b18 flywheel & double valve springs

[DOGSTAR]

Does anyone have experience with a lightened flywheel to
that of a standard, Brookhouse do a 5kg one but wondered how that would work on a daily driver?

Secondly does anyone know the base pressure of the standard and of the double valve springs when closed?

(that again brookhouse have https://classicvolvoparts.co.uk/part...+SPRING+SET%2E )

[Ron Kwas]

DS;

Would the question of double spring force not best be posed to the supplier offering that arrangement...?

Cheers

[DOGSTAR]

The suppliers who brookhouse used now do not trade and they do not seem to have the information on the item, i have asked about the standard springs but again seems to be a question that has not been asked. My engineer can work it oout but that is time=£

Originally Posted by Ron Kwas

DS;

Would the question of double spring force not best be posed to the supplier offering that arrangement...?

Cheers

[Rustinmotion]

Originally Posted by DOGSTAR

The suppliers who brookhouse used now do not trade and they do not seem to have the information on the item, i have asked about the standard springs but again seems to be a question that has not been asked. My engineer can work it oout but that is time=£

Don’t know if this helps from piper cams

[142 Guy]

The factory service manual provides the spring free length and the force required to compress the spring to different heights so you can work out the spring rate. Unfortunately the SM does not provide the installed height of the spring. However, if you measure the installed height of the OEM springs on your head you can use the specified free length, the spring rate and your installed height to calculate the installed pressure of the OEM springs.

As to the lighter flywheel / daily driver question, that depends on how much you value idle quality. With a lighter flywheel the RPM will fluctuate more between cylinder firings which may make for more engine shake. This will get worse with cams that have more overlap. You can compensate for this by increasing idle speed. I have had people advise me that their light flywheel engines idle perfectly well at 1250 RPM.

A lighter flywheel can make stop and go traffic more of a hassle because the engine speed drops faster as you engage the clutch which can lead to un expected stalls if you release the clutch too quickly. That is mostly fixed by modifying your driving style.

[paul staines]

I have had a lightened flywheel fitted for a few years now with no problems whatsoever. Car ticks over fine. Spins up even better. Bought mine exchange from Amazon cars. Great modification. Hope this helps. My Idle is set at
975 at the moment.

[classicswede]

Where the weight is removed from does effect how the flywheel effects idle. The TTV flywheel retains good idle, I have run a few of them and give no trouble in road use https://www.classicswede.org/shop/b1...light-flywheel

[DOGSTAR]

Hoi thanks for your info.
What weight flywheel are you using. I know Amazon cars do a 5kg or 8.5Kg i think.
Am i correct saying the original is 10Kgg?

Thanks

Originally Posted by paul staines

I have had a lightened flywheel fitted for a few years now with no problems whatsoever. Car ticks over fine. Spins up even better. Bought mine exchange from Amazon cars. Great modification. Hope this helps. My Idle is set at
975 at the moment.

[blueosprey90]

2 cents from the peanut gallery.

In my MG world (with engines of similar size and power), there is often objection voiced to a lightened flywheel due to spin up and idle concerns. But I've never heard of anyone who converted to a lightened flywheel thereafter object to performance. In my case, I have three MG engines, all with Fidanza aluminum flywheels. I think the weight differential is something like 28 to 11 pounds. When one considers the flywheel and clutch in combination, it represents something in the range of a 25% reduction in that combined rotating mass.

A reduction in rotating mass never hurt anybody. A lightened flywheel will make you feel like you have more HP, even though you don't. And it will take less energy to achieve the same power, meaning the engine does not have to work as hard. It may even help to extend the life of your lifters though nose pressure on the cam is likely far more important.

You may find this video helpful. See data at about 3:00 and at 8:42

https://youtu.be/T76pEw72NPQ?si=SvWGTcDnLaf8d8sm

[paul staines]

Originally Posted by DOGSTAR

Hoi thanks for your info.
What weight flywheel are you using. I know Amazon cars do a 5kg or 8.5Kg i think.
Am i correct saying the original is 10Kgg?

Thanks

Not sure but seem to remember 5kg saving in weight from original.