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Question, im in the process of building my extra motor for boost.
What are the pros/cons of having a lightweight flywheel opposed to using heavy factory one?

 
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revs will stay higher in between shifts

 
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I may be really dumb, but that makes absolutely no sense to me. I would actually think the opposite would happen. Since the flywheel is so much lighter than stock, and there is less rotating mass on the driveline, wouldn't the RPM's fall way faster with an aluminum flywheel? I mean the engine wants to slow down because of friction, and this only makes it easier. At least thats what i hear from a lot of my mustang buddies. In general, i've always been told you want an aluminum flywheel if your road racing, because you're not shifting that much all the time. Drag racing you want a billet steel piece, because it doesn't fall in RPM's as fast as the aluminum, but still gives good reving benefits over stock.

I mean, unless you are superman at shifting, i think the revs will fall way faster during shifts.

I could be completely wrong though, so someone please chime in and correct me if i'm wrong, but thats just me trying to think logically, lol.

 
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thats right.... revs fall faster because of the lack of intertia. the benefit if that when down shifting, the revs fly up real fast. the down side.... many if you're talking about a street car. when you let of the gas in gear, the car will slow down faster. you'll get that jolt of the car effect but even more so. (i believe this in the long run btw, will wear down the head) this will also lower your mpg because you'll have to be on the gas all the time to maintain speed. over all if youre looking for a race car, thats fine. for a street..... personal opinion. thats why ACT makes a "prolite" and a heavier "street lite"

 
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i wouldnt reccomend a flywheel for this car. it makes it hard to keep the rpms up. and it doesnt like to make power until your in the higher rpm range. it does rev quicker but for DD use dont do it.

 
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Ill vouch for that.. act prolight flywheel *only like 1.5lbs ligter than that of a type R* but its more responsive when reving the engine up, and its a hello of a lot quicker to slow down, if your not giving it enough gas and the clutch is fully engadged it can jerk too. Kind of anoying but worth the extra money in my book!

 
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LIES!!!

I love my 7lbs fidanza flywheel! 4 puck clutch for the WIN YALLL!!!

Hey Fam!

 
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I heard that a light fly wheel will affect the internal balance of the motor

 
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I used to have a 9lbs flywheel (stock was 21lbs) with my boosted Taurus SHO I didn't mind it, however, the car was a little harder to get going. I had to ride the clutch a little bit longer than normal. Revs come up and go down quicker due to lack of stored energy.

The biggest problem I found with my aluminum flywheel that caused me to change it back to stock was that the clutch I used seem like too strong for the flywheel. The clutch I use has a double diaphragm (two sets of pressure plate fingers, stacked) which give the clutch 3,500 lbs of clamp load. The flywheel didn't like that since it was aluminum. It puts a lot of stress on it and it flexed. One of my friends had he ring gear fall off.

Considering the Civic is fairly light and the power levels you're looking at don't include 600hp/500tq + you probably won't need such a heavy duty clutch. I think the biggest problem you'll see is taking off from a stop.

 
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taking off is a bi*ch!

 
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That's ONLY if the motor was externally balanced. In many cases, a lot of small block V8's are done this way. I would assume that Honda balanced these motors internally, which means you can mess with the flywheel weight all you want as long as the flywheel is balanced itself.

 
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learn somthing new everyday.
How would you get the FW balance?

 
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Once the flywheel is engaged, you'll have MORE available power being transmitting through the driveline. The only way you'll see a gain with a heavy flywheel is when you're actually revving up and engaging the flywheel. Again, once you're engaged, you'll lose torque to the wheels with the heavier flywheel at ALL RPM's.

It's not hard to keep the RPM's up and it makes rev matching much easier.

 
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You would be correct. Well at least the small block v8 part. Mine has a 50oz weight bolted to the flywheel, and that balances everything out. If i had to guess, i would say that the d17 is internally balanced, external balancing is kind of old school.

I would also be against this flywheel for your car. Thats just another piece you could have bought for a k20 swap.

 
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Most, if not all flywheels will be balanced from the factory. You can tell when they've been balanced as they'll have drill marks in them (generally on the outer edge). You could always take it to a machine shop and have them check/balance it.

 
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Yes, but the other side to that is, you have got to be one hell of a driver, in order to keep the RPM's up between shifts. That means either powershifting it everytime, or being lightning fast, and if you have a stock shifter, thats def. not an easy thing to do. And since, he said this car is going turbo, you really need the RPM's to stay up in between shifts, to keep that turbo spooled.

 
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I think a competent driver will be fine.

http://vids.myspace.com/index.cfm?fu...eoid=810055580

http://video.ls1tech.com/iplayer.asp...F-FC5F034A0C72

http://vids.myspace.com/index.cfm?fu...eoid=564043643

 
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i have the streetlite and its like 11lbs and its harder to keep the car going when launching. if your not powering through every shift you will lose momentum. taht is what i mean. it gets difficult for my wife to drive all the time. she complains about the power loss. but what i have found is her complaints are on the under revved motor not making the power. i told her its not going to make power in that gear at that low of an rpm. and if your on edge of the shift point or just below the threshold then you have to slip the clutch to keep the rpm's up in the power band. its a pin sometimes. especially if you have to sit in traffic everyday like most in cali do...



and hey blk have a couple on me LOL if you ever come to cali man hit me up for sure!! LOL

 
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for damn sure!^

Ill make it over to cali some day...

 
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thanks for the info guys. I already have a prolite flywheel now, but the car is still n/a. I've actually come to like how it drives now. Worst comes to worse if I dont like it I could always put my factory one back in I guess.

 
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i have the fidanza 11lb one. its great i love it, i noticed the difference as soon as i started up the car. its a real bitch though to go in stop and go traffic, you have to rev the car up kind of high to get it started. i dont know what everyone else feels about launching but i feed good launching my car with the flywheel. i dont think you want the 7lbs ones because your car will go through the rpm band too quickly and you wont be able to boost as long. imo stick with the 11lb.~

 
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To answer your question. Rotating mass takes energy to spin it from one RPM to another. Therefore, it takes power from the engine that could otherwise be used to accelerate the vehicle.

The significant measure of rotating mass is called the mass moment of inertia. To keep it simple, weight is bad, but weight farther from the center-of-rotation is much worse. The mass moment of inertia is measured by the mass (weight) multiplied by the distance between the weight and center of rotation squared. For instance if you had a weight of 10 pounds mass, 5 inches from the center of rotation, its' mass moment of inertia would be 10 lb x 5 in x 5 in = 250 lb in^2. That same 10 pounds only one inch from the center of rotation would only have a mass moment of inertia of 10 lb in^2 (96% less). This is why lower diameter flywheels are an issue and heavy larger wheels can have an effect.

When you were a child you may remember playing on hand pushed marry-go-rounds. Kids would stand on them and other children push to get them spinning. You may also remember that it was much harder to push when there were more kids on the marry-go-round and they stood near the edges.

Now for the stock flywheel. I am told the stock flywheel has a mass moment of inertia of 280 lb in^2 and I used this value in these calculations. Let me warn, the effect of rotating mass is not constant for RPM or road speed. In other words, the effect in 1st gear is different than second, and in any gear the effect changes with speed. This is why, if anybody quotes a given horsepower savings measured on a dyno, it is not accurate because chassis dynos DO NOT simulate accurate transients. They measure horsepower at the wheels just fine, but they can not measure the effect of a lightened flywheel, tires, or wheels. They will measure a difference, it just isn't accurate. But it is easy to calculate the difference.

From simple calculations the stock flywheel (280 lb in^2) takes 10-20 HP to spin it while accelerating in 1st gear. In second gear it takes about 5 HP. In 3rd gear it takes 2-3 HP. Therefore, if your lightweight flywheel had half the stock flywheel mass moment of inertia, you could save half the above values. To me, this would be more significant in a 1/4 mile run where the launch and 1st gear is very important. On a road course, not as important.

You might wonder why 1st gear is so much larger? The most stock engines (B or D series) spins from idle to REV LIMIT in less than 4 seconds (give or take) in 1st gear. It takes a lot of power to spin this mass to high RPM very quickly. In 4th gear, the stock flywheel takes 10-20 seconds to go from MID to REV LIMIT RPM, therefore, much less power required.

A transmission can be thought of as a fulcrum and lever in a car. First gear has a really long lever; second gear has a shorter lever, etc. The lever represents the mechanical advantage that gears give your vehicle. When your car is moving, you have two factors that are present during acceleration, one is driveline losses, which are constant and the variable, which is vehicle weight and the mechanical advantage supplied by each gear. We know that within reason, vehicle mass is a constant. Now imagine if you reduced the driveline loss from 45 to 35 with the use of a lightweight flywheel. Since the engine has less drivetrain losses to compensate for, this means the "gained" horsepower can be applied to moving the vehicle mass. Using mathematics, one can realize that the higher you go up in gears, the less effect that a lightened flywheel will have to the overall equation.

While the performance characteristics of a lightweight flywheel seem to be the perfect solution, there are compromises. Low end performance is affected. This usually means that higher revs are necessary for smooth starts due to the reduced rotational mass. For drag racers, this can be a BIG issue.

 
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And there you go!!!^^

Id rep you but I dont know how with the "new" 7th gen.

 
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I ran streetlite and loved it now i am going prolite so we will see how it does.

 
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well can you keep me updated on how you like.