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Location:
Brisbane
Registered:
December 2002
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Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 02:41
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I am going to be doing a 18r t0 18rgeu conversion soon, just thinking about all options before it goes in. IS there much benefit in getting a lightened flywheel. And if so can you do this to the standard one/ how is this done. Or do you have to get a specially made one.
your thoughts
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I supported Toymods
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 02:46
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You can lighten a cast iron flywheel, but you do so at your peril. They can fragment, sending shrapnel thru the transmission tunnel and into you.
Get one specifically made out of chrome moly or 6 series aluminium. It costs a bit more, but what price your legs?
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Location:
Brisbane
Registered:
December 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 03:14
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Is it worth doing to a standard 18rgeu. or is in just over kill. What price are we talking about, and who can I get one from in Brisbane??
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I supported Toymods
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 03:27
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For a std motor, probably little benefit.
Could get something like this for 370, and to get the cutaways done (to make it exactly as pictured) add another 100-150.
I believe the aluminium ones are about $5-600. They use a disc of friction material for the contact surfaces, usually screwed in place.
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Location:
Sydney
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 06:03
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If im not mistaken....lightening the flywheel makes u lose torque down low ???
Ta
Mani
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Location:
Brisbane
Registered:
December 2002
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Location:
South Australia
Registered:
July 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 06:37
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Lightening the flywheel can cause you to lose a few more revs between gears because your engine no longer has the same rotational intertia. Also, beware that you can't lighten it too much, otherwise when you rev the crap out of it when you are out of gear you can actually slip the cam timing belts and if you don't have a free running engine then you are screwed (or even a chain believe it or not if you have a chain). Just imagine valves hitting pistons 
So just be careful that you don't go overboard, cause it won't really increase your HP that much. I personally wouldn't bother unless I was shoving in a dog box or something like that, something that shifts really quick.
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Location:
Brisbane
Registered:
December 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 06:43
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From what I have gathered there is not much pint in doing this to an everyday drive car. Maybe some benefit for a racer but besides that i think I will leave it alone. 
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Location:
Brisbane
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 08:44
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A slightly lightened flywheel can be a good thing on a street-driven car, especially an RA23 which seems to come with a tractor flywheel from the factory. However, since you intend to use your Celica for a bit of towing, it may be wise to leave the heavy bastard in there; a light flywheel is definitely not an asset when you're trying to tow things.
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Location:
Brisbane
Registered:
December 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 10:46
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Thanks Norbie. I'm sure when I got to put the new engine in I will be needing some help.
thanks
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Location:
Sydney
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 10:48
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| Blaze wrote on Fri, 28 February 2003 17:36 |
Tell me if I'm wrong. (It's usually the case) But if the fly whell is lighter, the engine doesn't need to work as hard to rotate the flywheel, so I thought it would give a better performance starting off.
I can see where once a heavier fly wheel is at a certain speed, it would remain at that speed for a lot longer the a light one. which would help the engine not having to work as hard. but for torque i thought it was the engines ability strenght to turn the fly wheel. so to give it more down low you give it less work to do.
not sure if all that makes sense. I might have it back to front and be talking about HP.
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That actually makes sense
Can anyone comfirm whos right ???
Ta
Mani
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Banned by his request
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Registered:
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 11:17
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a lighter flywheel helps an engine rev quicker and reduces drag on the engine{hp loss}! the inertia that a heavier flywheel produces, gives more torque to the engine at very low revs. haha a very light flywheel is a pain in big car parks at 20 km\h or in bumper traffic and makes the need to bring the launch revs up alot high to add a bit of tyre slip so the engine dosnt bog down off the start.
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Location:
Brisbane
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 11:57
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A flywheel has absolutely no effect on an engine's torque output. The only time it does anything useful is when the car is stationary and you're slipping the clutch to get the car moving; in this situation the stored energy in the flywheel helps shove the car along. Once the clutch is fully engaged, the flywheel is just along for the ride.
After this point though, the engine has to accelerate the mass of the flywheel as well as the mass of the car, and in lower gears this can have a significant (negative) impact on acceleration. So a lightened flywheel is a tradeoff; better acceleration, but the car becomes more difficult to drive.
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Location:
Sydney
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 23:11
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| Norbie wrote on Fri, 28 February 2003 22:57 |
The only time it does anything useful is when the car is stationary and you're slipping the clutch to get the car moving;
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But isnt that EXACTLY what we're saying ?
Helps car move when stationary = torque down low
Am i mistaken ?
Ta
Mani
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: Lightened fly wheels?? what your thoughts
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Fri, 28 February 2003 23:28
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norbie are you saying im wrong? remmeber torque is twisting force. the help it gives{heavy flywheel} with clutch take-up is adding twist to the crank, hence torque ! read what i said in my first post again and it will make sense.
mick
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Location:
Brisbane
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 00:40
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Slight difference in semantics here. A heavy flywheel can briefly increase available torque at the wheels, but it does not increase or decrease the engine's torque.
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Location:
Sydney
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 02:29
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Well its torque at the wheels that counts isnt it ???
Ta
Mani
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Location:
Fl
Registered:
February 2003
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 03:03
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I have a ta27 with a 2tg the motor has stock 9.8 pistons 304 intake 288 exhaust header and 44mm mikunis with out the large venturis I have een running a lightened fly wheel with a centerforce clutch the car will start from stop with out slipping the clutch and accelerates very quickly above 3000 rpm the biggest difference is that you can't pull hole shots in the car other than that i have noticed no drawbacks.
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I supported Toymods
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 03:06
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If you want to get down to tin tacs, a flywheel actually alters momentum, not torque. Torque is generated by the engine. Some of this rotational energy is stored in the flywheel. This is known as momentum. A heavier flywheel has more angular momentum, but this doesn't mean the engine has more torque. If you were to put an engine on an engine dyno with the 2 different flywheel, the torque curve would be identical.
On the road, the extra angular momentum from a heavier flywheel translates to easier standing starts, less rpm drop between gear changes, and anecdotally, better towing and uphill performance. If that is what people perceive to be torque, fine, but it's actually 'stored' torque, more correctly termed momentum.
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Location:
Sydney
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 03:45
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Thanx for that Tomato
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Banned by his request
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moved to tamworth
Registered:
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 08:08
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my god! get it together guys! do you want to hear the fact from someone that is at the top end of the race car game or DIY mechanics? if you back of an engine on an engine dyno and put the power back on with 2 diffrent weight flywheels it will have a diffrent curve down very low as i keep saying. i know have seen it on many a race engine on the engine dyno!
if anyone has a question that would like answered just ask but god i get sick of dipsticks that have half an idea of what is fact and want to toss on about it. we dont even run flywheels on some of our race cars and yes they are manual.
mick
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 22:40
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Um, OK. I'm just wondering how a lump of metal makes torque? I understand how it might store and releaseenergy, but not how it might make it. I can also understand how a smaller lump of metal might store and release less energy, but not how it might affect engine thermodynamics such that the said engine produces less torque.
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Banned by his request
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 22:56
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that store and release is what ive been talking about the whole time. if you look at my post again i said give more torque at very low rev's, not make more torque!
i hope this has cleared it up!
mick
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Banned by his request
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 23:09
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just to make it a bit clearer! we mount the alternator on the diff{turned by tailshaft} on most of the race cars were possable to reduce power loss at the engine which gives us maybe 2-3hp at the wheels more than if mounted on the motor. this isnt a hp gain as such but a reduction in hp loss caused by friction. your not making more power your reducing the power loss! the power is there its just not being used to turn the wheels because its turning the alternator etc.
hope this helps
mick!
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Location:
Sydney, Australia
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Sat, 01 March 2003 23:50
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gainttomato is spot on. you wont see any differences on the dyno.
From my observation, taking off with a lightened flywheel is slightly more difficult - as you ease the clutch out, it gets to the point where you think it's just going to take off, and if you're not careful the thing just dies on you. It's even more noticable on hills. Since I've had an alloy one in my sprinter since I put the 4AGE in, I can't really comment on the differences with/without after that, but I don't really notice it on hills or anything.
sam
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Location:
Canberra
Registered:
December 2002
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 00:06
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Isnt it really just inertia that your looking at and a rotating mass:
Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.
So wouldnt this mean that a standard fly wheel with a larger mass (not weight) than a lightened one would be easier to drive on the street because of the low down effects.
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Banned by his request
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 00:14
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exactly jason
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Location:
Finland
Registered:
November 2002
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Location:
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 02:22
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| gianttomato wrote on Sun, 02 March 2003 13:18 |
I never intended for a slanging match.
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Look at it this way we all understand what we are all talking about now and we are that much wiser. Isn't that what these forums are for?
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 02:30
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Hehehe..right on.
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Banned by his request
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Registered:
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I supported Toymods
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 04:19
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Group hug.....er maybe not! 
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I supported Toymods
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 06:29
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I don't know if this was mentioned or not (okay, being the slack bastard I am, didn't really read the whole post too well...). Anyways, here goes...
As the flywheel (by definition) is a device that is designed to store energy in the form of angular momentum, it's purpose is to act in a similar fashion to a capacitor in an electrical circuit.
I think the effects of this on real and apparent torque was addressed in detail above. What I would like to point out here is that the flywheel is also used to make the engine appear to run "smooth". An engine doesn't generate constant power. It generates power in pulses during the power strokes of individual pistons. The flywheel mass helps to "smooth out" these pulses of power and the resultant harmonics such that the actual power delivery of the engine appears to be much smoother. In engines where you have very favourable harmonics/degrees of freedom (such as inline 6s or V12s), lightening the flywheel would have the minimum impact as far as this apparent smoothness goes in comparison to other engine configurations with less favourable harmonics/degrees of freedom. This might be another factor you might want to take into consideration. After all, you don't want a car that shakes like a tank.
Cheers
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Banned by his request
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 08:01
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just to correct you V12s have shocking harmonics, like joining two V6's. you will never see a large capacity V12 that revs because they have very bad harmonics. F1 could rev them hard as they only lasted an hour or so and where small capacity. hence why im not bringing any toyota V12's over here. because there power would be limited espically as they are all alloy. it would be one big floppy mess at any decent power level.
mick
haha a little of topic!
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 09:13
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I don't think you are entirely correct about large V12's not revving mick. Check out some specs on a McLaren F1 or a Lamborghini Murcielago, both of those feed on revs.
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Location:
Brisbane
Registered:
May 2002
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 13:18
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Yes, V12's are quite well balanced... they're more like two inline six's joined together, rather than two V6's. There are plenty of high-revving high-performance V12's around.
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I supported Toymods
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Re: Lightened fly wheels?? what your thoughts
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Sun, 02 March 2003 23:07
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What Mick says is valid. However, choosing the correct angle between the banks of cylinders is incredibly important in minimising these harmonics. For a V6 or V12, the ideal angle is 60, 120 or 180 degrees. For a V8 it is 90 or 180 degrees. For a V10, it's around 112 degrees. Of course, a 180 degree Vx engine is otherwise known as a boxer (Ferrari boxer 12, Porsche flat 6).
Things like the Commodore V6 or the old Capri V6 were 90 degree engines and as a consequence were/are rough as guts, and may necessitate the use of some auxillary harmonic dampener (eg balance rod in Commodore 6).
Sometimes these 'rules' are bent for some other important issues. In F1, the V10s have bizarre, unnatural bank angles because of space considerations.
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