freddiet

iTrader: (1)

I don't see how he got that backwards at all. When drag racing you want a lightweight flywheel. Mainly because the only time you start to loose momentum is when you are shifting. And when drag racing you are shifting quickly. But I really don't know anything explain to me how he is wrong and maybe i will see the light also...

ACTman

iTrader: (5)

We are offering two versions:
Prolite: 10.1 lbs but approx 17% thicker behind the friction surface (better heat tolerance)
Streetlite: 13.1 lbs with weight taken from the perimeter. It is over 50% thicker behind the friction surface (very stout for heat dissipation)
Prices will be competitive. One piece chrome-moly steel.
For reference, the stock is about 14.5 lbs.

Monkey

iTrader: (5)

heavier flywheel retains inertia. Inertia keeps the revs from falling off. Anytime you shift, you stay in the power band instead of having to get back into it

jdmevo8313

i get my info from experience and also the fact that i go to a automotive college, and im actually in a class right now called manual transmission and drivetrains. a lighter flywheel, will help u rev much faster and create boost faster also, but u mainly want that if u mostly drag race ur car, a heavier flywheel will actually take longer to rev but as u down shift or up shift ull already have the boost there and also the power.

'ringmeister

iTrader: (25)

for road racing you want the lightest flywheel possible. even world challenge cars cars that do standing starts use very light flywheels. it improves accel (although that is diminished in higher gears) better engine breaking, better throttle reponse. in drag racing, in theory, a light flywheel would allow better acceleration (ETs) but remember that when reving before engaging the clutch the flywheel store energy in the form of inertia. so a lighter flywheel means you need to launch at higher rpm. this can be problem in cars with lots of traction. for example, adam saruwataris(?) old rx7 drag car that was one fo the 1st imports into the nines. he ran heavier than stock flywheel to help launch the car. in our cars traction is usually not a problem, bogging is. so lighter flywheel may make an evo harder to launch. i'm not a hardocore drag racer so those that are should really chime in.

ACTman

iTrader: (5)

I am not a hard core drag racer, but there are at least a couple schools of thought. With a heavier flywheel, you are able to store up power in the form of inertia before the light turns green, and this inertia is what helps the car to launch so you don't have to feather the clutch. You can overcome the lack of weight by increasing launch rpm, but that isn't always advisable. The extra weight also helps in the gear changes to thrust the car forward instead of falling on it's face a bit. This comes at the cost of acceleration especially in lower gears. This is because some power is being stored in the inertia of the flywheel instead of accelerating the car.

My own opinion is to go as light as you can and still maintain consistency. On Brent Rau's car, he ran a conventional clutch and flywheel to around 7.5 sec. 1/4 mile times, with a heavy flywheel. The heavier flywheel helped him a lot off the line, especially with the traction of those huge tires and four link suspension. Gearing also has a lot to do with the choice too. With a shorter (lower speed) gear it doesn't take as much inertia to get the car moving. Of course there are tradeoffs with that too.
When Brent went to our slipper type unit, the additional weight wasn't necessary since the clutch is programed to slip at lower rpms and grab as rpms go up, so we chose a much lighter assembly. Brent recently became the first Pro Outlaw car in the 6's. Sorry, I had to throw that in.

berkel

iTrader: (5)

Sweet, thanks for the info!

Darn, now I don't know what version to go with. I was very happy with an extremely lightweight flywheel (~8-9lbs IIRC) and ACT clutch in my Integra. I did not have any driveability issues that people often complain about. Also, I kind of want every potential bit of gain I can get, so I'm leaning heavilly towards the prolite.

I'm torn though, since the Streetlite sounds like it's lighter enough to make a gain, but has much more material which would presumably improve wear and reliability? The 17% and 50% must be compared to the stock flywheel, right? Still, to save ~4 lbs vs the stock setup is very tempting. I think I'll be happier with the Prolite since I had a favorable experience in the past, but of course this was a 1.8 liter N/A car vs the FI Evo. Hopefully I'll start autoxing more next year, but for the most part the Evo is "just" a daily driver...

Any insight is appreciated.

Take care,

FB

Booztd 3

iTrader: (15)

Too bad the ACT ones arent coming out for roughly 3 weeks or so, I'm ready to buy something now, the clutch started slipping last night, and its still doing it (on the way to work today)

I need to replace the clutch ASAP and it would be nice to just do the flywheel

ACTman

iTrader: (5)

Yes, this is compared to stock. The Streetlite is more tolerant to heat from slippage and you will notice a slight improvement in engine response. It is not going to warp as easy as thinner flywheels. The Prolite will give you a more dramatic increase in response, and a slight increase in heat tolerance. As long as you know your driving style and respect the limitations of the clutch parts, the Prolite is going to be better for autocross. If you drag race, it is going to be more difficult to have respect for those limitations and more heat capacity is recommended, so the Streetlite is better IMO. By having some inertia, you can launch at a lower rpm and with less intentional slip than you would with an ultra-light setup.

TrinaBabe

iTrader: (3)

You must be assuming that people that drag race let off the gas between shifts There are not many people that do that when trying thier hardest for a good ET so that is completely irrelevant for drag racers. And trust me, I am still in the powerband when I shift... my gears arent that far apart I drop to about 23psi from 27psi between shifts. And for any other type of racing you could get good and hold the throttle on lightly between shifts instead of letting all the way off.

Granted the heavier flywheel will help launching (Makes it easier... not neccessarily better). All it does is make the car launch at lower RPMs more consistantly, you could just slip your clutch and do the same thing but that isnt as consistant as using more wieght spinning to do it. Eitherway it is doing the same thing, just in one case you need to hold the clutch differently and not dump it off as fast.

ACTman

iTrader: (5)

The first of the ACT flywheels shipped this week. They are selling faster than expected for this time of year. We had a record shipping day today partly because of the new flywheels. Get them while the getting is good!

x838nwy

I know this was some time back, however I just thought I should point out that the mass of the flywheel does _not_ give a complete picture of what the rotational inertia (aka the flywheel effect).

The Streetlite is only a little lighter but as it is thincker in the centre and most weight taken off around the perimeter, should have considerably less inertia than the stock unit which might be enough for road applications (as the name suggests).

The thicker clutch surface has more to do with heat retention/dissipation rather than allowing for wear. You can only wear it down as much as the clutch can engage properly (springs have limited travel).

Actman, we meet again on the same topic. Is it possible for you guys to post up the inertia figures rather than the mass?

2literv8eater

iTrader: (6)

I don't have one on the Evo, but I have the ACT flywheel on my AWD Talon and it feels great for daily driving. The car is more responsive, especially at low RPM's, faster spoolup with my laggy 18G and it just smoothed out, on - off throttle feel. Very worthwhile mod in my opinion, when it's time for a clutch a lightwieght flywheel will accompany it.

ACTman

iTrader: (5)

We design our flywheels in Solidworks which is a 3D modeling software. It spits out MOI (moment of inertia) with no trouble. The problem is that we have to draw up the stock flywheel in Solidworks in order to make the comparison. We desire to do this for every application, but haven't yet for sake of time. It just hasn't made it to the top of the list yet. I think I may have my engineer go ahead and do it for the EVO flywheel since there is so much interest compared to most applications. I will try and keep you posted.

x838nwy

Yippeeee!!! We use Solidworks too!!! Look forward to the info.