There have been some threads about this, but not for a few years, and I'd like to get more people's opinion.

About to have some transmission work done. Thinking about changing my flywheel out while I'm down there.

I bought my setup used, and it included a heavier than stock flywheel, I think 34 pounds. Guy said it would hold boost better between shifts, but I don't like it. The engine obviously takes a long time to rev down, and it really bugs me while I'm driving, not to mention such a heavy flywheel robs some power. I want to install some sort of no-lift shift/antilag setup, so I'm really not that interested in solving this issue via flywheel.

Car has 6.0L LQ9 engine with mild cam and rear turbo, makes ~500hp now, turning the boost up for ~700hp once tranny work is done and meth kit is installed. It has a Spec 3+ clutch, and the engagement can be pretty shaky at low speeds. I typically start out in 1st gear at ~2000 RPM or the car tends to shake a lot. I suppose a lighter flywheel will make this problem worse. Although I'm going from MN6 gear ratios to MN12 gear ratios, so I would think that would help the issue also?

I like the idea of a light flywheel and fast revs, but I don't want to go so extreme that it kills the drivability. I don't really care about noise and clutch chatter.

Wanted to hear some opinions on what weight works best for a mild engine, and if there's any real benefit to a heavier flywheel on turbo'd cars. I'm mostly interested in drag racing, don't plan on doing a lot of road or track courses.

 

typically, I think you wanna generate some sort of LOAD on the turbo(s)....especially a rearmount. A quick revving setup, I don't think is gonna help you just like I don't think 4.11's would help you as would like, maybe a set of 3.08's would.... the load generated on the turbos from the longer gears,...would generate some serious torque.

Just my own experience(s).

 

Do you need a clutch to handle hard drag launches, or one to handle the power for semi normal usage ?

If the latter, get a modern twin plate organic. It will truly drive like stock, no ****ing about and easily hold the power you're making and intend to make.

Ive one of these in my LS motor, and it's great. Others favour McLeod offerings.

http://www.summitracing.com/int/part...-g01/overview/

http://www.advancedclutch.com/t2s-g01

If you need it to hold more or less power/torque, there are versions with a stronger or lighter cover, which will mean either more or less pedal effort.

 

I have a new McLeod Billet Steel flywheel for sale (fits non-LS crank, I ordered by accident) that is perfectly balanced and weighs 30 lbs. I have the corresponding LS version in my car (newly installed with RST clutch assembly and RPM trans) and it's awesome. Revs quick, no vibrations.

This flywheel would save you about 4 lbs of rotating mass while not being so light to cause problems like you stated above.

I'll sell this for $320 shipped, McLeod charges $371.00.

 

The problem is if you go with a light flywheel, it may give your tuner hell and they'll most likely overcome it by slowing down the throttle body return to zero, which may feel as if you still have a heavy flywheel.

 

I just put this exact clutch in mine, still breaking it in so I can't comment on it too much... I would like to get my car into low 10s eventually so I hope it will hold... I thought about using a race disc and an organic disc but too late for that now haha

 

Ive run 10's in my car, circa 3700-3800lbs with the clutch. Although it wasnt at a proper drag strip, so launches were limited.

60fts barely struggled to get under 2s

At that it certainly shows no signs of weakness though, so I'm sure it would handle a 1.7, 1.8 etc

Whether it would handle a lot of 1.4 or 1.5's with a heavy car at a proper strip I cant say, but I didnt buy it for that.

 

that's good to hear... I don't ever plan to get too serious into dragging the car, I just go a few times a year for fun... I also have c6z brakes so I'm limited to tire/wheel size which rules out slicks... I just want to leave it in street trim and do low 10's and I will be happy with that... last time I weighed my car it was 3150lbs with me in it and a half tanks of gas, this was before the blower setup and brakes so now I'm prob around 3300lbs

 

Can you explain this a little more? I tune the car myself, so I don't mind fine tuning for stuff like this. I have a bachelors degree in physics, but still trying to translate that knowledge into useful car/tuning knowledge

Are you saying the engine will tend to spin up and down too quickly, and so it may be necessary to reduce the speed of the throttle body to compensate?

 

A couple things, but first off a heavier flywheel will help spool just like a tighter converter does increasing the load on the engine as mentioned smoove. It will also make launching the car easier as it stores more energy and I recommend running one when stepping up to the more aggressive friction material needed to hold the increased power. A lighter one will require more rpms to take off increasing the glaze build up which produces the chatter you're talking about. It's counterintuitive, but slipping it less will actually cut down on the chatter after you deglaze it. A full face ceramic disc makes that harder to do as well as it weighs a lot comparatively and doesn't shift as quick. Hope that helps, don't hesitate if you have any questions about a Monster clutch.

 

I also had chatter issues with a spec clutch. I run a RPS carbon/organic twin clutch now and highly recommend it. drives like a stocker and holds all I can throw at it so far.
I will be running a slightly lighter and stronger flywheel on the stage 2 build. Have run light flywheels before; didn't like the way they drove on the street.
Our turbo cars need a little help getting out of the hole for dig racing, I think you will find the heavier wt will help the launch if you have the traction.
I also highly recommend the N2MD two step box. I can build 3-4# off the line, and with 3.90s and DRs it leaves hard if it hooks. Plus no lift shifting that keeps it spooled up while shifting.

 

Unless you are running a small diameter race clutch and matching flywheel, I doubt there is a flywheel/clutch package so light you would ever have idle, driveablity, launch problems etc.

By nature of the LS's clutch physical size and diameter, they are all bloody heavy, "lightweight" flywheel or not
And it's not like it's hooked up to a lightweight rotating assembly either.

As for a heavy or light flywheel affecting spool. With drive engaged vehicle weight is a lot more than the flywheel or clutch. So it wont make one bit of difference.

 

So yours revs like this?

 

No...but I dont drive like that either....and neither does the car in the video.

Because when your foot is on the clutch you have no drive !

 

I'm not sure what you mean exactly, but that's my C5 and it had a tiny 218/230 116 cam. It was such a drastic difference that it had to be completely retuned and caused me to drop ~.3 off my 60', great for rev matching on the road course though. Another thing to note lighter flywheel/clutch combo will also not absorb the the engine harmonics as much and can make bucking/surging worse with a large cam that has a lot of overlap. Of course it's not just total weight, but where the weight is located in relation to the point of rotation as well (MOI) and is what ultimately determines how drastic the change is...assuming that's what you were trying to say?

 

My first statement was very clear. As I said, Unless you are running a small diameter race clutch and matching flywheel, I doubt there is a flywheel/clutch package so light you would ever have idle, driveablity, launch problems etc

Clearly the clutch in the video you mention IS a clutch of that nature.

As for the comment someone made about a lightweight clutch affecting spool...it cannot.

 

I just don't like blanket statements of a "lightweight" clutch as the weight has to be relative to something. Our singles with the lighter weight flywheel are not that drastic, but still do a make a difference just not as extreme of course in the average vehicle. However the difference between a Gen1 CTSV dual mass OE clutch assembly that weighs in at ~74lbs and our lightweight single disc at ~44lbs (which is not a "race" clutch) is a similar comparison to a stock C5 clutch of ~52lbs and the one in the video at ~22lbs is all I'm trying to say. Where you draw the line is subjective, I just want to paint the full picture.