SD_EM1

i'm planning on purchasing a new flywheel for my civic si soon and was wondering what suggestions you guys had for me. the flyhweel that i'm considering is the ACT flywheel, but i can't decide one whether or not to get the 8.8lb (prolite) flywheel or the 12.5 (streetlite) flywheel. can someone please layout the pros and cons of each flywheel? also i've heard rumors of flywheels breaking under intense usage. can someone verify this rumor? thanks in advance.

skribblah

never heard of a flywheel breaking. but there is a GIGANTIC debate about lightweight flywheels. but i would go for the 12LB one. not the 8.

SD_EM1

thanks for the reply. can you link me to where the discussion is at? if it's on the board, sorry for not searching hard enough. thanks

<edit>wait i believe i found the thread. sorry about that


Modified by One Slow Civic at 10:11 PM 7/27/2003

irev210

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by skribblah &raquo;</TD></TR><TR><TD CLASS="quote">never heard of a flywheel breaking. but there is a GIGANTIC debate about lightweight flywheels. but i would go for the 12LB one. not the 8.

</TD></TR></TABLE>

why would you go with the 12lbs one? Out of experiance, or are you just saying what "you heard on the net" like that harmonic balancer bullshit..

Okay, speaking from experiance here...

I would go with the 8lbs flywheel unless your going to be a DRAG ONLY car. Ive had from 8lbs to 14lbs to 19lbs... I had the most fun with the 8lbs one personally, I found it was great for daily driving and not as killer as everyone makes it out to be. Its just like stock for daily driving when just at a stop goin to 5mph and back to a stop. The difference is when it comes to rev matching, you are able to actually rev match faster then ever, and it makes it fun rolling into a turn downshifting from 4th to 2nd and just buzzing through a turn.
The only DISADVANTAGE with a really light flywheel is the rpms drop so fast, your car drops to about 500rpm then kicks back up to 800 when you push the clutch in. Atleast it did for me, maybe I had an abnormal car. I dunno. I only comment on **** I have experiance with.

I had an exedy billet chromoly flywheel tested to 15k RPM, I couldnt see it shattering. The reason why alot of flywheels fail is because after alot of heat buildup, the ring gear which is a press fit onto the flywheel heats up and has a different rate of expantion then the metal used on the flywheel. Aluminum flywheels are great examples of this.
The exedy flywheel has the ring gear milled onto the flywheel so you dont have to worry about that.

ACT makes a nice flywheel aswell.

Summery:
Looking for something a lil better then stock, 12.5 will do just fine... looking for something to have fun with, 8lbs for sure.

mmuller

get the 8.8 pound one, i have it and its great, besides the idle thing that irev210 sayd, i got that too.no biggie though.

irev210

k i was worried I was the only one w/ that problem hehehe

thx mmuller, someone else who is actually speaking from experiance....

I hate people that just feed off of rumors and what "other people said" etc

Rocket

Make sure you upgrade your valvesprings with the lighter flywheel and avoid compression braking and downshifting where possible. This really kills your head and connecting rods.

vtec_r

get the 8.8 I have it and I love it . I installed it a year ago.

SD_EM1

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Rocket &raquo;</TD></TR><TR><TD CLASS="quote">Make sure you upgrade your valvesprings with the lighter flywheel and avoid compression braking and downshifting where possible. This really kills your head and connecting rods.</TD></TR></TABLE>

i'm not questioning your knowledge or anything, but are new valvesprings really necessary? my engine is stock internal wise right now. i don't have any plans on changing the redline or anything... as i thought that that's what valvesprings are needed for: an increased redline, not a faster revving engine. are there any other people out there with lightweight flywheels running on stock internals? thanks in advance

AllmotorJunkie

I had an 8lb flywheel but it was too light for my setup. I lost some torque as a result. I recently went with a 12.5lb and I like it more.

Rocket

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by One Slow Civic &raquo;</TD></TR><TR><TD CLASS="quote">

i'm not questioning your knowledge or anything, but are new valvesprings really necessary? my engine is stock internal wise right now. i don't have any plans on changing the redline or anything... as i thought that that's what valvesprings are needed for: an increased redline, not a faster revving engine. are there any other people out there with lightweight flywheels running on stock internals? thanks in advance</TD></TR></TABLE>

Increased accelaration rates on the motor will float your valves. Valves can flow at 4k rpm as well as 8k rpms. Stock valves are way soft from the factory. Running a lighter flywheel make this problem worse.

aeolus

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AllmotorJunkie &raquo;</TD></TR><TR><TD CLASS="quote">I had an 8lb flywheel but it was too light for my setup. I lost some torque as a result. I recently went with a 12.5lb and I like it more. </TD></TR></TABLE>

How did you know you lost torque?Did you do a dyno comparison???I really can't see how an engine will loose torque from a lighter flywheel..

Rocket

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by aeolus &raquo;</TD></TR><TR><TD CLASS="quote">

How did you know you lost torque?Did you do a dyno comparison???I really can't see how an engine will loose torque from a lighter flywheel..</TD></TR></TABLE>

He prolly means that he lost flywheel moment (kinetic energy stored in the spinning flywheel). This will show up as bogging off the line in some cases or not chirpping the tires as hard on up shifts.

StinkyTofu

I've never heard of people upgrading their valvesprings because of a lighter flywheel. Can anyone claim that? I'm pretty sure there are a bunch of people here running even lighter flywheels with stock valvetrain. Lets get some more input on this from some people who have upgraded their flywheel.

AllmotorJunkie

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by aeolus &raquo;</TD></TR><TR><TD CLASS="quote">

How did you know you lost torque?Did you do a dyno comparison???I really can't see how an engine will loose torque from a lighter flywheel..</TD></TR></TABLE>

Thanks Rocket for helping me out. When I had the 8 lb flywheel, It indeed accelerated fast but there was no PULL. Plus I had alot of chirping noise too. I recently replaced the flywheel to a 12.5 lb and I really fell my engine pulling.

So I gained more rotational inertia by using the 12.5 lb and with my engine setup I like it more than the 8 lb.

So about torque...I guess I mistaken that for feeling pinned to your seat when you full throttle.

MikeSarr_GSR

I dont know, feeling a car pull in most cases is misleading. I have yet to drop it
on the dyno or on the strip... however my car is faster. I recently went to the
7.5lb clutchmasters flywheel and I love it. It takes a bit to get used to, but now
that I am I wouldnt go back. Good investment IMHO. Since I have GSR gearing
with my 165whp car any help I can get in the top of third and bottom to top of 4th
is very welcome

oh yea on the flywheel/valvespring issue:

vavletrain in GSR head:
ITR springs, LMAs on GSR valves and GSR cams.
I agree with rocket about the whole engine acceleration/valve float issue...
it just makes sense.

integraautox

I have a 7.5lb fidanza/clutchmaster flywheel. I would highly recomend going as light as possible. Unless you are going forced induction then I might reccomend a dhromoly one. Don't get a 12lb flywheel thats like buying an axle back exhaust instead of catback. Go 7.5lb

StinkyTofu

What rocket said does make sense to me too. I just never knew your acceleration levels would increase so much to the point that you would need upgraded valvesprings.

Rocket

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StinkyTofu &raquo;</TD></TR><TR><TD CLASS="quote">What rocket said does make sense to me too. I just never knew your acceleration levels would increase so much to the point that you would need upgraded valvesprings. </TD></TR></TABLE>

Think about what happens when say you shift from 3rd to 2nd at 50mph. If your rpm is 1000 rpms when your foot is on the clutch and then you engage the clutch your rpms shoot to 7k in less than 1 sec. Thats alot of engine acceleration. Your springs are not going to like it much. Also your rod/rod bearings won't like it either.

This is not just theory. I've taken apart heads with beat *** valve springs, guides etc and I ask the owners did you down shift and the answer was yes and do you run a lightened flywheel the answer was yes.

SD_EM1

alright everything makes sense now. so what would you suggest if i don't upgrade the valvesprings? not getting a lightweight flywheel and sticking with my stock one? or would 12.5 lbs be ok? or would that still pushing it on a stock valvetrain? how about a type r flywheel?


Modified by One Slow Civic at 11:58 PM 7/31/2003

SD_EM1

bump

MikeSarr_GSR

rocket,

what kind of downshifts are you talking about..? I downshift all the time and regularly. I understand the idea of bearing shear on hard, fast downshifts.
I can understand a mishift-over rev but normal every day downshifting?
I always match rev and double clutch so my engine doesnt absorb the full impact of rpm changes. I run a 10-40w oil also for a little extra cushion... for those of us
that run a 7.5lb-er how soon should we inspect the rod bearings? I just put mine in and my R block has 27K miles on it...

Thanks...

spoonek4

Some great info for me!

Keep the info coming please I want to learn more!

Rocket

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MikeSarr_GSR &raquo;</TD></TR><TR><TD CLASS="quote">rocket,

what kind of downshifts are you talking about..? I downshift all the time and regularly. I understand the idea of bearing shear on hard, fast downshifts.
I can understand a mishift-over rev but normal every day downshifting?
I always match rev and double clutch so my engine doesnt absorb the full impact of rpm changes. I run a 10-40w oil also for a little extra cushion... for those of us
that run a 7.5lb-er how soon should we inspect the rod bearings? I just put mine in and my R block has 27K miles on it...

Thanks...</TD></TR></TABLE>

Two types.

1) Compression Braking is BAD. Don't do it.
2) Down shifter where you "pop" the rpms up is bad.

Having a lighter flywheel allows for faster engine acceleration and in these cases it's bad.

1. is bad for you rod bearings, con rods, piston pins, valvtrain
2. is bad for your valve train.

MikeSarr_GSR

what exaclty is compression braking?&gt; nomenclature...

my guess is while under full threshold braking you let out the clutch to the friction point where you feel the clutch disk grab and use the motor/clutch assy and the brakes to stop the car.. I stopped doing that a long time ago when I got some real brake pads/fluid in my car. I used to do that ALOT and my B18C1 block spun a rod bearing. I never FULLY realized this could have been a cause. I had an ITR flywheel on it with a ACT HD/SS.

when I threshold break now it is usually from 80mph or so in 3rd or 4th. I will stay in that gear and brake with the pedal to the speed I want and then double clutch or match rev when I downshift.

it kinda depends, its a timing thing.

so have I accurately described this compression braking? if not, please explain.