jaehyun127

i'm looking to get the SR Motorsports Lightened flywheel and counterweight and their extreme clutch and pressure plate package installed -- so i've been calling around shops that have rotary mech's with at least 15 years of experience.

apparently, one of the mech's, before i even made an appointment ( i just asked for a quote ), advised AGAINST the flywheel...

he said that the rotary's aren't reknown for torque (obv.), and that the way their flywheel is designed, it's not meant for rotary power. He said that although throttle response will and might improve, that the car will seem very sluggish at low-mid rpm's... but esp in the low RPM's... even more than now.

I want to go w/ the SR package now b/c 2 ppl had problems with the RB setup -- they were flawless, now their image is tarnished (imo).

Has anyone else heard about this problem with the rx8 tranny?
i mean, many, almost ALL the people that have upgraded to the ligthend flywheel have commented about how they love it, and no regrets, etc... Heck, MS even makes one.

feel free to share opinions.

neit_jnf

less inertia means you'll need to rev higher to launch it and may bog down easier

Kicker774

Yes the topic comes up often on the Honda board I frequent.
I can't vouch for RX-8s but with Honda's people who upgrade to a sub 10 lb flywheel notice a big difference on the downside with their daily drivers. Always having to keep the revs up or it will bog down as noted above.

15 Lbs is about average for sacrificing some daily drivability for more performance.

Your Results May Vary

teebee

I have the MS flywheel, it's lighter than stock however still "heavier" than other lightened flywheels. I think it makes the car drive better. It revs up much faster now and just makes it feel easier to accelerate. Yes I guess you could argue that at very low RPM (say under 1500) that there is less torque, but it's not noticeable since you are reving up much faster anyway.

jaehyun127

i get NO power at like 1.5k as of now... my car lurks and tries to die, until it gets to at least 2.5k.
anyways, the SR motorsport flywheel is 9.75lbs, and they say that it's not like the very very light flywheels that aren't "Streetable," but rather, conveniently --fun to drive.

rotarygod

I've had 2 rotaries now with 9lb aluminum flywheels (not including the counterweight) and I love them. I've had them on nonturbo RX-7s which lack a ton of power compared to the Renesis. I see no issues with them at all. There are different viewpoints on which flywheel to use but I've never heard anyone say not to use a lighter one at all. To say that a flywheel isnt designed for a rotary engine is pure crap. The type of motor is irrelevant. I do believe for street use you can get too light but I don't feel the stock one is anywhere near as light as it should be. If you are a drag racer you may want a heavy flywheel to help you get a good hard launch but they really aren't that bad on the street. I'd get a new mechanic.

jaehyun127

well, i'm waiting on the other one... this mech actually drives a rx7 (i believe). but yea, i agree with everything that you've said. But for 1/4 drag's heavy flywheels are better for launch?? how so?

but on LI, there's not that many experienced rotory mech's...

army_rx8

i had the ms flywheel didn't notice anythig negative about it at all (the clutch gave it some wear and i'm resurfacing it right now which is why i said "had")

jaehyun127

wasn't Racing Beat's merchandise "bad" or whatever? i mean, i remember reading about you ( i think ) and another person having the same problems b/c you guys used rb's goods... the brand is tainted to me now... it's a shame.

it seems that SRMotorsports' stuff is: exedy pressure plate (extreme: and same as RB), but their Clutch is by ACT. i don't know what stage it is, but i know that it's extreme application. the fit and finish on that unit is basically perfect...

and as many already know, their flywheel is ridiculously overpriced, but it comes with interchangeable parts (so you dont' have to resurface? and u can just replace worn parts).
i just like SR now b/c their goods are of really high quality -- they are very overpriced for an introductory firm though.

army_rx8

RB's pressure plate is made by exedy, and their street/strip disk are made by clutchnet...good stuff....dunno why they didn't work out for me..hopfully RB's engineers will have osm eanswers when i call them tomarrow to get the 411. Rb's been doign this for about 35 years or so...so they do good stuff....but anythign man made can have defects..adn at times will fail for no good reason......you just have to keep rolling the dice.

besides teh stock set up is good for about 220 ft/lbs of torque so abotu 330 hp....(took the numbers off what anouther forum member said)...stock pieces are both made by Exedy :D

so i'd just get teh mazdaspeed flywheel...or whichever one you want...keep the stock clutch. every turbo i've seen is still running the stock clutch assembly..so even if you went FI it'll last for a while (not sure how long though)

edit:Rb flywheel comes with a removable friction plate as well...and i think mazdatrix.com sells a flywheel where you can change out the friction plate so you don't have to resurface teh flywheel...there's anouther on to check out. :D

Ajax

more mass = more weight = more low end torque = better launch
more mass also = higher moment of inertia (higher resistance to angular movement) = slower revving (longer time to rev to red line)

so if we do math T = I*(dw/dt) where T = torque, I = moment of inertia and (dw/dt) is the change in angular momentum with respect to time.
A heavier flywheel will have a higher value for I and thus more torque when angular momentum isnt changing rapidly enough to overcome that value. With a lighter flywheel (dw/dt) is going to be capable of large enough to overcome a large static I, however, I is always constant.

so in essence what you get is with a lighter flywheel you have a lower I and a possibly greater dw/dt (because it takes less time to rev to red line).

army_rx8

^ oo i like math :D

but very valid points...most top end drag cars i knwo of don't have super light flywheels....but it all depends on what you are going to be using your car for...i do daily driving aroudn town....not a lot of drag racing (only done it once in almost 2 years)

jaehyun127

it's scary when you think that physics can be applied and can explain almost all functioning aspects of our daily lives ... ::shiver::

i hate physics - math, eh. - econ = future major...
i loooove business though -- market economy excites me

Razz1

Ah..... there are several people that have the RB flywheel with no problem.

I think your barking up the wrong tree. I would bet there is nothing wrong with RB flywheels. I think it has to do with the clutch or the install.

Ask around and you will find plenty of satisfied customers with the RB flywheel.

jaehyun127

Actually Rzz1, you're absolutely right. i am barking @ the wrong tree.. haha, i didn't mean flywheel. their flywheel seems sturdy and well built -- but i was talking about the clutch indeed. exedy is reputable though, but 2 consumers and 2 same instances... makes me wonder still.

i dont' know -- rb is good though -- they were the first to actually put out "real" numbers for their gains, so they are honorable... so we'll see what happens and how they remedy this situation

jaehyun127

i re-read, and i don't htink i've ever bashed RB's flywheel. just the clutch and possibly pressure plates they were providing. i was just asking about how heavier flywheels = faster launch

Hey Ajax, i know that you said that heavier Flywheels lead to faster launches, but what if i take the lightend flywheel, and dump teh clutch at a high rpm, and @ redline, shift, etc. when you dump the clutch, aren't we going past the fast launch b/c we're breaking the co-efficient of friction and were just slipping... but once the tires grip, then quicker revs = faster times?

monzter

I experienced this with my previous vehicle after switching to a lighter flywheel. Car had a tendancy to try and bog a bit easier unless I got the rev's up high. Which then led to me losing traction. My 60' times actually improved when I went back to the heavier stock flywheel.

dmp

...and who gives a rat's *** about 'low rpm power' - the car has 'nearly none' anyway as-is.

(shrug)

Downshift!

army_rx8

^hahaha true true..........rx8 = high reving why bother with such a small end of the fun spectrum :D

MadDog

word. haha. Even on casual starts I'm above 1500RPM.

Get the friggin' flywheel. I can't remember a single person on this forum who got one and wished they hadn't. There are dynos that prove it reduces drivetrain losses. The 'reduction in driveability' is a bunch of bullshizzle. There are lots of threads to this effect.

neit_jnf

who drives around at 1500 rpm anyways?

rotarygod

The reason why a light flywheel isn't necessarily the best thing for drag racing is because it is harder to launch off the line. There might be a tendancy to bog a little. Many drag races are won or lost at the launch so it is very important that you get this part right. No a car with a heavier flywheel can't accelerate as fast as one with a lighter one, but if you were to put them against each other in a race and had the heavy flywheel car get a good launch and the light flywheel car bog even a little, the heavy flywheel car already has a head start. The light flywheel may or may not be able to catch it by the end of the track. The heavier flywheel car could be launched very good but it has far less room for error. Alot of drag racing is also based on consistency. You'll get that with a heavier flywheel.

I don't drag race anyways and fell it is a waste of time without a large engine. I obviously love a light flywheel. The car is alot more fun to drive. It just feels like a new car. It responds to throttle inputs much faster and gets a race car feel to it. I'm never concerned with how fast I can get off the line anyways. I don't street race. A heavy flywheel might be a little better to launch with but the light flywheel is better everywhere else. I for one do all of my driving while actually moving and don't spend alot of it trying to initially get moving. A road longer than a quarter mile seems a lot more fun this way and you never launch hard in traffic.

jaehyun127

good info. i'm looking about roughly $350 for install of the flywheel, clutch, pressure plates, and counterweight... is that "expensive" for the install?

teebee

That seems pretty cheap to me. Hope they know what they are doing.

juikster

with what has been said through out the discussions here it obviously not in ones best interest to spend xxxx.xx amount of money for a lightened flywheel assembly, or any other mod. if all someone wants is a thrill with what comes stock and that extra power edge is not important... But, on the other hand unless money is not an issue,(and in fact in most cases it is) it is know dought, all out nut crunching results is the main objective Its an all out power war, and who can come up with the best configuration that can obtain it is king. :D