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thinking of a turbo
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Discussion Starter · #1 ·
as above has any one had one fitted and did it make a difference? and to wot model. and wots the advantages and dissadvantages of theses
 

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Advantage is that it takes less for the engine to spin up so can rev faster (no increase in power). Disadvantage is that you will have to make lots more gear changes (especially up hill) as there will be less momentum also more difficult around town as it makes the engine less smooth. Going down hill you get a bit less engine braking as well and gear changes can be erratic as the engine spins up and down quicker so can be quite choppy.
 

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thinking of a turbo
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831 Posts
Discussion Starter · #3 ·
Advantage is that it takes less for the engine to spin up so can rev faster (no increase in power). Disadvantage is that you will have to make lots more gear changes (especially up hill) as there will be less momentum also more difficult around town as it makes the engine less smooth. Going down hill you get a bit less engine braking as well and gear changes can be erratic as the engine spins up and down quicker so can be quite choppy.
so would you say its worth doing? as i wanna take it down santpod but only a couple of times a year but mainly use it around town etc
 

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in layman's terms, it makes your engine use the existing BHP is has more effectively. Therefore if you had to identical cars one with a lightened flywheel and the other without, the one with a lightweight flywheel would be fast BUT have the same BHP output if you get me? IMO its only really worthwhile if you have other mods to compliment it really, on its own wont make much difference
 

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what FX is trying to say is that the engine power output stays the same, but in theory the power at the wheels (the important one) should be higher.

if ur going to do other mods then go for it :)
 

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Rover Owner
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I have one fitted to the 160...I'm not sure whether it actually makes a difference. On a fully balanced bottom end it would help more but the theory is that is just reduces 'unsprung weight' helping the car to use its power more efficiently. The same principle applies to using lightweight wheels and lightweight brake disks (aluminium floating bell disks for example)
 

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I have one fitted to the 160...I'm not sure whether it actually makes a difference. On a fully balanced bottom end it would help more but the theory is that is just reduces 'unsprung weight' helping the car to use its power more efficiently. The same principle applies to using lightweight wheels and lightweight brake disks (aluminium floating bell disks for example)
Sorry Miker, how does this reduce 'unsprung weight'? I thought unsprung weight is the mass of the suspension, wheels and other components directly connected to them rather than supported by the suspension which is the 'sprung mass'. Wouldn't the flywheel, being bolted to the engine, fall under the 'sprung mass' criteria?

Lightweight wheels and discs would certainly help with unsprung weight and help with handling as the suspension is able to react quicker.
 

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Rover Owner
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As I understood it Nick (and i may have used the wrong terminology, or may just have missed the mark entirely) any mass directly acting on the drivetrain can be considered part of the same grouping. Reducing the mass of the flywheel will have the effect of reducing unsprung weight because this is now a smaller mass for the crank to be moving. Then you can follow the path of the engines drive and apply the same theory to any other mass subject to movement as a direct result of this; which would be driveshafts, hubs, disks and wheels. Effectively this lot will all be slowing down or straining the engine crank so anything you can do to lower this mass safely (whilst keeping items balanced) will help the engine rev quicker. That is how I understand it anyway. Thoughts?

Edit: this doesn't consider the gearbox although I know very little about how this would be treated if at all. Perhaps this is one reason for using close ratio boxs on race cars? Obvioulsy as well as to help keep engines in powerbands.
 

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Unsprung weight is only concerned with the suspension at the wheels and anything else bolted to that part such as the discs (as long as they are outboard discs and not inboard discs....inboard discs are sprung mass), hubs calipers etc. Anything else that is supported by the suspension (the body and anything else attached to the body such as the engine, transmission) is considered to be the sprung mass.

http://en.wikipedia.org/wiki/Unsprung_weight

http://www.tuning.wanadoo.co.uk/lightening.htm
http://kapitalmoto.co.uk/node/37
 

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Rover Owner
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In which case I have used the wrong term. Although my point still stands with regards to the effects of the mass of the flywheel and other rotational masses forming part of the drivetrain.
 

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Rover Owner
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Is there a term for refering to this particular set of masses?
 

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Sorry Miker, how does this reduce 'unsprung weight'? I thought unsprung weight is the mass of the suspension, wheels and other components directly connected to them rather than supported by the suspension which is the 'sprung mass'. Wouldn't the flywheel, being bolted to the engine, fall under the 'sprung mass' criteria?

Lightweight wheels and discs would certainly help with unsprung weight and help with handling as the suspension is able to react quicker.
Unsprung weight is only concerned with the suspension at the wheels and anything else bolted to that part such as the discs (as long as they are outboard discs and not inboard discs....inboard discs are sprung mass), hubs calipers etc. Anything else that is supported by the suspension (the body and anything else attached to the body such as the engine, transmission) is considered to be the sprung mass.

http://en.wikipedia.org/wiki/Unsprung_weight

http://www.tuning.wanadoo.co.uk/lightening.htm
http://kapitalmoto.co.uk/node/37
I really didn't get the need for all this, i understood what miker ment in his first post, even though it had been miss worded, and i am in no doubt that a man with your intelligence understood what he ment too nick. Seems like it was an arse about face way of belittling him rather than the tiniest of corrections that was needed. I will just put it down to morning stresses and bad moods getting the better of people.

Coffee anyone? John's (forestfighter's) mum's making?
 

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I really didn't get the need for all this, i understood what miker ment in his first post, even though it had been miss worded, and i am in no doubt that a man with your intelligence understood what he ment too nick. Seems like it was an arse about face way of belittling him rather than the tiniest of corrections that was needed. I will just put it down to morning stresses and bad moods getting the better of people.

Coffee anyone? John's (forestfighter's) mum's making?
I knew what Miker meant and in no way was I trying or meaning to belittle him. Hopefully Miker (who I have met on several occassions and who I know to be highly intelligent and knowledgeable on a lot of things as well as a whole load that I know nothing about) hasn't taken this to be what I was trying to do either? There are a lot of people on here who may or may not know the difference between sprung and unsprung mass (I think I got it confused during a discussion with Hob over exactly the same things) and I was only trying to clarify terminologies and avoid any confusion now or in the future for others who may be reading this thread.

I apologise to Miker if it seemed I was trying to belittle you, that certainly wasnt my intention and thank you for pointing it out to me!
 

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Rover Owner
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It's fine Nick I took it all in good humour, clarified a few things for me too. And thankyou Ade for jumping to my rescue even if on this occassion it wasn't really necessary :D

I think if someone asked me whether or not as an isolated modification it was worth the hastle I'd say no unless you were replacing the clutch anyway in which case it's easily done. Would really benefit a fully balanced bottom end but this is a very expensive process and to the majority on here not applicable.
 
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