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Location:
Canberra
Registered:
May 2002
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3TGTEU flywheel weight
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Tue, 30 July 2002 13:02
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anyone know the weight of a standard 3TGTEU flywheel? I've searched the forums, but cant find a previous topic.
Thanks in advance
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Location:
Newcastle, NSW, Australia
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Wed, 31 July 2002 01:40
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9kg according to digital bathroom scales.
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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 Re: 3TGTEU flywheel weight
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Thu, 01 August 2002 09:48
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The one here is 7kg according to Bathroom scales of questionable accuracy ! ?
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Location:
New Zealand
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Thu, 01 August 2002 10:31
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there is a post not so long ago on this.
2T = 12KG !!!!
2TGEU = 8KG
2TGEU lightened = 6.5KG (mine.)
3TGTEU = 15lbs apparently = 7.8kg or something.
That's if I remember correctly, would pay to check.
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Thu, 01 August 2002 12:39
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Yep Karl thats them as best I have weighed too ! 3TGTE one being the only variant ! (mine at 7kg yours at 7.
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Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 06:40
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Just how worthwhile is it having your flywheel lightened?
does it noticably affect performance??
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Location:
New Zealand
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 06:44
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yep, flywheel makes big difference. I endorse it.
Revs faster, engine brakes faster. all round excellent.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 07:29
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but doesn't it reduce torque and makes the car slower in up hill situations like a lightned flywheel wouldn't be good for hill climbs?
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Location:
New Zealand
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 07:38
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well, people say that it reduces torque... and in theory I guess it would as you have less mass turning. However, I find that it is only less torquey below about 2000rpm in my stock 2TGEU. After that, it starts building faster. I think..... only a dyno graph would really show this.
I think in a hill climb situation when you are "on cam" or "on boost" it'd be sweet.
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 07:45
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the light flywheel does not reduce the torque of an engine. it only changes the driving characteristics of the engine. it allows freer revving, by reduces the rotational inertia of the engine. this means the engine is less likely to maintain a given speed. so as you predict, going up a hill the engine may drop revs quicker due to less inertia stored in the spinning flywheel.
but that's only a small downside. imagine accelerating from a standing start. if the engine has less load to spin up to speed, it will reach that speed faster. hence the result is a faster acceleration, which some might say gives the illusion of having more power/torque!!!
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Location:
Wollongong
Registered:
July 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 07:47
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It can't reduce the amount of torque that a motor makes, it can make it feel like it has maybe because the inertia of the big heavy flywheel is reduced so the compression strokes will have a more marked effect making it not want to lug itself along so easily.It will make it more responsive as there is less mass to overcome so the motor can spin up faster.
So if you are trying to go uphill for example you couldn't just let it pull its way up in top gear like you might normally, you'd have to drop a gear.
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 07:51
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karl
a light flywheel is not visible on a dyno graph. this is becaure dyno graphs are not a function of time, only engine speed vs power output. so two graphs of different engines making a given power at a given spped, how do you know which one reached that point first??? on a dyno, the engine will still make the same amount of power at any given engine speed with a light flywheel. but it's all about how quickly it will be able to reach that speed, hence produce that power.
case: two identical cars, one with a lighter flywheel. on the dyno they will look identical, power output, engine speeds, etc. however on the road the car with the lighter flywheel will reach speed quicker every time and it always win on the drag strip!!!!
[Updated on: Fri, 02 August 2002 07:56]
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Location:
New Zealand
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 07:55
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there we go. Rotational inertia that's the one..... less energy stored. yep. Very good explanations 
I still endorse light weight flywheels.
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 08:19
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hmmm its a tough one i'd like the engine to have a little more punchy acceleration but i also like the fact that when i hit a hill i never have to down change and gets up with ease.
someone please tell either there's no lightned flywheel for a 18rc or tell me its very expensive and heaps of hassil installing it.
that will help make my decision easier 
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Location:
New Zealand
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 11:54
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true..... never thought of the dyno graph being revs vs power...... I was thinking of the slope of the graph at the time. but you are correct, dyno graph wouldn't show it. Man I've been a bit out on this one. Thanks for clearing it up for me dorikin, mr supra, GIN51E
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 12:06
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hold on a sec, ok you hit a hill with a lightned flywheel and engine revs drop off quicker but if you then just plant your foot down it shouldn't have a problem as the engine's revs will be able to pick up quicker so even if you hit a hill all it means is you have to put your foot further down on the gas pedal sooner? this correct or make sense?
i tell u one thing you guys are a bad influence since i've joined this forum all i want to do is spend money on my car 
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I supported Toymods
Location:
NE Melbourne
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 13:01
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yeah, but spending money on your car is good. as for fitting a new flywheel, it's not all that difficult, but can be expensive!!! gearbox out is about 1/2 hour in a RWD celica with the correct tools. swapping the flywheel over is a piece of piss, i reccomend a new clutch, but not necessary, and reinstall gearbox in another 1/2 hour.
the flywheel itself is the expensive part. a properly manufactured light steel or alloy flywheel can cost as much a $1000, but typically around the $400-$600 mark.
as for your question about going up a hill.... i'm still trying to wrap my mind around it so i can explain it easily. i suppose the argument is that with a light flywheel the engine can rev up quicker... so at a hill if you stomp it it should go up the hill easier?? this is not the case as has been described by ppl in practice. i suggest the it's noticable as the initial change in engine speed is so abrupt that the engine revs drop below the point where the engine makes sufficient power and torque to pull the car up the hill in that gear. once so far below this point, the engine is really relying on raw torque to pull it out, and if too far gone, a lower gear selection is necessary.
hmmmm, i think this sounds right. how does it sound to you???
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I supported Toymods
Location:
Perth
Registered:
May 2002
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Re: 3TGTEU flywheel weight
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Fri, 02 August 2002 13:22
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Engines with bigger torque seem to be less affected by the effect of a lighter flywheel. I could go into all these descriptions, but I think all the guys here have done a pretty damn good job so far.
For a test though, grab yourself a PS2 and GT3, grab yourself a car with pea shooter engine (by game standards) ie. Sprinter or something, then grab something with a bit more torque...chuck a super-light flywheel on both. You'll find that on the straights both cars are indeed faster, but up hills, it knocks the edge off, markedly more on the Sprinter!
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Location:
canberra
Registered:
August 2002
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flywheel weight
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Mon, 11 November 2002 03:21
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How about some of the basic science?
Of the power that is left after burning your fuel (and throwing the majority (60-70%) out the exhaust) you may lose 20% due to things like friction, windage, pumping, and VIBRATION.
Of this amount, I can use it to :
1/ accelerate
2/ store as rotational inertia (in the flywheel - BTW the weight of the flywheel is not as important as where the weight is, varies as the cube of the distance to the crank)
The more I store in the fly, the less is available to accelerate!
So, why have a fly at all?
1/ You're not always at F/T (although we might like to be)
2/ Smoothing of VIBRATION (increase in efficiency and longevity)
3/ Maintenance of rotational inertia
1 -> At partial throttle settings, you are at lower efficiency with less available power, so the losses tend to be more signficant. The fly tends to smooth the delivery to the 2,3 or 4 small explosions which occur every time the crank rotates.
2 -> With no fly, almost no engine would idle at a reasonable speed (or run well at low RPM), due to the slowing of the crank during compression, exhaust and intake strokes. This is more apparent when you have less power to play with (check out the size of the fly on a mower / chainsaw compared to the size of the pot). Having a rotating mass, means that power is stored and delivered to the other necessary strokes in the cycle. The smoothing of this and other vibrations increases available power (vibration wastes energy).
Consider a crank rotating. If large amounts of power are applied at low RPM (crank having slowed to a minimum speed in the cycle), the crank will bend more than if the power was applied at a higher RPM (an averaged speed due to the fly). The bending of components means that there is higher losses due to friction, plus the elastic bending generates extra heat. Added to this is the consideration that vibrating parts will fail in fatigue sooner than well balanced components (try bending metal back and forth until it breaks).
3 -> It is desirable to have an engine not react significantly to small changes in external conditions (such as going over a small rise). An engine without energy stored will slow quicker than one which can draw from this source. So although you may have slightly more power available w/ a lightened flywheel, if the terrain, RPM and gearing requires more power than the engine can develop, then it will slow at a quicker rate.
The choice is yours as to whether you wish to have an engine which accelerates hard (will be more prone to vibration and fatigue type failures) or one that is for cruising (but will not spin as freely).
Hope this helps
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