flywheel weight
 

So I am finally getting ready to finish my engine build and am starting to think I might be fucking up so I am asking for your advice. The car is a daily driver first and foremost so driveability is paramount. I am married and this will be driven by my wife a lot, she is bitchy on good days and will make my life hell if the car is too twitchy or difficult to drive.

The engine is a ported VVT head with +1 valves on 8.6:1 pistons. This engine will have an EFR6258 on it in front of a 6 spd with 3.9 rear.

My question is this, what weight flywheel would you recomend and why.

The car is currently bone stock. My 94 has a complete VVT engine from a 2002 miata with a 11 lbs flywheel and it is a lot harder to launch than the stock 10AE. I bought a ACT prolight (9lbs) flywheel but am rethinking my decision. While I would love the quick revs but fear I am building a car that is not as much fun to drive daily.

Thank you for your input.

Imo, a clutch has a much bigger effect than a flywheel on driveablity. And all turbo clutches are much worse than the stock clutch (which is pretty much weightless).

A light flywheel just makes it harder to tune PID idle

I bought a slightly used clutch before I decided to do it right the first time. It is rated for 350tq I think. I hope it last for a while.....I am not going to push it hard on a regular basis. This is my wifes daily driver that I will take to the mountains on the weekends and will keep the boost down to make about 270ish whp. My next clutch will be the FM happy meal. I want a full disc sprung clutch for easy engagement. That is what the clutch I have is and the guy I bought it from (here on MT) said it has a very stock feel with only slightly stiffer pedal. I am also building a high compression NA motor for the 94 and am thinking the 9# ACT flywheel might make more sense in there? I don't mind a slightly higher idle but need a civil car...... I have no idea what to expect with this build and worry a little that the lower compression engine might not be happy with the reduced inertia.....

k let me rephrase it

your engine will not care about what flywheel is attached to it.

ANY clutch rated to hold 2-3 times the stock torque will NOT have stock engagement. It will either have a much heaveir pedal, a different engagement window, or any combination of the above. you and your wife will get used to it very quickly.

I hated my ACT.
I was okay with the FM2.
Flywheel wise if daily driver the answer is simple = stock flywheel. Nothing will be as smooth.

But Vlad, we all know you're a flapping vagina, so of course you hated it.

<-- 6-puck+light weight flywheel.

Will never do it again.

I'm buying an FM2 clutch next week with the heavy flywheel.

I like to not be sweaty and tired when driving my street cars, because they don't replace my wimminz :dealwithit:

dude, you have no idea
but if you're tired from using a high clamp load pressure plate, perhaps you shouldn't be driving during your critical days.

^ 1.6shitty and a 60lb/min turbo



yeah, i'll trust your opinion on clutches/flywheel. not.

yeah well I was supercharged when I did th....oh wait, I'm not helping myself.

ACT Clutch was never a option for me. I will do the FM2 clutch when that time comes but was thinking I should do the stock flywheel for "smoothness" as Vlad describes. It is not just about being able to drive the car but having a smooth daily driven car as well. So the ACT Prolite flywheel will go on my NA engine with ITB FTW.....

Welp you're the expert on miata's around here so we'll all trust your opinion.....wait no we won't cause no you're not. lol

For what it's worth I had a stock flywheel and went to 8.5lb flywheel and stock clutch. I felt, realistically, no difference. I know have a FM level one and the same light weight flywheel and I still don't notice a difference...even going from my car to thirdgen's car which I believe is the FM level 1 and stock flywheel. Only thing I notice is maybe it rev's a tiny bit faster in neutral, and its a little bit noisier when pulling away from a stop.

I notice a HUGE difference between the 11# flywheel and the 19# flywheel. So does the wifey. Am I really alone here? I wanted the quick revs to get me in boost faster but now I am concerned about driveability issues.

lower inertia doesn't get you into boost faster. quite the opposite actually. less load = less exhaust = less boost/spool

you're not alone. I've preached stock flywheel to all daily driven cars around here for years. fgts like soviet who daily drive "RACECAR" make fun of me but that's because they're frustrated closet gays who make up for their penis size by removing ps and ac and calling themselves manly men.

ILU soviet:giggle:

you require AC to cool down your multiple layers of fat, its ok, I understand.

btw I never said that a light flywheel is manly. I said it makes no difference in driveability.

You want this clutch. Its whats in my car. If no one told you any different you'd think it was a stock clutch with a light flywheel. Its not as light as the 949 super clutch but its the next lightest off the shelf clutch/fw setup. While its rated to 300ftlbs, I spoke with brian goodwin about it and he told me that they were actually pushing more out of that in one of the shop cars with no problem. At worst you could most likely call speed sport and have them make you one with a stiffer pressure plate. If I ever need to replace this clutch I'll likely do that, because the clutch pedal feels too light to me. Even though "replacing the clutch" involves pulling it out and replacing 16 carbon pads and putting it back in.

The 2 things I dont like about it is that the clutch pedal is lighter effort that I'd like now that I'm used to the wrx leg press machine stock clutch. And they packed it with the wrong clutch tool. But its just about as easy to drive as a stock clutch and fw, maybe needs a touch more revs but its so easy to modulate and predictable that I dont notice.

I just recently installed the 949racing "Sport" clutch with flywheel.
SuperMiata Sport Clutch Kit Miata BP

I really like it. Different engagement feel, but not appreciably harder to drive.

I have stalled it twice, but that is me avoiding slipping the clutch while in the 500 mile break in.

:rofl:

Full-face disc = lightweight flywheel
Pucked disc = stock flywheel

Make sure you get an unsprung disc too.

My old response to this used to be. Jesus no, but my clutch doesnt have one an I notice no real difference. Though some of that might be because of the carbon on carbon nature of the clutch.

+1 for the clutch being the bigger factor.

A pucked clutch is a lightswitch. There is very little engagement window, so if you use one with a light flywheel you'll probably hate it. This doesn't mean that the light flywheel is the culprit for the hit on driveability, though.

OP, go ahead and use a light flywheel, but pair it with a full-face, gentle clutch. I have the Fidanza flywheel and an ACT HD on my car and my wife drives it just fine.

I had reservations on the FM happy meal clutch/flywheel kit with the lightest flywheel....

Got it and loved it. Near stock engagement and zero idle issues, take of from standing start, hill start etc.

Zero.

Was a lovely clutch and kit.

+1. I've driven an ACT XT with a 9lb Fidanza and it was the shittiest clutch I've ever experienced (including my ceramic twin-disc). You could get the ceramic twin to the grocery store and back without getting arrested if you needed to, but that would be impossible with the XT/Fidanza combo. The only way to not stall it was to dump the clutch from 2000rpm and spin the tires a little bit.

I DD'ed a sprung 6-puck ACT HD with a stock flywheel for ~20k miles and it was a non-issue - took a little getting used to, sure, but not at all unstreetable. The stock-weight flywheel made the difference.

I now have a 9lb Fidanza with an ACT HD and a street disc in Rover, and it may as well be stock. Buttery smooth engagement, totally slippable, your grandmother could drive it.

TL;DR:

:giggle:
my car has a 9lb flywheel, 6-puck ACT clutch and XT "Xtreme" pressure plate
you'd LOVE it

in my defense, I paid $400 for everything

Oh I say I hate the XT and you call me a flapping vagina and Sav says the same thing and swing off those freshly dropped nuts like a kid on a playground

https://www.miataturbo.net/attachmen...ine=1369979153

:dealwithit:

Baby, It's not what it looks like
I treat you like I treat all my women

I have a 3.8kg (~8lb) TODA flywheel designed for a 1.6, plus a modified organic Exedy clutch. I daily drive the car and I find it's very drivable. The revs drop a bit quicker than normal but it's very easy to get used to.

It also sounds like a sports bike when you rev it in neutral. :giggle:

You say that, have you heard a car with the 949 twin disk in neutral. That revs like a sports bike.

I have an ACT XACT Prolight 10 pound flywheel and a SPEC stage 3 6-puck sprung 320 pounds torque clutch. Engagement point is nearly the same as stock, though it shudders during engagement unless you rev to 1500 or so. I drove it for 3 years in stop and go traffic, the only reason I stopped is because my shift changed and I don't have to stop so often. Yes, it sucked at first but it's painless once you get used to it. I don't even break over 1k rpm to get the car rolling anymore.

I like that my car shudders a bit when taking off from a stop, it lets my passenger know to https://www.miataturbo.net/attachmen...ine=1370020265

Until you have to start replacing parts that are getting pounded from all the shuddering and bogging.

I only get shudder if I try to slip it for longer than a second (e.g. creeping in 1st gear)

^ That.

Would you describe your wife using similar phrasing to the following?
So that probably makes his opinion the best proxy for Amellrott's wife's.

As a husband whose wife refuses to even ride in my car, let alone drive it (edit: because Miata, not because racecar), I would suggest you go with a stock or slightly lighter flywheel (e.g. the FM 13.5 lbs unit) and a full-face clutch if possible given the expected torque output of the setup.

Save the 9 pounder for your naturally aspirated build.

so much win
:bowrofl:

I have the FM 13lb flywheel and FM stage 1 clutch. Drives like stock. Pedal force is not high, engagement is smooth. My wife drives it with no issues. However, she drove a C2 vette to high school, and a manual trans 4wd K1500 GMC pickup for 10 years, so she may not qualify as a normal wife.

To be clear - what I understand your statement to mean is that believe the benefits of a lightweight flywheel to not be a worthwhile upgrade when you are already adding power with a turbo or supercharger.

I somewhat agree with you, but there are a few lightweight flywheel/clutch combos that will handle the torque without being "nasty" and in those circumstances I believe it is a worthwhile upgrade.

Drive the 949racing sport clutch with lightweight flywheel. Drive the Flyin' Miata Happy Meal. Both have reputations of being very street friendly while still having the benefits of a lighter flywheel and increased torque capacity.

In my opinion, with the right package a lightweight flywheel is a worthwhile upgrade.

I read nothing but the title in this thread, and here is my post:

I owned a car with the FM happy meal, with a 10.4lb fw (or whatever FMs lightest fw weight was) and loved it. I noticed zero drivability issues (note: no a/c or power steering). And the responsiveness was a huge plus while driving.

This is coming from a strictly street driven miata point of view.