garner Posted December 11, 2003 Share Posted December 11, 2003 I've read a bunch of signatures that specify lightened flywheels. How are you guys doing this? I assume they are chucked up on a lathe and the motor side turned down a bit. Any tricks for getting the flywheel chucked up? I think the end of the crank shaft would make a good fixture for this. Maybe there are some other trick you know of? How far can one go with out making it weak? I think Skip took 6lbs off his, is this the limit? Any advise or experience would be very helpful thanks Link to comment Share on other sites More sharing options...
WJM Posted December 11, 2003 Share Posted December 11, 2003 All i know is that its worth it! Skip has determined that 6lbs is the safe mark. im sure more can be taken off....but then, you get into an unknown area....I dont know if the Skip'ster has taken more off and experimented...as 4wd flywheels tend to be...not so common, and not cheap. Ask skip what he did to my flywheel, as the specs for my flywheel, and with the XT6 clutch set (NEW NAPA Clutch) is an EXCELLENT combo. Very grippy, and has not slipped a micro! Its got strong engagement, and all the components in the set is NEW stuff, right from JAPAN. With a normal flywheel, I dont think it woudl be much better than my wagon...which is so-so, but with the flywheel, its a PERFECT match. Link to comment Share on other sites More sharing options...
garner Posted December 11, 2003 Author Share Posted December 11, 2003 I know that light flywheels make a big difference. Man, the stock flywheel is a tank. I have access to some very nice metal lathes as I don't trust my little South Bend for critical machining. questions: Is all the material removed from the motor side? I assume you retain the timing marks. How much in inches is 6lb. as in how much dimensional material is removed to take 6 lbs off the sucker? thanks Link to comment Share on other sites More sharing options...
Guest taprackready Posted December 11, 2003 Share Posted December 11, 2003 Why do want a lightened flywheel? The weight of it is what makes Subarus good 4x4's. Bill Link to comment Share on other sites More sharing options...
Warp3 Posted December 12, 2003 Share Posted December 12, 2003 I've got a 9.5lb flywheel on my Impreza and absolutely love it...does no-one sell lightweight flywheels for the older cars? Link to comment Share on other sites More sharing options...
garner Posted December 12, 2003 Author Share Posted December 12, 2003 I am building this Brat for the streets primarily. It will be stock height, maybe lowered. I ain't runnin' no 30"s on it. Some people have said that the mass of the flywheel helps the car accelerate, I don't really understand the logic. It seems to me that the less mass the engine has to get spinning, more of the engines power gets to the wheels, the engine revs up faster and easier. Once it's up to speed, sure the mass of the flywheel keeps the wheels powered even when the right foot is off the gas. To me, for acceleration it seems, the lighter the better I've done several google searches on lightened flywheels. there is a lot of info out there but much contradiction. Anyone have some scientific input on the flywheel weight and its various effects on cars acceleration, hp to the wheels, etc.? I'd love to hear it. garner Link to comment Share on other sites More sharing options...
rallyruss Posted December 12, 2003 Share Posted December 12, 2003 lightened fly wheels are good for getting a motor to rev. up quicker. like for street racing or auto/rally cross. not good at all for you off road type. when I had my VW fly wheel lightened they took it all off the clutch side. it was a mild weight reduction dont know actuall weight. Link to comment Share on other sites More sharing options...
bushbasher Posted December 12, 2003 Share Posted December 12, 2003 A light flywheel will make for slightly better acceleration once you are moving. A heavier flywheel will make it easier to start from a stop without stalling, but will slow your aceleration a bit once you are moving. Subaru flywheels are heavy enough for alot of weight to be removed before you really have to worry about stalling though. The only time a flywheel takes energy is when accelerating (or deccelerating). Remember force=mass x acceleration, so the lighter the flywheel, the faster the acceleration of the flywheel. So if your car is slow, you are accelerating the flywheel at a slow rate, therefore the flywheel is using less energy. If your car accelerates fast, you are accelerating the flywheel faster and it is using more power. So on a 15sec to 60 car a light flywheel wont mean much, but on a 4 sec car it will matter alot. This is saying that the slow car is slow because of bad power to weight, with a percentage being used on the flywheel, not because the car has a humongous flywheel and is therefore slow. Link to comment Share on other sites More sharing options...
Warp3 Posted December 12, 2003 Share Posted December 12, 2003 Lightweight flywheels are great for rev-matching on downshifts. With a stock flywheel you usually have to punch the gas for a second for it to rev, with a lightweight flywheel you just tap the gas and the RPM shoots up...hehe Takeoffs are a little trickier but nothing you can't get used to after a few takeoffs (reverse moreso than 1st). Plus there is the obvious acceleration advantage due to lower rotating mass. Link to comment Share on other sites More sharing options...
Skip Posted December 12, 2003 Share Posted December 12, 2003 Garner, email me if you want to talk turning tech. Email the Electric Monk and ask him about the concept of angular momentum. Link to comment Share on other sites More sharing options...
GeneralDisorder Posted December 12, 2003 Share Posted December 12, 2003 A heavier flywheel will give you more torque - because, as Skip mentioned breifly, of angular momentum. The more wheight you have spinning like that, the more resistant to changes in speed it is, and thus for torque you want heavy. Depending on the weight of the car, and what your running for tires ect, will depend on how much your flywheel should weigh. It's a balancing act - you want good accereration, but you also want hard launches, and for that your need weight. If a lighter flywheel was always better - why have one at all? See my point? GD Link to comment Share on other sites More sharing options...
Warp3 Posted December 12, 2003 Share Posted December 12, 2003 Agreed...if the lighter flywheel was always better, then they would come with lightweight ones from the factory. The reason I like mine so much, is that I autocross and it is absolutely great for that. If I were planning to offroad the car regularly, a lightweight flywheel would not have been on my mod list at all. Link to comment Share on other sites More sharing options...
garner Posted December 12, 2003 Author Share Posted December 12, 2003 I do understand that this is a balancing act. I will not be doing more off roading than driving on some dirt roads. I want this thing fast on the street. I'm not going to go crazy with it, just take a few lbs off. On a related note: How about crank pulleys? For newer Impreza you can buy light weight pulley kits (not underdrive) that get nearly 10 more hp to the wheels. (I know, that might be exagerated). What is the deal here? I understand it does nothing to make more hp but frees it up to get to the wheels (which is, of course, the place for it) Link to comment Share on other sites More sharing options...
archemitis Posted December 12, 2003 Share Posted December 12, 2003 ALSO, when you shift, the rpms will drop more, because the lightened one does not have as much inertia, as a heavy one. Link to comment Share on other sites More sharing options...
gravelRX Posted December 13, 2003 Share Posted December 13, 2003 and your going full tilt boogie into a hard , say, right hander(2), the lightened flywheel will allow you to gear down, blip revs quickly , notch it into a lower gear and never upset the weight balance of the car until you want it for setting up the corner. Trail braking can be done with the brakes and gas at the same time, OR just don't match the rev of the next lowest gear and let the tail drag into the corner. then it turns into a balancing act til you clomp back down on the go pedal. Hence, "Don't look where you are going, look where you want to go." Just lightened mine 4 1/2 pounds. We'll see. Aren't I just full of myself tonight? Jay Link to comment Share on other sites More sharing options...
Skip Posted December 13, 2003 Share Posted December 13, 2003 Gad Arche, if it takes you that long to shift -- you have to try one of By the Sea's short shifters- BAM! Ask Trogdor he's shifted one- mine end of story Link to comment Share on other sites More sharing options...
electryc_monk Posted December 13, 2003 Share Posted December 13, 2003 Originally posted by Skip Garner, email me if you want to talk turning tech. Email the Electric Monk and ask him about the concept of angular momentum. LOL Oh Skipper thank you. I needed a good one recently! Big ole Thanks Link to comment Share on other sites More sharing options...
garner Posted December 15, 2003 Author Share Posted December 15, 2003 electryc_monk, Should I even ask? garner Link to comment Share on other sites More sharing options...
archemitis Posted December 15, 2003 Share Posted December 15, 2003 good ole skip, just here to poke fun. puts away Link to comment Share on other sites More sharing options...
electryc_monk Posted December 16, 2003 Share Posted December 16, 2003 its a Fizix Thang! (AKA its a physics thing, and welll, as its been a lulu of a semester for me and stufff) You see Skip-ster and I have a little kin-ship of sorts for scholastic endeavours. Physics and well, there may be a year or two between us.... I went into the military first..... anyways. Centripedal force or angular momentum. I personally like the "big Omega" but, the seat of the pants prefer the centripedal experience. Especially when one can safely drift the car thru a corner and not disturb a bee keepers hives. (whistles to self, wonders off to bed) Link to comment Share on other sites More sharing options...
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