Lightweight Flywheel and Pulleys and the Subaru Boxer CEL

[Rasmus]

Decided to spawn a new thread. We were getting off topic in the other (http://thefactoryfiveforum.com/showthread.php?6540-Working-on-the-donor/page5).

So the question continually comes up

"Does running both a lightweight flywheel and a lightweight pulley system on the Subaru Boxer cause it to throw a Check Engine Light (CEL)?"

I run both right now on my daily:

http://i162.photobucket.com/albums/t278/RasmusHansen/SubaruParts/IMG_4586.jpg
http://i162.photobucket.com/albums/t278/RasmusHansen/SubaruParts/IMG_4585.jpg
Unorthordox Racing pulleys

http://i162.photobucket.com/albums/t278/RasmusHansen/SubaruParts/IMG_3768.jpg
Crazy light "ACT Prolite" flywheel (mated to an OEM replacement clutch and pressure plate). 4.254 kg = 9.38 lb

How did I avoid the code? I know in the other thread I wrote that I prevented the CEL by disabling the code in RomRaider. I was wrong.

I just checked my ECU image in RomRaider Editor and I forgot to disable those codes all those years ago. I've been running like this for 2.5 years in my daily driver. Not one CEL.

P0301 Misfire Cylinder 1 - Enabled
P0302 Misfire Cylinder 2 - Enabled
P0303 Misfire Cylinder 3 - Enabled
P0304 Misfire Cylinder 4 - Enabled
P0335 Crankshaft POS. Sensor A Malfunction - Enabled
P0336 Crankshaft POS. Sensor A Range/Perf - Enabled
P0340 Camshaft POS. Sensor A Malfunction - Enabled
P0341 Camshaft POS. Sensor A Range/Perf - Enabled
P0365 Camshaft POS. Sensor B Bank 1 - Enabled
P0365 Camshaft POS. Sensor B Bank 2 - Enabled

[Racebrewer]

Thanks Rasmus,

What is actually happening if lightweight rotating components cause a CEL for mis-fire?

John

[Rasmus]

The hypothesis is the the ECU gets delayed or incorrect information about the position of the crankshaft and fires the spark plugs/fuel injectors too early/late/wrong cycle. This causes a P0301-P0304 or P0335 P0336 CEL to come on.

I've just never experienced this infamous problem in the 2.5 years I've been running this setup. And I run some of the lightest, if not THE lightest, pulley/flywheel setups.

[skullandbones]

Rasmus,

Wouldn't the engine timing be a major factor in creating the CEL? I saw that in the advertisement of the ACT flywheels they claim that their forged flywheels have never caused a CEL. Do they give you detailed support on how to tune your engine with their components (recommend a certain setup)? So are there lighter flywheels that have caused the problem if this one doesn't? Also, does this lead to catistrofic engine failures or is it just an inconvenience to have to reset the error code? It sounds to me like the CEL is caused by something other than the light weight components. JMO, WEK.

[Rasmus]

I run the ACT Prolite. ACT sent torque specs, tightening sequence, then warned me several times that this product is for "Offroad Use Only". That's it. I didn't do a single change in the ECU to timing or anything else. After the install I hooked the Negative Battery Cable back up and drove off. I was amazed at the increase in RPM climb.

I don't know what causes what. Or really even why. I'd like to know.

[Etos]

Don't get lightened crank pullys. There's a harmonic dampener on the OEM pully for the engine. You just end up causing the crank assembly to be really undampened. There's plenty of good pullys that may not be lighter but provide much better dampening for higher HP use. Rarely does anyone actually use them cause of all the marketing surrounding lightened pullys being the best thing since sliced bread. I actually have one that is much heavier then OEM but it provides the best dampening possible so the crank and all the bearings are super happy especially at higher RPM where it matters the most.

[Flamshackle]

Don't get lightened crank pullys. There's a harmonic dampener on the OEM pully for the engine. You just end up causing the crank assembly to be really undampened. There's plenty of good pullys that may not be lighter but provide much better dampening for higher HP use. Rarely does anyone actually use them cause of all the marketing surrounding lightened pullys being the best thing since sliced bread. I actually have one that is much heavier then OEM but it provides the best dampening possible so the crank and all the bearings are super happy especially at higher RPM where it matters the most.

Using super light alloy crank pulleys "MAY" shorten the life of your motor... possibly... but iv run nothing but light pulleys on all my subaru turbo's for the last 12 years and never had a problem with bearings. If you want performance then lighter they will be!

if you want to treat your motor like a princess then go for the dampened pulleys.

[PhyrraM]

My take on it is.....The stock Subaru pulley is lighter than most other cars lightweight pully options. It's also much smaller diameter than most, keeping the mass it does have nearer to the centerline - where any reductions are minimized anyways.

Question: What is the documented gain of just a lightened pully -on a street, daily driver, type of Subaru - at the wheels?

[longislandwrx]

Question: What is the documented gain of just a lightened pully -on a street, daily driver, type of Subaru - at the wheels?

no gains. just faster revs which means you're in your power band faster.

[PhyrraM]

no gains. just faster revs which means you're in your power band faster.


I guess I'm too technical to fully get this. "Faster Revs" is exactly what WOULD show up on a dyno.

Are you talking non-driving revs? Blipping the throttle or down shifting?

I only ask because on one of my Legacies I did a lightweight flywheel and really couldn't tell the difference. After that I always kinda wondered if it was more a placebo.

[hakalugi]

Don't get lightened crank pullys. There's a harmonic dampener on the OEM pully for the engine. You just end up causing the crank assembly to be really undampened. There's plenty of good pullys that may not be lighter but provide much better dampening for higher HP use. Rarely does anyone actually use them cause of all the marketing surrounding lightened pullys being the best thing since sliced bread. I actually have one that is much heavier then OEM but it provides the best dampening possible so the crank and all the bearings are super happy especially at higher RPM where it matters the most.

what's your source for that bold'd statement?

per this page, "pulley faq":

http://forums.nasioc.com/forums/showthread.php?t=444518



Q:Isn't replacing the stock harmonic damper (pulley) bad?

A: Subarus do not come with a harmonic damper or balancer like some other vehicles do. For other manufacturers' vehicles, this is a legitimate concern.

Proof:

"Thank you for your patience as I checked with our Technical Services Department regarding your message below. They advised that the crank pulley is a pulley and nothing else. It is not used as a harmonic damper/balancer.

Thanks for the opportunity to be of assistance. If you need any future assistance, please feel free to contact us again."

Best wishes,

John J. Mergen
Customer Service Department
Subaru of America, Inc.

[hakalugi]

Dupe

[Etos]

I guess I'm too technical to fully get this. "Faster Revs" is exactly what WOULD show up on a dyno.

Are you talking non-driving revs? Blipping the throttle or down shifting?

I only ask because on one of my Legacies I did a lightweight flywheel and really couldn't tell the difference. After that I always kinda wondered if it was more a placebo.

You can't see the speed of the revs on a typical dyno graph. There's no 'time' factor. It's like taking a car and loading it with 2000 extra pounds vs empty. The powerband should be the same but the revs are going to climb faster in the lighter car. Now that's just an example and honestly crank pullys don't make squat of a difference even clutch in. They're falsely justified bling. If you truly want faster revs from a lightened drive train you get CF driveshaft(well can't do that with an 818), lighter wheels, lighter brake rotors, lighter CV axles, ceramic hubs.

[skullandbones]

You can't see the speed of the revs on a typical dyno graph. There's no 'time' factor. It's like taking a car and loading it with 2000 extra pounds vs empty. The powerband should be the same but the revs are going to climb faster in the lighter car. Now that's just an example and honestly crank pullys don't make squat of a difference even clutch in. They're falsely justified bling. If you truly want faster revs from a lightened drive train you get CF driveshaft(well can't do that with an 818), lighter wheels, lighter brake rotors, lighter CV axles, ceramic hubs.

You can slap a supercharger on an engine and get instant 30% hp increase. You can also do a lot of small changes such as reduce weight of the rotating mass (valve train or crank assembly), use smaller pullies, leave off AC or PS, and things like reducing unnecessary heat in the engine bay. The idea that one thing like pulley weight will make a difference is really hard to measure. Personally, I believe that a faster reving engine will save you time on the track or the drag strip. So if you get to your power band faster than the other guy, you will out perform him even if it is measured in fractions of a second. But if you multipy all those fractions (faster shift time) during a race, you will finish ahead usually. There is also the "bang for the buck" factor. Lots of people don't want to spend for things like an aluminum DS when they can spend that toward a set of light wheels.

I read an article about a drag racer who used the criteria of "if it didn't make me go faster, I took it off". That's a pretty good rule of thumbs! WEK.

[PhyrraM]

The type of dyno that 95% of us use to measure/tune our cars is based on rotational inertia. The same rotational inertia that we are talking about with pullies and flywheels.

Wheels, driveshafts, flywheels, pulleys, hubs, bearings, etc will all show up on this type of dyno as long as the wheels are not slipping and the reduction of mass ("adding of HP") is within the sensitivity of the dyno to record. The repeatability of the dyno also plays into this.

I agree, a 'load' type of dyno that holds the RPMs constant and measure pure torque generation will never show these types of improvements. However, a inertial dyno should, and will if signifiacnt enough.

All of the above only applies when the clutch is out and trying to accelerate the car. I totally see possible advantages in rev matching, scycro life, ease of a dragstrip launch (with heavier flywheel), etc.

In any case, I think I have my answer. Thanks.

[rjh2pd]

no gains. just faster revs which means you're in your power band faster.

If you rev faster you accelerate faster. Each rpm has a direct speed related to it. (in each gear of course)

[RM1SepEx]

that's why when you race lighter is better, reduction of rotational weight is top priority... every little bit helps though it may not be practically measureable in a piecemeal fashion... add em all up and the diff between winning and losing!

make it lighter until it breaks, then back it up in weight/strength just a wee bit

that's an accurate description of Colin Chapman's approach with Lotus in racing..

led to ton's of success and many dead race car drivers...

[Xusia]

Great discussion!

Something else to consider is that reducing the weight of the flywheel may have other effects. Depending on your use and/or point of view, these may be good or bad. Reducing the engine's rotational mass generally leads to more twitchy throttle response, more engine braking (when in gear), RPMs falling more quickly (when out of gear - making it more difficult to match RPMs for down shifting), etc. On a motorcycle, these are very noticeable, almost always negative, and therefore you don't see lighter flywheels used much. Admittedly, I think the effect is probably much greater on a motorcycle because of the power-to-weight ratio (3.75 pounds per HP, vs. 10ish on the 818). I only point them out so that people have all the facts and can make an informed decision.

[Rasmus]

Colin Chapman's approach with Lotus in racing..

led to ton's of success and many dead race car drivers...

You could say the drivers in Chapman's cars were...

dead weight.

http://instantyeah.org/YEAH.JPG
YEAAAAAAAAAH!

[Rasmus]

Here's a shot of the OEM pulleys.

http://i162.photobucket.com/albums/t278/RasmusHansen/SubaruParts/IMG_4876.jpg
Front Sides

http://i162.photobucket.com/albums/t278/RasmusHansen/SubaruParts/IMG_4877.jpg
Back Sides

The main crank pulley does have a rubber ring sandwiched in the middle. I think that's an isolator for NVH, not part of some sort of harmonic balancer.

[Etos]

That rubber piece is part of the harmonics damper. Here's a little technical paper from subaru, read top right corner:

http://site.6starspeed.com/tmp/1989-saeej22.png

Now I never said it was a high quality one. Most OEMS use the cheapest thing that will work. Regardless, subaru did put one in tuned for a specific RPM range where it is needed. Using a lightweight pully without one not only does nothing in performance, but also hurts the engine a bit. How much does it hurt? I don't think much but why pay more for something that does nothing but bling in a spot you can't see anyway(818 engine position)?

[Rasmus]

Fascinating. Thanks for the scan. Looks like I'm wrong about the Harmonic Balancer.

I don't agree that a lightweight pulley "does nothing in performance". I only have "butt dyno" to back up my claim, though. Looks like I'd have to record some real world acceleration data on both sets of pulleys to prove it.

[skullandbones]

Wow! That's some pretty heavy technology. So is the moral: if you're not an expert, don't screw around with what Subaru has done on the short block? WEK.

[Xusia]

ALWAYS good advice!

[Mechie3]

I've never seen that particular paper before, but had seen a letter from SOA claiming that the pulley wasn't a damper. Supposedly they had asked FHI for an answer. Guess you never know who to believe.

I run a Worx Tuning pulley. Supposed to be designed to minimize vibrations and won a SEMA award for its design. Does it do as supposed to? Dunno. Never had an engine failure from running it (all of mine were from other issues).

This is the pulley I have (not my video though)
http://www.youtube.com/watch?v=e5VPh9LqjaI

[Flamshackle]

Using a lightweight pully without one not only does nothing in performance, but also hurts the engine a bit. How much does it hurt? I don't think much but why pay more for something that does nothing but bling in a spot you can't see anyway(818 engine position)?

Sorry but you are incorrect that it does nothing.

The gains may be small but they are all part of the crumbs that make the cake when it comes to performance enhancement.

If you go to the race track you will find SUPER lightweight pulleys everywhere.

My own current subaru race car has superlight rims,flywheel, cam pulleys, crank pulley and clutch assembly.

I have removed over 10KG from the rotating mass of the flywheel, crank and cam pulleys. oh boy does it make a difference in throttle response and acceleration. its just plain physics.

The wheels add to all this as well (albeit a smaller increase) in that my rims weigh 15.8 pounds which saves me a large when all added up and the acceleration gains are not only measurable but obvious to all that drive it when all added together.

[Racebrewer]

Don't forget tire mass. It can be a big killer.

Due to the bigger diameter adding pounds of tire weight more than offsets any savings in wheel weight.

John

[Etos]

Sorry but you are incorrect that it does nothing.

The gains may be small but they are all part of the crumbs that make the cake when it comes to performance enhancement.

If you go to the race track you will find SUPER lightweight pulleys everywhere.

My own current subaru race car has superlight rims,flywheel, cam pulleys, crank pulley and clutch assembly.

I have removed over 10KG from the rotating mass of the flywheel, crank and cam pulleys. oh boy does it make a difference in throttle response and acceleration. its just plain physics.

The wheels add to all this as well (albeit a smaller increase) in that my rims weigh 15.8 pounds which saves me a large when all added up and the acceleration gains are not only measurable but obvious to all that drive it when all added together.

The weight savings on the subaru light weight crank pully is exactly as you said, a crumb. Not even a slice of the cake, it's simply a tiny little crumb. As stated earlier, an OEM subaru crank pully is already as light as other cars light weight crank pullys due to it's size. Maybe with much bigger crank pullys it makes a slight difference, though still only slight.

When I go to a car show- I always see every sporty looking race car have like a bunch of lights and super loud BOVs and massive chrome wheels and nos like every car! Man that must mean all that stuff makes a car faster! It's called marketing hype. Yes I know you'll point out that you said race track and not wanna be race ricer boy car show but marketing affects both either way. I can find just as many people with parts they simply never needed at the track and did plenty of times.

Also don't forget everyone of those pieces you bought is a double sided blade. Yes they give a nice upside but you're making a trade is all. Lightweight flywheel, pain in the *** to engage. Crank pully, little to no weight savings, lose of all dampening. That's a pretty big deal with a track car like yours which will see a constantly high RPM for long sessions at a time. Lightweight wheels, well only con really is the stupid expensive price and if you damage one that's more money out the window. I'm very surprised you didn't bother to get a CF/Alum driveshaft. That easily makes the biggest difference on your list at an almost no downside(limited car speed).

[longislandwrx]

You could say the drivers in Chapman's cars were...

dead weight.



funniest thing i've read in a week ty

[Flamshackle]

Also don't forget everyone of those pieces you bought is a double sided blade. Yes they give a nice upside but you're making a trade is all. Lightweight flywheel, pain in the *** to engage. Crank pully, little to no weight savings, lose of all dampening. That's a pretty big deal with a track car like yours which will see a constantly high RPM for long sessions at a time. Lightweight wheels, well only con really is the stupid expensive price and if you damage one that's more money out the window. I'm very surprised you didn't bother to get a CF/Alum driveshaft. That easily makes the biggest difference on your list at an almost no downside(limited car speed).

I don't have any problems engaging the car from a start or any other time.

Don't know if I have said it but iv never blown an engine and I didnt buy my pulley I made it myself.

CF drive shafts are ridiculous prices.

[longislandwrx]

If you rev faster you accelerate faster. Each rpm has a direct speed related to it. (in each gear of course)

Sorry to clarify, I meant no measurable horsepower gains. As far as what it feels like to rev it it does feel more responsive imho.

I imagine if you were to time your rev time from say 2000-7000rpm it would be a fraction of a second faster with the pulley.

As far as engine longevity, I have 86k miles on one car, 40k on another, both running Cobb Pulleys. I know NUMEROUS people with well over 100k miles on their lightweight pulleys.

For $90 I think its a very worthwhile mod.

[longislandwrx]

CF drive shafts are ridiculous prices.

+1 around here, a cf driveshaft while it does save about 10lbs of rotating weight, costs about $1000usd.

[Rasmus]

Having a lightweight pulley wouldn't matter if you ran a CVT (http://thefactoryfiveforum.com/showthread.php?7508-Lineartronic%AE-CVT) *evilgrin*.