SpecE46: Harmonic Time Bomb Disaster
First I want to say I love the idea of this SpecE46 class, and big thanks to Jason Tower & James Clay for getting this going.
As a racer (SCCA) I have a few different concerns on a few things, but one major concern in particular; Harmonic Oil Pump Failure. I believe the first year or two will be a Very Expensive learning curve for both the racers & promoters in this new class.
From personal experience I can tell you that the aluminum block M54B30 is NOT well suited to long duration RPM pulls down a straight away in stock (SpecE46) trim as the current rule book is written. There is a well known & documented high RPM issue concerning Harmonics & Oil Pump Failure in the M54B30, that mostly happens in the 6700 to 6800 RPM range. This Harmonic OPF is greatly exacerbated by three (3) different issues.
1) A light weight flywheel & clutch, instead of the stock 38.5lbs (heavy) Dual mass flywheel & clutch. (the stock dual mass flywheel acts as an Extra Damper on the back of the motor)
2) Any ECU "tune" that extends RPM past the stock 6500 RPM limit. Namely a tune that goes to 6800 to 7200 RPM.
3) Any race track with a long straight away that allows the motor to sustain the dangerous 6700 to 6800 RPM Harmonic failure range. Typically multiple 8 to 12 second (or more) pulls in any gear, (namely 4th or 5th) that allows the motor to "stay" in this dangerous 6700-6800 harmonic window.
As the rulebook is currently written, the SpecE46 race community will probably see many Harmonically caused OPF engine failures.
"Specifications & Rules"
Engine: Stock M54 motor, "flywheel and clutch may be upgraded". This rule should be changed to: Stock flywheel & clutch.
"A custom ECU tune may be specified in order to ensure compliance and maximize power/reliability." This rule should be changed to either: 1) A stock ECU must be used with NO tuning software.
Or 2) A custom "Tune" may be used, but with a Maximum 6500 RPM limit.
I would Strongly suggest a change to the rulebook allowing the use of either or both:
1) An upgraded oil pump, in the stock location.
2) The use of an upgraded engine balancer.
The money that would've been spent on a LTW Flywheel & Clutch, and the money that would've been spent on the ECU "Tune" would be much better spent on the upgraded Oil Pump & Engine Balancer. This change in thinking will not only provide the SpecE46 racer with a more sustainable motor, but will provide a more level playing field for every entrant. That of course is because the "guy" with the biggest bank account will be able to afford a custom Ultra LTW Flywheel & Clutch, not to mention the use of a "Super Tuner" that can extract every last ounce power out of his motor,.....at any cost.
Some things for SpecE46 to consider.......
appreciate the feedback rob. let me address your two concerns as best i can:
1. there are several reasons we may utilize a spec ecu tune (ensure compliance, fix various electronic issues, make more power, richen the mixture for safety, etc) but raising the rev limit is not one of them. engine longevity is absolutely something we're trying to preserve so a 6500 rpm limiter (6700 tops) is all this class will see.
2. we've gone back and forth on the flywheel/clutch multiple times, right now we've permitted light flywheel/clutch to make the cars as fun to drive as possible. we're expecting that the conservative rev limit will keep the motors in their safe range, and we are allowing oil pump modifications (and harmonic balancer replacement may be permitted in the future as well). plus the light flywheel is optional, not required. the performance gain is minimal, it's mostly about making rev matching easier. with a 3.46 diff i don't think these cars will spend any significant time banging against the limiter in 5th.
finally, i want to point out that Evan Levine has been part of the Spec E46 team from day one, in fact it was his suggestion to use the E46 platform (my original proposal was to use the E36 M3). he's in the final stages of buying a new house and hasn't been quite as active on the public side of things but he's as much a driving force behind se46 as james or myself.
Thanks for the post and concerns - certainly well-presented and well-received. A few points (repeating Jason in some cases):
At the end, Jason and Evan are making the decisions and I helping to provide answers and options, so this is one for them to expand on or discuss as needed.
Agreed - Excellent feedback thanks. I hope the considerations we've made will address this, and I think we all support a low enough rev-limit to avoid problems. That extra couple hundred RPM really don't make the cars faster enough to justify it in a Spec class, especially if not having them makes the cars more reliable.
The balancer is really the only remaining piece, and it's not off the table as James mentioned. But my hope is that we get a few test cars running, built by people willing to experiment a bit, and see if that's truly necessary. Prices on these things have crept up and anywhere we can help keep that down would be preferable at this point. Ultimately though we won't sacrifice reliability if it comes to that.
I'm very happy with these excellent responses, they show that all of you are on top of these issues & are open minded to addressing this "Harmonic" problem.
I really like the idea of the LTW flyweel & clutch James Clay has come up with, it will make the SpecE46 car more fun to drive and add definite life to the clutch package simply because it won't wear out quickly.
I also really like the Idea of "Spec" software that everyone would use. I do believe that a maximum of 6500 RPM should be utilized, this 6500 RPM limit really will help with motor longevity, and will offset any negative effects of using a LTW flywheel & clutch.
On to the Damper; As an owner of a highly modified N/A 2003 330Ci that currently has a ATI Super Damper mounted on it, all I tell you is there is a VAST difference in the amount of harmonic (Greatly Reduced) vibration in the 6700 to 6800 RPM range. Now when I run my Bimmer at the track, or down some empty highway in 4th gear between 6600 to 7000 RPM the "Buzz" or Harmonic vibration is virtually gone. My thought on something like the ATI Super Damper is this: BimmerWorld would purchase a large supply (10-20) of these from ATI at a discounted rate, and then pass the savings on to the SpecE46 racers. I am a FIRM believer that this one piece will add great longevity to any M54B30 race motor.
The oil pump: There's a reason why BMW sells a $3000 dollar oil pump upgrade kit for a racing M54B30, that's to solve the issue of the aluminum block vibrating like a tuning fork at 6700 to 6800 RPM and in some form or another destroying the stock oil pump. I certainly don't think anyone should spend 3K to help solve this issue, but I do believe the SpecE46 rulebook should be written to allow either:
1) A stock oil pump with a welded or wire tied oil pump nut.
2) A stock oil pump with a VAC Motorsports oil pump kit installed. (about $200)
3) A "Super" oil pump like the one I run. Cost is about $750, its a TC Kline/ Greg Smith - vaio76109 pump. There are several threads on this pump, here's a link
http://forum.e46fanatics.com/showpos...56&postcount=1 lots of pictures thanks to Adam (PEI330Ci).
Again, Good luck,
PS, Jason I responded to your PM.
Two more very inexpensive motor saving/longevity aids should be added to the list of helping a M54B30 race motor stay together.
1) S54 Timing Chain Tensioner.
This M3 timing chain tensioner is a Direct fit and will "firm up" the timing chain from thrashing around as much as it currently does with the stock M54 part. The motor will feel smoother at high RPM with this tensioner.
2) INA (Over-Running) Alternator Clutch Pulley.
Again, this will help smooth out the motor. With the stock M54 solid Alt. pulley, the ribbed belt "whips" back & forth under deceleration from high RPM causing a lot of unneeded vibration.
Both of these parts are Super easy to install, and are cheap insurance at holding a M54B30 motor together under the extreme environment of racing.
Does the m54b25 suffer from harmonic balance issues?? I plan on tracking my 2001 325ci in nasa time trial 2014.thx
Worth noting 2003 M54s have a different harmonic balancer (albeit also a smaller rib count). From what I understand, these don't fail as frequently. Maybe best to just have everyone run the 2003+ damper?
Is this harmonic issue really true?
Should i be worried if i supercharge or chip my 330 for street driving.
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