DXD flywheel & Lighter flywheel discussion

[krracing]

something i have noticed with the manual 125 ... pretty much no engine braking... take your foot off the accelerator and the car will slow down quite slowly as compared to our previous polo gti, its almost like its in neutral.
for my liking 1st gear is too short.

I'm curious about the DXD flywheel that APR provide - the engine compression in a turbo-charged motor will definately be less than that of a naturally aspirated motor to compensate for the extra compression/boost that is created, but even still, the Tig's 'engine braking' is non-existant!! I wonder if it's a very heavy flywheel that's amplifying this, hence my interest in the DXD flywheel that APR provide...

Might ask a few questions!

[Pullstarter]

I think you'll find the Tig TSI compression is the same as the NA 2.0, 10.5 IIRC? Be interested to hear what the engine breaking is like with an NA motor? Then again remember the Tig is quite heavy which would cancel out some of the effect, but you could be onto something with the flywheel, you need to buy one and tell us how it is

[Transporter]

I'm curious about the DXD flywheel that APR provide - the engine compression in a turbo-charged motor will definately be less than that of a naturally aspirated motor to compensate for the extra compression/boost that is created, but even still, the Tig's 'engine braking' is non-existant!! I wonder if it's a very heavy flywheel that's amplifying this, hence my interest in the DXD flywheel that APR provide...

Might ask a few questions!

The lighter flywheel will improve engine braking, but you will have to rev the engine more, also you will have to be quick on changing the gears or you would stall the engine. Install too light flywheel and and you will hate driving that car in the traffic.

I definitely recommend some reading on that topic, before you go ahead with the idea.

[Pullstarter]

Stall the engine with a lightened flywheel? Are you serious? If that were the case the engine wouldn't idle and I can tell you I've had 3 cars with lightened flywheels that have NEVER stalled. Don't mean to be confrontational but are you for real?

[Transporter]

Yes, I'm for real!
When generally speaking about lightened flywheels.

Unless you already have lightened flywheel in your Tiguan, you can't tell that it will not have any negative effects because every engine is different.

Stall the engine with a lightened flywheel? Are you serious? If that were the case the engine wouldn't idle

the engine would idle, but maybe not as smoothly, ...and you can stall the engine that doesn't idle properly when you change the gear or when taking off. I'm sure that many people experienced that the engine simply just cuts off when idle is erratic, either on take off or gear change. If it never happened to you; than you're a better driver.

It also depends how much lighter lightened flywheel is, engine still could run reasonably well, but you may notice some changes. So, if you tell me that it never happened to you, all I can say to you is that maybe your engine had some other work done and the lighter flywheel was part of that modification, in other words the engine was blueprinted.

How ever simple removal of flywheel on stock standard engine and replacing it with lightened flywheel (again it will depend how much weight was removed) may have some other effects.

Hmm, maybe in original post I should use the words "could stall the engine" rather than "would stall the engine"

[Pullstarter]

None of the engines in which I had a lightened flywheel were blueprinted and I had no adverse reactions whatsoever. I've been around modified cars for the better part of 25 years, even full blown race cars with stupidly light flywheels made of rare and exotic alloys and I have never encountered or even heard of this problem. We will have to agree to disagree on this one.

[Sharkie]

I can understand where you're coming from Transporter, but also agree with Pullstarter here ...

In compression ignition engines (diesels in other word), the weight of the flywheel may certainly have an effect on engine idling.

However (and I've also had a few cars with lightened flywheels) in modern spark ignition engines (petrols) the ECU controls the idling speed of the engine very effectively and automatically speeds it up as required and Ive never had an issue.

Before and after flywheel changes no difference at all to the idling speed. The big effect of a lightened flywheel in any petrol car is that the revs climb much much quicker and drops of dramatically after easing off the throttle. It won't stall on the way down as the ECU prevents that. What you do lose is torque .... and the ability to sustain motion uphill .... unless you have a turbo ....

I did have to adjust (very slightly ... 100-200rmin) the idling speed on a pre ECU 1800 16V Golf to compensate for the lightened flywheel, so this used to be somewhat of an issue, but in modern cars its no longer an issue ..... showing our age here Transporter ....

[Transporter]

Well, if that was that simple and without any ill effect on engine, don't you think that VW and other manufacturers would make lighter flywheels already? Instead, they go the other way - they make them heavier and dual mass.

And I hear you already they make cars to suit even the worst driver.

[Sharkie]

Well, if that was that simple and without any ill effect on engine, don't you think that VW and other manufacturers would make lighter flywheels already? Instead, they go the other way - they make them heavier and dual mass.

And I hear you already they make cars to suit even the worst driver.

Its all about cost and the lowest common denominator..... lightweight flywheels are made of more exotic materials and are much more expensive to produce .... 3-4x the cost of a normal one ....

And 99% of people will not appreciate the advantages you get out of a lightened flywheel.

So in VWs eyes, why produce something that costs more and given the fact that very few customers are actually performance enthusiasts, very few will notice..... especially if it is available aftermarket ....

Its all about the bottom line and not what is actually a better product ....

[Transporter]

Hmm, and I thought that flywheel is for balancing rotating masses, pistons, conrods etc.?

[Sharkie]

Hmm, and I thought that flywheel is for balancing rotating masses, pistons, conrods etc.?

Ummm ... no .... pretty sure thats what the crank and balancing weights are there for .... .... flywheels are much more closely related to the clutch ....

How 'bout you have a look here at what a flywheel actually does ....

HowStuffWorks "Fly Wheels, Clutch Plates and Friction"

and a comparison between lightened and stock

Flywheel - Does a lightened flywheel actually benefit your car | Basics | CHICANE CULTURE dot COM

EDIT: and a really good explanation of all things flywheel including SMF and DMF ones .....

http://www.europeancarweb.com/tech/0701_ec_flywheels/index.html

and yes, it does state that a flywheel that is too light can cause stalls .... but nothing about balancing rotational masses ....

[Transporter]

I obtained my knowledge by working on petrol and diesel engines for over 34 years (that includes 4 years in trade school) and the basics of automotive mechanics didn't change during that time. That doesn’t mean I don’t top up knowledge when new information becomes available.

Ummm ... no .... pretty sure thats what the crank and balancing weights are there for .... .... flywheels are much more closely related to the clutch ....

While these weights can balance the crankshaft completely, they cannot completely balance the motion of the piston, for two reasons. The first reason is that the balancing weights have horizontal motion as well as vertical motion, so balancing the purely vertical motion of the piston by a crankshaft weight adds a horizontal vibration. The second reason is... keep reading in these two links.
Engine balance - Wikipedia, the free encyclopedia
Crankshaft - Wikipedia, the free encyclopedia

Unlike, How Stuff Works and Chicane Culture dot com links
The text in the links above matches and widens info in BOSCH Automotive Handbook (references to 6th edition pages 459-463) I checked it.

Conclusion from my side:
By changing the flywheel for a lighter one - your engine will not explode or fail. You know it, you’ve done it in the past, right?