Balance Shaft Replacement Alternative

Just thought I would fill you guys in on an alternative I have been reviewing. I have been looking at this because I plan to continue to push the HP limits with my BHW engine, and do not desire to have a BS module. I know this thread should almost be in the performance section, but thought it would be more appropriate here.

The reciprocating mass in the BHW engine is a fair bit more than that of other TDI's, whether ALH or BEW, or BRM. I do not have a lot of info on the ARL, but I think it is probably in the same weight range as BEW's.

This is a summary of parts I have recently weighed:

ALH Piston - 582g
ALH Rod - ?? no sample
ALH Pin - 206g
BEW Piston - 589g
BEW Rod - 631g
BEW Pin - 203g
BHW Piston - 620g
BHW Rod - 672g
BHW Pin - 203g - same as BEW

Piston weight includes rings, but not pin.
Rods weight include rod bolts.

For curiosity, I have found that the BKD, which is the 16V PD140 in Europe uses the same rod as the BHW, and uses balance shaft assembly. I suspect that it uses the same heavy piston design, but with a center bowl, rather than the offset bowl for the 8V PD's.

If we add up assembly weight:

BEW Rod/Piston Assembly - 1423g
BHW Rod/Piston Assembly - 1495g

The BHW assembly is 72g more than the BEW assembly. BEW is fairly smooth idling without BS, BHW is not.
SO these are the two changes I am considering:

No1 - Reciprocating Mass Weight Reduction

This can be accomplished by a replacing a number of items:

• Rosten Rods - Stronger and lighter weighing in at 575g (97g savings), cost, approx- 650US
• Titanium Wrist Pins - Stronger and lighter weighing in at 130g (73g savings), cost - 450-600US/set depending on quantity

If I go with both the above options, I will be pretty comfortable running a 6000RPM rev limit.


No2 - BS Elimination:

• Replace BS drive sproket on BHW crank with BEW Sprocket from donor crank and use BEW oil pump, or..*
• Replace BHW Crank with EDIT - PD130/150 crank (or BEW crank with correct Rosten rods) and use BEW oil pump*

*Both of these options would require the front cover being replaced.

EDIT - checked through all my ETKA sheets today double checking Main and Rod Bearing Sizes. BEW/BRM Mains are same as BHW, but use the smaller Rod bearings. BHW mains and rods are the same as PD130, PD150 (ARL), BKD..53.7mm. I have gone through my text and added (ARL where appropriate)

I beleive the ARL crank will fit the BHW block/Rods without any issues because I have found that the ARL & BHW share the same Rod Bearing shell's, main bearing shell's, and thrust bearing. I will add these part numbers to this thread when I get a chance.

BHW, PD130/PD150 Con Rod Bearings: 038-105-701-B & 038-105-701-A (53.7mm Journals)
BEW/BRM Con Rod Bearings: 045-105-701 & 045-105-701-A (50.6mm Journals)
BHW/PD130/PD150/BRM/BEW Main Bearings: 038-105-561-AM & 038-105-591-AM



One other issue I have been considering is increased oil pump capacity. I suspect that the BHW may have a higher GPM oil pump than the BEW(or ARL). It would be nice to get a hold of an old BHW oil pump from a disgarded BS assembly and compare the flow rate to the BEW pump(or ARL). This could be done with a simple bench top set-up to get some hard numbers. If this is true, the BHW has an advantage over the BEW (or ARL).

I will also be doing some minor changes to my pistons, one of these will be a small increase in the omega bowl size. I would like to retain the same geometry proportions in this procedure, but it will give me a slightly larger opening that will fit a bit longer duration of injection, and a slightly lower compression ratio for higher boost levels. I have a cross section of a BHW piston which I will post later this week for general interest. It shows the thickness of the material in the various areas, the design of the omega bowl, the oil cooling passage, etc.

And I would like to thank texascadillac42 for donating his parts to me for a bit ( and he would like to sell them if possable ) and I would also like to thank Oilhammer for shipping them out so promptly.

Feedback and comments welcome.

Section through center of BHW Piston:




I have some other pics that will show comparisons between the BHW piston, ALH and BEW. I will also post a few comparison pics on the BHW/BEW rods.

TDIsyncro said:

Section through center of BHW Piston:

I have some other pics that will show comparisons between the BHW piston, ALH and BEW. I will also post a few comparison pics on the BHW/BEW rods.

Click to expand...

Allright a Canadian comes out with a better solution eh. I worked in Canada for a while. Great nice people and always willing to help others. Thanks for the thorough study on this on going subject. It looks to me it's a possibility, do you know how much it will cost to build one?
I'm just thinking of dropping a CRTDI, wouldn't it be less headaches?

T_D_I_POWER said:

Allright a Canadian comes out with a better solution eh.

Click to expand...

.......it only seems appropriate considering the TDIClub was created by a Canadian .

I would put the thread in the TDI hot rodding VWs diesel section.

While very interesting, its not a feasible alternative.

DezlDan said:

.......it only seems appropriate considering the TDIClub was created by a Canadian .

Click to expand...

Canada is a great country with great people. What would we do w/o a great neighbour like you guys. Wouldn't mind to go back there to work if there's another opportunity again.

Smokerr said:

While very interesting, its not a feasible alternative.

Click to expand...

And your reason is?

Not feasable for most BHW owners that is, you know, the normal ones...

abctdi said:

Not feasable for most BHW owners that is, you know, the normal ones...

Click to expand...

For us the balance shaft to gear conversion is the way to go...

T_D_I_POWER said:

Canada is a great country with great people. What would we do w/o a great neighbour like you guys. Wouldn't mind to go back there to work if there's another opportunity again.

Click to expand...

well, thank you from all Canadians.

Smokerr, I can understand that it is not feasable to most B5.5 owners. I take my cars and engines apart almost as much as I go for an evening at the movies. LOL I am sure there are a small handfull of B5.5 owners that are interested in a different option. If I discount labour (which I do myself), parts costs are probbaly par for par with gear BS parts. So very feasable for a do it your selfer.


Perhaps what I will do is trim back my thread here and move the body to the performance section or my build thread.

TDIsyncro,

You have a great idea, and I think it'll work if you plan it carefully. If I had the money, I'll commission you to do the conversion.....I'm saving mine to drop in a CRTDI though. Watch I'm going to get shot for thinking such a thing.....

T_D_I_POWER said:

TDIsyncro,

You have a great idea, and I think it'll work if you plan it carefully. If I had the money, I'll commission you to do the convertion.....I'm saving mine to drop in a CRTDI though. Watch I'm going to get shot for thinking such a thing.....

Click to expand...

I know a few of the Euro tuners figure they can run the CR with EDC15P, but the intigration of EDC15P into B5.5 would be difficult like mine was. The CR ECU into B5.5 would probably be difficult too, but neither is insurmoutable if your determined.
I have also looked at using the BKD piston and head on the BHW bottom end. Its a good match up, but more than I want to spend right now. I will stick with head porting, custom cam, bottom end upgrade and nitrous for this year.

Feedback and comments welcome.

Click to expand...

I can understand the intent of reducing reciprocating/rotating mass, but not how it relates to a DOUBLE crank speed balance shaft.
Were the balancer rotating at crank speed, I'd fully agree than reciprocating mass reduction would allow elimination of the balancer.
But.... The BHW balancer rotates at twice crankshaft speed. Why? To counteract the power impulses that come twice each crank rotation.

Lug_Nut said:

I can understand the intent of reducing reciprocating/rotating mass, but not how it relates to a DOUBLE crank speed balance shaft.
Were the balancer rotating at crank speed, I'd fully agree than reciprocating mass reduction would allow elimination of the balancer.
But.... The BHW balancer rotates at twice crankshaft speed. Why? To counteract the power impulses that come twice each crank rotation.

Click to expand...

Why does the BHW shake more than a PD150 if the balance shafts are removed? Power pulses..I don't think so. Yes the counter weights help smooth out power pulses, which makes the BHW ultra smooth in comparison to other PD's, but I am pretty sure the extra mass is what makes the BHW go from regular PD vibrations to an uncomfortable level. The counter weights on the balance shafts turn at twice the speed because it counteracts vertical force when the piston deaccelerates to TDC & BDC, as well as when it accelerates away from these point. A net force acts on the crank to pull/push the block in the reaction direction. The counter weights are exactly 180 deg to this force. They also counter rotate to one anouther such that they face one anouther in the center, and oppose one anouther on the outside..this completely cancels out the net horizontal forces the counter weights would produce internally to the balance shaft assembly, leaving only the vertical componant of the force they produce. The double speed also provides additional velocity which increases the force a small weight can produce, substantially.

EDIT - OK Lug Nut. I am going to put more thought into this. Thank you for your comment.

This what TDIMeister had to say about it.


http://forums.tdiclub.com/showthread.php?t=202297&page=19

TDIMeister said:

God****** the balance weights are HUGE and heavy!!! Compare each of those to something like this:

But they're that big and heavy for good reason. The Diesel reciprocating components and conrods are heavy, and you have a long stroke. All contribute to increased 2nd order vibrations, which is what the balance shafts deal with.

Click to expand...

The momentum change (same piston mass through the stroke, but different piston speed through the stroke) causes a change of rotational inertia. All four pistons are stopped at one instant (TDC and BDC), then all four are moving at maximum velocity 90 degrees later.
Since two are moving up and two are moving down there is no crankshaft vertical load change due to the crank rotation.
The typical firing order is 1-3-4-2. Or if starting from another point: 3-4-2-1. It is this 3-4 followed by 2-1 that causes a rocking or oscillation as pistons 3 and 4 fire they are pushed down, but the same force is attempting to push up on the head and the head is trying to pull up the block.
A few degrees later the 2-1 punch tries to lift the front of the block as the pistons are pushed down.
These are the second order impulses. More traditionally balance shafts to counter these forces hade has lobes 180 degrees out of phase and at ends of the balance shaft. Like spinning "balanced" bicycle pedals the offset of these weights causes an opposing force that is intended to counter match the second order forces of the "balanced" crankshaft and they rotate in sequence with the masses that create these second order vibrations.

THe BHW on the other hand has central, counter-rotating lobes. These are intended to only induce an up and down counter shake to negate an opposing down and up shake. Not end to end to counter the inherent 4 cylinder four stroke 1-3-4-2 rocking, not to try to maintain a constant reciprocating / rotating momentum of changing piston velocity, but to counter the vertical impulse of each power stroke.

You are more than welcome to lighten the reciprocating mass of the pistons, but don't expect as much from this as I believe you might be hoping to get. I doubt that you'll find that the reduction in piston mass will allow the removal of the balancer set without restoring inherent shaking.
You'll have less than others that have machined off the lobes and have restored the shake, but I really don't think you'll be pleased with the result.

Good luck.

What balance factor are you using for your calculations? 50 %?

eddif

TDIsyncro said:

well, thank you from all Canadians.
Smokerr, I can understand that it is not feasable to most B5.5 owners. I take my cars and engines apart almost as much as I go for an evening at the movies. LOL I am sure there are a small handfull of B5.5 owners that are interested in a different option. If I discount labour (which I do myself), parts costs are probbaly par for par with gear BS parts. So very feasable for a do it your selfer.
Perhaps what I will do is trim back my thread here and move the body to the performance section or my build thread.

Click to expand...

I have to disagree as interesting as the attempt is, and obviously entertainment for you. I would be surprised if you are not alone in this as attempting an alternative. While like others I will follow developments.

I have worked on diesel engines up to 2500 hp (rebuild). I don't take my engines apart just for fun. Actually, I don't do them at all anymore, I don't have the place to do it, nor the set of tools, nor the time (and I can't afford a mistake that costs us many thousands of dollars).

Now I am in the process of moose proofing the back yard to save my wife's beautiful flowers and garden! That is worth time, money and effort (and I am guaranteed success as I understand all the aspect of what a mosse can and cannot get over.

Your project not only a lot of time and effort, but a major financial aspect as well (car out of servcie and not available and cost of failure).

And, like all projects without analysis, its going to have one or more flaws.

That will then result in a damaged engine, and a regroups until solved or realization is acheived that you do have to have an engieering anaylis and understaing of the forces involed, why and where they occur and coutnre them if possible.

As they went with a counter balance module, its not a simple thing, otherwise a harmonic balancer would have been adequate. Good luck 0of course!

My guess is that it will end up failing, and you will revert to a gear ballance shaft.

I should note that, the BGW engine is otherwise identical to the BHW except it uses no balance shafts, and is bolted to a manual transmission. So, TDIsyncro's car is also a manual as I understand, and therefor may not be a good test bed to see if the engine can do OK without the setup or would it simply have too high of NVH for most drivers' tastes.

I have to think if VAG did not want it in place, they would not have spent the time/money/effort on putting it there, however shortsighted that time/money/effort has proven to be. I mean, clearly the chain drive setup could not have passed much in the way of durability testing. I am getting these cars in at 50k miles or less making all kinds of racket!!!

Smokerr said:

Your project not only a lot of time and effort, but a major financial aspect as well (car out of servcie and not available and cost of failure). And, like all projects without analysis, its going to have one or more flaws.
That will then result in a damaged engine, and a regroups until solved or realization is acheived that you do have to have an engieering anaylis and understaing of the forces involed, why and where they occur and coutnre them if possible.
As they went with a counter balance module, its not a simple thing, otherwise a harmonic balancer would have been adequate. Good luck 0of course!
My guess is that it will end up failing, and you will revert to a gear ballance shaft.

Click to expand...

My car will be down for one week. I have 3 other vehicles to choose from, not a concern. There is no cost of failure. It will not fail. I may not get all the results I want, but at minimum, it will meet some of my goals. Don't forget that my goals include HP levels that factory rods are not sufficient for, and an increase RPM redline. Rosten rods are pretty common upgrade, so nothing crazy there.

without analysis? Well, I'm not running into this blind Smokerr. Have I thought of everything? No, probably not, as LUG_Nut pointed out. And I am still researching the situation. However, please take note, as Oilhammer pointed out, that the BGW uses the same rods and pistons as the BHW without BS module. Does it fail? no. All the other PD1.9 engines do not have BS modules? What is the vibration level like of those PD's? Is it acceptable? Why? I guess we need to define fail? I have thought about Lug_Nut's most recent post, and I really can't poke any holes in it. So, yes, I may not get as much as an improvement as I hope for. However, how do we explain the difference in vibration between BEW (and ARL etc) and a BS free BHW, and why one needs a BS, and one does not need one? Is it because the BHW has a 1.5mm bigger bore? That’s only 3.7% more surface area...
If I were to take my BHW bottom end off, and attach BEW pistons, and install in BEW block, would it have bad vibration? If I sleeved the BHW block and installed BEW pistons, would it now vibrate just like a BEW? Should there really be a difference in vibration level between these two engines?

As for you not having any desire to pull your engine apart... I don't expect most would want too either, the B5.5 crowd is not really a tuner crowd. However, there are lots of people out there that enjoy customizing engines for performance and there might even be one or two with BHW engines? I was PM's by one of those 3 months ago. There is also a few people out there running BHW pistons (or other 81mm Pistons) with Rosten rods, without vibration issues. So is it some other problem with my set-up that’s causing the vibration I do not like? My timing is bang one, my injector balance looks pretty good, cam looks like new, tune is good..If we go down this argument you can come to one of a few conclusions:

• some other problem is causing my engine to uncomfortably vibrate, which means the normal BHW vibration level is probably acceptable (same as 1.9PD's) without BS module and therefore there is nothing wrong with using the BEW pump sprocket and eliminating BS assembly, or
• It's the difference in reciprocating mass between the 1.9PD's and the BHW that’s causing the enhanced vibration when compared to the 1.9PD's
• or what else guys??

Anyways, I will give everybody an honest opinion on the results. I all ready have a BEW donor crank here, and will order some Rosten Rods, rings, head gasket, head bolts, crank seals, etc in a month or so.

EDIT - The BEW crank will not fit up with the BHW Rods, but the sprocket should be useable. If I was looking at a crank swap, I could go with the BEW and get the Rosten Rods to match PD130/150/BHW pistons to PD100 BEW crank, or I could fit in a PD130/150 crank, as it has all the correct bearing sizes, and use the standard PD130/150 Rosten Rods.

Oilhammer has a valid point on the auto tranny vs. manual tranny test bed issue. Back to BEW's as an example, what are they like with Auto tranny option?

balance shafts certainly aint essential. It's likely that VW went with the BS system in certain models because of their position in the marketplace/ competitors. A "hot hatch" may be accepted with a degree more NVH than a luxury sedan.

PSA also toy with BS modules in some models. Only the 2.2HDI has'em, they're deemed unnecessary on the 2- litre (and smaller) lumps.

Well again I say until we see (feel) a 2.0L BHW bolted to the 01V ZF autobox without the balance shafts, we can only guess.

This project holds my interest more from a performance standpoint than anything else, and I am hoping some day I will get to ride in the car that sports the fruits of these efforts!

oilhammer said:

This project holds my interest more from a performance standpoint than anything else, and I am hoping some day I will get to ride in the car that sports the fruits of these efforts!

Click to expand...

If we ever meet up, you can take it for a drive. Nothing like first hand experiance.

The reason for the balance shafts to to eliminate the "2x buzz" inherent in 4cyl 4stroke engines. This buzz comes from the fact that at 90 degrees of crank rotation from tdc, each pair of pistons moving together are NOT at half travel and their inertia is not exactly cancelled by the other pair. This results in a vibration straight up and down occurring at twice the frequency of crank rotation. So it is easily cancelled by two counter rotating shafts with eccentric weights spinning twice crank speed.

The balance shafts have nothing to do with torsion vibrations in the crank, or torsional accelerations from firing pulses.

There is a good description of this in Bosch Automotive Handbook, and some SAE literature.

On small engines, this vibration is tolerated. On larger 4bangers, it gets obnoxious. On expensive vehicles, NVH reduction is worth the money to eliminate, thus the balance shafts.

For performance engines, you could eliminate the balance shafts, but be prepared to replace broken bolts and such that fracture due to the higher than normal level of vibration.

Reducing piston and rod mass will proportionately reduce the 2x buzz, but you cannot reduce that mass enough to make a significant change. The pistons and rods need most of their mass to do their jobs and not fail, especially at 6k rpm chipped.

Good debate on this issue guys. It has made me think a bit more. I found
this link and read through it.

http://www.vibratesoftware.com/html_help/html/Diagnosis/Engine_Speed_Related.htm

I have decided to borrow a vibration meter from somebody I know and confirm the frequency of the vibration with the RPM to determine if it is in fact a 2nd order vibration I have, or some other issue. Apparently 1st order 2nd order and fourth order vibrations indicate different issues.

Very interesting, up until this day,I had no idea what this pesky balance shaft module does except house the oil pump... so the actual "balancer shafts" don't drive anything?? (I assume)

maktas said:

Very interesting, up until this day,I had no idea what this pesky balance shaft module does except house the oil pump... so the actual "balancer shafts" don't drive anything?? (I assume)

Click to expand...

The crank drives the chain, the chain drives the #1 balance shaft, #1 shaft drives number #2 shaft via a gear, #2 shaft drives the oil pump via the hex shaft.

On engines not using a balance shaft module, the chain drives the oil pump directly.

Lug_Nut said:

I can understand the intent of reducing reciprocating/rotating mass, but not how it relates to a DOUBLE crank speed balance shaft.
Were the balancer rotating at crank speed, I'd fully agree than reciprocating mass reduction would allow elimination of the balancer.
But.... The BHW balancer rotates at twice crankshaft speed. Why? To counteract the power impulses that come twice each crank rotation.

Click to expand...

There are 4 componenents that an engine has to overcome vibration
Free forces of the 1st and 2nd order & free moments of the 1st & 2nd order. For a 4-cyl, the 1st, 3rd,& 4th components are 0s, but the 2nd component isn't. The 2nd component of the free forces of the 2nd order = 4.F2. The pair of counter rotating balanceshafts are designed to produce 0 force. The speed of the counter rotating balance shafts = 2w (one cw, and the other ccw) and F2 = m0.r.w2.L.cos2a

Generally, a 4-cyl engine with engine displacement > than 1.9 L requires a pair of counter rotating balance shafts to quell the vibration.

T_D_I_POWER said:

The 2nd component of the free forces of the 2nd order = 4.F2. The pair of counter rotating balanshafts are designed to produce 0 force. The speed of the counter rotating balance shafts = 2w (one cw, and the other ccw) and F2 = m0.r.w2.L.cos2a

Click to expand...

T_D_I_POWER, can you give a definition of all the formula variables (m0, r, w2, L, 2a)? I can guess at them...but would probably be wrong on some.

Keep in mind that this is a diesel, not just a gasoline engine.

further more, its a very high speed diesel. Even the old Detroit’s that were indestructible were not pushed passed 3k.

Frankly, I was astonished when I started reading the specifications on this.

that wide RPM band, as well as peak torque band that comes in and peaks low rpm, and then stays there for a wide range (3900?) is incredible.

The only diesel I ever worked on that didn't have a fluidic harmonic damper on it, has counter balancer shaft. I think they could get away with no harmonic balance on it due to low run hours.

So, along with the gasoline engine forces, you have to account for the heavier diesel pulses in this engine (17 to 1 compression? )

TDIsyncro, you're absolutely spot on to reduce 2nd order vibrations through reducing reciprocating mass. Expensive, but good