Project E46 M3: Part 13 - Lightweight clutch and flywheel, and more!

Lighter is almost always better!

by Pablo Mazlumian

Our E46 M3 is really coming along. It handles and slows down incredibly well, thanks to our UUC swaybars and Wilwood/UUC big brake combo that influence our sticky BF Goodrich Rival tires. Our naturally aspirated 3.2-liter inline-six cylinder engine also has plenty of grunt, thanks to basic performance upgrades like a full exhaust using Fabspeed/VAC Motorsport headers, a Castro Motorsports CSL-style air box, and total engine management controlled with an MKC-tuned AEM Infinity. Okay, so maybe the latter EMS isn’t so “basic”.

Still, try and find us an engine this size that’s generating over 320 wheel horsepower without the addition of a turbo or supercharger, let alone major engine work (this car’s valve cover has only been off once for its factory-suggested valve adjustment). And while the S54 engine breathes well with its renowned, high-flowing and high-revving cylinder head, even the torque—which is what is really limited by engine displacement in naturally-aspirated engines—is also very impressive.

The E46 M3’s peak 260-plus lb-ft of torque to the wheels rivals that of several newer and larger-engine high performance cars, including the 4.0-liter BMW M3 and non-GT3 RS 3.8-liter 997s and Cayman Porsches. In fact, if you need to compare it to something of this car’s age, we would have to go to a 3.6-liter Ferrari 360 Modena, which puts out only about 10 more wheel horsepower but over 10 lb-ft less torque, even with its 340 cc larger displacement (I know it's not the 430 or 458 but hey, it's still a Ferrari of the same year).

So now we’re at a point that getting a lot more out of the car is going to require either getting into the engine or going forced induction. While those are still future possibilities, in the meantime there are a few things we can do to enhance performance and the overall driving experience, mainly in the name of lighter weight.


When we contacted BimmerWorld for their advice on the car, given our setup and goals they suggested using a Clutch Masters FX400 clutch.
For a smoother, yet more direct pedal feel, Clutch Masters also suggests using its own high performance hydraulic Bearing.
Here's a sneak peak at some of the other upgrades we’ll be installing as well, starting with this Megan mid-section exhaust, which replaces the factory Section 2 on an E46 M3. We got it from Bavarian Autosport.
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Tuesday, September 27, 2016 2:52 AM
Wow, I'm surprised by the choice of an aluminum flywheel. I feel like ACT offers better options through their selection of single-peice, chromoly flwheels for the E46 M3. Their "Streetlite" flywheel is a more reasonable fifteen and a half pounds which would have made for a far more streetable setup. That said, their "Prolite" offering is even half a pound ligher than the aluminum unit in this article while still maintaining the benefits of single-piece steel construction.

Based on my experience, I'm gonna say that super-light aluminum flywheel shall generate some very noticeable deceleration buzz. Personally, I don't think that's an acceptable compromise on a street car. An ACT Prolite probably would have done the same thing, making an ACT Streetlite the ideal choice in my mind. I suppose added noise would be much easier to tolerate if you got the aluminum flywheel for free, which you very well might have for this article.

As usual with MotoIQ builds I can't deny there's a lot of coolness going on here. Do you have any plans to win back some smoothness and streetability after going with this rather extreme clutch setup?

I would definitely suggest an uprated harmonic balancer as your next modification, *especially* after losing so much damping action by ditching the OEM dual mass flywheel. The stock balancer is a known point of failure on the E46 anyway, so upgrading it would be a nice bit of preventative maintenance.

VAC Motorsports offers an extremely robust harmonic balance that was designed and manufactured by ATI Performance Products. That part should add a little smoothness back into the drivetrain while also protecting the crank, oil pump, and other internal components from damaging harmonic vibration. As has been espoused by Mike Kojima, straight six engines are definitely not immune to harmonic vibration despite their "ideal" balance.

Thumbs up for a hellafunctional build, looking forward to seeing where it goes next.

Pablo Mazlumian
Pablo Mazlumianlink
Tuesday, September 27, 2016 7:26 AM
Thanks. Totally agree at looking into harmonic balancing via the ATI/Fluidampr type route, and have worked with VAC Motorsports before on previous projects (including this one). To be honest, even with the AC on there is very little-to-no vibration. This is my fifth aluminum flywheel setup and I can tell you that I know what you mean with the clutch rattle, but now having run a second setup from Clutch Masters in a row (the last was a CM/JB fly combo in an E36 M3), there is no noise. To be honest I simply forget it's even there, and this time I even used UUC tranny mounts.
Tuesday, September 27, 2016 5:54 PM
Damn, color me surprised!

Then again, an outfit as big as Clutch Masters has the resources to R&D the crap out of parts like these. They must have put a ton of work into reducing NVH. With enough trial, error, and engineering, it's amazing how much civility can be squeezed from race-grade parts.

We had a similar experience with our own Project Hoondy. We recently installed a Cusco RS differential and *everyone* in our online community told us that it would be absolutely unbearable to drive on the street. Project Hoondy is a daily driver, so we went nuts with the WPC treatment, applying it to every single one of the many parts in our diff. Combined with low spring pressure, our modifications made the race-grade LSD absolutely civilized for street duty. It juuust crunches the tires enough to let you know it's there, mostly when making hard 90 degree turns at very low speeds. We wouldn't have it any other way!
Wednesday, September 28, 2016 12:35 AM
Put this puppy on a truck scale, we need a number!
Wednesday, September 28, 2016 9:20 AM
I got the Spec Stage 1 aluminum fw/pp on my Z06 and lost 20# of rotational mass and the thing is still perfectly streetable. Like the clutch used here, it's only about 1 tick above stock so it's not going to be grabby enough to turn the thing into an on/off switch. It always bothers me when people get on the soap box and denounce the lightening of the clutch package. You don't know how light is too light until you try it yourself. I am curious why Pablo went with that internal slave though, my Z06 has one and I'm not a fan.
Friday, September 30, 2016 11:51 AM
I was a little surprised at this comment, "this car’s valve cover has never even been removed", does that mean a valve adjustment has never been performed? That is a every 30,000 miles maintenance item!
Thursday, October 06, 2016 9:11 AM
Honda J32a2 makes over 300whp and 270wtq with just intake, exhaust, pulley, and tune.
Pablo Mazlumian
Pablo Mazlumianlink
Monday, October 10, 2016 8:32 AM
Indeed, these lightweight flywheels are totally streetable. Having run seven now (six of them weighing between 10.5-12 lb) on inline-six motors, I've yet to have a problem. Sure, some rattled a bit, but my last two with CM have been great. Also that's two bad you had problems with the internal slave setup, I only noticed a stiffer feel initially but then it settled down to where it should be with no real draw backs.

@Phil: Good thinking--I was thinking more on the lines of "this car has stock cams" when I put that. I went ahead and edited it to avoid confusion. This car got a valve adjustment between 30-40k by the first owner I bought the car from (just wasn't thinking about it when I wrote article). Thanks for pointing that out.

@brian6speed: if true then yeah that is impressive. But don't those cars dyno like 220-230whp stock? That's an awfully big gain for such basic mods. Too bad those come on fwd cars.

And thanks to whoever posted the link!
Wednesday, October 26, 2016 8:16 AM
Still another 40-50 SAE NA rwhp on the table via bolt ons, if you want them. There are tons of (street and track driven) e46 M3's making 35X-36X SAE rwhp on M3forum, and a couple in the 37Xs. On the stock ecu (albeit most of them are running a modified CSL engine management program at this point, as it works better with the CSL airboxes-- it's MAP based instead of the stock programs MAF based. Some Schrick cams, better headers (SS stepped), better airbox, and a proper tune would get you to 35X-36X SAE rwhp (or more, if you believe your ecu somehow generates more power than the stock one), add throttle bodies to that and you'd be in the 37Xs with a proper tune/stock ecu.

Might be worth going through the dyno thread on M3forum to see what hardware combinations result in what power levels, before heading down the turbo road.
Wednesday, October 26, 2016 8:21 AM
Also, it looks like you're having a huge torque loss below 4000 rpm (stock s54 makes >80% of it's torque from 2300 to 8000 rpm). That loss is almost always the result of an improperly located merge in the section 2 of the exhaust. If you put your section 2 back to stock, I bet you'd gain that torque back without losing power anywhere else...
Wednesday, October 26, 2016 8:25 AM
Just looked at your exhaust article and it doesn't appear that your section 2 actually has a merge. For sure that's the cause of your missing 40-50 ft lbs of torque below 4000 rpm. Free fix, though: back to stock! There's little to no power to be gained from an aftermarket section 2, but lots of room for loss.
Pablo Mazlumian
Pablo Mazlumianlink
Monday, March 06, 2017 5:29 PM
Obioban, you are correct. Going to be featuring a final exhaust setup with that stock Sec2 back in place :)
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