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View Full Version : what does Flywheel do


Mohamed 525i
07-28-2003, 11:37 AM
SInce I have e34 model 91 and I've heared about anging the flywheel


What does it do ??

will it give any power since know its work only to start the car and which is the best and fits my car


thanx


Mohamed

BMWdreamer
07-28-2003, 11:00 PM
Well it makes you rev a hell of alot faster, so you go faster quicker. There is no Hp gains, but because you lightened it less force is needed to move it so you accel quicker. There is a major problem with lighten the fly. You could lose drivablity, because you went to light so starts become a nightmare, or you could drive around and warp the damn thing. I just did my clutch on my jetta, I wish I got the fly ligthened because every thing helps on 2.0L 4 cyl. I like the idea of lightening the fly because it reduces loads on engine.

Mohamed 525i
07-29-2003, 11:16 AM
thanx man,,

so do u suggest me to change it or not


thanx

Mohamed

cheffy
07-29-2003, 01:19 PM
you should definitely change it !
but i guess from other's experience, don't go too light. ie. don't get anything lighter than 13 lbs and it won't affect drivability much.

bmwwade
07-29-2003, 03:45 PM
Advantages: revs faster
Disadvantages: harder starting
less torque
noise and vibration ay all engine speed
more expensive than stock.

Autotechnica
07-30-2003, 04:32 PM
The major disadvantage is that the engine RPM drops very quickly, so it becomes very difficult to maintain a constant speed. This is a plus for racing since your car will slow down faster before you turn. On the streets I find it's just a pain in the ass to drive, especially in a traffic jam situation. Sometimes you may have to rev it up a bit just to keep it from stalling.

The advantage is that the car accelerates much quicker. However, when going uphill the car will loose it's speed very quickly.

Do not get a stock machine lightened flywheel, it will be very weak and most likely crack. If you do not want to compromise driveability then I suggest you just leave the flywheel alone.

Bry

skillton
07-30-2003, 07:11 PM
Originally posted by Autotechnica
The major disadvantage is that the engine RPM drops very quickly, so it becomes very difficult to maintain a constant speed. This is a plus for racing since your car will slow down faster before you turn. On the streets I find it's just a pain in the ass to drive, especially in a traffic jam situation. Sometimes you may have to rev it up a bit just to keep it from stalling.

The advantage is that the car accelerates much quicker. However, when going uphill the car will loose it's speed very quickly.

Do not get a stock machine lightened flywheel, it will be very weak and most likely crack. If you do not want to compromise driveability then I suggest you just leave the flywheel alone.

Bry
I have a 9lbs flywheel in my car (89 GTI 16v) and it's not a pain to drive on the streets... i do have to rev it up a bit higher but i can start off @ 1500rpm's, i can even start off without pressing the gas but it takes a while, and i never have to give it any gas not to stall the car, also the car doesn't accelerate much quicker but you can feel a bit of a difference, i can slowly accelerate uphill @ 2000rpm's in 5th without flooring it

Autotechnica
07-31-2003, 01:58 AM
Originally posted by skillton
I have a 9lbs flywheel in my car (89 GTI 16v) and it's not a pain to drive on the streets... i do have to rev it up a bit higher but i can start off @ 1500rpm's, i can even start off without pressing the gas but it takes a while, and i never have to give it any gas not to stall the car, also the car doesn't accelerate much quicker but you can feel a bit of a difference, i can slowly accelerate uphill @ 2000rpm's in 5th without flooring it

You can start off without pressing the gas? I don't get it. On a stock flywheel that would stall the car, how would having a lighter flywheel make that any different? If anything it would make it easier to stall.

If your car doesn't accelerate any quicker, then the flywheel you bought probably wasn't 9lbs.

Why would you accelerate uphill on 5th gear at 2000RPM? Are you purposely trying to stall the car?

Sorry, but your not making any sense.

Bry

330DTM
07-31-2003, 02:12 AM
Originally posted by Autotechnica
You can start off without pressing the gas? I don't get it. On a stock flywheel that would stall the car, how would having a lighter flywheel make that any different? If anything it would make it easier to stall.

If your car doesn't accelerate any quicker, then the flywheel you bought probably wasn't 9lbs.

Why would you accelerate uphill on 5th gear at 2000RPM? Are you purposely trying to stall the car?

Sorry, but your not making any sense.

Bry

The only reason why I would see his car slowly accelerating when he clutches out in first is because his revs at idle are raised by a reprogramed/aftermarket chip. My friend's A4 idles higher than stock therefore if he clutches out but still modulates the clutch, the car will start moving forward. However it is still possible to stall on his car if you clutch out like how you do for normal driving. Done it before.

skillton
07-31-2003, 04:42 AM
Originally posted by Autotechnica
You can start off without pressing the gas? I don't get it. On a stock flywheel that would stall the car, how would having a lighter flywheel make that any different? If anything it would make it easier to stall.

If your car doesn't accelerate any quicker, then the flywheel you bought probably wasn't 9lbs.

Why would you accelerate uphill on 5th gear at 2000RPM? Are you purposely trying to stall the car?

Sorry, but your not making any sense.

Bry
i can start off slowly by letting the clutch out slowly, but i'll only accelerate up to like 5-10km/h without giving it gas, if you know your car you can do it with pretty much any car if you have enough low end, and no i'm not purpousely trying to stall the car, i just tried it to test my low end torque, i dont usually do it, i don't do this often and i jus said it to prove a point
And i said my car doesnt accelerate much quicker but i can feel a difference
my stock flywheel is only like 12.5lbs tho so 9lbs wasn't to big of a change change

Autotechnica
07-31-2003, 01:31 PM
Originally posted by skillton
i can start off slowly by letting the clutch out slowly, but i'll only accelerate up to like 5-10km/h without giving it gas, if you know your car you can do it with pretty much any car if you have enough low end, and no i'm not purpousely trying to stall the car, i just tried it to test my low end torque, i dont usually do it, i don't do this often and i jus said it to prove a point
And i said my car doesnt accelerate much quicker but i can feel a difference
my stock flywheel is only like 12.5lbs tho so 9lbs wasn't to big of a change change

I see, but giving advice to someone driving a BMW would be a tototally different story seeing as how the BMW stock flywheel is more than 22lbs. If your flywheel was only 12.5lbs to begin with you probably should have saved your money and kept your stock flywheel, 12.5lbs is quite lightweight.

Bry

Jon@Bimmersport
07-31-2003, 01:50 PM
do u mean starting off the line with the idle RPM..slowly clutching out then adding some gas?? thats what i did and it worked..i dunno if ur talking about the same thing....

bryan is right..stock flywheels are heavy like a bitch..its hard to properly rev match my bro's car compared to when i tried in the egg (light flywheel) when i was learning stick

Autotechnica
07-31-2003, 03:44 PM
Originally posted by E46_lover
do u mean starting off the line with the idle RPM..slowly clutching out then adding some gas?? thats what i did and it worked..i dunno if ur talking about the same thing....


I think his idle is a bit higher than normal at around 1500RPM as Mike mentioned it's similar on Nick's Audi. With the higher RPM he can just engauge the flywheel without giving any gas and the car would still go. I think if his idle RPM was any lower the car would probably stall. However, he was saying that his car has enough torque to push it without gas and it wouldn't stall. Something like that I think.

Bry

330DTM
07-31-2003, 05:02 PM
Originally posted by E46_lover
do u mean starting off the line with the idle RPM..slowly clutching out then adding some gas?? thats what i did and it worked..i dunno if ur talking about the same thing....

bryan is right..stock flywheels are heavy like a bitch..its hard to properly rev match my bro's car compared to when i tried in the egg (light flywheel) when i was learning stick


No I think he means no adding gas at all.

Just for clarification Nick's car idles slightly higher than stock idle because he has an aftermarket/repgorammed chip.

Tough to rev match? Well you got to give it more gas in that case, that's if your rpms tend to rise after you clutch out from rev matching. Eventually you'll adapt and actually get used to rev matching properly on your brother's car.

nzer
08-02-2003, 12:06 AM
I can add no gas at all and let the clutch in normal speed and it won't stall, provided its not uphill or anything. My idle is around 1300.

Autotechnica
08-02-2003, 02:06 AM
Originally posted by nzer
I can add no gas at all and let the clutch in normal speed and it won't stall, provided its not uphill or anything. My idle is around 1300.

On a stock flywheel? Isn't that a little high? You may have you adjust your idle with your TB.

Bry

Slowered318
08-02-2003, 07:49 AM
Well for a fact i know drag racing cars use heavy flywheels so they hold the momentum of the engine when the car is launched.

A lighter flywheel will provide faster shifts, shorter breaking and quicker spool up but it really won't make your car any faster. think about when your on the highway cruiseing and you need the momentum of your flywheel to keep you at a constant speed.

97 Z3 2.8
08-07-2003, 02:43 PM
Mohammed,

Unless you plan on tracking your car don't bother with the lightened flywheel. If you weren't sure what it was and did you may want to do a few other things first. Try intakes, exhausts, software before you start getting to the guts of you're car. Swapping flywheels isn't the easiest thing unless you're pretty farmilliar with mechanics. If it does happen, you may as well throw in a stronger clutch while it's apart. Check out AA or Turner for pricing.

Bill