[cervan]

Ya I did spin the tires a lot with the lightweight flywheel actually. What clutch do you run?

im running the 6 puck 1md from action clutch. Its a very grabby clutch, i suppose if i ran a full faced disc i wouldnt have such an issue with the lightweight flywheel. But since i cant really slip the clutch its tough to find the perfect balance when taking off.

 

[patprimmer]

The lightweight flywheel does not in itself change clutch durability, but it does make it harder to drive without working the clutch harder AND this does tend to reduce clutch life.

 

[transzex]

A stock CX flywheel is 12lbs. Maybe find one of those used if possible.

Again wrong info, no beer for you.

As has been covered before, General OEM flywheel weight is 18 lbs. 92-95 CX/VX are 15 lbs.

For street and strip 12-12.5 lbs worked the best for me with a stock or Centerforce Dual Friction setup. The new Action 1MW that Aquafina just posted is the same concept. Slips enough at FULL THROTTLE launch ON SLICKS but maintains stored energy. If the car does not 60' and 330' the lighter flywheel will not gain it back on the top end.

My CRX cam with a Stage 2 clutch and 7.5 lbs flywheel, TOO much for NA or 75 shot on a stock 1.6L. The driveline shock may snap an axle. For Autox the light flywheel is PERFECT yet a PITA to drive at times for me.

That said I have a 10 lb steel flywheel that will go in with a CFDF setup I got with the HART motor. The lighter 10 lb flywheel with 1800 lb car vs. 12 lb and 2100 lb car (both before my fatass!) should be a perfect match.

Finding the perfect balance, few seem interested in finding it. Reread through BigTuna's posts, there are tidbits of hidden info in there.

Heavy PP with OEM disc or OEM PP with stage 2 disc? Both react differently and depending on the starting line prep can make a difference.

The clutch person in the top ranks of NHRA/IHRA is VITAL to the car gets down the track or smoking the tires at the hit.

If you compare some of the big shots intervals, from 330' to 1320' they are very consistent. Getting 1100+ whp planted that first 330' is EVERYTHING!!!!

YING/YANG

 

[psjones13]

The lightweight flywheel does not in itself change clutch durability, but it does make it harder to drive without working the clutch harder AND this does tend to reduce clutch life.

That is exactly what I was thinking, and why I posted the second question. Thanks Pat.

Again wrong info, no beer for you.

As has been covered before, General OEM flywheel weight is 18 lbs. 92-95 CX/VX are 15 lbs.

For street and strip 12-12.5 lbs worked the best for me with a stock or Centerforce Dual Friction setup. The new Action 1MW that Aquafina just posted is the same concept. Slips enough at FULL THROTTLE launch ON SLICKS but maintains stored energy. If the car does not 60' and 330' the lighter flywheel will not gain it back on the top end.

My CRX cam with a Stage 2 clutch and 7.5 lbs flywheel, TOO much for NA or 75 shot on a stock 1.6L. The driveline shock may snap an axle. For Autox the light flywheel is PERFECT yet a PITA to drive at times for me.

That said I have a 10 lb steel flywheel that will go in with a CFDF setup I got with the HART motor. The lighter 10 lb flywheel with 1800 lb car vs. 12 lb and 2100 lb car (both before my fatass!) should be a perfect match.

Finding the perfect balance, few seem interested in finding it. Reread through BigTuna's posts, there are tidbits of hidden info in there.

Heavy PP with OEM disc or OEM PP with stage 2 disc? Both react differently and depending on the starting line prep can make a difference.

The clutch person in the top ranks of NHRA/IHRA is VITAL to the car gets down the track or smoking the tires at the hit.

If you compare some of the big shots intervals, from 330' to 1320' they are very consistent. Getting 1100+ whp planted that first 330' is EVERYTHING!!!!

YING/YANG

Thanks for all that

 

[patprimmer]

One more point.

A lighter flywheel is a smaller heat sink, so the clutch heats up faster if you slip it to much. This also can reduce clutch life.

 

[psjones13]

UPDATE

Okay guys, I did a back to back comparison of the lightweight and stock flywheels. Every other variable was unchanged, other than the flywheel itself. Its a d16z6, 91 si cable tranny, Exedy stage 1 clutch, with the kevlar, sprung disk. Previously I had the exedy 12lb flywheel, now I have the stock 91 si flywheel which weighs approximately 18 # according to my scale.

I have to say, I really like the stock flywheel a lot better for daily driving. Things I immediately noticed: Smoother idle at lower rpm and when in neutral the revs don't drop as quick when revving. Driving: It takes a ton less work to take off smoothly. I used to feather the throttle a lot upon take-off and I was pretty good at taking off smoothly, but with the stock flywheel I barely have to feather at all. I just rev it up once and start letting the clutch out and it goes with no chatter. Shifting is very noticeably smoother going from one gear to the next while the clutch is disengaged and doesn't really jerk at all when going into the next gear when the clutch is released quickly. Rpms stay higher in-between shifts and I'm physically throwing the shifter slower now, which is going to mean good things when I'm racing and I am throwing it faster. One last thing, not that its a very important quality, but whatever, when on a totally flat road and at idle, I can let the clutch out slowly with no gas without the car stalling. Before that was impossible, at least some gas was necessary.

Acceleration is a BIT slower, but IMO it makes up for it by all the other previously mentioned qualities. Also, going up small hills does seem to be noticeably easier. I barely have to tip in the throttle to get over one. There are a TON of hills here so that's a great benefit to me. I won't be surprised if I pick up a little bit more mpg's now.

I think that's all. I don't think I'm gonna waste any money in the spring on putting a lightweight back on here.

I wish I would have intended to do this test and got some before and after datalogs to share, but I didn't, so sorry. You'll just have to take my word for it. :bigok:

 

[JerBear]

Cool! I was thinking about a Lightweight for my CRX but after that, I might just stay Stock unless a lightweight lands on my dooe step

REP psjones13!

 

[psjones13]

I forgot to mention before. It also doesn't "engine brake" as much as before. For example: there is a really long, not very steep, road down a mountain here that I travel frequently. Before when going down in 5th gear, totally off the throttle, the car would eventually slow down so much that I had to get back on the gas for a little bit to get back up to speed but then I'd let off again. That usually happened 2 - 3 times going down the road. With the stock flywheel I only had to just barely touch the throttle one time after some curves and that was it. I like that a lot, more fuel savings down hills.


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[Nasty_Canasta]

My vote made it a tie.

Better call in Rosie O'Donnell...

I voted for Ike because he was the smartest kid in the class.

 

[transzex]

psjones13, what I've been preaching for years you have just confirmed it.

I've ran 7 lbs to 18 lbs flywheels in my Honda's

BUT I got my best MPG with a 12.5 lb flywheel due to a TPS adjustment that allowed me to crack open the TP to limit the closed throttle braking when coasting. yet the ECU never gets TPS signal that it is opened slightly.

 

[007]

somewhat similar to the decrease in engine braking in diesels because of the absence of a throttle plate Bone?

 

[transzex]

I've only ever drove one coal burner and I believe it had a throttle plate.

Then again as a teeneager I watched a CAT motor run without an intake manifold or carb, I knew NOTHING about diesels at the time.

 

[007]

for a while now I have been thinking about adding a little solenoid valve connected to the intake manifold activated by a switch that would throw the solenoid open and switch the ECU to a TPS based map so that I could flick it on during highway driving and be able to coast that little bit longer. haven't gotten around to it yet but I will some day.

 

[transzex]

for a while now I have been thinking about adding a little solenoid valve connected to the intake manifold activated by a switch that would throw the solenoid open and switch the ECU to a TPS based map so that I could flick it on during highway driving and be able to coast that little bit longer. haven't gotten around to it yet but I will some day.

why all that?

Blundar's quick tune + my educated right foot = unreal numbers.

If refined there is likely another 10-15% more to be gained which is why I've been hanging onto the CRX.

 

[007]

why all that?

because of this:

The term engine braking usually refers to the braking effect caused by the closed-throttle partial-vacuum in petrol (gasoline) engines when the accelerator pedal is released. While some of the braking force is due to friction in the drive train, this is negligible compared to the effect from the vacuum.

When the throttle is closed, the air flow to the intake manifold is greatly restricted. The concept can be illustrated by the amount of effort required to blow/suck through a thin tube vs. a thicker one. It is the work the engine has to do against this restricted air flow that provides the braking effect.
[edit]
Diesel engines

Diesel engines do not have engine braking in the above sense. Unlike petrol engines, diesel engines vary fuel flow to control power rather than throttling air intake and maintaining a constant fuel ratio as petrol engines do. As they do not maintain a throttle vacuum, they are not subjected to the same engine braking effects.

in addition to the tune, if I can make the car coast for a longer distance with my foot off the gas and / or lose less speed while coasting, it wouldn't hurt. the trick as far as I see it is to stop the ECU from squirting fuel while keeping the throttle wide open, which should be achievable with a bypass valve and ignoring MAP input.

 

[psjones13]

Thanks guys.

When engine braking and I also apply the real brakes, it definitely feels like they have to work a lot harder than before. Makes sense, just wanted to note it here. I engine brake a lot and now I have to hit the brakes a little sooner than before. The car also seems to "buck" less at lower rpm cruising. Before if I left it in 4th around 2k rpms it would sometimes "buck" and I would shift into 3rd. I hardly notice that at all now.

Totally off topic, but about the diesel.. I know very little about diesels, but we have a diesel tractor, and I have a friend who is a diesel mechanic who has explained some things to me. Diesel's don't have a throttle plate, the engine speed is controlled by the fuel timing and amount of fuel dispersed. Our tractor will drive forever unless you put it in neutral, and it will not shut off until you shut off the fuel pump. IF a diesel has a plate in the intake tract, it's there as an engine brake only. It can be closed to help slow the engine down at higher speeds. It helps save the wheel brakes because they fail so often on big trucks.


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