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lightend and balenced flywheel

1K views 37 replies 13 participants last post by  whitie 
#1 ·
what are the pros and cons of these?

i know it allows the engine to rev up and down faster due to less weight,etc

but i also read a post by someone saying it moves the power band up, losing low down pull:confused:

thanks for any info
 
#4 ·
Lightening a flywheell has NO effect on power band, engine torque or the ability to climb hills.
It allows the engine to rev up and down more quickly and will improve acceleratio in 1st gear by a few percent, but that effect falls off as you move up the gears.
 
#6 ·
no toms lying hes making it up, all of it.

What tom said is accurate.

Basically it will go faster.

Flywheels are pretty heavy these days, for not only a nice smooth idle but to enable a lower idle speed. The Americans have 500rpm idle speeds and thus need a big heavy fly to keep the thing going.

So that means on certain uk engines that are shared with the yanks you can lose a fair chunk o weight off the buggers.
 
#8 ·
region17rc, just read your article, sounds good, seeing the figures you came up with
for the mass lost on flywheel Vs mass lost on chassis


i plan on taking mine to a shop in birmingham, its in the back of CCC mag,
'autosprint' , £75 for a full balance, not sure about the lightening
i take it someone with this kind of business will know how much to take off?
what else can be lightend? the crank? what charicteristcs will this give?
same as the flywheel basically?
any dangers, such as weakening and breaking?
i supose not it he knows what hes doing and doesnt remove to much metal?

thanks
 
#9 ·
autosprint will know what to take off yes, well if they are worth thier salt they will! i'd get the whole bottom end balanced including the clutch as this will benefit more than just the flywheel, depends how far you wanna go though!
 
#10 ·
well, £75 was a full 4cyl balance, so depending on how much
each lightening is
and what else can be done, il go for it, i supose a better clutch than standard would be a good idea
any recomendations? the vw boys use diesel items for 3-4 hundred horse engines
 
#11 ·
for a clutch i'd get a helix paddle,not as bad in traffic as people will tell you, and took two years of abuse from me and my 8500 rpm c1xe without even flinching and still going strong!

as for what else to do, when i had mine done i had the crank nitrided for strength, double doweled the flywheel(if it isnt already on a 2.0 xe) and i fitted arp rod bolts, these are all good mods for a revvy motor, but the nitriding may be a buit ott tbh!

of all of the above, if you are gonna rev it, srp bolts are the most important thing!
 
#12 ·
whitie said:
region17rc, just read your article, sounds good, seeing the figures you came up with
for the mass lost on flywheel Vs mass lost on chassis


i plan on taking mine to a shop in birmingham, its in the back of CCC mag,
'autosprint' , £75 for a full balance, not sure about the lightening
i take it someone with this kind of business will know how much to take off?
what else can be lightend? the crank? what charicteristcs will this give?
same as the flywheel basically?
any dangers, such as weakening and breaking?
i supose not it he knows what hes doing and doesnt remove to much metal?

thanks
I would be cautious with autosprint, have heard stories about them smacking cranks with lump hammers after they have bent with heat treating!!!

They charged me £150 once for setting up my mini when it was turbo 'A' series, they couldn't work out why it was producing ony 9hp, for 3 days they give me bull****, reset my cam timing and allsort, in the end I investigated and found the the air filter was super dirty, took it off and it showed 98 hp straight away!!!, t055as still charged me 150 quid.:mad:
 
#13 ·
What flywheel have you got Lee? How much does it weigh? I've got the pot type one and its been lightened. I weighed it when I got it back (forgot before it went) and it weighs 6kg I think, which seems quite heavy. They said they took as much off as they felt it was safe too...
 
#16 ·
hell yeah, one of the best things i've fitted is the atb, have got a pic of my flywheel here, to show where they took the 'shoulder 'of it off to get rid of the weight



sorry if its a bit big
 
#19 ·
think sbd do bilet ones around the 4kg mark, thats about as light as you'd want really, or you wont get an idle below 1500 and you wont have much in the way of engine braking either, cool for a race car, not for the road really, bear in mind that you may need a special starter/ring gear and maybe clutch with a billet item
 
#20 ·
autosprint did my bottom end from top to tail and have proven to be very good for me as proven lol. I was lazy so just sent whole bottom end away to be fully worked as had money at time but no time of my own to tinker
 
#22 ·
Yes I have a lightened flywheel.
SBD jobby, cos for £60 I thought that was OK price.
I have a 16v lightened one for my new bottom end.

http://www.tomstickland.co.uk/astra/mods2/engine/engine.htm#flywheel1





Also take a look at the bottom of http://www.tomstickland.co.uk/astra/homework/acceleration_model/model1.htm


The effective mass of the vehicle has now been increased, with a term depending on the engine inertia and a term due to the wheel inertia. Some typical numbers might be: car mass 800-1200Kg, first gear 3.42, final drive 3.55, engine inertia 0.04Kgm2, wheel rolling diameter 0.58m, radius 0.29m, inertia of a wheel 0.8 kgm2. This means that in first gear the engine inertia appears as an extra 55Kg of weight. This falls off in the higher gears. The wheel inertia appears as approximately an extra 35Kg of mass.
 
#23 ·
on that page from your website, that lists the changes to your engine
one is a crank regrind, during the bottom end re-build.
just wondering, can you get re-grinds like re-bores?
i.e. a re-bore to a very small increase, due to damage , etc
and a re-bore to dramatically increase cc?

or would that take a totaly new crank, to increase the stroke?

thanks
 
#25 ·
Yes you can get cranks reground and undersize bearing shells to match them.
However, the machine shop inspected my crank and said it was fine as it was, so no regrind needed.

With rebores, you can get 0.5mm oversize standard pistons. This takes capacity up to 2.05L roughly. you can go up to 2.198 roughly, but pistons expensive.
 
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