Heaver vs. Lighter Flywheel
03-31-2007, 08:25 AM
#31
As mentioned in one of the threads, I think this theory can also be applied to the drive train, i.e. the difference between a spool and diff where this may even have alot more effect on the direction change of a car.
My K-Factory spool weighs 32g, whereas my diff weighs 50g. Not to mention the planetary gears of the diff are in a large dia. / orbit compared to the weight of the spool. A huge difference in rotational mass.
So it seems to me it would be much better to setup my car to run on a spool which would yield much better overall results based on the above theory.
I wonder if this is the reason the NT1 went with much smaller dia of diff???
My K-Factory spool weighs 32g, whereas my diff weighs 50g. Not to mention the planetary gears of the diff are in a large dia. / orbit compared to the weight of the spool. A huge difference in rotational mass.
So it seems to me it would be much better to setup my car to run on a spool which would yield much better overall results based on the above theory.
I wonder if this is the reason the NT1 went with much smaller dia of diff???
03-31-2007, 08:37 AM
#32
Originally Posted by TomB
here is my response i posted on mtx4 thread, i still think it is a valid point;
*********
dude, i think artificial is wrong. a lightweight transmission on a car is beneficial especially when the engiens we use rely on rpm to produce power. Your example of a motorcross bike is wrong to apply to a rc car. why? because a flywheel on a motorcross bike is on the rear wheel. you are getting more traction not due to the heavier flywheel, but due to the added weight on the rear wheel which acts as a lever pushing the tyre down more (ie imagine accelerating a bike as 5 guys push down on the rear).
guys, a lightweight drivetrain is the best modification you can do to a car. Remember that these engines rev upt o 41K + so therefore the quicker you get it up to it's peak rev range (whatever it may be...20,000 to 30,000, or whatever it is) then the more punchy the car will be and the better power it will have out of the corners.
a lightweight drive train does not make the car less grippy, this is a falacy, that originates from a bad example (ie motocross). a car that is close to minimum weight will wear out the tyres less (to an extent) use less fuel (to an extent) place less strain on the engine (to an extent) and will be more punchy out of corners.
drivetrain mass i remember someone saying here ages ago, is equivalent to x2 static weight (or something like that) basically what i am saying is that rotating mass is x2 more important and worthwhile eliminating than static weight.
artificial your comment of pivot balls being better to lighten goes against what you said about motocross bikes and your flywheel example. ie, if your flywheel motorcross example was correct, then the heavier pivot balls would also seem a better option if we continue your analogy. ie more weight then on the ends of an arm, according to the motocross flywheel principle would be better as it places more downwards force on the wheels, hence more grip right? BUT OF COURSE THIS IS WRONG! reduction of unsprung weight is important, and so is rotating mass.
experiment by drilling holes in a flywheel (ACURATELY!) and you will eventually find the maximum you can drill it out to without affecting idle. this is the lightest the flywheel can go without ruining the idle...done problem solved, and fallacy of a heavier flywheel is good analogy solved!
remember these are not drag cars, or motocross bikes, two things that require and rely on weight over rear wheels to lay down power effectively. 
*********
dude, i think artificial is wrong. a lightweight transmission on a car is beneficial especially when the engiens we use rely on rpm to produce power. Your example of a motorcross bike is wrong to apply to a rc car. why? because a flywheel on a motorcross bike is on the rear wheel. you are getting more traction not due to the heavier flywheel, but due to the added weight on the rear wheel which acts as a lever pushing the tyre down more (ie imagine accelerating a bike as 5 guys push down on the rear).
guys, a lightweight drivetrain is the best modification you can do to a car. Remember that these engines rev upt o 41K + so therefore the quicker you get it up to it's peak rev range (whatever it may be...20,000 to 30,000, or whatever it is) then the more punchy the car will be and the better power it will have out of the corners.
a lightweight drive train does not make the car less grippy, this is a falacy, that originates from a bad example (ie motocross). a car that is close to minimum weight will wear out the tyres less (to an extent) use less fuel (to an extent) place less strain on the engine (to an extent) and will be more punchy out of corners.
drivetrain mass i remember someone saying here ages ago, is equivalent to x2 static weight (or something like that) basically what i am saying is that rotating mass is x2 more important and worthwhile eliminating than static weight.
artificial your comment of pivot balls being better to lighten goes against what you said about motocross bikes and your flywheel example. ie, if your flywheel motorcross example was correct, then the heavier pivot balls would also seem a better option if we continue your analogy. ie more weight then on the ends of an arm, according to the motocross flywheel principle would be better as it places more downwards force on the wheels, hence more grip right? BUT OF COURSE THIS IS WRONG! reduction of unsprung weight is important, and so is rotating mass.
experiment by drilling holes in a flywheel (ACURATELY!) and you will eventually find the maximum you can drill it out to without affecting idle. this is the lightest the flywheel can go without ruining the idle...done problem solved, and fallacy of a heavier flywheel is good analogy solved!
remember these are not drag cars, or motocross bikes, two things that require and rely on weight over rear wheels to lay down power effectively.
I have a friend with a newer car , he just got a lightweight flywheel. Now all he does is spin in first and complains to me why. It does feel more peppy and all. But if you cant get traction , his quarter mile is suffering now.
Want to know why. Because the car can now rev up in rpm much faster than before , the same goes during deacceleration.
Therefore your going to spin the tires in low traction areas or stop and go or low speed situations coming out of a tight turn. Because of its ability to spool up quicker. Yeah a lightweight flywheel is just a term , just like adding a softer shock can increase grip but remember there are points of diminishing returns. To where too lightweight of a situation you tap the gas and its going to spin the tires because of its vast ability to spin the drivetrain from slow speeds therefore = loss of traction.
To calm your car down some and make it more consistent a heavier drivetrain would be more optimal for stop and go situations where traction and the rolling momentum of the chassis isnt there and it needs to get upto speed.
Slow speeds to high speeds is where your going to get traction losses. Afterwards a flywheel is kinda moot , except for responsiveness.
The big benefit of a lw drivetrain for a mtx-4 driver though is it will apply less stress to the spur gears and less slap when shifting gears.
Last edited by Artificial-I; 03-31-2007 at 05:02 PM.
03-31-2007, 10:04 AM
#33
Originally Posted by V1-RRR-WC
As mentioned in one of the threads, I think this theory can also be applied to the drive train, i.e. the difference between a spool and diff where this may even have alot more effect on the direction change of a car.
My K-Factory spool weighs 32g, whereas my diff weighs 50g. Not to mention the planetary gears of the diff are in a large dia. / orbit compared to the weight of the spool. A huge difference in rotational mass.
So it seems to me it would be much better to setup my car to run on a spool which would yield much better overall results based on the above theory.
I wonder if this is the reason the NT1 went with much smaller dia of diff???
My K-Factory spool weighs 32g, whereas my diff weighs 50g. Not to mention the planetary gears of the diff are in a large dia. / orbit compared to the weight of the spool. A huge difference in rotational mass.
So it seems to me it would be much better to setup my car to run on a spool which would yield much better overall results based on the above theory.
I wonder if this is the reason the NT1 went with much smaller dia of diff???
03-31-2007, 11:02 AM
#34
The lighter the better for me. I think everyone else in my class should run really heavy ones though!
03-31-2007, 11:04 AM
#35
Tech Master
Originally Posted by Artificial-I
To calm your car down some and make it more consistent a heavier drive-train would be more optimal for stop and go situations where traction and the rolling momentum of the chassis isnt there and it needs to get upto speed.
03-31-2007, 04:42 PM
#36
Originally Posted by fritzD
torque is directly proportional to the moment of inertia of the rotating body. Moment of inertia is depends on mass. 
more mass > more moment of inertia > more torque
Now notice the lower left equation on the image i attached. The solution to this simple differential equation is on the 2nd pic attached. Notice that the angular velocity on the left side also depends on the moment of inertia. More moment of inertia>> lesser maximum angular velocity
lesser moment of inertia>> greater maximun angular velocity
in short, heavier flywheel will give you more torque and a lighter one will give you more RPM..
more mass > more moment of inertia > more torque Now notice the lower left equation on the image i attached. The solution to this simple differential equation is on the 2nd pic attached. Notice that the angular velocity on the left side also depends on the moment of inertia. More moment of inertia>> lesser maximum angular velocity
lesser moment of inertia>> greater maximun angular velocity
in short, heavier flywheel will give you more torque and a lighter one will give you more RPM..
All of this is somewhat unimportant. What we all really care about is acceleration. We want as much as we can put to the ground. It takes energy to move objects. The heavier the object, the more energy it takes to move that object.
Last edited by Scott Fisher; 03-31-2007 at 05:07 PM.
03-31-2007, 04:52 PM
#37
Originally Posted by Rich Browne
This is said in fun and isn't meant to offend. I respect many of your thoughts but, you should let the guys in Formula 1 know your theory. They are going about things all wrong. They should be running cast iron V8's and big ass transmissions. They would be thrilled to know they could cut down on all the exotic materials - they would save big bucks - and would thank you like crazy!
Also traction control is used in those cars. They just point and stab the gas pedal now a days and let the computer sort it out. They are setup at the limit, but yeah I gurantee you those guys do use lots of different methods to achieve the ipidimy of a race chassis as we know it. Where v8's and big ass transmissions come into play , Iam completely baffled. They are setup to run how they are and in those settings you can gurantee they change things and test them and if they run right then ok. Iam merely giving examples of what will happen if you add or remove weight from the tranny.
Either way , feel free to say some points that make sense and Ill gladly respond. Ive been writing performance articles for years , work for a automotive magazine and been racing since I was able to drive. I didnt create this thread allthough it was started by some simple advice/knowledge that I threw out in a mtx-4 thread. Iam only stating facts of tuning , not saying anything one thing is better. Just that certain elements create optimal setups for certain track conditions. You tune to the track in racing if you want to win and in that Ive offered my advice.
Last edited by Artificial-I; 03-31-2007 at 05:25 PM.
03-31-2007, 05:16 PM
#38
Originally Posted by Scott Fisher
I disagree. I am simplifying somewhat, but torque is a measure of twisting force. The engine produces the same amount of twisting force no matter how much the flywheel weighs. It uses/takes more torque to spin a heavier flywheel. The engine does not produce any more energy with a lighter or heavier flywheel. At any given RPM using a heavier flywheel there is more momentum. If I attach a 100lb flywheel to my engine, the engine probably would not even be able to turn it, but yet you are saying it is producing more torque?
All of this is somewhat unimportant. What we all really care about is acceleration. We want as much as we can put to the ground. It takes energy to move objects. The heavier the object, the more energy it takes to move that object.
All of this is somewhat unimportant. What we all really care about is acceleration. We want as much as we can put to the ground. It takes energy to move objects. The heavier the object, the more energy it takes to move that object.
If anything we should ask BK from nitrodynesystems to show us some real world rc engines with lightweight flywheels on them and see if he can come up with some differences in numbers.
Otherwise its just toooooo much conflict to both sides of this theory to really say any one of them is true.
Furthermore its really not even the point at hand. Its the fact that a flywheel/drive train weight really changes the way that the power is laid down. Simple as that. Its almost mind boggling , to think the power isnt really changed...both sides can agree to that. Just one side thinks that there is some change , while the other thinks there is none. At the same time. The point is that it allows the engine to rev up and down easier. This creates traction problems. I myself have run a way too lightweight flywheel on my real car thinking it wouldnt be anything but a benefit (I was young), when in fact my car got slower because I couldnt accelerate out of the hole quicker. I soon realized and set my car back to stock flywheel weight and tada....my launches were hard and grippy again.
In any event at this point Ive figured Ill let the manufacturer sort it all out and they are the ones doing the tuning and spending large amount of dollars on doing so.
With RC ive figured that the flywheel is important to stick with stock for one simple reason. The stock units will most likely have a smoother unit made with more precision. Now I could of course find an aftermarket company who makes one smoother and more precision so the weights engage smoothly and properly but so far it seems the flywheels ive looked at from certain companies , these companies dont normally offer the best of precision.
Where as mugen , kyosho etc have pretty much fully tested there cars with the stock flywheels and hopefully in most cases if any problems were there put some effort into correcting whatever problem and releasing a unit that would properly function.
Everywhere else flywheels have the clutch plate press against the flywheel itself. Where as in rc , there is a fly weight that moves in and out of the angled flywheel to create proper engagement. The flywheel stores energy your correct. So when you lighten your flywheel, youll actually need to rev higher to get the car moving too. At least in a real car. Why because that same weight is now less and you need the weight of the flywheel to get you moving.
Long story short , its all in the shafts for rc and having a car with a ultra lightweight drivetrain. IT IS good for acceleration chassis wise / engine power wise. But for the tires that connect this chassis to the road, thats a different story. The improved/accelerated rotation might end up simply causing traction problems in low traction situations. Simple as that and thats the small point I wanted to make in the mtx-4 thread.
In a high traction situation. Go as lightweight as possible. A lightweight piece on a car does make it easier to turn and all that , that is an outside factor of a lightweight car. Just like running small batteries , or lightweight servos. It helps reduce weight on top of the car , lowering the CG and having less weight to change direction. As well as better mpg , less wear on motors , transmission , tires , suspension , more power to weight etc etc.
So in conclusion, Yes having lw shafts is really a darn good thing if your track has the grip to afford that. Especially if your racing on a flowing track. If your a drag racer you might want to look into a heavier tranny to calm and smooth the motor so you can get more grip. Grip is what makes you win , you spin , you loose.
Happy tuning. A.I
03-31-2007, 05:50 PM
#39
Originally Posted by Scott Fisher
I disagree. I am simplifying somewhat, but torque is a measure of twisting force. The engine produces the same amount of twisting force no matter how much the flywheel weighs. It uses/takes more torque to spin a heavier flywheel. The engine does not produce any more energy with a lighter or heavier flywheel. At any given RPM using a heavier flywheel there is more momentum. If I attach a 100lb flywheel to my engine, and it was able to turn it (probably not) you are saying I am producing more torque?
All of this is somewhat unimportant. What we all really care about is acceleration. We want as much as we can put to the ground. It takes energy to move objects. The heavier the object, the more energy it takes to move that object.
All of this is somewhat unimportant. What we all really care about is acceleration. We want as much as we can put to the ground. It takes energy to move objects. The heavier the object, the more energy it takes to move that object.
Torque is an analog of Newtonian Force but applied to rotating bodies. The concept of torque was defined by physicists to make Newtonian analysis on rotating bodies rather than taking into account the forces involved.Yes, it can be called a twisting force. But its more of a vector quantity that can rotate a an object about a pivot point. But, of course, torque is equal to the force perpendicular to the lever times the lever arm. I'm not answering based on my experience as a racer but as an applied physics major. just my 2cents.
03-31-2007, 06:22 PM
#40
OK. If there is more torque with a heavier flywheel, what happens in an extreme case. How come if I attach a heavy enough flywheel it won't turn at all?
Is it because there is not enough torque to overcome inertia?
You obviously have more knowledge on this subject than I do, but I do know that if I make my flywheel heavier, I have less of the engines power available to move my car.
AI: I agree with one of the important points you are making. Too much power to the ground is not a good thing if all that happens is the tires spin.
I guess what I will say is this: The engine produces a finite amount of power/energy. That energy has to turn the flywheel, clutch parts, spur gears, clutchbell, various shafts and parts of the drivetrain in order to make the wheels turn and propel the car. The heavier those parts are the less of that power/energy will be at the rear wheels.
Is it because there is not enough torque to overcome inertia?
You obviously have more knowledge on this subject than I do, but I do know that if I make my flywheel heavier, I have less of the engines power available to move my car.
AI: I agree with one of the important points you are making. Too much power to the ground is not a good thing if all that happens is the tires spin.
I guess what I will say is this: The engine produces a finite amount of power/energy. That energy has to turn the flywheel, clutch parts, spur gears, clutchbell, various shafts and parts of the drivetrain in order to make the wheels turn and propel the car. The heavier those parts are the less of that power/energy will be at the rear wheels.
03-31-2007, 06:33 PM
#41
Originally Posted by Scott Fisher
OK. If there is more torque with a heavier flywheel, what happens in an extreme case. How come if I attach a heavy enough flywheel it won't turn at all?
You obviously have more knowledge on this subject than I do, but I do know that if I make my flywheel heavier, I have less of the engines power available to move my car.
AI: I agree with one of the important points you are making. Too much power to the ground is not a good thing if all that happens is the tires spin.
I guess what I will say is this: The engine produces a finite amount of power/energy. That energy has to turn the flywheel, clutch parts, spur gears, clutchbell, various shafts and parts of the drivetrain in order to make the wheels turn and propel the car. The heavier those parts are the less of that power/energy will be at the rear wheels.
You obviously have more knowledge on this subject than I do, but I do know that if I make my flywheel heavier, I have less of the engines power available to move my car.
AI: I agree with one of the important points you are making. Too much power to the ground is not a good thing if all that happens is the tires spin.
I guess what I will say is this: The engine produces a finite amount of power/energy. That energy has to turn the flywheel, clutch parts, spur gears, clutchbell, various shafts and parts of the drivetrain in order to make the wheels turn and propel the car. The heavier those parts are the less of that power/energy will be at the rear wheels.
03-31-2007, 06:52 PM
#42
Im not sure Scott who you were referring too in your entire post. I can see some directed towards me. Also you kinda changed what I said and it kinda makes a different arguement. Yes wheel spin is bad. The problem is the fact that when your tires spin way UP too fast. Just makes for a car that likes to spin in 1st gear.
Anyhow.
Here is an amazing article on the subject. After contact with Fidanza today. One of the leading flywheel/clutch companies out there. If youve heard of them. They led me to this article.
Here it goes , good read:
Die-hard racers and serious performance fanatics are always looking for ways to save weight in their street or track cars. They know that weight robs performance. It's not unusual to see carbon-fiber body panels, gutted interiors, and lightweight wheels on track and some street performance vehicles. Reese Cox, owner of MTI Racing, is a die-hard racer. He is a former crew chief for a major Corvette endurance racing team and a SpeedVision (World Challenge) GT competitor, and he currently spends his time tuning customer Corvettes. He contacted Team VETTE with a wild idea--modifying both a brand-new ZO6 and one of his tuner ZO6s with a lightweight flywheel plus a high-performance clutch and pressure plate. Reese was convinced that we would see a nice bump in performance from both cars after such a change. Intrigued, we set up some test parameters. First, we wanted the cars tested on a drum-style chassis dyno to determine their rear-wheel horsepower. Next we required that each of the cars be pre- and post-dyno-tested on the same day. Reese agreed to our terms and to provide the cars and labor if we could find parts for the project.
Team VETTE has high regard for Fidanza products, so we contacted their Marketing Manager, Bob Sheid, with our idea. Bob was very excited about Reese's proposal and agreed to provide us with two of their latest lightweight flywheels. He also convinced us to install SPEC pressure plates and clutches into our test cars. Bob was so excited about our project that he decided to attend the installation along with owner Lou Fidanza to provide on-the-spot technical advice! We called Reese back and told him the project was a go. After all of the parts were delivered, Bob Sheid, Lou Fidanza, and Team VETTE met at Reece's shop in Marietta, Georgia, to start the project. As promised, Reece found a customer who volunteered his brand-new Commemorative Edition ZO6 for our test. We are not kidding about brand new! Denny Stradtman's beautiful new car only had a little over 700 miles on the clock. Our second test car is Reece's personal black '01 Z06 "development" car. This car has had its intake, heads, cam, exhaust, brakes, suspension, and wheels modified. It's fast and sounds bad.
Reese arranged to take both cars to a dyno before their modifications. First up was the new ZO6, which produced 357.3 hp and 351.8 ft-lb of torque on its third run. Water temperature was 191oF and oil temp was at 210oF. Outside temperature was 53oF. The runs were made in fourth gear from 2,000 rpm to 6,400 rpm, and it took 14 seconds for the car to reach its maximum horsepower. Now that we'd established a baseline, it was time to install the new parts in Denny's ZO6. Reese's crew consisted of himself, David Munder, Chris Harwood, and Jesus Garcia. In a blink of the eye, the center console, wheels, rear suspension, transmission, and torque tube were removed from the new ZO6. Next, the stock pressure plate, clutch, and flywheel were removed and weighed. The three factory parts hit the scale at 51 pounds. The new Fidanza 12.5-pound aluminum flywheel (PN 198571, retails at $439.00), and the 14.5-pound Spec Stage 1 clutch/pressure plate unit (PN SC091, retails at $299.00) totaled 27 pounds--a savings of 24 pounds of rotating weight at the crankshaft! The team installed the new flywheel, clutch, and pressure plate in record time, and they all fit perfectly. Three hours and ten minutes after the first wrench was turned, the crew had finished reinstalling all of the parts, and the car was returned to the dyno!
Fortunately our weather was holding and the outside temperature was 54oF for our repeat test. On the way to the dyno, we noticed a slight increase in clutch pedal pressure over the stock unit, but it was not annoying. Our best of three runs netted 366.6 hp and 360.4 lbs of torque--a gain of 9.3 hp and 8.6 ft-lb of torque. Maximum horsepower was achieved in 11 vs. 14 seconds with the stock parts, and maximum torque was seen in 9 vs. 11 seconds with the stock parts! Back on the road, Denny's Z06 revved a little quicker and required a lighter push on the loud pedal. We could feel the difference. Satisfied with our results, we headed back to the shop to make preparations for the next day.
The MTI team started the next day off by taking Reese's black, modified Z06 to the dyno. The outside temperature was 56oF, and three runs were made in fourth gear from 2,000 to 6,500 rpm. The third run produced the best readings with 437.5 horsepower and 376.2 ft-lb of torque at the rear wheels with the factory flywheel/ clutch/pressure plate. Water temperature was 193oF and the oil was 209. The car was returned to the shop to install the new parts. The team installed another Fidanza PN 198571 flywheel, this time with a SPEC Stage 3 Clutch with Hybrid Pressure Plate (retails for $699.00). The job took four hours because the long tube headers on this car are a tight fit and are difficult to remove. Back at the dyno, the outside temperature was 58oF, and Reese made three runs in fourth gear from 2,000 to 6,500 rpm. The third run produced 449.2 hp and 400.3 ft-lb of torque. Water temperature was 194oF and the oil was 210 degrees. This was a net gain of 12 hp and 21.10 ft-lb of torque. Maximum horsepower was achieved in 8 vs. 9 seconds with the stock parts, and maximum torque was achieved in 5 vs. 6.4 seconds with the stock parts.
At the conclusion of the tests, Reese shared his observations with us about installing the Fidanza and SPEC components into our test cars. "The important thing to look at in this test procedure is the time to speed relationship, not necessarily the increase in horsepower. Keep in mind the test device we used was an inertia dyno. A flywheel does not make any horsepower, but it shows up as a horsepower gain because you have reduced the inertia on an inertia dyno. So you need to look at the reduction in time to speed that was created by the reduction of inertia. We went from 14 to 11 seconds to 145 mph on the stock Z06. What that tells you is how the car is going to feel on the street. It is going to accelerate quicker to the redline."
And after all isn't that what we expect to gain from a good diet--more speed from less weight!
--
So it seems that a flywheel increase power to the wheels!!!! Thats I think the missing point a lot of us overlooked and didnt know. Id say even myself.
The car is making more horsepower per say. As well its just simply getting up to PEAK power quicker.
Now as much as I like Fidanza. I cant help but make comment. This is power readings. This still doesnt stray from the fact that a LW flywheel in first gear , low speed , stops , etc etc you get the point. It going to make it harder to launch consistently. Yes one of those times you might get it right and you will probably get the best launch or grip of all times. Due to the fact that the car can get up to speed quicker via quicker rotation.
What I wished these guys did was a 1/4 mile test as this is where those precious dyno numbers truly show the benefit in real world environments. I kinda feel as if Fidanza is more or less tossing money at these dyno guys as in most cases of advertisements and reviews via even reputable magazines or online performance archives. They just dont want to pay good money to look bad.
But it does kinda proove to me that the power might in fact show more , but at the engine itself its of course not improving and thats where I was even getting a little boggled. Now it makes sense cause of course its not like the motor just got a peformance add-on which usually consists of increased air flow , compression or stroke.
But that it seems to remove parasitic drag on the power of the motor and allows more power to be used at the wheels.
The one big thing though that kinda prooved to me that there will be traction losses is the great change in time to peak power output. 14 to 11 seconds. Thats a pretty good change.
But kinda brings together my theories. Think of it like this , even if the power was the same. Its now happening 2-3 seconds faster. So what it looks like on paper is , the same powerbands. Just shrunk to a smaller more compressed version.
Well take the tires in that theory. They arent changing, so they are going to suffer from this new quicker to rev setup. The power was indeed changed , but then again for a 50% weight drop it wasnt that big of a deal.
Im sure we are doing about the same though in weight losses when running lw / hollow shafts. So power might not change much but like Reese stated "with us about installing the Fidanza and SPEC components into our test cars. "The important thing to look at in this test procedure is the time to speed relationship, not necessarily the increase in horsepower. Keep in mind the test device we used was an inertia dyno. A flywheel does not make any horsepower, but it shows up as a horsepower gain because you have reduced the inertia on an inertia dyno. So you need to look at the reduction in time to speed that was created by the reduction of inertia. We went from 14 to 11 seconds to 145 mph on the stock Z06. What that tells you is how the car is going to feel on the street. It is going to accelerate quicker to the redline."
Therefore its going to spin tires , with having only moderate gains in power. Even with all this info placed before me it doesnt make sense and would probably only make full sense if they just ran the darn car in a 1/4 mile.
I mean if it can accelerate quicker youd think it would be faster. Rather than just being able to spin quicker. Its weird...but just like they say , spin around with your arms out , then while spinning pull your arms inward. The same power you can spin faster , but your not any stronger.
Thats why I more or less forget all this nonsense and just use my own real world tests. Which its very obvious, its just easier to spin tires. In fact in the rain I would stop the gas in like 4th from ultra low rpm and would just laugh how easy I could spin the tires. Reason why in my street car where stopping and going is a good portion of driving. Ive stuck with a heavier drivetrain. Because its very easy to spin the tires already. It all comes down to available traction. The driving in the rain is a big point on that. When its easier to spin a tire (not talking about traction loss , just the ease of being able to rotate it quicker). When traction goes down , this tire is going to take off on its own.
I cant really get into it much more , because even after all this is still boggles my mind. I really dont know why it would want to spin more. I mean I do , but its weird. It doesnt make sense to me how its going to spin but not grip the same as before. But I know what I know and it just does. Especially when grip is needed.
Basically, what im 100% sure about is. If traction is an issue. Dont go and lighten the cars drivetrain a bunch.
Ha.
Anyhow.
Here is an amazing article on the subject. After contact with Fidanza today. One of the leading flywheel/clutch companies out there. If youve heard of them. They led me to this article.
Here it goes , good read:
Die-hard racers and serious performance fanatics are always looking for ways to save weight in their street or track cars. They know that weight robs performance. It's not unusual to see carbon-fiber body panels, gutted interiors, and lightweight wheels on track and some street performance vehicles. Reese Cox, owner of MTI Racing, is a die-hard racer. He is a former crew chief for a major Corvette endurance racing team and a SpeedVision (World Challenge) GT competitor, and he currently spends his time tuning customer Corvettes. He contacted Team VETTE with a wild idea--modifying both a brand-new ZO6 and one of his tuner ZO6s with a lightweight flywheel plus a high-performance clutch and pressure plate. Reese was convinced that we would see a nice bump in performance from both cars after such a change. Intrigued, we set up some test parameters. First, we wanted the cars tested on a drum-style chassis dyno to determine their rear-wheel horsepower. Next we required that each of the cars be pre- and post-dyno-tested on the same day. Reese agreed to our terms and to provide the cars and labor if we could find parts for the project.
Team VETTE has high regard for Fidanza products, so we contacted their Marketing Manager, Bob Sheid, with our idea. Bob was very excited about Reese's proposal and agreed to provide us with two of their latest lightweight flywheels. He also convinced us to install SPEC pressure plates and clutches into our test cars. Bob was so excited about our project that he decided to attend the installation along with owner Lou Fidanza to provide on-the-spot technical advice! We called Reese back and told him the project was a go. After all of the parts were delivered, Bob Sheid, Lou Fidanza, and Team VETTE met at Reece's shop in Marietta, Georgia, to start the project. As promised, Reece found a customer who volunteered his brand-new Commemorative Edition ZO6 for our test. We are not kidding about brand new! Denny Stradtman's beautiful new car only had a little over 700 miles on the clock. Our second test car is Reece's personal black '01 Z06 "development" car. This car has had its intake, heads, cam, exhaust, brakes, suspension, and wheels modified. It's fast and sounds bad.
Reese arranged to take both cars to a dyno before their modifications. First up was the new ZO6, which produced 357.3 hp and 351.8 ft-lb of torque on its third run. Water temperature was 191oF and oil temp was at 210oF. Outside temperature was 53oF. The runs were made in fourth gear from 2,000 rpm to 6,400 rpm, and it took 14 seconds for the car to reach its maximum horsepower. Now that we'd established a baseline, it was time to install the new parts in Denny's ZO6. Reese's crew consisted of himself, David Munder, Chris Harwood, and Jesus Garcia. In a blink of the eye, the center console, wheels, rear suspension, transmission, and torque tube were removed from the new ZO6. Next, the stock pressure plate, clutch, and flywheel were removed and weighed. The three factory parts hit the scale at 51 pounds. The new Fidanza 12.5-pound aluminum flywheel (PN 198571, retails at $439.00), and the 14.5-pound Spec Stage 1 clutch/pressure plate unit (PN SC091, retails at $299.00) totaled 27 pounds--a savings of 24 pounds of rotating weight at the crankshaft! The team installed the new flywheel, clutch, and pressure plate in record time, and they all fit perfectly. Three hours and ten minutes after the first wrench was turned, the crew had finished reinstalling all of the parts, and the car was returned to the dyno!
Fortunately our weather was holding and the outside temperature was 54oF for our repeat test. On the way to the dyno, we noticed a slight increase in clutch pedal pressure over the stock unit, but it was not annoying. Our best of three runs netted 366.6 hp and 360.4 lbs of torque--a gain of 9.3 hp and 8.6 ft-lb of torque. Maximum horsepower was achieved in 11 vs. 14 seconds with the stock parts, and maximum torque was seen in 9 vs. 11 seconds with the stock parts! Back on the road, Denny's Z06 revved a little quicker and required a lighter push on the loud pedal. We could feel the difference. Satisfied with our results, we headed back to the shop to make preparations for the next day.
The MTI team started the next day off by taking Reese's black, modified Z06 to the dyno. The outside temperature was 56oF, and three runs were made in fourth gear from 2,000 to 6,500 rpm. The third run produced the best readings with 437.5 horsepower and 376.2 ft-lb of torque at the rear wheels with the factory flywheel/ clutch/pressure plate. Water temperature was 193oF and the oil was 209. The car was returned to the shop to install the new parts. The team installed another Fidanza PN 198571 flywheel, this time with a SPEC Stage 3 Clutch with Hybrid Pressure Plate (retails for $699.00). The job took four hours because the long tube headers on this car are a tight fit and are difficult to remove. Back at the dyno, the outside temperature was 58oF, and Reese made three runs in fourth gear from 2,000 to 6,500 rpm. The third run produced 449.2 hp and 400.3 ft-lb of torque. Water temperature was 194oF and the oil was 210 degrees. This was a net gain of 12 hp and 21.10 ft-lb of torque. Maximum horsepower was achieved in 8 vs. 9 seconds with the stock parts, and maximum torque was achieved in 5 vs. 6.4 seconds with the stock parts.
At the conclusion of the tests, Reese shared his observations with us about installing the Fidanza and SPEC components into our test cars. "The important thing to look at in this test procedure is the time to speed relationship, not necessarily the increase in horsepower. Keep in mind the test device we used was an inertia dyno. A flywheel does not make any horsepower, but it shows up as a horsepower gain because you have reduced the inertia on an inertia dyno. So you need to look at the reduction in time to speed that was created by the reduction of inertia. We went from 14 to 11 seconds to 145 mph on the stock Z06. What that tells you is how the car is going to feel on the street. It is going to accelerate quicker to the redline."
And after all isn't that what we expect to gain from a good diet--more speed from less weight!
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So it seems that a flywheel increase power to the wheels!!!! Thats I think the missing point a lot of us overlooked and didnt know. Id say even myself.
The car is making more horsepower per say. As well its just simply getting up to PEAK power quicker.
Now as much as I like Fidanza. I cant help but make comment. This is power readings. This still doesnt stray from the fact that a LW flywheel in first gear , low speed , stops , etc etc you get the point. It going to make it harder to launch consistently. Yes one of those times you might get it right and you will probably get the best launch or grip of all times. Due to the fact that the car can get up to speed quicker via quicker rotation.
What I wished these guys did was a 1/4 mile test as this is where those precious dyno numbers truly show the benefit in real world environments. I kinda feel as if Fidanza is more or less tossing money at these dyno guys as in most cases of advertisements and reviews via even reputable magazines or online performance archives. They just dont want to pay good money to look bad.
But it does kinda proove to me that the power might in fact show more , but at the engine itself its of course not improving and thats where I was even getting a little boggled. Now it makes sense cause of course its not like the motor just got a peformance add-on which usually consists of increased air flow , compression or stroke.
But that it seems to remove parasitic drag on the power of the motor and allows more power to be used at the wheels.
The one big thing though that kinda prooved to me that there will be traction losses is the great change in time to peak power output. 14 to 11 seconds. Thats a pretty good change.
But kinda brings together my theories. Think of it like this , even if the power was the same. Its now happening 2-3 seconds faster. So what it looks like on paper is , the same powerbands. Just shrunk to a smaller more compressed version.
Well take the tires in that theory. They arent changing, so they are going to suffer from this new quicker to rev setup. The power was indeed changed , but then again for a 50% weight drop it wasnt that big of a deal.
Im sure we are doing about the same though in weight losses when running lw / hollow shafts. So power might not change much but like Reese stated "with us about installing the Fidanza and SPEC components into our test cars. "The important thing to look at in this test procedure is the time to speed relationship, not necessarily the increase in horsepower. Keep in mind the test device we used was an inertia dyno. A flywheel does not make any horsepower, but it shows up as a horsepower gain because you have reduced the inertia on an inertia dyno. So you need to look at the reduction in time to speed that was created by the reduction of inertia. We went from 14 to 11 seconds to 145 mph on the stock Z06. What that tells you is how the car is going to feel on the street. It is going to accelerate quicker to the redline."
Therefore its going to spin tires , with having only moderate gains in power. Even with all this info placed before me it doesnt make sense and would probably only make full sense if they just ran the darn car in a 1/4 mile.
I mean if it can accelerate quicker youd think it would be faster. Rather than just being able to spin quicker. Its weird...but just like they say , spin around with your arms out , then while spinning pull your arms inward. The same power you can spin faster , but your not any stronger.
Thats why I more or less forget all this nonsense and just use my own real world tests. Which its very obvious, its just easier to spin tires. In fact in the rain I would stop the gas in like 4th from ultra low rpm and would just laugh how easy I could spin the tires. Reason why in my street car where stopping and going is a good portion of driving. Ive stuck with a heavier drivetrain. Because its very easy to spin the tires already. It all comes down to available traction. The driving in the rain is a big point on that. When its easier to spin a tire (not talking about traction loss , just the ease of being able to rotate it quicker). When traction goes down , this tire is going to take off on its own.
I cant really get into it much more , because even after all this is still boggles my mind. I really dont know why it would want to spin more. I mean I do , but its weird. It doesnt make sense to me how its going to spin but not grip the same as before. But I know what I know and it just does. Especially when grip is needed.
Basically, what im 100% sure about is. If traction is an issue. Dont go and lighten the cars drivetrain a bunch.
Ha.
03-31-2007, 07:01 PM
#43
Originally Posted by Scott Fisher
OK. If there is more torque with a heavier flywheel, what happens in an extreme case. How come if I attach a heavy enough flywheel it won't turn at all?
Is it because there is not enough torque to overcome inertia?
You obviously have more knowledge on this subject than I do, but I do know that if I make my flywheel heavier, I have less of the engines power available to move my car.
AI: I agree with one of the important points you are making. Too much power to the ground is not a good thing if all that happens is the tires spin.
I guess what I will say is this: The engine produces a finite amount of power/energy. That energy has to turn the flywheel, clutch parts, spur gears, clutchbell, various shafts and parts of the drivetrain in order to make the wheels turn and propel the car. The heavier those parts are the less of that power/energy will be at the rear wheels.
Is it because there is not enough torque to overcome inertia?
You obviously have more knowledge on this subject than I do, but I do know that if I make my flywheel heavier, I have less of the engines power available to move my car.
AI: I agree with one of the important points you are making. Too much power to the ground is not a good thing if all that happens is the tires spin.
I guess what I will say is this: The engine produces a finite amount of power/energy. That energy has to turn the flywheel, clutch parts, spur gears, clutchbell, various shafts and parts of the drivetrain in order to make the wheels turn and propel the car. The heavier those parts are the less of that power/energy will be at the rear wheels.
Adjusting power is one thing and even then in some low power cars you can spin the car easily its that even in those low low powered cars with a lw flywheel you can just simply spin the tires at a non effective rate with the traction of the tires to the road.
Its these things that have directed me to believe what I do. I talk with people who are pushing the limits of their cars and after only hearing lw flywheels were good when I was young. I installed one and then found it was very interesting to me to hear these hardcore drag racers etc were adding large all sorts of goodies and then finding a heavier flywheel was netting them much better launches and times.
So thats the reason why im posting this info. Just to inform people that there is some tuning to be had by adjusting drivetrain weight.
Sorry to see the conflict between some of you guys, which truly we shouldnt blame one another. This subject has brought many communities to a boil as its just a lot of conflicting information. But this should pretty much put things to rest.
Happy Tuning. A.I
04-01-2007, 02:20 AM
#44
This is a touchy subject it seems
From my experience with my real car i would have to say that a lighter flywheel has definate benefits as mentioned ie: faster spool up and spool down ,a bit more cammy/erratic idle etc.
But it did not sacrifice torque/tractive effort.
In fact when done in stages you would find that the engine with lightened flywheel to have definate benefits to drag racing as well as road course races in that the engine response is improved.
We have noticed on our race and drag cars that we loose less hp through the drive train with a lightened flywheel and also with higher diff ratios.This would equate to what was mentioned about reduced transmission ratios ,etc...
The lightening would improve transmission efficiency and power delivery and it involve another discipline of chassis setup and mechanical grip to harness this extra power delivery.
It would be stupid to spend the effort to improve the drivetrain and ignore the setup of the car.
In artificial-i's argument that he had less traction with his lightened flywheel on his 1:1 car and it gave him less acceleration/traction as the wheels were spinning is a example of relying on the engine transmission to give you more performance but ignoring that you need to get more mechanical grip etc to put that power down.
On my Golf 2 VR6 my fastest et was 15.1sec on the 1/4 mile in stock trim after a flywheel and damper change to lighter units i managed to better that to a 14.7sec.
With a change to a smaller wheel from a 17inch to a 16inch i managed a faster time of 14.4secs.On 15inch low profile tyres i managed my fastest et at 13.9sec.
On the dyno my hp was 181hp in stock form ,after lighteneing etc it went up to 189hp and after all the gearbox ,wheel combos used we maxed out at 209hp with out doing any work to the engine itself obviously we have to take in account various factors but transmission efficiency is a key component to perfomance.
We started testing various vehicles with this idea and noticed that all vehicles made a improvement on the strip but it had to coincide with changes to suspension setup to benefit from the lightened drivetrain and shorter overall gearing.
From my experience with my real car i would have to say that a lighter flywheel has definate benefits as mentioned ie: faster spool up and spool down ,a bit more cammy/erratic idle etc.
But it did not sacrifice torque/tractive effort.
In fact when done in stages you would find that the engine with lightened flywheel to have definate benefits to drag racing as well as road course races in that the engine response is improved.
We have noticed on our race and drag cars that we loose less hp through the drive train with a lightened flywheel and also with higher diff ratios.This would equate to what was mentioned about reduced transmission ratios ,etc...
The lightening would improve transmission efficiency and power delivery and it involve another discipline of chassis setup and mechanical grip to harness this extra power delivery.
It would be stupid to spend the effort to improve the drivetrain and ignore the setup of the car.
In artificial-i's argument that he had less traction with his lightened flywheel on his 1:1 car and it gave him less acceleration/traction as the wheels were spinning is a example of relying on the engine transmission to give you more performance but ignoring that you need to get more mechanical grip etc to put that power down.
On my Golf 2 VR6 my fastest et was 15.1sec on the 1/4 mile in stock trim after a flywheel and damper change to lighter units i managed to better that to a 14.7sec.
With a change to a smaller wheel from a 17inch to a 16inch i managed a faster time of 14.4secs.On 15inch low profile tyres i managed my fastest et at 13.9sec.
On the dyno my hp was 181hp in stock form ,after lighteneing etc it went up to 189hp and after all the gearbox ,wheel combos used we maxed out at 209hp with out doing any work to the engine itself obviously we have to take in account various factors but transmission efficiency is a key component to perfomance.
We started testing various vehicles with this idea and noticed that all vehicles made a improvement on the strip but it had to coincide with changes to suspension setup to benefit from the lightened drivetrain and shorter overall gearing.
04-01-2007, 04:44 AM
#45
guys, stop using real racecar examples for an RC car. it doesn't fit in some instances. Artificial, the example of your mate who was spinning wheels on the quarter is an example of a real 1;1 car right?
show us an example of a RC car that has had laptimes go UP due to a excessively light transmission, vrs a heavy transmission car with lower times, (SAME DRIVER) then there will be a whole lot more of evidence on your side.
i might be wrong, but it just doesn't sound right what you are saying. sure i agree with idling characteristics etc, but these engines rev...torque is up high in the range.
lets talk purpose built tracks also, because if you are bashing in a car park track then, in most cases the car is over engineered for the use you push it to anyway sorry, no offense, but it's true. These cars are designed to win world championships, and WC's are held at high traction, purpose built tracks, lightweight drivetrains rule when the traction is high.
Xray with small diffs? = less rotating mass? yep, awesome. the NT1 is the car to beat in my opinion...even though it hasn't won anything big yet, it's the most evolved so far, so you'd assume it's technically the best ...and i'm a mugen fan, so i'm not saying it due to an affiliation, or "love" of a brand. Imagine the Slovaks stealing the thunder from the Japanese!? man, that would start a tourer wars for sure! can't wait.....
show us an example of a RC car that has had laptimes go UP due to a excessively light transmission, vrs a heavy transmission car with lower times, (SAME DRIVER) then there will be a whole lot more of evidence on your side.
i might be wrong, but it just doesn't sound right what you are saying. sure i agree with idling characteristics etc, but these engines rev...torque is up high in the range.
lets talk purpose built tracks also, because if you are bashing in a car park track then, in most cases the car is over engineered for the use you push it to anyway
sorry, no offense, but it's true. These cars are designed to win world championships, and WC's are held at high traction, purpose built tracks, lightweight drivetrains rule when the traction is high.Xray with small diffs? = less rotating mass? yep, awesome. the NT1 is the car to beat in my opinion...even though it hasn't won anything big yet, it's the most evolved so far, so you'd assume it's technically the best
...and i'm a mugen fan, so i'm not saying it due to an affiliation, or "love" of a brand. Imagine the Slovaks stealing the thunder from the Japanese!? man, that would start a tourer wars for sure! can't wait.....