The benefit of the dual mass flywheel....
11-08-2005, 12:13 PM
#1
The benefit of the dual mass flywheel....
would be momentum carry-over from one gear to the next. The initial wind-up in first gear is slowed by the dmfw, but wouldn't the momentum of the fast rotating flywheel have a benefit from there on?
11-08-2005, 12:36 PM
#2
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Intuitively, you are correct. The minute you disengage the clutch, the rpm start dropping. Faster with the LWF, so you just have to shift faster. However, if your objective is to get close to redline faster before each shift, I still feel you will get there faster with the LWF.
11-08-2005, 12:43 PM
#3
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I can only add seat of the pants feel.....having changed from DMF to LWF my bum tells me that there is a difference in the LFW in first and second gears...it spins up faster and when I changed over I noticed hitting the red line in 1st/2nd much easier....this is purely subjective and I have no other data from my car to base this on....also it feels like it has more desire to spin up faster when you are in slow moving traffic without having to change down a gear...again subjective
11-08-2005, 02:04 PM
#4
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I believe this has been discussed before and from my engineering mind it seems that once the clutch is engaged, the weight of the FW is deminimus compared to the mass of the engine/vehicle and thus should not affect acceleration at all. Unweighted throttle response would obviously be greater.
11-08-2005, 03:24 PM
#6
Nordschleife Master
Despite Trojanman's dubious college education and choice in football teams (ok, ok, the bruins blew it big time this weekend ;( ), I think he's correct... once the clutch is engaged, you "shouldn't" really be able to feel much of a difference. But people seem to.
o A dual mass flywheel should help eliminate "bog" when launching the card hard from a stop.
o A LWF is a little harder to get a smooth engagement (or a lot harder)
o A LWF makes the engine feel much more responsive when matching revs when downshifting.
o There is no HP gain from a light flywheel.
o A LWF sounds cool when revving the engine with the clutch disengaged.
IMHO
o A dual mass flywheel should help eliminate "bog" when launching the card hard from a stop.
o A LWF is a little harder to get a smooth engagement (or a lot harder)
o A LWF makes the engine feel much more responsive when matching revs when downshifting.
o There is no HP gain from a light flywheel.
o A LWF sounds cool when revving the engine with the clutch disengaged.
IMHO
11-08-2005, 04:28 PM
#7
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11-08-2005, 04:48 PM
#8
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Benefit... They make good anchors for boats, tents, awnings, etc. FEMA has a search for as many of these as they can find right now as prep for the next storm to hold things down. As far as a benefit for a car, as in a rotating mass assembly..... can't think of one...
Last edited by viperbob; 11-09-2005 at 08:50 AM.
11-08-2005, 04:53 PM
#10
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Originally Posted by viperbob
Benefit... They make good anchors for boats, tents, awnings, etc. FEMA has a search for as many of these as they can find right now as prep for the next storm. As far as a benefit for a car, as in a rotating mass assembly..... can't think of one...
I'll drink to that!
11-08-2005, 05:13 PM
#11
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No, a lightweight flywheel won't add hp. But it CAN improve acceleration, both in theory and real world. Imagine a ridiculous 200-lb flywheel; spinning this thing up will take a LONG time, and you can bet your a$$ that you won't be accelerating very fast. Why? Given the same hp & torque curves, the car that can move up the curve fastest will have the best acceleration. And acceleration is all anyone really cares about, not hp.
11-08-2005, 05:28 PM
#12
Eric
Pls explain how you would get a car to accelerate faster without any increase in power?
Trojanman has it right, the weight of the flywheel compared to rest of the drivetrain is miniscule, therefore you only get a miniscule amount of gain in actual power. I think someone on the 964 board estimated (with pretty heavy mathematics) that at *best* it was a 2-4hp increase - and I wouldn't notice 20 let alone 2. Of course, you would also save around 10lbs in *actual*weight which would aid acceleration but not in any form you would notice.
Personally, the car feels so much more fluid with it - at least when you are not sitting in traffic.
Pls explain how you would get a car to accelerate faster without any increase in power?
Trojanman has it right, the weight of the flywheel compared to rest of the drivetrain is miniscule, therefore you only get a miniscule amount of gain in actual power. I think someone on the 964 board estimated (with pretty heavy mathematics) that at *best* it was a 2-4hp increase - and I wouldn't notice 20 let alone 2. Of course, you would also save around 10lbs in *actual*weight which would aid acceleration but not in any form you would notice.
Personally, the car feels so much more fluid with it - at least when you are not sitting in traffic.
11-08-2005, 05:35 PM
#13
Nordschleife Master
Christer,
Did you read the article that 993RS (Phil) mentioned in his link? It explains very well how the car accelerates faster with no "actual" HP increase. A great explanation.
Did you read the article that 993RS (Phil) mentioned in his link? It explains very well how the car accelerates faster with no "actual" HP increase. A great explanation.
11-08-2005, 05:41 PM
#14
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Originally Posted by Christer
Eric
Pls explain how you would get a car to accelerate faster without any increase in power?
Trojanman has it right, the weight of the flywheel compared to rest of the drivetrain is miniscule, therefore you only get a miniscule amount of gain in actual power. I think someone on the 964 board estimated (with pretty heavy mathematics) that at *best* it was a 2-4hp increase - and I wouldn't notice 20 let alone 2. Of course, you would also save around 10lbs in *actual*weight which would aid acceleration but not in any form you would notice.
Personally, the car feels so much more fluid with it - at least when you are not sitting in traffic.
Pls explain how you would get a car to accelerate faster without any increase in power?
Trojanman has it right, the weight of the flywheel compared to rest of the drivetrain is miniscule, therefore you only get a miniscule amount of gain in actual power. I think someone on the 964 board estimated (with pretty heavy mathematics) that at *best* it was a 2-4hp increase - and I wouldn't notice 20 let alone 2. Of course, you would also save around 10lbs in *actual*weight which would aid acceleration but not in any form you would notice.
Personally, the car feels so much more fluid with it - at least when you are not sitting in traffic.
It is rotational mass that is the issue. You make the engine work harder with the DMF compared to the LWF therefore it takes longer for the engine to spool up.
You don't increase the horsepower of your car when you remove heavy items but it will accelerate faster. You can also change the gearing in a 993 and increase acceleration without an increase in power.
11-08-2005, 06:46 PM
#15
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Originally Posted by Christer
Eric
Pls explain how you would get a car to accelerate faster without any increase in power?
Trojanman has it right, the weight of the flywheel compared to rest of the drivetrain is miniscule, therefore you only get a miniscule amount of gain in actual power. I think someone on the 964 board estimated (with pretty heavy mathematics) that at *best* it was a 2-4hp increase - and I wouldn't notice 20 let alone 2. Of course, you would also save around 10lbs in *actual*weight which would aid acceleration but not in any form you would notice.
Personally, the car feels so much more fluid with it - at least when you are not sitting in traffic.
Pls explain how you would get a car to accelerate faster without any increase in power?
Trojanman has it right, the weight of the flywheel compared to rest of the drivetrain is miniscule, therefore you only get a miniscule amount of gain in actual power. I think someone on the 964 board estimated (with pretty heavy mathematics) that at *best* it was a 2-4hp increase - and I wouldn't notice 20 let alone 2. Of course, you would also save around 10lbs in *actual*weight which would aid acceleration but not in any form you would notice.
Personally, the car feels so much more fluid with it - at least when you are not sitting in traffic.
I bet those "heavy" mathematics did not include the gear factor.