Lets Talk Flywheels
Discussion
More on lightened flywheels here.....
https://www.pistonheads.com/gassing/topic.asp?h=0&...
And these are the facts
For safety V8 Developments will not go any lighter than 22lbs on a standard cast flywheel, this is however already a huge improvement on the 28lb millstone you got in all Chimaeras except of course the five litre cars, the 5.0 ran a bespoke cast 20lbs flywheel.
I ran one of V8D's lightened standard cast flywheels for years which weighed in at 22.5lbs, this made a massive difference and the results were only positives, some time later I sold that flywheel to a fellow PHer for £120. I put the money towards my lighter £336.00 TTV racing steel flywheel I had TTV spin down to 18.74lbs (8.5kg) so it effectively cost me £216.00, it's now over 9lbs lighter that what the car left the factory with in 1996.
For the record 9lbs is the weight of your average sledge hammer, and a weight loss of one third over the original. However, I now think I could have gone lighter still, I currently have what I believe to be a leaky rear main seal which could mean the box will have to come out yet again, if I'm proved correct my steel flywheel will go off to TTV and get spun down to 16lbs making it a whopping 12lbs lighter than the original, a weight loss of 43% over the original so getting on for half the weight!
One thing is without question, any weight you can get out of that original ridiculously heavy 28lb original millstone is a good thing, and there's a long long way to go before you ever reach the point where drivability is affected. Keep in mind the curb weight of a Chimaera is a third lighter than that of the Rover SD1, and is why my TTV racing flywheel hasn't affected the drivability of my Chimaera at all.
The only difference you'll feel is vastly better throttle response, and on the lazy revving old Rover V8 anything you can do to help the lump spin up a bit faster is a significant positive!!!!!
Especially in a 1060kg sports car
Basically its a no-brainer
https://www.pistonheads.com/gassing/topic.asp?h=0&...
And these are the facts
| Rover SD1 | 32lbs |
| Standard cast 400/450 Chimaera | 28lbs |
| V8 Developments lightened standard cast | 23lbs |
| Bespoke TVR cast 5.0 litre | 20lbs |
| My final TTV chro/mo steel | 18.74Lbs |
| TTV stock RV8 light weight chro/mo steel | 14.55Lbs |
| TTV RV8 race spec chro/mo steel | 7.5Lbs |
For safety V8 Developments will not go any lighter than 22lbs on a standard cast flywheel, this is however already a huge improvement on the 28lb millstone you got in all Chimaeras except of course the five litre cars, the 5.0 ran a bespoke cast 20lbs flywheel.
I ran one of V8D's lightened standard cast flywheels for years which weighed in at 22.5lbs, this made a massive difference and the results were only positives, some time later I sold that flywheel to a fellow PHer for £120. I put the money towards my lighter £336.00 TTV racing steel flywheel I had TTV spin down to 18.74lbs (8.5kg) so it effectively cost me £216.00, it's now over 9lbs lighter that what the car left the factory with in 1996.
For the record 9lbs is the weight of your average sledge hammer, and a weight loss of one third over the original. However, I now think I could have gone lighter still, I currently have what I believe to be a leaky rear main seal which could mean the box will have to come out yet again, if I'm proved correct my steel flywheel will go off to TTV and get spun down to 16lbs making it a whopping 12lbs lighter than the original, a weight loss of 43% over the original so getting on for half the weight!
One thing is without question, any weight you can get out of that original ridiculously heavy 28lb original millstone is a good thing, and there's a long long way to go before you ever reach the point where drivability is affected. Keep in mind the curb weight of a Chimaera is a third lighter than that of the Rover SD1, and is why my TTV racing flywheel hasn't affected the drivability of my Chimaera at all.
The only difference you'll feel is vastly better throttle response, and on the lazy revving old Rover V8 anything you can do to help the lump spin up a bit faster is a significant positive!!!!!
Especially in a 1060kg sports car
Basically its a no-brainer
spitfire4v8 said:
I alluded to this in one of the previous threads on light flywheels .. with 4 firing pulses per rev, and a heavy crank, I don't know why people just don't go for a very light flywheel
I'm inclined to agree, but how light is 'very light' Joolz 
My current thinking is I could have just jumped to 16lbs with no ill effects
Your thoughts and experiences are welcomed
spitfire4v8 said:
Plenty of people running 5kg flywheels on 4cylinder fords, with less crank mass and half the firing events per rev .. so I would have thought 5kg/11lbs would be fine, BUT of course we have a big diameter so whether you can get to those numbers without the special race flywheels costing a fortune I don't know .. but it would seem that significantly lighter than what you have now should be possible.
Remember we have relatively low compression engines, and a firing pulse / crank pin angles turning the crank every 90 degrees of rotation, and a heavier crank than a little 4pot engine would have.
It all adds up to our engines being able to take a much lighter flywheel compared to a 4 pot..
The TTV light flywheel for the Cerbera is 3.4kg !!
Wow, 3.4kg! Now that is light Remember we have relatively low compression engines, and a firing pulse / crank pin angles turning the crank every 90 degrees of rotation, and a heavier crank than a little 4pot engine would have.
It all adds up to our engines being able to take a much lighter flywheel compared to a 4 pot..
The TTV light flywheel for the Cerbera is 3.4kg !!
Alan Crisp of TTV once told me its not so much the overall weight of the flywheel that counts, its where the flywheel caries that weight, this made sense to me. Basically what he was saying was if you take two flywheels of the same weight but one of them has most of the mass in the centre and the other caries most of its mass on the outer ring gear edge, despite both flywheels weighing exactly the same the one with the mass in the centre will alow the engine to spin up faster.
The lighter you can make the outer ring gear edge of the flywheel the faster the engine will spin up, you can see this in the following RV8 flywheel from V8 Tuner which almost certainly is made by TTV Racing (£420) but V8 Tuner doesn't state how much it weighs, when you go on the TTV website you see what appears to me the same flywheel described as being 3.4 Kg (7.5lbs).
This is however described by V8 Tuner as a 'Competition Flywheel' so maybe a step too far for the road, didn't Engineer1949 fit this flywheel to the orange supercharged Chimaera, but promptly removed it as it was found to be too light
V8 Tuner also offers what they call their Rover V8 Super Lightweight Steel Flywheel which they say is approximately 6.85kg (15lbs), again this flywheel almost certainly comes from TTV, if you go on the TTV site you'll find this one they state is 6.6kg (14.55 lbs)
http://ttvracing.com/product/rover-v8-lite-for-9-5...
I think I'll have Alan Crisp spin down my 18.74 lbs TTV Racing flywheel to 14.55 lbs and let him choose where to take the weight out as he clearly knows his stuff, I suspect most of the weight will come out of the outer ring gear edge, one thing is for sure each time I go lighter the more I like the results, and as yet I've suffered absolutely no drivability issues in the process.
| Rover SD1 | 32lbs |
| Standard cast 400/450 Chimaera | 28lbs |
| V8 Developments lightened standard cast | 23lbs |
| Bespoke TVR cast 5.0 litre | 20lbs |
| My final TTV chro/mo steel | 18.74Lbs |
| TTV stock RV8 light weight chro/mo steel | 14.55Lbs |
| TTV RV8 race spec chro/mo steel | 7.5Lbs |
I have to say I absolutely love my 18.74 lbs chro/mo steel TTV Racing flywheel 
I couldn't imagine ever going back to the old 28 lb SD1 millstone the car came with from the factory, whatever you do to lighten this huge mass will make a massive difference to the way the engine responds to throttle inputs, indeed if you're replacing your clutch fitting a lighter flywheel undoubtedly represents the best 'bang for buck' modification you can make to a 4.0 litre Chimaera.
With help from V8 Developments I took the comically heavy 28 lb original down to 23 lbs, the 5 lbs weight loss was immediately noticeable with no drivability downsides whatsoever, I was so happy with the results when the opportunity presented itself I went another 4.26 lbs lighter settling on 18.74 lbs (8.5kg).
For safety it's not recommended to go much lighter than 22.5 lbs on the original cast flywheel, so this next weight reduction step involved going to TTV for a steel unit which gave even better results, and again there were absolutely no drivability negatives whatsoever. At the end of the day I played it safe 18.74 lbs (8.5kg), I now feel I could have just taken one of TTV's off the shelf 14.5 lb RV8 flywheels but that will have to wait until I address slight oil leak from the rear main, the good news is I already have the flywheel, I'll just get TTV to take another 4.25 lbs out of it.
By this time, and in three separate steps, I will have ended up going a whopping 13.5 lbs lighter than the 28 lb original millstone, and hopefully my lovely drivability will still be retained
I couldn't imagine ever going back to the old 28 lb SD1 millstone the car came with from the factory, whatever you do to lighten this huge mass will make a massive difference to the way the engine responds to throttle inputs, indeed if you're replacing your clutch fitting a lighter flywheel undoubtedly represents the best 'bang for buck' modification you can make to a 4.0 litre Chimaera.
With help from V8 Developments I took the comically heavy 28 lb original down to 23 lbs, the 5 lbs weight loss was immediately noticeable with no drivability downsides whatsoever, I was so happy with the results when the opportunity presented itself I went another 4.26 lbs lighter settling on 18.74 lbs (8.5kg).
For safety it's not recommended to go much lighter than 22.5 lbs on the original cast flywheel, so this next weight reduction step involved going to TTV for a steel unit which gave even better results, and again there were absolutely no drivability negatives whatsoever. At the end of the day I played it safe 18.74 lbs (8.5kg), I now feel I could have just taken one of TTV's off the shelf 14.5 lb RV8 flywheels but that will have to wait until I address slight oil leak from the rear main, the good news is I already have the flywheel, I'll just get TTV to take another 4.25 lbs out of it.
By this time, and in three separate steps, I will have ended up going a whopping 13.5 lbs lighter than the 28 lb original millstone, and hopefully my lovely drivability will still be retained
^^This^^
There's really no problem fitting one of TTV Racing's off the shelf flywheels, they're flywheel experts and do not sell problems to their customers.
Keep in mind I've fitted one of TTV's lovely chro/mo steel flywheels and it worked absolutely brilliantly, my engine also remained super smooth! I tried to be clever and have TTV spin me up a custom 18.75 lbs flywheel, basically because I was too chicken to go to their off the shelf RV8 14.5 lb unit, while it works fantastically well and I absolutely love it I now think I can go lighter.
I want to hear feedback from mateypeeps1, especially on drivability, but my guess is his new flywheel will just give even better throttle response with no downsides despite being a further 4.25 lbs lighter than mine. As far as I'm concerned a lighter flywheel is an absolute no brainer, any weight you can take out of the original 28 lb millstone is going to give great results in a 1060kg TVR, and there's a lot of weight to remove before you even come close to running into drivability issues.
Let us all know how you get on mateypeeps1
There's really no problem fitting one of TTV Racing's off the shelf flywheels, they're flywheel experts and do not sell problems to their customers.
Keep in mind I've fitted one of TTV's lovely chro/mo steel flywheels and it worked absolutely brilliantly, my engine also remained super smooth! I tried to be clever and have TTV spin me up a custom 18.75 lbs flywheel, basically because I was too chicken to go to their off the shelf RV8 14.5 lb unit, while it works fantastically well and I absolutely love it I now think I can go lighter.
I want to hear feedback from mateypeeps1, especially on drivability, but my guess is his new flywheel will just give even better throttle response with no downsides despite being a further 4.25 lbs lighter than mine. As far as I'm concerned a lighter flywheel is an absolute no brainer, any weight you can take out of the original 28 lb millstone is going to give great results in a 1060kg TVR, and there's a lot of weight to remove before you even come close to running into drivability issues.
Let us all know how you get on mateypeeps1
mateypeeps1 said:
A few pics of the ongoing process. A good time to get a good view of one's chassis condition, too, with the gearbox and prop shaft out of the way. V pleased with mine, good to know. Took the opportunity to change the rear main seal while the flywheel was off, and finally found a good use for the original heavyweight - makes a good pressing tool to fit a new seal squarely, just ease the lip over the flange, then mm by mm tighten 4 bolts evenly. All you need to do then is tap it gently in square and flush with a bit of suitable timber. Also fitted some 50mm square battery leads while the bell housing was out of the way, this is going to be one good starting Chimaera, new starter also. Clutch arriving tomorrow
SILICONEKID 357HP said:
What does the 5l flywheel weigh ?
I thought the a light fly wheel is difficult at low speeds .
Didnt engineer1949 have problems with a race flywheel .
The answers to all your questions are contained within this very five page thread Daz, you've just got to read it mate I thought the a light fly wheel is difficult at low speeds .
Didnt engineer1949 have problems with a race flywheel .
ChimpOnGas said:
More on lightened flywheels here.....
https://www.pistonheads.com/gassing/topic.asp?h=0&...
And these are the facts
For safety V8 Developments will not go any lighter than 22lbs on a standard cast flywheel, this is however already a huge improvement on the 28lb millstone you got in all Chimaeras except of course the five litre cars, the 5.0 ran a bespoke cast 20lbs flywheel.
The TTV RV8 race spec chro/mo steel 7.5Lbs flywheel fitted by engineer1949 is made for a race clutch, its also half the weight of TTVs very lightest road spec flywheel, as such this combination is highly unlikely to be suitable for a road car, it's no surprise to me he quickly removed it.https://www.pistonheads.com/gassing/topic.asp?h=0&...
And these are the facts
| Rover SD1 | 32lbs |
| Standard cast 400/450 Chimaera | 28lbs |
| V8 Developments lightened standard cast | 23lbs |
| Bespoke TVR cast 5.0 litre | 20lbs |
| My final TTV chro/mo steel | 18.74Lbs |
| TTV stock RV8 light weight chro/mo steel | 14.55Lbs |
| TTV RV8 race spec chro/mo steel | 7.5Lbs |
For safety V8 Developments will not go any lighter than 22lbs on a standard cast flywheel, this is however already a huge improvement on the 28lb millstone you got in all Chimaeras except of course the five litre cars, the 5.0 ran a bespoke cast 20lbs flywheel.
My 4.0HC runs a bespoke TTV chro/mo steel 18.74lb flywheel mated to an AP five litre clutch fitted by Mat Smith, at the same time he machined down my release bearing carrier as TVR hadn't allowed sufficient free play from new which caused all sorts of issues over the years. The 5.0 AP clutch with the correct free play is a joy to use and combined with my TTV flywheel works extremely well, it's light years better than the standard RV8 clutch and massively heavy 28lb flywheel combo the car came with from new, especially as TVR hadn't allowed sufficient free play/clearance so the clutch dragged when hot.
When combined with a V8 Development Stealth cam the engine character is transformed, flywheel lightening on this engine fitted in such a light car is a no brainer and I may well go even lighter still, I'm extremely tempted to get TTV to spin down my flywheel to 14.55lbs. I also have a first refusal agreement with Matthew Poxon on his ACT twin plenum as he's currently in the process of going to throttle bodies with his new engine, the theory is shaving a further 4.2lbs off my TTV flywheel and fitting Mathew's hand me down ACT twin plenum should take my throttle response to the next level without breaking the bank
My Brembo four pot caliper and big disc conversion, Mk4 Tuscan 'S' spec Bilstens, Stealth cam, TTV flywheel and Canems Dual Fuel engine management system have already transformed my Chimaera into quite the B road weapon, all this in a super smooth driving yet old school analogue shouty V8 sports car that delivers the petrol cost equivalent of 50mpg just goes to prove you can definitely have your cake and eat it
And people still think LPG is only for taxis and fork lift trucks
Gassing Station | Chimaera | Top of Page | What's New | My Stuff