Lightened gti6 flywheel on hdi engine, yay or nay?

[Paul_13]

Just a question to see what people reckon, was thinking of putting my lightened gti 6 flywheel on when I do the clutch (change to dturbo pull type setup) 

Pros: 

-Has timing teeth for crank pickup 
-lighter-quicker up the revs 
-possibly more driveable as the engine won't need to labour as much 
-direct fit 
-larger clutch bolts 

Cons:
-decrease in mpg?! 

Any other opinions from you guys? 

[Poodle]

Allegedly it can cause issues with injection timing, although it seems unlikely to me... Try it and see.

[Paul_13]

I think I'm going to give it a go. The ecu would surely compensate for that any way

[HDi--Power]

It will give the engine a misfire of sorts when there is only a light load on the engine, tried it and it doesn't work as well as you would hope.

[Ruan]

Yeah, the ECU is calibrated for the weight of the stock flywheel - the ECU measures crank acceleration per injection event to correct for individual injectors which may not perform quite as expected and give you a perfect idle. So I'd expect it to struggle to cope with low RPM usage as it'll be attempting to compensate for the greater increase in RPMs due to the crank accelerating faster than expected and probably hunt about quite a bit.

[powerandtorque]

For what it's worth, my HDi is running a standard GTi-6 flywheel which is lighter than the standard HDi one by a few kilograms, although I can't remember exactly how much.

No issues at all with idle hunting etc even after having disconnected the battery (so losing any learnt compensation values on the ECU). It has done best part of 20k miles with that flywheel now with (touch wood) no ill-effects.

Whether it'll cope with a flywheel a couple of kilos lighter again is another question, but I can't immediately see why it would be terrible unless there's another fault (like very tired injectors) that is masked by the flywheel inertia damping the individual firing pulses.

Worth pointing out though that the benefits of a lighter flywheel will be somewhat lost with long diesel gearing compared to a high revving petrol on a short box.

[Paul_13]

Might just stick with a std 6 flywheel then and sell the lightened one

---

Does any one know what a hdi fly wheel weighs compared with a lynx lightened fly wheel?

[powerandtorque]

From memory, the standard GTi-6 flywheel is ~6.5kg, the standard HDi one is ~10kg and the Lynx GTi-6 ones are ~4kg

[Paul_13]

10kg! Christ!

[powerandtorque]

It was a heavy old lump! Very obvious difference looking at the two (HDi vs GTi-6) side by side.

(I'm sure I took some pictures, so I'll have a look for them tonight if I remember)

[Paul_13]

Cool, I wonder if an extra 2 5 kgs will make a difference if the 6 flywheel is that much lighter already

[Ruan]

End of the day, these engines have an amount of hysteresis (delay between what your foot does to when the engine revs up) to protect the drivetrain when you're going over a cobbled road and your foot moves about on the pedal so you don't end up eating the steering wheel, also to make it driveable for your grandma and also not smoke under fast transient changes - there's a lot of compromise going on to make the car good for everyone to drive.

To get any real sort of improvement in terms of throttle response, the calibration of this would need to be changed... However it's not a case saying "response +1 y0!!" it would probably take a significant amount of playing with to make it responsive, but not hunt or have a mind of it's own.

The flywheel plays a very small part in how fast the engine will rev up in comparison.

[welshpug]

basically, get a petrol engine on bodies if you want better throttle response 

[toseland]

The HDi guys like having torque lol

[Paul_13]

I'll stick with the 6 flywheel then and sell the lightened one

[306rhys]

Have you got any feedback on using the gti6 flywheel and changing to the dturbo clutch? Also how hard of a job is it to change to a dturbo clutch what else is needed?

[Paul_13]

No problems what so ever.
Works a treat without the auto adjuster, feather light still.

You need a 6 flywheel, d turbo clutch and flywheel bolts (hdi are different) and the pull type cable

Also need to swap the fork which hooks into the release bearing for a dturbo one and the black bracket which the cable hooks into

[Poodle]

There's a guide in the guide section, lots of people run that set up successfully.

[lolsteve]

Exactly it's not just response +1.

It's just +10% on every map for all dat power yo

[pugbug]

A bit off topic, I weighed my Isuzu trooper DMF that thing weighed 29KG O_O on a 3.0 engine.

[Paul_13]

f*ck me sideways

[Poodle]

Oh lol that's this thread, totally didn't read back when i responded, whoops. Good to know it's working fine, interesting.