.
 

Hecz

New Member
Registered VIP
Registered OG
5+ Year Member
10+ Year Member
Balance shafts are most common in inline four cylinder engines which, due to the asymmetry of their design, have an inherent second order vibration (vibrating at twice the engine RPM) which cannot be eliminated no matter how well the internal components are balanced. Four-cylinder flat engines in the boxer configuration have their pistons horizontally opposed, so they are naturally balanced and do not incur the extra complexity, cost or power loss associated with balance shafts (though the slight offset of the pistons introduces a rocking couple). This vibration is generated because the movement of the connecting rods in an even-firing four-cylnder inline engine is not symmetrical throughout the crankshaft rotation; thus during a given period of crankshaft rotation, the descending and ascending pistons are not always completely opposed in their acceleration, giving rise to a net vertical inertial force twice in each revolution whose intensity increases quadratically with RPM, no matter how closely the components are matched for weight.[2]

The problem increases with larger engine displacement, since the only ways to achieve larger displacement are with a longer piston stroke, increasing the difference in acceleration, or by a larger bore, increasing the mass of the pistons; either way, the magnitude of the inertial vibration increases. For many years, two litres was viewed as the 'unofficial' displacement limit for a production inline four-cylinder engine with acceptable NVH characteristics.
2 "Shaking forces of twin engines", Vittore Cossalter, Dinamoto.it
Noise, vibration, and harshness (NVH), also known as noise and vibration (N&V), is the study and modification of the noise and vibration characteristics of vehicles, particularly cars and trucks. While noise and vibration can be readily measured, Harshness is a subjective quality, and is measured either via "jury" evaluations, or with analytical tools that provide results reflecting human subjective impressions. These latter tools belong to the field known as "psychoacoustics."
From Wikipedia, the free encyclopedia
There is some debate as to how much power the twin balance shafts cost the engine. The basic figure given is usually around 15 hp (11 kW), but this may be excessive for pure friction losses. It is possible that this is a miscalculation derived from the common use of an inertial dynamometer, which calculates power from angular acceleration rather than actual measurement of steady state torque. The 15 hp (11 kW), then, includes both the actual frictional loss as well as the increase in angular inertia of the rapidly rotating shafts, which would not be a factor at steady speed. Nevertheless, some owners modify their engines by removing the balance shafts, both to reclaim some of this power and to reduce complexity and potential areas of breakage for high performance and racing use, as it is commonly (but falsely) believed that the smoothness provided by the balance shafts can be attained after their removal by careful balancing of the reciprocating components of the engine
Four cylinder applications

Mitsubishi Motors pioneered the design in the modern era with its "Silent Shaft" Astron engines in 1975, with balance shafts located low on the side of the engine block and driven by chains from the oil pump, and they subsequently licensed the patent to Fiat, Saab and Porsche.[1]

Saab has further refined the balance shaft principle to overcome second harmonic sideways vibrations (due to the same basic asymmetry in engine design, but much smaller in magnitude) by locating the balance shafts with lateral symmetry but at different heights above the crankshaft, thereby introducing a torque which counteracts the sideways vibrations at double engine RPM, resulting in the exceptionally smooth B234 engine.
^1 a b "Engine Smoothness", Mark Wan, AutoZine Technical School, 1998–2000
Weighing the Benefits of Engine Balancing


Larry Carley


Balancing goes hand-in-hand with performance engine building. Balancing reduces internal loads and vibrations that stress metal and may eventually lead to component failure. But is it worth the time and effort for mild performance applications, everyday passenger car engines or low-buck rebuilds?

From a technical point of view, every engine regardless of the application or its selling price can benefit from balancing. A smoother-running engine is also a more powerful engine. Less energy is wasted by the crank as it thrashes about in its bearings, which translates into a little more usable power at the flywheel. Reducing engine vibration also reduces stress on motor mounts and external accessories, and in big over-the-road trucks, the noise and vibration the driver has to endure mile after mile.

Though all engines are balanced from the factory (some to a better degree than others), the original balance is lost when the pistons, connecting rods or crankshaft are replaced or interchanged with those from other engines. The factory balance job is based on the reciprocating weight of the OE pistons and rods. If any replacements or substitutions are made, there’s no guarantee the new or reconditioned parts will match the weights of the original parts closely enough to retain the original balance. Most aftermarket replacement parts are "balanced" to the average weight of the OEM parts, which may or may not be close enough to maintain a reasonable degree of balance inside the engine. Aftermarket crank kits are even worse and can vary considerably because of variations within engine families.

If the cylinders are worn and a block needs to be bored to oversize, the larger replacement pistons may be heavier than the original ones. Some piston manufacturers take such differences into account when engineering replacement pistons and try to match "average" OE weights. But others do not. Most high performance pistons are designed to be lighter than the OE pistons to reduce reciprocating weight for faster acceleration and higher rpm. Consequently, when pistons and rods are replaced there’s no way of knowing if balance is still within acceptable limits unless you check it.

If you’re building a stock engine for a passenger car or light truck that will spend most of its life loafing along at low rpm, your customer might question the value of balancing such an engine. But if a customer values durability and smooth operation, selling them a balance job shouldn’t be too difficult – and it will add some extra profit, too.

On the other hand, if you’re building a performance motor, a stroker motor or an engine that’s expected to turn a lot of rpms or run a lot of miles, balancing is an absolute must. No engine is going to survive long at high rpms if it’s out of balance. And no engine is going to last in a high mileage application if the crank is bending and flexing because of static or dynamic imbalances.

Forces In Action
To better understand the mechanics of balancing, let’s look at the theory behind it. As everybody knows, a rotating object generates "centripetal force." Centripetal force is an actual force or load generated perpendicular to the direction of rotation. Tie a rope to a brick and twirl it around and you’ll feel the pull of centripetal force generated by the "unbalanced" weight of the brick. The faster you spin it, the harder it pulls. In fact, the magnitude of the force increases exponentially with speed. Double the speed and you quadruple the force.

The centripetal force created by a crankshaft imbalance will depend upon the amount of imbalance and distance from the axis of rotation (which is expressed in units of grams, ounces or ounce-inches). A crankshaft with only two ounce-inches of imbalance at 2,000 rpm will be subjected to a force of 14.2 lbs. At 4,000 rpm, the force grows to 56.8 lbs.! Double the speed again to 8,000 rpm and the force becomes 227.2 lbs.

This may not sound like much when you consider the torque loads placed upon the crankshaft by the forces of combustion. But centripetal imbalance is not torque twisting the crank. It is a sideways deflection force that tries to bend the crank with every revolution. Depending on the magnitude of the force, the back and forth flexing can eventually pound out the main bearings or induce stress cracks that can cause the crank to snap.

Centripetal force should not be confused with "centrifugal" force, which is the tendency of an object to continue in a straight trajectory when released while rotating. Let go of the rope while you’re twirling the brick and the brick will fly off in a straight line (we don’t recommend trying this because its difficult to control the trajectory of the brick).

Back to centripetal force. As long as the amount of centripetal force is offset by an equal force in the opposite direction, an object will rotate with no vibration. Tie a brick on each end of a yardstick and you can twirl it like a baton because the weight of one brick balances the other. If we’re talking about a flywheel, the flywheel will spin without wobbling as long as the weight is evenly distributed about the circumference. A heavy spot at any one point, however, will create a vibration because there’s no offsetting weight to balance out the centripetal force.

This brings us to another law of physics. Every object wants to rotate about its own center of gravity. Toss a chunk of irregular shaped metal into the air while giving it a spin and it will automatically rotate about its exact center of gravity. If the chunk of metal happens to be a flywheel, the center of gravity should be the the flywheel’s axis. As long as the center of gravity for the flywheel and the center of rotation on the crankshaft coincide, the flywheel will spin without vibrating.

But if there’s a heavy spot on the flywheel, or if the flywheel isn’t mounted dead center on the crank, the center of gravity and axis of rotation will be misaligned and the resulting imbalance will create a vibration.

Applied Physics
Okay, so how does all this scientific mumbo jumbo translate into the real world dynamics of a spinning crankshaft? A crankshaft, like a flywheel, is a heavy rotating object. What’s more, it also has a bunch of piston and rod assemblies reciprocating back and forth along its axis that greatly complicate the problem of keeping everything in balance.

With inline four and six cylinder engines, and flat horizontally opposed fours and sixes (like Porsche and Subaru), all pistons move back and forth in the same plane and are typically phased 180° apart so crankshaft counterweights are not needed to balance the reciprocating components. Balance can be achieved by carefully weighing all the pistons, rods, wrist pins, rings and bearings, then equalizing them to the lightest weight.

On V6, V8, V10 and V12 engines, it’s a different story because the pistons are moving in different planes. This requires crankshaft counterweights to offset the reciprocating weight of the pistons, rings, wrist pins and upper half of the connecting rods.

With "internally balanced" engines, the counterweights themselves handle the job of offsetting the reciprocating mass of the pistons and rods. "Externally balanced" engines, on the other hand, have additional counterweights on the flywheel and/or harmonic damper to assist the crankshaft in maintaining balance. Some engines have to be externally balanced because there isn’t enough clearance inside the crankcase to handle counterweights of sufficient size to balance the engine. This is true of engines with longer strokes and/or large displacements.

If you’re rebuilding an engine that is internally balanced, the flywheel and damper have no effect on engine balance and can be balanced separately. But with externally balanced engines, the flywheel and damper must be mounted on the crank prior to balancing.

Customers should be told what type of engine balance they have (internal or external), and warned about indexing the position of the flywheel if they have to remove it later for resurfacing. Owners of externally balanced engines should also be warned about installing different flywheels or harmonic dampers and how it can upset balance.

Balance Shafts
In recent years, the auto makers have added balance shafts to many four and six cylinder engines to help cancel out crankshaft harmonics. The counter-rotating balance shaft helps offset vibrations in the crank created by the firing sequence of the engine.

On these motors, make sure the balance shaft is correctly "phased" or timed to the rotation of the crank. If the shaft is out of sync, it will amplify rather than diminish engine vibrations.

Balance shafts are not a substitute for normal engine balancing, nor do they reduce the vibration and stress the crankshaft itself experiences as it turns.


Engine Builder | Copyright © 2010 Engine Builder All Rights Reserved.
google "balance shaft" and just read away man... read away.
 

lilskater519

Bronze!?
Registered VIP
5+ Year Member
google "balance shaft" and just read away man... read away.
oh trust me i have..
i came here to find somone with previous experience or somthing because there is always mixed emotions on the topic..
everywhere i go theres the same thing as u and phantom going down lol so im not sure what to think.
i already knew what the balace shaft does,
i just wanted to know the core posi's and negi's and if its worth it.
 

Hecz

New Member
Registered VIP
Registered OG
5+ Year Member
10+ Year Member
imo, there are no positives. i don't call 15hp gain a positive, specially if it means that you have to remove the balance shaft.
 

PhntmSk8r

H23VTEC
Registered VIP
5+ Year Member
imo, there are no positives. i don't call 15hp gain a positive, specially if it means that you have to remove the balance shaft.
IMO it depends on what your goals are

does my motor run noticeably more rough? yes. does it bother me? no.

Maybe it's different for the OP but for me i built a race car, not a daily driver; so it doesnt bother me.
 
Hate to bump a 4 year old thread but instead of making a new post here I am I've read so many of these post on deff sites and still can't find my? If u just cut e belt off the shaft y not keep it to do it's job? Why don't people just leave it on ( the ones that cut it off) thanks for anyone that help out
 


Top