hello all,

does any body know the advantage and disadvatage involved with a light weight flywheel upgrade?

RandyBMC are you testing any yet?

thanks,

bbt4

 

It is supposed to allow for a betetr rev, faster throttle response. Not an expert though...

 

Lighter weight decreases the amount of energy required to get the flywheel spinning, which directly affects the motor's ability to rev up. It also decreases the inertial energy while spinning down although engine management systems (ECU) control that more now for emissions reasons.

So, potentially, faster rev up and rev down, less HP loss at the flywheel, and better throttle response. The flywheel becomes more 'transparent'.

right?

 

>>Lighter weight decreases the amount of energy required to get the flywheel spinning, which directly affects the motor's ability to rev up. It also decreases the inertial energy while spinning down although engine management systems (ECU) control that more now for emissions reasons.
>>
>>So, potentially, faster rev up and rev down, less HP loss at the flywheel, and better throttle response. The flywheel becomes more 'transparent'.
>>
>>right?

Hhhmmmm, 2 comments:

doesn't the theoretically faster throttle response just about disappear because of the amazingly slow throttle response of the MINI's fly by wire system?
I'm not sure if it's only my 03 MCS, but I have NEVER EVER come across a throttle that is so infuriatingly slow to respond!!

Also, with a lighter flywheel, I think you would get noticeably rougher idle.

Markus

 

>>Hhhmmmm, 2 comments:
>>
>>doesn't the theoretically faster throttle response just about disappear because of the amazingly slow throttle response of the MINI's fly by wire system?
>>I'm not sure if it's only my 03 MCS, but I have NEVER EVER come across a throttle that is so infuriatingly slow to respond!!
>>
>>Also, with a lighter flywheel, I think you would get noticeably rougher idle.
>>
>>Markus

Good point, Markus. The drive-by-wire may negate much of the positive effect from the lighter flywheel, and the higher rotating mass of the stock should smooth the idle.

I am not as infuriated by the throttle response though. Seems fine to me. Are you sure there's not a problme with yours?

 

hello again,

so does any of you guys think that the mini-madness flywheel is engineered for max. throttle response while somehow maintaining good idling. basically, can there be an "ideal" flywheel weight that would give me the best of both worlds (throttle response and idling)?

i don't like rough idles.

thanks,

bbt4

 

almedia and bbt4,

I would really like to hear from RandyBMC about this.
My 03 MCS may have a problem, although throttle response is only slow in some instances, for example when accelerating and THEN rapidly letting off gas, it slows down, but doesn't really start with engine braking until 1-2 whole seconds later. However, I have read somewhere that this is a particular response done on purpose for emission purposes.
I don't know about the MINI mania flywheel, and how it is engineered. Remember, that MINI has a small engine (displacement wise), and so it will idle a bit rougher anyway than a bigger displ. engine. I remember reading somewhere that this is why the MINI flywheel is unusually hefty.

 

I'm not an expert on the drive by wire part of it, but the scenario you described where engine braking doesn't occur for 1-2 seconds is due to a heavy flywheel not reducing rpms quickly....now would the drive by wire negate the effects of a lighter flywheel I don't know...I know a few people running a light flywheel in the S - let me see what they have noticed.

 

I'll second Casey, part of that is the drive by wire. It's done to help with emissions.

 

Well let me tell you, as someone who's held both a stock Cooper flywheel and a "lightened" one at the same time...the difference in weight is mind boggling. The stock is made of cast steel. The MINI-Madness flywheel is aluminum with steel contact. I can't wait to hear back from George. Car goes into the shop this week for Quaife, flywheel/clutch and one other really, really cool goody. Wish I could spill the beans, but it's not my call. But once the car is back and tested a bit I hope to be able to report as to the mystery goodie.

Anyway, I digress. As long as the flywheel is not too light it will theoretically be fine. But if it's too light you can encounter idling issues. As for throttle response, it should be noticeablly improved. True the Siemens ECU is not the quickest to respond. Ah but with the flywheel allowing for faster revs, and some engine management (like EVOTECH chip or the like) you should be able to capture gains.

R

 

well, I have the lightweight flywheel so consider this:

it is labor intensive to install, figure 10 hours, and it involves removing the trans, and clutch, so while you are there...get a LSD, its only another thou or so.

The basic physics is that rotating objects resist changing their rotational speed (up or down) depending on their moment of inertia. More weight farther from the rotational axis will have a larger moment of inertia.

Specifically Mini related: the stocker is a heavy pig, maybe 35 lbs, and incorporates a torsional vibration damper. The L/W is about 12 lbs and has no damper. So you should change the clutch disc while you are at it to one with torsional anti-****** springs (the stocker has a solid hub).
Without the flywheel dampening, you will get a bit of gear clatter at idle; it's harmless.

Benefits:
you have to expend energy to change the rotational speed; the more the moment of inertia, the more energy needed.

If you are drag racing, you basically speed up the engine once, at the line, and then keep the rpm's up there while you deal with wheelspin and shifting. No need to be concerned about wasting E to get the rpm's up, and the resistance to rpm change of the heavyweight F/W will help keep the rpm's up there and offset the chance of bogging down.
If you are autocrossing or track racing,, you will be changing rpm's in and out of corners, so the L/W will be of much more use.

I'm happy with mine.

 

>>I'm not an expert on the drive by wire part of it, but the scenario you described where engine braking doesn't occur for 1-2 seconds is due to a heavy flywheel not reducing rpms quickly....now would the drive by wire negate the effects of a lighter flywheel I don't know...I know a few people running a light flywheel in the S - let me see what they have noticed.

Thanks for thoughts, Casey and others.
I'm not sure my 1-2 sec lag is the flywheel, in fact I'm pretty sure it's the DBW and not flywheel, because the decrease in rpms is not gradual, but a distinct two-step function: slight decrease first, much steeper decrease after 1-2 secs.
Nevertheless I agree, a lightened flywheel may help that.

Davbret:
would an aluminum flywheel run a greater risk of warping due to the different thermal expansion coefficient? Do you think there are any long-term reliability issues with having an aluminum flywheel?
Can't wait to get your report on the Quaife LSD!

Great thread, thanks!
Markus

 

The biggest issue I see with the flywheel is the labor. If you thought the pulley was bad - that's like an intake compared to the flywheel.

That said, the lighter rotating mass of the flywheel will help reduce the amount of power lost in transferring it to the wheels - in other words, you reduce your drivetrain loss. It also helps with throttle response, as the motor doesn't have all that inertia keeping it from making abrupt changes in velocity.

This does sometimes cause issues with idling, but with the BMP flywheel, those issues haven't surfaced.

The stock flywheel is around 27 lbs, where as the Madness and BMP units are around 13-15 lbs. With those reductions you will see a noticeable throttle response difference, regardless of the ECU issues.

The other big issue is the type of clutch used. MINI uses the flywheel instead of the clutch plate to abosrb drivetrain shock. If you replace the flywheel, you lose that absorption, and while if you are easy on the clutch it shouldn't cause too much of a problem, it will introduce more vibration to the cabin. The easiest and proper way to fix that is to change the clutch at the same time you change the flywheel to a spring centered type.

The ECU does hold the RPMs slightly for emmisions, but the throttle response is a combined issue of reciprocating mass and ECU.

Let me know if there are any other questions.

Randy

_________________

Click It!

 

Well it seems jlm already made some of the points while I was writing!

The aluminum has a steel insert for the friction surface. It is designed to withstand the expansion, and I haven't ever seen a problem arise out of the material issue in other applications under really tough conditions.

 

jlm, Good points, I know several people who were surprised after installation of a lightened flywheel, to actually see their 1/4 mile times get WORSE. One other thing to consider is that MINI's 1598cc engine has a considerably larger bore than stroke (85.8 mm bore X 77 mm stroke). This gives the pistons more reciprocating mass than, say, a VW 1.8T (81 mm bore X 86.4 mm stroke). Also, having the supercharger constantly spinning at 2.06 (or 2.35 for us lucky ones ) acts as an additional flywheel.

_________________
2003 MCS DS/DS Black Leather
Packs: Prem/Sport/Cold, PDC, SatNav

Helix/P&D 15% Pulley, MTH Chip, Magnaflow Exhaust 165.0 whp (14.5% HP gain, 14% Torque gain)

My MINI

 

bbt,
We really won't know if this is a cost effective & reliable mod on the MINI until some brave soul tries one. The usual reasons given for for not using aluminum flywheels on street cars are; 1) As mentioned by others, If the wheel is too light, you can end up with an erratic idle. The heavy stock wheel serves to dampen vibrations. I do not know how engineers determine what the optimum weight is for a given motor. 2) Construction. Most lightweight flywheels are sold "for racing only" on motors that are routinely torn down at very low mileage intervals. Most aluminum flywheels use ring gears that are heat shrunk on & some do not even pin the ring gear to the flywheel. Having a ring gear pop off can ruin your whole day! The clutch friction surface must be of sufficient quality to withstand high mileage street applications. Obviously, the assembly must be carefully balanced.
I put a 12LB racing flywheel on a 1/2 race 1147cc Triumph that was street/solo driven . A radical camhaft necessitated an idle speed of 1200RPM to idle properly so I can't honestly say if the flywheel affected the idle in any way. It was very carefully balanced with the rest of the bottom end & never caused any reliability issues in15,000 miles. The biggest difference was that the engine revved MUCH faster in nuetral, which was a big help in down shifting quickly (sounded great too!). A quick blip of the throttle while heel'n'toeing would get the revs right up there.
Speaking of which, I'm wondering what techniques work best for others to heel& toe on the MINi, but perhaps that's best left for another thread?

 

Randy, I think you mean rotating, not reciprocating, mass, although the arguments are similar. With reciprocating masses (pistons and valves going up and down) mass is the enemy; with rotating objects it is mass and radius of the mass form the axis.

 

hello all,

i'm glad i'm taking dynamics right now because if not, i might not understand all this "rotating rigid body" talk. everything i read thus far makes perfect sense. i guess i'll just wait until RandyBMC post a write up before i decide if i want this flywheel and clutch upgrade.

thanks,

bbt4

 

Personally I can't wait to change the flywheel and the LSD. It'll probably be done within a week of purchasing the car. Overall, it sounds like the lighter flywheel just makes it more... more fun! Quicker revs, seat-of-your pants performance increase, hey, that sounds awesome! Count me in!

 

>>Randy, I think you mean rotating, not reciprocating, mass, although the arguments are similar. With reciprocating masses (pistons and valves going up and down) mass is the enemy; with rotating objects it is mass and radius of the mass form the axis.
>>

jlm,

Thanks for catching that - I fixed it. I've been doing the whole 3 hours of sleep a night - aarrggh.

You brought up a great point of also considering the radius from the axis - one of the reasons we are seeing very small (4-5&quot multi-disk clutch packs. The weight is similar to the single disk clutch, but the radius from the center is considerably smaller. We are working on this for the MINI, but it would be race only application - as the clutch becomes more of a switch and wouldn't be much fun on the street.

 

Randy I have a question for you about this install. IF you were going to change the flywheel, what dhould also be replaced at the same time because it is sucha hard install? The clutch, what else???

 

Great question CooperSpeed.

If you go through all of the trouble to pull the gearbox, I would do the flywheel, the clutch/pressure plate, and the Quaife LSD. The only issue is soem fitment problems with the Quaife that require slight machining. We are still waiting for that to be addressed.

Randy

 

Don't hold your breath too long, The Quaife size is pretty much set in stone. We have done a few of them and the area that needs some grinding is pretty small. I think it is something that we will have to learn to live with. Oh well. The labor on the quaife wil run you around $800, so it is not a bad idea to do other things while your @ it.