3000M transmission loss
Discussion
Typical drivetrain losses between flywheel and road are 15%-20%. I don't know how much of this is in the transmission but there are ways of reducing the loss.
One way is to properly align the bellhousing with the flywheel. Another is to use friction reducing additives in the transmission or lower viscosity lubricants. As you can imagine, there are drawbacks to doing this.
Another place to look for drivetrain losses is in the angle at the universal joints. I have read that 2deg is required to make the bearings turn and from there on up, friction is increased.
B.
One way is to properly align the bellhousing with the flywheel. Another is to use friction reducing additives in the transmission or lower viscosity lubricants. As you can imagine, there are drawbacks to doing this.
Another place to look for drivetrain losses is in the angle at the universal joints. I have read that 2deg is required to make the bearings turn and from there on up, friction is increased.
B.
Bernard,
I'm not looking at reducing the losses (not yet anyway) I'm trying to get a fairly accurate idea of what flywheel bhp I have to see if I've realistically gone as far modifying with the engine (within a normal person's budget) as I can.
A 20% loss says I probably have, 15% suggests there is a bit more to come!
Thanks for the ideas though.
John
I'm not looking at reducing the losses (not yet anyway) I'm trying to get a fairly accurate idea of what flywheel bhp I have to see if I've realistically gone as far modifying with the engine (within a normal person's budget) as I can.
A 20% loss says I probably have, 15% suggests there is a bit more to come!
Thanks for the ideas though.
John
I'd agree with that figure, when I last RR'd my car, I got 165rwhp, which the tuner reckoned was around 200bhp, Slow M's 20%. I reckon that figure is reasonably right as between 30-90 my car would out accelerate my Impreza Turbo (235bhp) (Impreza weight 1300kg, TVR 1000kg).
GAjon might be more help here as his car was a regular RR visitor!
Anyway more importantly what were the numbers?
davidy
GAjon might be more help here as his car was a regular RR visitor!
Anyway more importantly what were the numbers?
davidy
Also 'normal' and TVR are mutually exclusive!!!!
I'd also suggest that if you in the 5% zone, then more improvement can be had through driver training rather than extracting the last few bhp from the engine. Everyone can always improve.....
davidy
I'd also suggest that if you in the 5% zone, then more improvement can be had through driver training rather than extracting the last few bhp from the engine. Everyone can always improve.....
davidy
Edited by DavidY on Monday 16th February 16:59
DavidY said:
Also 'normal' and TVR are mutually exclusive!!!!
I'd also suggest that if you in the 5% zone, then more improvement can be had through driver training rather than extracting the last few bhp from the engine. Everyone can always improve.....
davidy
I think Linda has tried driver training but has given it up as a dead duck.I'd also suggest that if you in the 5% zone, then more improvement can be had through driver training rather than extracting the last few bhp from the engine. Everyone can always improve.....
davidy
Edited by DavidY on Monday 16th February 16:59
N
I would say it's near to 20%, although I've never had the car on the rollers and then the engine on a dyno, to say with any degree of accuracy.
I come to the 20% by estimates of what the engine should, or was predicted to put out with various works and then the actual roller results with the work completed, calculated back.
So no real science, as my M was (and probably still is) always tempremental on the rollers.
I 've also got round about the same numbers from different tuners on different rollers.
John.
I come to the 20% by estimates of what the engine should, or was predicted to put out with various works and then the actual roller results with the work completed, calculated back.
So no real science, as my M was (and probably still is) always tempremental on the rollers.
I 've also got round about the same numbers from different tuners on different rollers.
John.
heightswitch
Fair enough, at least I didn't mention personal fitness and diet!!! How much extra a lap is a kilo worth?? !!!!!!
Seriously John, don't worry about the 5%, just concentrate on learning to drive it and extract the best from it. I started going a lot faster when I stopped messing about with car and just learnt to drive it!
If you want it straight, you could do a lot worse than getting a professional driver to take it for a few laps, and pass judgement, would also be interesting for you to see how much speed they could carry/maintain.
All the best
davidy
Fair enough, at least I didn't mention personal fitness and diet!!! How much extra a lap is a kilo worth?? !!!!!!
Seriously John, don't worry about the 5%, just concentrate on learning to drive it and extract the best from it. I started going a lot faster when I stopped messing about with car and just learnt to drive it!
If you want it straight, you could do a lot worse than getting a professional driver to take it for a few laps, and pass judgement, would also be interesting for you to see how much speed they could carry/maintain.
All the best
davidy
The car when last dynoed was poorly, but it made good figures at the wheels - maybe the dyno was optimistic, maybe it wasn't as poorly as I thought!
It's being brought back to life at the moment, has a new more efficient exhaust system, will have stronger valve springs, a bit more compression (and wills ringed block to keep the compression!) and it's being generally freshened. I also expect maybe a few more BHP when a long awaited cold air box mod is done. The car will then go to Colin Blower Motorsport for a good basic set-up and corner weighting etc, and as DY suggests then I will just get on and learn to drive it. To be honest, the car came with what seemed like a good set-up from HHC last year and all I've played with was the damping and that was to soften it (only once) and have left well alone since then - other than finding ideal? tyre pressures.
I've thought about personal fittenss and weight loss, but the beer loss this involves puts me off. I'm too content with the lifestyle I have and to try to change it will only depress me, that said I'm dropping some weight through additional excercise at work.
The T5 swap went well and it will be a huge improvement when it has a few more miles on it. I'm pleased with the overall gearing now with the .87:1 final drive in 5th. The staright cut fifth is noisey though.
The weight loss associated with the change of box and bell housing (combined with a lighter starter) make a big difference and I expect the the car will top the scales at around 875 kilos with a few litres of fuel on board when its weighed at Cadwell. Thats probably light enough for now.
In terms of proffessional instruction, yes I would like to do some, but I never seem to have the time, as Niel suggests, I am difficult to train although I do more or less understand the difference between yes and no (others may disagree) - but a good start methinks. There's also some addage about old canines and new tricks....
I've avoided quoting figures for now but I'll let you know as soon as it's run-in and dynoed before the first race at Cadwell in April. As a guide, I expect around 225 bhp - we'll see, but I'll be happy if thats the number.
Thanks for the responses.
John.
It's being brought back to life at the moment, has a new more efficient exhaust system, will have stronger valve springs, a bit more compression (and wills ringed block to keep the compression!) and it's being generally freshened. I also expect maybe a few more BHP when a long awaited cold air box mod is done. The car will then go to Colin Blower Motorsport for a good basic set-up and corner weighting etc, and as DY suggests then I will just get on and learn to drive it. To be honest, the car came with what seemed like a good set-up from HHC last year and all I've played with was the damping and that was to soften it (only once) and have left well alone since then - other than finding ideal? tyre pressures.
I've thought about personal fittenss and weight loss, but the beer loss this involves puts me off. I'm too content with the lifestyle I have and to try to change it will only depress me, that said I'm dropping some weight through additional excercise at work.
The T5 swap went well and it will be a huge improvement when it has a few more miles on it. I'm pleased with the overall gearing now with the .87:1 final drive in 5th. The staright cut fifth is noisey though.
The weight loss associated with the change of box and bell housing (combined with a lighter starter) make a big difference and I expect the the car will top the scales at around 875 kilos with a few litres of fuel on board when its weighed at Cadwell. Thats probably light enough for now.
In terms of proffessional instruction, yes I would like to do some, but I never seem to have the time, as Niel suggests, I am difficult to train although I do more or less understand the difference between yes and no (others may disagree) - but a good start methinks. There's also some addage about old canines and new tricks....
I've avoided quoting figures for now but I'll let you know as soon as it's run-in and dynoed before the first race at Cadwell in April. As a guide, I expect around 225 bhp - we'll see, but I'll be happy if thats the number.
Thanks for the responses.
John.
Edited by TVR_owner on Tuesday 17th February 07:07
John
Given your setup I would have expected nearer 240bhp and in 875kg it's not going to be slow, especially with your right foot!
I think that instruction is harder as you get older, there is a resistance to change, but maybe the suggestion of getting a professional to drive the car would be good as you will get set-up advice (which you can choose to take or ignore) but more importantly you will be able to get an idea of how much speed can be carried through corners, and what I learnt is how light the inputs need to be to chieve that (less wrestling at the wheel!!)
All the best
davidy
Given your setup I would have expected nearer 240bhp and in 875kg it's not going to be slow, especially with your right foot!
I think that instruction is harder as you get older, there is a resistance to change, but maybe the suggestion of getting a professional to drive the car would be good as you will get set-up advice (which you can choose to take or ignore) but more importantly you will be able to get an idea of how much speed can be carried through corners, and what I learnt is how light the inputs need to be to chieve that (less wrestling at the wheel!!)
All the best
davidy
DavidY said:
John
Given your setup I would have expected nearer 240bhp and in 875kg it's not going to be slow, especially with your right foot!
I think that instruction is harder as you get older, there is a resistance to change, but maybe the suggestion of getting a professional to drive the car would be good as you will get set-up advice (which you can choose to take or ignore) but more importantly you will be able to get an idea of how much speed can be carried through corners, and what I learnt is how light the inputs need to be to chieve that (less wrestling at the wheel!!)
All the best
davidy
I'll see if I can get one of the more experinced Challenge drivers to try the car at a test day as a start point, but you are right about resistance to change - I'm more considered than I was 20 years ago and probably not quite so brave.Given your setup I would have expected nearer 240bhp and in 875kg it's not going to be slow, especially with your right foot!
I think that instruction is harder as you get older, there is a resistance to change, but maybe the suggestion of getting a professional to drive the car would be good as you will get set-up advice (which you can choose to take or ignore) but more importantly you will be able to get an idea of how much speed can be carried through corners, and what I learnt is how light the inputs need to be to chieve that (less wrestling at the wheel!!)
All the best
davidy
240bhp seems a little on the high side as with 20% losses it would mean 300 flywheel BHP, something I'm not sure I would see with 3100cc. I'll be more than happy with 225.
DavidY said:
Sorry didn't realise you were quoting rwhp, it sounds strong engine, I'd leave well alone.
davidy
I will David if I get the read outs I expect, but I needed to strip the motor to do some maintenance work (wills rings as head gaskets were struggling to seal at 12:1 CR) and a little upgrading to the valve train. I'd bent some valves and had two broken valve springs due to a very wayward gearchange, but the engine was seeing valve bounce at max revs in any case so stronger springs have been installed.davidy
DavidY said:
BTW I think Neil should be made to ingest your RR printout, just to let him know that old tractor engines can make decent bhp! Your figures are nearly 100bhp/litre, good by any engine standards, but excellent for a primitive one.
davidy
davidy
But my old henry makes those numbers with a 2 barrel carb and standard camshaft
To give John a fighting chance this year I am going to stick to the M section historics (nothing to do with budget...honest!)
N.
Edited by heightswitch on Tuesday 17th February 17:44
TVR_owner said:
The car when last dynoed was poorly, but it made good figures at the wheels - maybe the dyno was optimistic, maybe it wasn't as poorly as I thought!...
John, as far as I am aware, all modern (computerised) cassis dynamometers apply correction figures for altitude, barometric pressure and temperature. These are pre-set in the program as a base line and frequently not coordinated by the operator with every minute change in real-life conditions. It may be worth your while to determine how the settings compare with actual conditions on that day which may be available from the nearest airport.
The settings used may be on your print-out.
B.
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