I have already looked into making a true harmonic damper for the car, just because of the issues of the stock one coming apart.

 

UGH, powdered metal. At least we don't have powdered metal connecting rods like the Cooper. Maybe you are both right. Maybe the solid crank pulley does add additional strain on the ancillaries but the weak link is the oil pump gear. The only real way of knowing is to test with a billet gear and see what happens at high rpm's.

 

That'd be nice, since BMW can't seem to get it right.

 

this is the same reason the SRT4 guys went to the billet oil pump gears

 

the stock ones do tend to come apart, that's why I have looked into making ones that will last the life of the car

 

Things are never what they seem to be in the lab. When BMW was testing the Tritec before committing to hundreds of thousands of units, they surely did not have EXACT production pieces. Engines were assembled and disassembled by skilled people. Machining and foundry materials were not production spec. Everything could have proven out just fine in BMW's durability testing, but......... When production goes full swing it's another story. Materials are substituted by bean counters to save a few cents. Production schedules dictate that engines keep coming off the assembly lines no matter the materials, personnel issues etc. Even had BMW flown an entire plant full of engineers to Brazil to run the plant I don't think they could have controlled the quality in such a budget minded engine if they wanted to. The truth of the matter is once projects start production, most development teams move on and new folks take over the project anyway so some of the knowledge is lost. Could be why a dampener found it's way into an engine that theoretically doesn't need one. In the lab everything is controlled, in the real world a certain safety factor is necessary.


Seems that the community has found the weak link when the harmonic balancer is changed, could be something else if the gears weren't breaking first. If Jan makes the billet gears and folks keep running the solid pulleys we'll surely find it.

 

Very nicely said.

 

With that said, how much more are you commited to this engine? Are you going to be ditching it soon in favor of the R56's engine?

 

I seem to be the only one still working on it, I have no intention of going away from it as there are many projects we are still working on

 

A Fluidampr for the Tritec would be nice.

http://www.fluidampr.com/HOWITWORKS.htm

 

Sweet !!

 

The main purpose of the existance of the harmonic balancer is to keep the crank from tearing itself to pieces. Ryan is correct, 90 degree V8's are particullary nasty at this, but any other engine can have resonance issues as well. There is a woefully long record of big 600lb. V8's, making only 200hp from 400ci, and driven by little old ladies snapping the snouts off of cranks when the dampener failed. This is not new or top secret, in fact this very theory is part of the testing to become an ASE certified mechanic, as I eluded to earlier.

 

Here is a link on mini2 for what it is worth
http://www.mini2.com/forum/gt-tuning...re-causes.html

 

Not a lot of data there but thanks for the link.

 

If we are drawing conclusions in this Court of Public Opinion called NAM, an undocumented conversation with an unnamed person who cannot be contacted is simply not admissible evidence.

I'm not saying you are speaking falsely, but your second-hand hearsay is simply not something I'd bet an engine on, nor would a judge allow it in any court of law, because recollections from past years are very unreliable.

The correlation stated by Jan, from his personal experience with more than one engine, is far stronger evidence for accelerated wear on some components, caused by an undamped pulley. The fact that these are engines that take more abuse than most is likely demonstrating accelerated wear at higher rpm and power levels, which should not be a surprise.

And, BTW, as to cost, I could make one of the aftermarket pulleys in my basement from a $10 piece of alum. plate. It's a simple lathe job that could easily be automated to churn them out for a few bucks worth of manufacturing content. Making a balanced and damped pulley would require use of a more costly series of separate machines and materials, and more manufacturing operations and cost.

If Jan comes out with a better-quality and light damped pulley, it will be interesting to see what it costs. By contrast, "development time" for the undamped pulleys offered in the market would be measured in minutes of shop time.

 

Where is the oil pump on a Tritec? Outside the block like a Honda or 4G?

I would fork over cash right now for a good set of oil pump gears. Not something to skimp on. And it would be alot more appealing to be able to yank the pump with the motor in the car.

 

it's right behind the crank pulley
that silver cover is the housing for the oil pump assembly

 

Well work out the cost for 10 of them. I'm willing to put up cash for a set.

 

so at this point we have some anecdotal or empirical (the term we use in the medical field for evidence that is based upon a physician's clinical experience but hasn't been subject to actual research based criteria) evidence (in other words - Jan's experiences) that the aftmkt crank pulleys may be detrimental.

Out of curiousity Jan, any of these pump failures occur with ppl who have maintained a 0% crank pulley or are these all 2-4% pulleys.

additionally, we have some anecdotal evidence from a few owners who have upgraded both and at this point have no negative outcomes that they would chalk up as a result of the aftrmkt crank pulley.

this almost seems like the kind of argument a patient may arrive in my office with hopes that i can settle. they've heard or read a lot of conflicting information about how or why or what medication X does in relation to treating their illness or causing side effects, etc. but, what they don't have is the clear explanation of what or how the medication actually works (ie the pharmacology of the medication and pathophysiology of the illness). it seems like we have a bunch of ideas both for and against an upgraded crank pulley in addition to an upgraded sc pulley - but what we don't have is anyone who has clearly articulated what changes mechanically related to a smaller sc pulley in terms of how, why or what is beneficial or not with regards to upgraded crank pulleys. however, given the empirical experience that Jan speaks about (in addition to those owners who have upgraded sc pulleys without also upgrading the crank pulley) it is likely safe to add a reduction sc pulley while maintaining the oem crank pulley. Likewise, given the few owners who have contributed their experience given both an upgraded sc and crank pulley, that may also be safe.

at this point, i'll venture a guess, in the absence of data and/or a solid, thorough explanation of the detailed relationship between smaller sc pulleys, crank pulleys and engine physics (keeping in mind that as medical school graduate i did actually have to do well in college physics - but i don't profess to be anywhere near an engineer!!!!) that i or anyone else for that matter, will be just fine upgrading the sc pulley and keeping the crank pulley stock.

 

2 were 0% and 2 were 2%

 

thanks Jan

 

You better go a 4% then as they don't seem to cause any problems
(sorry couldn't help myself)

 

To wrap up:

A reduction supercharger pulley will increase the rpm of your supercharger thus increasing boost. The down side - spin too fast and the heat generated by compressing air will exceed what the intercooler can handle and there is no benefit.

A light weight crank pulley allows for faster spin up of the superchargerby lowering rotational mass

A light weight crank pulley may lead to oil pump failure there have been several cars that this has happened on. There are quite a few more that it hasn't. Nobody has kept count so nobody can say it will happen 2% of the time or 40%. That's your gamble.

To the OP here are some calculations for you based off the actual measued diameters of the stock crank and supercharger pulleys and the M7 2% oversize and 16% reduction pulleys. The basis rpm is 6500 which is a nice round number roughly near red line from the factory.

Crank pulley stock 142.5mm
sc pulley stock 65mm
M7 2% crank 139.65mm
M7 16% sc 54.6mm

engine rpm @ 6500

both stock pulleys in place will spin the sc pulley at 14250 rpm
stock sc and 2% crank sc pulley spins at 14535 rpm
stock crank and 16% sc sc pulley spins at 16964.29 rpm
25 and 16% pulleys sc pulley spins at 17303.57 rpm

a 2% crank pulley produces a 2% increase in sc pulley rpm
a 16% sc pulley produces a 19.04% increase in sc pulley rpm
both 2% and 16% produces a 21.43% increase in sc pulley rpm

To the OP a reduction crank pulley will bump power but not by much do the SC pulley but get a steel one like M7s not an aluminum one like some of the others and you'll love the difference.

 

Were either of the 2% pulleys M7's?

I wonder if material has anything to do with this...

 

ok i'll bite - why steel vs aluminum? i guess i haven't heard or read that anyone has had any unusual probs with either material (that could or was at least chalked up to it being steel vs aluminum or vice versa)