Balance Shaft Removal??!?!?!

[kpt4321]

Originally posted by LousyDriver
The DSM will run the quarter mile faster with the balance shaft in place.

Wrong.

There. I said it. I am even willing to say it again. I'll shout it from the hills if I have to. I'll even clarify why I feel this is the case. It's all because of what KTP said about a lightweight flywheel being like "Adding 100 horsepower in first gear."

Don't worry, I will show you why you are wrong.

Actually, a 12 pound flywheel with an effective diameter of 40 cm spinning at 6000 rpm will store 5,500 watts of energy, or about 7 horsepower. If the stock flywheel weighs twice this, then it stores 14 hp.

Stock flywheel weighs over 20 pounds. However, it's not that simple. A large majority of the weight is contained around the outside of it, and thus the moment of inertia is higher than you would expect.

It's not the stored energy that is stored at a constant speed that matters, it is the energy required to ASCCELERATE it up through the rev range that matters. The higher the rate of acceleration, the higher the amount of energy required. That's why you see the greatest gains in first gear when you get a lightweight flywheel.

That's at least 93 HP off from what was said above, but that's not the critical point.

I wasn't talking about stored energy, I was talking about acceleration energy.

However, I realized my mistake. I made a type, it's like your car weighing over 100 POUNDS less, not 100 horsepower. Sorry.

Let me ask you, when you are sitting at the tree, and that last amber light is glowing, what are you doing? you'd better be revving the engine, if you plan to win this race. Reving the engine at around 5000 RPM right? what happens when you drop the clutch? the engine rpm falls, the car accelerates, and your off. WAIT A MINUTE! During the critical first second of the race, the RPM's are FALLING, not climbing.

They shouldn't be.

Hold the rpm's steady, slip the clutch out, and go. If the RPM's are falling, then you are bogging.

What happened to all that energy that was stored in the flywheel, the crank, and the balance shaft? Well, it either spun the tires, wore the clutch, or ACCELERATED the car.

If doesn't matter. If the rpm's are dropping, then that means that you are slipping the clutch. If you're slipping the clutch, then you always have more power avaliable to you, just slip it less.

This scenario only happen under clutch slip. If the flywheel was lighter and thus had less stored energy, you could simply rev higher at the line, slip the clutch differently, ot launch with boost.

That's right, the energy stored in your flywheel is critical to launching the car. Any drag racer can tell you that the first sixty feet are critical to having a good run. A small difference at the beginning of the track translates into a huge difference at the end of the track. Having a heavy flywheel on a car that has poor traction will simply break the tires loose, but having a heavy flywheel on a car with excellent traction is an advantage.

Yup. It's easier to launch a car with a heavier flywheel. However, the launch isn't necessarily any faster, and the rest of the run is going to be slower.

Now, let recap. The flywheel (and also the balance shaft) is an energy storage device. The energy that is stored is generated by the engine BEFORE the green light flashes. This energy is then available to accelerate the car off of the line. The energy is robbed from the engine at the end of the track (but in between shifts, the energy stored in the flywheel is again available to accelerate the car) where it would have less of an impact on the ET.

In all of the situations where the greater stored energy of the flywheel could help you, are are free-revving the motor and then slipping the clutch. If the flywhel was made lighter, you could simply rev higher to achieve the same stored energy, without the extra weight.

As a final note, I repeat what I said above, the balance shaft is a rotating mass, equvalent to a heavier flywheel.

But much less so.

Now, the reduction in mass of the car as a whole is worth something, and it works against my argument above. As a conceptual tool, let's observe that it is possible to build a car that can travel the quarter mile with no engine, entirely on energy stored in the flywheel. (assuming the flywheel was spinning to begin with)

But it's not just the reduction of dead mass. The flywheel is rotating mass, so the car will accelerate faster with a lighter one. It's not just the loss of 10 pounds that is helping you, it's the loss of 10 pounds of high-speed rotational weight, which is like 10 times that in dead weight.

Now, I have asserted that the energy storage is enough to make up for the added mass.

You can only tap into this stored energy when the RPM's are dropping. For how long in a drag race is your engine speed decreasing? Probably like 3%. For the other 97% of the race, the engine speed is increasing, and the lighter flywheel is better.


In short: The stored energy only applies when you slip the clutch and let the rpm's drop, which really should be never in a drag race. If you'e rpm drops on launch, you need some practice.

However, if you are using the energy of the flywheel: If you make it lighter, just rev higher, and you will have the same power avaliable to you, plus all the gains associated with the lighter flywheel the other 97% of the time.

 

[set3422]

Balancer shafts are there to balance secondary and nth order unwanted forces created by the combustion process. Our dsm's are 4123 firing order, so primary forces on 1 and 4 ared cancelled out with 2 and 3. Secondary forces are derived from the residual masses from primary forces. Front balancer shaft balances most of the unwanted secondary forces. And rear shaft takes care combination of masses from primary, secondary, and nth order forces.

To eloborate more what's in nth order forces, I think this would the unaccounted jerk forces, unaccounted oil pump gears for rear shaft, gearing backlash, and etc.

 

[1badgsx]

Remove the balance shafts. There is a reason Mitsu itself sells the parts. You will also get an increase in oil pressure from this.

 

[kpt4321]

Originally posted by 1badgsx
There is a reason Mitsu itself sells the parts.

Yeah, because the 1.6L mirage motor uses them.

They don't sell them specifically for us to remove balance shafts. Nope.

 

[swing lo]

Stop Talking, everybody go buy a 50trim..................................

 

[Morphius]

Originally posted by kpt4321
WTF? Are you trying to tell me that the balance shafts balance out the injector pulses? WHAT THE ####?

They balance out the "ignition?"

I don't even know what the #### you are trying to say.

Balance shafts balance out the second-order piston and rod vibrations, which occur in the front to rear plane of the vehicle. They spin at twice the engine speed, and only do balancing in the forward and reverse vectors.

-DaimlerChrysler Engineer

 

[BUCK]

SILENT SHAFTS are the ROOT of all evil>>>>
- the cause of bouncing around in First gear
- the cause of oil starved Turbos
- the cause of the dreaded CRANKWALK
- the ANTI-Christ of ALL that is DSM>>>>>>>>>
- only the anal FREAKING engineers defend them..........

 

[Defiant]

I think the Silent Shafts are rather a clever design, and I can't even spell injenear.

 

[kpt4321]

Originally posted by Morphius


-DaimlerChrysler Engineer

Are you planning on providing us any information with that, or are you just going to roll your eyes and tell us you're an enginer? Frankly, I don't give a ####; I'm an engineer too, and it doesn't mean shit for this scenario as long as you're not retarted.

Originally posted by BUCK

- only the anal FREAKING engineers defend them..........

I'm an anal engineer, and even I think that they should come out. If that's not a good reason to yank them, I don't know what is!

 

[Morphius]

Originally posted by kpt4321
I'm an engineer too.

Student?

Be more professional.






-DaimlerChrysler Engineer

 

[kpt4321]

You're doing a great job posting useless information. If you have something to share, I would absolutely love to hear it, On the other hand, I don't give a crap if you're going to waste our time.

 

[Groomz]

I hope I'm not the only one laughing at this thread. I find it hard to believe that people are defending keeping the balance or silent or superhappyquietfastracesupergoodtime shafts. No high powered DSM built by any DSM shop has run the balance shafts, especially after a motor rebuild. I don't want to contribute to this episode of "Flamewars: The saga of the Keyboard Racer", but they are not advantages to the balance shafts other than comfort. There just isn't. The perception that they provide stored energy is crap. A small rod spinning at twice the engine speed does not have the stored energy of a 20 pound flywheel at half the speed. The shafts just weigh a whole lot less and and have a shorter distance to travel per revolution.

The benefit of the balance shafts removal is for safety first and foremost, reducing the chance of belt failure. Higher oil pressure and less weight are minimal benefits and should not be the reason for the modification.



Benefit of keeping balance shafts, thats a good one.......:laugh:

 

[kpt4321]

Originally posted by Groomz
....Awesomeawesomeawesomeawesome....

wOOt! Good point Groomz.

Everyone takes them out. They suck. End of story.

 

[GaRn]

if you want to take em off, do it, i wish all you wannabe genius's would calm down ..

it wont make any noticeable difference, unless you have an ass of thin china or balsa wood.. The reason i would do it if i did would be the belt breaking..

 

[entropy138]

Wow this thread has good potential ... but I haven't seen it quite make it to that point yet...

Here is one issue that I have yet to see addressed. The rear balance shaft and its relationship to the oil pump drive gear. (Now I may get this a little backwards as I haven't gone thru this process yet, but I'll try my best.)

There is recent question of whether the rear shaft is needed to provide support for the oil pump drive gear to counter the tension that the timing belt puts on it. There is a thread on dsmtalk discussing this and one suggestion was that instead of removing the rear shaft, that it be turned down in a lathe to remove the countweight, but the shaft itself remain inplace to counter the tension of the t-belt. During this discussion a number of people came forward and said that their oil pump had died sometime after BS removal and that this could be a cause of that lack of support.

AARRRRRGHh instead of me botching what was discussed I'll jsut go find the thread....



http://www.dsmtalk.com/forums/showthread.php?threadid=110541&highlight=lathe


Here you go... Read away!!! And then lets see a good discussion going ... No more talk of leaking belts and 100hp GAINS from a flywheel

 

[Groomz]

Thats a good thread. I would prefer to have an oil pump fail than a balance belt. With an oil pump failure you would be able to notice that it has happened from the oil pressur gauge reading zero. Balance shaft failure is usually sudden and violent, tearing through the timing belt and taking the head and valves with it. Its the lesser of two evils.

 

[entropy138]

YEAH.... very true... but why not eliminate both evils while your at it?? If you can remove most of the mass of the shaft so that its parasitic drag is negligible why not?? (Granted I don't know that it would be negligible as there would still be friction and what not...but well something to think about)

Question for anyone who's had their BS removed for awhile... have you had any problems w/ the oil pump??

 

[kpt4321]

Originally posted by entropy138
There is recent question of whether the rear shaft is needed to provide support for the oil pump drive gear to counter the tension that the timing belt puts on it.

I'd say that theory is junk.

The 1.6L Mirage motors have a very similar oil pump setup, and the same manner of timing belt drive. They also use the same stubby shaft that we use for balance shaft removals. I don't hear of tons of Mirage oil pumps failing, do you?

More likely, I think, is that those pumps were on their way out the door anyway, due to high mileage, contamination, and possibly a badly done balance shaft removal.

 

[Defiant]

Here's an image that Morpheus asked me to upload, because he couldn't get it to upload from his end. I suspect his modem is missing its balance shafts.

As you can clearly see, this is a global view of Africa, showing how the practice of engine balancing progressed from Ghana, across through Egypt, and on to the Silk Road where Marco Polo brought the idea back to the Medici family of Venice (who laughed his ass back to Siam).

Um.... or, it's something else. Morph will be along shortly to elucidate.


I hope.

 

[Taboo]

Originally posted by kpt4321
I'd say that theory is junk.

The 1.6L Mirage motors have a very similar oil pump setup, and the same manner of timing belt drive. They also use the same stubby shaft that we use for balance shaft removals. I don't hear of tons of Mirage oil pumps failing, do you?

And I don't hear of too many Mirages with 16 70psi valve springs, aftermarket cams with higher lift or engines producing over 400 pounds of torque with 8.5K redline, do you?
The "theory" - that was actually based on well known and documented cases of the oil pump failure - was in regard to serious 4G63 race engines where the thrust on the drive gear of the oil pump is greatly increased, not the stock 1.6L Mirage or the stock 4G63.

As for the balance shaft removal argument... Although they do store a certain amount of kinetic enegry, their parasitic drag at higher RPM greatly outweights their contribution to accelerating a 3200 lbs car.

Same for aluminum flywheels. Once the clutch is engaged, the engine doesn't accelerate just the flywheel, but also the clutch disc, pressure plate, all shafts and gears in the tranny and transfer case, the driveshaft, rear differential, axles, brake rotors, wheels - and finally the entire 3200 lbs dead weight of the car. The parasitic drag in the entire AWD driveline is so great that the chunk of aluminum one uses as flywheel means extremely little. If somebody thinks he just gained 40HP or saved 100 lbs of weight by spending $400 on Fidanza flywheel, how many HP does he gain by cross-drilling or slotting the brake rotors and making them lighter? How many HP does 4-spider center differential or 4-bolt rear end with thicker axles rob? How about bigger Brembo or Baer brake rotors?

 

[BUCK]

And I don't hear of too many Mirages with 16 70psi valve springs, aftermarket cams with higher lift or engines producing over 400 pounds of torque with 8.5K redline, do you?

I greatly respect your opinion Taboo so let me see if I have this straight...

So the Higher RPM's had to do with the Oil Pump Failures - NOT the Mirage shaft with the identical Bearing Surfaces - because Belt Tension is Belt Tension is Belt Tension - & that Belt Tension is ALL the side load that bearing will see.

 

[onegee]

i read earlier in the thread that a motor wouldn't last 150k mile w/o BS. what is the validity of this statement? i plan on getting a new motor soon and if the BS kills the longevity of it i might opt against it.

 

[BUCK]

The odds are your motor won't survive 150K miles WITH Balance Shafts - that has been damn sure documented!

 

[onegee]

uhh.. i have 152k miles on my motor now.

 

[BUCK]

posted by BUCK The ODDS are your motor won't survive 150K miles WITH Balance Shafts - that has been damn sure documented!

& the ODDS are against you making it much further - you are the EXCEPTION - I sincerely wish you the best of luck - you NEED it.

Also the comment you were referring to MAY have been one that MAY have been posted by a knowledgable Chrysler Engineer stating the ELECTRONICS on an engine MAY not last 150K miles without balance shafts - he MAY well be correct... I absolutely do not differ with that opinion in any way.