LQ4-E39

iTrader: (7)

So, I’m in the middle of my swap/build, and it’s time to buy a flywheel. I was wondering if you guys could make some recommendations.

Background info:
2001 BMW 540i Sedan (~3800 lbs)
2003 Iron LQ4 6.0 block
Stock bottom end
317 heads milled .026” to 66cc chambers for raised compression
Yellow LS6 Springs
Stock LS2 cam out of a 2005 Corvette
Some sort of custom headers (modified shorties)
F-body accessories, LS1 intake manifold

Stock rebuilt T56
3.15 BMW M5 rear end
Diamond Clutch, Stage 2, brand new (off a member on here)


My goal is to have a fast revving, responsive car that is fun to drive with a light flywheel. However, I don’t want something that has revs drop too much between shifts, and I don’t want to have trouble getting the car going on the street as I live in the city. By no means am I wary of using the throttle to get the car moving, I just don’t want like a 12lb flywheel or something insane like that.

Car will probably see the track once a year (if that). More of a comfortable road trip highway bruiser.

I did some preliminary research, and found that many members are happy with their lightweight flywheels. I obviously don’t want stock weight flywheel, and I was reading that the 18lb flywheel is a great aftermarket choice for most people. I think that’s a great choice, but here’s my question:

Do Monster, TDP, Diamond, Tick, etc sell flywheels individually, since I already have a clutch?
Would you recommend going with a diamond flywheel since I have a brand new Diamond Clutch going in?

Is there any cheaper alternative to the vendors listed above? Spec, maybe?

Any flywheels I should watch out for or avoid?

Thanks everyone.

LQ4-E39

iTrader: (7)

I found this. 15.45 lbs. anyone running this?

http://www.ebay.com/itm/F1-FORGED-RA...item2578e5e0ea

Jeremy@RPMTransmissions

iTrader: (12)

With a car that heavy and a rear gear that high I would recommend a heavier, stock weight flywheel. Your engine will be more responsive with no load with the lighter flywheel. But it will also bog much easier because the lost rotating mass of the light weight flywheel. When launching the car it will be much more difficult to keep the engine up in its power band.

I highly recommend the Monster 28lb billet flywheel. They are very nice quality.
http://www.monsterclutches.com/shop/...8lbbillet.html

Storm Trooper

iTrader: (11)

If you really think a lightweight flywheel is what you want for your set up, I would go with the Fidanza Aluminum Flywheel weights 12.5 and its not too expensive, about 350... I would go with that over that off-brand ebay flywheel

Exidous

iTrader: (11)

18lb monster for lightweight but with the weight of the car I'd go with the 28lb.

SS#1531

iTrader: (4)

I like my Fidonza with an LS7 clutch. But like others said, with that weight and gearing, I'd second guess a lightweight flywheel.

raysadude

iTrader: (11)

can you guys elaborate for me what's the relation between weight, gearing and flywheel decision? i'm a newb in this area. Thanks in advance

I have ls7 clutch with the heavy *** flywheel, i think they weigh around 25 pounds.

Jeremy@RPMTransmissions

iTrader: (12)

With a heavy flywheel spinning on the back of the crankshaft it will retain a lot of inertia. When an object is in motion it wants to stay in motion. So when you apply the clutch the heavy flywheel will turn that twisting motion into the drivetrain without bogging the engine down. With a light flywheel it will not make as much inertia and will be bogged down when applying the clutch.

Gear ratio comes into play because with a numerically higher gear ratio like 4.10 it requires less power to run the wheels because the added leverage of the 4.10 gear allowing the engine to stay in its power band. With a numerically lower gear like 3.15 it requires the engine to work harder to get the car rolling because the higher gear wants the engine to turn less RPM.

And the weight of the car causes everything to have to work harder to get it moving from a dead stop.

I hope that was clear as mud lol.

raysadude

iTrader: (11)

Not sure if i get it right, but i'll try. Thanks for the explanation.

so, is that why with the lightweight flywheel once you apply the clutch, the flywheel(which is lighter and has less inertia) will slow down faster than it would with the heavier flywheel and bog the engine?

Jeremy@RPMTransmissions

iTrader: (12)

Yup, you've got it.

LQ4-E39

iTrader: (7)

Thanks for the replies everyone. I am going with a stock flywheel out of a 2000ish Trans Am.

raysadude

iTrader: (11)

oh and OP bad a swap man, i used to have e39 540 also...VERY comfortable car

here's the pic of the car:

LQ4-E39

iTrader: (7)

They're wonderful cars minus the somewhat unreliable and finicky engines. I was tired of worrying about potential problems with VANOS, timing chain guides, 1000 oil leaks from valve cover down to pan, and the inevitable cooling system failure.

The goal for this one is an extremely comfortable long distance cruiser that can lay the hurt on some unsuspecting cars, while staying bulletproof and reliable.

raysadude

iTrader: (11)

Haha i hear ya bro, i traded my e36 m3 for the 540, met the guy in connecticut and drove back to oklahoma.
The minute i got in oklahoma, the fan clutch locked and the fan went boom...left a dent on my hood..

Still i miss the car alot, i drove all the way to california and back to oklahoma and it was the best trip ive had. Weird thing was the car gave me zero problem when we were on trip lol

TDP

iTrader: (23)

I wouldn't go any heavier than stock, which is 23lbs.

ls1 1990 VN

Damn sure stock is more than 23lb

Can you actually get a flywheel heavier than stock!!!!!!

And why would anyone want to anyway....silly response really.

studderin

iTrader: (28)

heavier FW will make a engine idle better (smoother) with a big cam too.

TDP

iTrader: (23)

Yes, 100% positive stock is 23lbs
I wouldn't think the engine efficiency loss w/ a heavier flywheel would really be worth the difference. And to answer the other question, Yes, there are many heavy flywheels made by various places. 25lb, 28lb & 30lb
I use the lightweight fly for most applications and it works great. When looking at rotating weight, you have to look at the weight of the clutch and flywheel. For example, a Diamond kit w/ light flywheel weighs 43lbs and a stock clutch/stock flywheel is 49lbs. 6lbs is barely noticable, as its only 12% less.

dr_whigham

iTrader: (49)

I run the 18# from Monster myself and noticed no change in driveability, and the throttle response and shifting/down shifting is much quicker.

LS1T56FTW

iTrader: (3)

+1 same.