Lightweight Flywheel

[Guest]

Me again!!

I've read something somewhere that stated a light weight flywheel on a boxer engine doesn't work?

I am a strong believer in removing rotational mass from any drivetrain, but am worried by what I've read??

I have made something like 3 light flywheels in my time and have always immediately felt the benefits. Why would a boxer be different?

[Pitman 188]

Not sure where you heard that:

 

http://www.fensport.co.uk/Parts/Model_108/Category_3/4769

 

http://www.fensport.co.uk/Parts/Model_108/Category_3/4250

 

http://www.fensport.co.uk/Parts/Model_108/Category_3/4870

 

Drivetrain spec for the Fensport GT86R

 

Helix lightweight steel flywheel, Helix uprated clutch cover and 4 paddle cerrametalic clutch plate, M factory carbon propshaft, M factory 4.4 final drive and 1.5 way plate LSD. Standard Gearbox.

[Guest]

Wow, quick response!! I think I read the info on FT86.com? I have always thought that 1pound off the flywheel at launch is equivalent to 100lbs off the weight of the car?

I am actually looking at the Fidanza Ali one. I reckon Ady will do me a good deal if I call him up tomorrow.

[Lee 82]

I have always thought that 1pound off the flywheel at launch is equivalent to 100lbs off the weight of the car?

 

 

haha no way on that one Nigel - be good if it was though!

 

You probably read about light weight crank pulleys being a no no

[Guest]

Sorry Lee, but I think you'll find its true, but only at standing start launch. I got it from one of my old school books many years ago.

I can say that I have felt massive acceleration improvements from lightened flywheels. I can also say that fitting solid bushes to the torque reaction rod on a FWD car feels like 30hp at launch.

[Keethos 842]

I've read on the FT86 forum that some people with lightweight pulleys and light weight fly wheels were having idling issues and the car stalling but Adrian from Fensport said it's not really a problem, especially if you get the car remapped.

[Stan Hawrylak 23]

I've read on the FT86 forum that some people with lightweight pulleys and light weight fly wheels were having idling issues and the car stalling but Adrian from Fensport said it's not really a problem, especially if you get the car remapped.

I have the pulleys and the flywheel and have no issues with idle.

I wouldn't say the improvements in acceleration are massive though. Noticeable a more appropriate way to describe it.

Haversack

[Guest]

Stan, is that with or without a remap that your car idles smoothly? Is it otherwise stock?

[Stan Hawrylak 23]

That's with the remap. Err I have a few other mods.. Samco intake, Blitz panel filter, Milltek catback system, M Factory 4.67 final drive, and carbon prop.

Altogether they make a good package of improvements but no one element is the magic bullet.

Next step is a new manifold and hopefully an electric water pump. Will need to be remapped again for these Adrian tells me.

Haversack

[Guest]

Thanks for your input Stan.

So, I'll put a question out to you all, will the Aluminium flywheel categorically not work well with out a remap?

I'll be going FI some time soon, and don't want to have a map twice, but want to see how much I can improve the NA car first.. if you get me?? I also want to do things one at a time.. guess that's the engineer in me??

I guess I could always buy the ECUTEK kit and license, then Adrian could send me the remaps, (Until we reach the point where we need a custom map), right???

[Kodename47 446]

You could always buy the license and cable and map it yourself. Use the OFT tunes as a base...

[Keethos 842]

Nige, can't say for certain that you will have problems, it's just something I vaguely remember reading somewhere, you maybe fine, might be worth asking someone like Adrian at Fensport to be certain.

[Sideways? 33]

Spouting some fluff you can ignore as you wish I believe you can run into trouble with an impreza running lightweight pulleys and a lightweight flywheel without a remap... I believe some of the people posting on ft86club.com are basing their assumptions solely on this experience which I don't think is very good grounding. I don't think there are the same problems with the GT86/BRZ since it has a "new" engine design...

[rob275 1817]

Apparently our car doesn't have a harmonic balancer on the crank pulley which would normally be the issue as lightweight pulleys do away with the harmonic balancing element. But i'm no expert, replacing your pulleys for lightweight ones is fine afaik. I'm not too keen on chancing a change in crank pulley if it's going to bugger the engine up. I can't see the flywheel being an issue as nobody has had any on here yet.

[Guest]

After speaking with Adrian tonight at length on this subject, he confirmed that you can in fact run the Fidanza flywheel with no remap, however the idle will drop slightly and may be an issue with Aircon, lights et al switched on. I know the idle on my brand new '86 sometimes drops very low already?

 

Seeing as I will be going FI and low CR I'll be needing a map anyway, so I have decided to buy the Ecutek and license so I can just raise the idle speed back up to where it feels most comfortable. Apparently he'll send me a map that does that, and I need to plug it in??        HELP!!!

[Keethos 842]

Changing just the pulleys won't be an issue, mine has been change after the remap so the map hasn't been optimised for the pulleys and I'm sure chosenman had his pulleys put in before his remap but I could be wrong, again, what I read (weather it was from experience of the 86 or any other car) was it was the flywheel or the flywheel and pulleys that caused idling issues.

[Guest]

Well, it's done... I have bought the Fidanza flywheel, Helix organic plate and Helix uprated cover from Fensport.

 

Now I have an excuse to pull my engine out and start painting things again!!

[Danellen2989 8]

Nigelr32, I have the fidanza flywheel, helix organic plate and helix uprated cover as part of my stage 3 FI. All work fine with no issues. Enjoy mate

[Special K 442]

Nigelr32, I have the fidanza flywheel, helix organic plate and helix uprated cover as part of my stage 3 FI. All work fine with no issues. Enjoy mate

 

Excellent !  Are we likely to see you at an event?

 

Spec K

[Church 209]

From what i've gathered up from posts (including views of tuners/service guys that rebuilt many boxer engines) in several threads of other side of pond forum, lightened crank pulley (on rest of pulleys gains are minimal unless one also decides to go undersized) OR lightened flywheel are fine, just not both in same car, otherwise seen almost busted bushings even just after 10K miles, due no harmonic dumpening in lightened CPs.

LW FW might be better choice, but is much more work to install, as for replacing in front LW CP and other pulleys is easier/faster. Saw also post that better LWFW on manual & LWCP on auto, no clue about reasoning.

Idle is not much affected by these lightened parts. In one case reported idle rpms fluctuating case was found to be caused by AC kicking in every some seconds. Daily drivability is fine (except one case whith both FW & CP lightened, where owner ended with putting stock CP back).

Not much to see in dyno gains, but lightening rotational mass positively for most affected real driving/acceleration/feel. Except that with just pulleys upgrade that was not too drastically, most reporting more noticeable gains also upgraded to aftermarket driveshaft (alu or CF, PST or DSS).

Upgrading to LWCP on auto might require extra tool to fix rotating of shaft. Manual can do with in gear & parking brake.

Aftermarket Pulleys weight data (and comparison vs stock)

There are two dumpening upgrades to CP with dumper, but:

ATI's undersized , Fluidampr weights more then OEM

Subaru America response

"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."

Few vendors making/selling lightening pulleys like Perrin / FT86 Speedfactory and others, posted that due nature of boxer natural balancing, these engines should be safest to run with lightweight pulleys/flywheel from all the engine types. However:

Quotes from Infamous Performance posts (#1 #2 #3 #4..):

 

 

A LWCP will not destroy your bearings.
A LWCP combined with a LWFW in MT cars is not recommended as it has been proven to cause bearing failures in horizontally opposed blocks.
A LWCP will add a slight amount of performance to your car.
A LWCP can increase fuel efficiency, but most never see it and it is not the number 1 selling point. Increased acceleration due to decreased mass is the number 1 selling point.

..

Customer chose the FW over the pulley. I have seen it so many times I never recommend both. If I see both, I note it on the invoice and inform the customer.

..

I have now rebuilt 2 FA20 motors (1 super charged and 1 turbo charged) that were using a LWCP and a LWFW. Both had bearing issues just like the EJ's do. I confirmed with another local builder and they too have seen the same issues. I build about 3 motors per month. They build about 40. We have the same experiences and we make the same recommendations.

..

I have not seen a LWFW destroy bearings on its own, unless... it was too light. On an EJ anything

under 14lbs is pushing it. 12lbs is a no go. At 12lbs the FW is so light it causes misfires.
I have not tried to find the breaking point in an FA. It gets kind of expensive, lol.

..

Exactly, 1 or the other. Both is what goes boom.
On an AT you can feel the slight improvement in acceleration. Throttle response is snappier and the car gets off the line quicker. If you are uber nice to the throttle while cruising you can usually see a 1-2mpg increase as well.
On the MT it is not as noticeable. Same changes, just a smaller dose.

 

DIY links:   Aftermarket Crank Pulley Install   Removing the Crank Pulley

 

 

Misc. posts from several threads:

 

# -

1) The stock flywheel is not dampened. The stock pulley is.
2) Look at the diameter of the flywheel compared to that of a crank pulley. You're reducing the rotational mass. However, because the diameter of the flywheel is much larger than that of the pulley, you're reducing more rotational mass and you will get MUCH better benefits with a lighter flywheel. And this is without the risk of a undampened pulley

..

Raceng: This can be done as a DIY. The hardest part is getting the crank pulley bolt to loosen.
It requires a breaker bar and some effort. The other pulleys are simply bolt off and bolt new pulley on.

..

The crank pully is the only one that sounds like you need to seriously pay attention to.

..
The other pulleys are pretty straight forward minus the alternator pulley, which sounds like
a pain in the ass to get the bolt off

..
Worth installing aftermarket headers (those going front & up) after pulleys.

..

 

 

One more bit - most oem & aftermarked pulleys are balanced on their own, not as whole mounted set. IIRC even many subary dealership techs simply slap on, w/o any complete engine balancing later on. So one can ignore balancing marks on pulleys (which are also no manufacturing defect, like some purchasers guessed).

 

_{Sorry for necro posting, but thought that it may help others to not redig all nfo individually.}

[JamesP1991 222]

From what i've gathered up from posts (including views of tuners/service guys that rebuilt many boxer engines) in several threads of other side of pond forum, lightened crank pulley (on rest of pulleys gains are minimal unless one also decides to go undersized) OR lightened flywheel are fine, just not both in same car, otherwise seen almost busted bushings even just after 10K miles, due no harmonic dumpening in lightened CPs.

LW FW might be better choice, but is much more work to install, as for replacing in front LW CP and other pulleys is easier/faster. Saw also post that better LWFW on manual & LWCP on auto, no clue about reasoning.

Idle is not much affected by these lightened parts. In one case reported idle rpms fluctuating case was found to be caused by AC kicking in every some seconds. Daily drivability is fine (except one case whith both FW & CP lightened, where owner ended with putting stock CP back).

Not much to see in dyno gains, but lightening rotational mass positively for most affected real driving/acceleration/feel. Except that with just pulleys upgrade that was not too drastically, most reporting more noticeable gains also upgraded to aftermarket driveshaft (alu or CF, PST or DSS).

Upgrading to LWCP on auto might require extra tool to fix rotating of shaft. Manual can do with in gear & parking brake.

Aftermarket Pulleys weight data (and comparison vs stock)

There are two dumpening upgrades to CP with dumper, but:

ATI's undersized , Fluidampr weights more then OEM

Few vendors making/selling lightening pulleys like Perrin / FT86 Speedfactory and others, posted that due nature of boxer natural balancing, these engines should be safest to run with lightweight pulleys/flywheel from all the engine types. However:

Quotes from Infamous Performance posts (#1 #2 #3 #4..):

 

 

DIY links:   Aftermarket Crank Pulley Install   Removing the Crank Pulley

 

 

 

_{Sorry for necro posting, but thought that it may help others to not redig all nfo individually.}

 

So that is basically saying just do one or the other, but not both together from his experience? 

 

I went for a lightweight flywheel over a crank pulley, however will probably get the lightweight alternator and water pump pulleys further down the line. 

 

Getting it fitted next month so will see what effect it has. 

[Church 209]

So that is basically saying just do one or the other, but not both together from his experience? 

I went for a lightweight flywheel over a crank pulley, however will probably get the lightweight alternator and water pump pulleys further down the line. 

Getting it fitted next month so will see what effect it has. 

From what i've understood - yes. Both - only if at reasonable lightening extent (most purchasable are lightened too much for that imho) and/or CP keeps harmonics dumpening functions (i found only two non-OEM and mentioned their cons (in my eyes)). Or if it's overtuned track-only car, engine of which not expected to live past 10K anyway due other reasons , not just busted crankshaft(?) bearings, and will be completely overhauled/rebuilt often.

Then again if one wishes to go for extracting every small bit of performance out, one may go for undersized pulleys, or AC pulley delete kit, so that at same crank revolution count auxiliary systems are 'turned' less times due diameter differences, or not turned at all, freeing up power at crank/lessening total rotational inertia to leave more for transmission/wheels. Probably safer engine life wise, yet same results, as simply installing both flywheel and crank pulley of lightest aftermarket purchasable ones. And one can also lighten mentioned driveshaft, use lighter wheels, lighter brake kits at that. For pure NA tracking/racing i would also consider rising final drive ratio on engine/transmission side.