Atom 4 standard flywheel rev time

[Anon]

For comparison, here's a supercharged Nomad doing the same sorta thing:

This is much better, of course they are different engines but do you have the lightweight flywheel?

I still don't know if you would notice this at speed on a track for example.

[phil4]

Hi Simon, I think it's the K20 flywheel, so lightened I believe over the standard K24 flywheel.

So I suspect this is the effect changing to the lightened flywheel would have on your car.

If it's of a similar degree, then the above doesn't cause me to stall lots or anything like that, it's perfectly driveable.

[ooinaru]

Are we sure comparing while the car is stationary is the way to go? Most cars have a different throttle map when the car is stationary (not sure if the atom also has it) compared to when it’s moving.

[phil4]

I doubt the throttle map covers removal of the foot from the pedal?

[Karl V]

Actually, there is a different map between speedo = 0 and speedo > 0; the most obvious being that max RPM at stand still is circa 5,000 RPM.

I know this because when I picked the car up after it's newly fitted SC and flywheel etc, it was ticking over beautifully at stand still. 2 miles into driving home, I noticed that tick over was hunting between 800 RPM and 1,200 RPM when the car was coasting with my foot on the clutch. I of course headed straight back to the factory and we saw that the ECU mapping was screwed and needed to be reflashed.

And the big question... why was I 'coasting' with my foot on the clutch? Because it drops revs so quickly with the lighter flywheel that where I was used to having time to down shift while slowing down for a left turn, the revs drop almost immediately and I noticed it hunting at tick over before I lazily changed gear and took the turn. At first, I thought that the rev counter was screwed because of how quickly revs dropped, but the ear didn't lie.

I don't know the ins and outs of the two maps (only that there are 2 - and maybe even 3 with a 'limp home' mode or what not?), but I can confirm that on the road, the car behaves as Phil shows in his stationary video.

[Anon]

I think you guys have convinced me, I will ask Rooke to give me a price to add the lightweight flywheel onto the sequential when I get this through, they are still working on it.

I will then do another video, also while driving before and after.

[speedmachine]

I think you guys have convinced me, I will ask Rooke to give me a price to add the lightweight flywheel onto the sequential when I get this through, they are still working on it.

I will then do another video, also while driving before and after.

I didn’t know you could add the sequential without the lighter flywheel! I believe it was mandatory at the 3.5 to add those together

[Anon]

I am not so sure it is with the 4, but I am still waiting for a list of parts and a price to fit it so will know then when I receive it.

[Toilet Duck]

As a few people have been asking whether or not to spec the lightweight fly wheel, I did a quick vid after my run out this evening (my neighbours love me!) to show how responsive it is. If I get a lightweight one I will do a comparison not sure I need one just yet. But hopefully from this you can see how responsive it is just by slightly revin'g the engine. It's less easy to do this while driving.

Granted that's a very short/limited video, but that doesn't look particularly responsive to me. I'd go so far to say that the speed at which the revs return to idle appears lethargic, not unlike a diesel engine with a boat anchor for a flywheel.

[robfitz]

That is what I thought! It must be a dual mass surely so switching to something half the weight will hopefully make a big difference.

Might check with clockwise if their k20 flywheel will fit as the one I had was only 2.9kg.

[Toilet Duck]

That is what I thought! It must be a dual mass surely so switching to something half the weight will hopefully make a big difference.

Might check with clockwise if their k20 flywheel will fit as the one I had was only 2.9kg.

Either that or it is made of lead! Really surprised how slowly that returns to idle, must weigh a ton.

For what it's worth, I measured the "standard" flywheel weight in my K20 atom 3 when I had the engine/box out for a clutch change and it came in at appeox 4.8kg which is very light for an OE flywheel. I had planned to fit a lightweight version but didn't bother as the standard one is pretty decent.

[Anon]

It looks to be this dual mass flywheel: https://www.dream-automotive.com/collec ... ype-r-2015

These guys Dream Automotive are very close to me in Bedford too. They sell performance kits, they seem to sell a lightened flywheel but this includes an up-rated clutch too.

May give them a call tomorrow. Interestingly they sell this Hondata flash pro, but it's an MBE on the car not Hondata: https://www.dream-automotive.com/produc ... 9369&_ss=r

[Anon]

These guys have a separate page for Atom4: https://www.dream-automotive.com/collections/atom-4

I wish I never found this....

[robfitz]

That is what I thought! It must be a dual mass surely so switching to something half the weight will hopefully make a big difference.

Might check with clockwise if their k20 flywheel will fit as the one I had was only 2.9kg.

Either that or it is made of lead! Really surprised how slowly that returns to idle, must weigh a ton.

For what it's worth, I measured the "standard" flywheel weight in my K20 atom 3 when I had the engine/box out for a clutch change and it came in at appeox 4.8kg which is very light for an OE flywheel. I had planned to fit a lightweight version but didn't bother as the standard one is pretty decent.

8.2kg according to Tom, 4.4kg for the lightweight one.

The one I had on the clockwise engine in my Elise was 2.9kg but not listed for the k20c.

https://www.clockwisemotion.co.uk/produ ... 20-FLY-725

[robfitz]

These guys have a separate page for Atom4: https://www.dream-automotive.com/collections/atom-4

I wish I never found this....

That just looks like a page of parts for the Civic despite the heading.