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Anonymous
Guest
well considering this topic has gone on for 2 pages,there obviously are people who are interested/care about transmission losses.Nad said:
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N1SMO
Guest
if you think it would cost £3000 pounds to dyno an engine you must be mad.
When my engine was rebuild and was getting the gems ecu mapped to it i could ether have the engine done on a dyno or mapped on the road the difference price was nothing to talk about but i opted for it to mapped on the road. If i had went for the dyno all it would cost to find out the difference in bhp would be a £60 rr run
so think before you pull number out of a hat.
When my engine was rebuild and was getting the gems ecu mapped to it i could ether have the engine done on a dyno or mapped on the road the difference price was nothing to talk about but i opted for it to mapped on the road. If i had went for the dyno all it would cost to find out the difference in bhp would be a £60 rr run
so think before you pull number out of a hat.
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N1SMO
Guest
the only reason i wanted to know the differece was people claim 400 BHP i assume they mean at the flywheel. so how do they know they have 400bhp.
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Anonymous
Guest
GTIR-LOZ said:
Well unfortunatly that is exactly what happens, this topic has been done to a death on the GTR forum partly due to the nature of the GTR 4WD system but also the high HP figures involved with some of the cars.
Most try to just get an at the wheels figure as we know its impossible to get an actual flywheel figure with the engine installed. Its generally considered that if you are showing 750ish at the wheels you are at the 1000 at the flywheel.
Another problem with the GTRs is that when on a RR the car will be in constant 4WD and show a higher loss, in reality on the road as long as the rear wheel had traction the car would be in RWD mode and have a lower transmission loss.
Its all very confusing with no good way to say for deffinate who is wrong but the easiest and considered by many to be the most acurate is to use a percentage loss and extrapolate the figure and yes that percentage does stay fixed regardless of the output
Nad
Active Member
[quote="oap-r]well considering this topic has gone on for 2 pages,there obviously are people who are interested/care about transmission losses.[/quote]
But this seems to be just about the power rather than why the loss actually occurs and how to improve it. It has always been around 24% but my point being people only dispute it because they want it too look like they have more power then they really have, but IMO its a bit petty.
They original question was when a power figure is stated where is it from, normally it is at the flywheel, which is usually roughly calculated from the wheels. Why not just leave it as a measurement at the wheels, where it is more accurate, and overall more important as it takes into account the drivetrain which many people have put money into i.e. light wheels and even carbon props.
Nad
But this seems to be just about the power rather than why the loss actually occurs and how to improve it. It has always been around 24% but my point being people only dispute it because they want it too look like they have more power then they really have, but IMO its a bit petty.
They original question was when a power figure is stated where is it from, normally it is at the flywheel, which is usually roughly calculated from the wheels. Why not just leave it as a measurement at the wheels, where it is more accurate, and overall more important as it takes into account the drivetrain which many people have put money into i.e. light wheels and even carbon props.
Nad
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Anonymous
Guest
lets have the info then and no blo%dy excuses.where exactly can you get your engine removed,fitted to a pukka dyno,with a few hours on the dyno,then refitted to your car for less than £3k.N1SMO said:
simple question!
lets have a simple answer 8)
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J-GTi-R
Guest
Just ring Norris Designs and ask, he has an engine dyno and all the kit required to hook up an SR20DET.
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Anonymous
Guest
that would certainly save a bitJ-GTi-R said:
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J-GTi-R
Guest
You're right though, without the kit, running an engine on a dyno is a HUGE amount of money. I think that Northampton place (mainly does Ford rally/race engines, if it is the same one) charges £125 an hour from memory, and that's not including the cost of hooking up the engine, making the brackets etc. You're also looking at a good few hours even if you already have the kit. It's not a matter of just sticking an engine on a bench and starting it up...
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Anonymous
Guest
when i priced it up with this place a couple of years ago it was £2700 and i`m sure vat had to go on.that`s why it`s only the serious prof outfits like btcc,wrc and f1 that can afford to get their engines dyn`d.J-GTi-R said:
I would hav thought that the loss would be the same i.e.
300bhp engine looses say 30bhp
400bhp engine looses 30bhp aswel
Or even the figure mite go down due to the fact that the engine is much more powerful and producing more torque, thus being able to drive the drivetrain easier????
300 looses 30bhp
400 looses 25bhp
The resistance of the drivetrain cant possibly increase unless it was seizing, could it????????
Just my thought on the subject!
Tony....
300bhp engine looses say 30bhp
400bhp engine looses 30bhp aswel
Or even the figure mite go down due to the fact that the engine is much more powerful and producing more torque, thus being able to drive the drivetrain easier????
300 looses 30bhp
400 looses 25bhp
The resistance of the drivetrain cant possibly increase unless it was seizing, could it????????
Just my thought on the subject!
Tony....
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Anonymous
Guest
the transmission losses are the same,if it loses 25% thru trans losses then that is true whether it is a 10bhp car or a 1000bhp car.Tony said:
the only way of reducing trans losses is to experiment with different types of bearings,materials and oil viscosities.
skiddusmarkus
Active Member
I think you might mean a rolling road dyno,bot an engine dyno.
Mine was RR'd at Well Lane(always thought of as a bit generous)at 240bhp @ the wheels.They added their calculated losses to get 333bhp @ the fly.So a 93bhp loss which is approximatley 28%.
I'd be interested to see what figures at the wheels Dakar versions get compared to standard box with same mods as their much lower gearing should transmit into more bhp at the wheels.
but would "your" 10bhp car be able to drive the drivetrain??????????
I see wot your saying, but why duz it hav to be a percentage as opposed to a fixed figure. The drivetrain can`t be adjusted so therefore cant take any more power from a more powerful engine. which using a percentage indicates it duz!!!
know wot i mean?????????
Tony....
I see wot your saying, but why duz it hav to be a percentage as opposed to a fixed figure. The drivetrain can`t be adjusted so therefore cant take any more power from a more powerful engine. which using a percentage indicates it duz!!!
know wot i mean?????????
Tony....
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Anonymous
Guest
wish i had the answers for you but i don`tTony said:
perhaps we could interrogate the r/r guys on the 25th,you could even threaten to fry them if they don`t give up the info :twisted:
Dont talk about fire!!!!!!!
I`ve just set all my engine bay covers and caps on fire by trying to make them dry quicker with a blow torch after spraying them
Didnt know how easily polystyrene set alight either!!!!!!!!!!!! :shock:
I know it woz a stupid thing to do but i want to get away from work on time!!!!!! :roll:
Tony.... :idea: pop
I`ve just set all my engine bay covers and caps on fire by trying to make them dry quicker with a blow torch after spraying them
Didnt know how easily polystyrene set alight either!!!!!!!!!!!! :shock:
I know it woz a stupid thing to do but i want to get away from work on time!!!!!! :roll:
Tony....
:idea: pop
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Edd
Guest
I got 282 @ fly @ powerstation
175 @ wheels
that's 107 :shock:
that's 38% loss :shock:
also transmission loss is dependant on a lot of other factors, tyres, tyre temp, tyre pressure, engine temp, flywheel, clutch, gearbox, gearbox oil temperature.
I had miine rolling roaded at powerstation in the summer when i had driven the car 5 hours back from cornwall, slapped it on the rollers, it had 3bhp less at the wheels BUT 20bhp less at the fly as due to the hot gearbox oil etc, the there would be less resistance and hence less loss
175 @ wheels
that's 107 :shock:
that's 38% loss :shock:
also transmission loss is dependant on a lot of other factors, tyres, tyre temp, tyre pressure, engine temp, flywheel, clutch, gearbox, gearbox oil temperature.
I had miine rolling roaded at powerstation in the summer when i had driven the car 5 hours back from cornwall, slapped it on the rollers, it had 3bhp less at the wheels BUT 20bhp less at the fly as due to the hot gearbox oil etc, the there would be less resistance and hence less loss
The reason that you get more transmission loss with a more powerfull car is that it takes more power to spin your gears, prop, wheels etc if you are accelerating quickly(a powerfull engine) than if accelerating slowly( a less powerfull engine)
Think about it, you know when you were kids, and you turned your pushpike upside down, and turned the pedals?, it takes more effort to accelerate the back wheel quickly, than if you were to build up speed slowly. You are still turning the same wheel, just as you are turning the same transmission, only quicker.
As i understand it, thats how a dyno measures power, how long it takes to turn the drum of the dyno. A dyno actually only measures torque, which is then equated into horsepower. Its something to do with that formula Power= work done in a given time, sounds a bit too much like algebra to me though, and i hated school!
I think the reason it's important,(if it is important at all) is that there are a lot of people quoting flywheel power figures, when the car hasnt been anywhere near an engine dyno, would be nice to know how they arrived at the figures they get.
Also, its important to understand why, and where we lose power, so that we can do something about it, would be nice to get an extra 20/30 bhp, just by messing about with the transmision somehow
Cheers, Dave
Think about it, you know when you were kids, and you turned your pushpike upside down, and turned the pedals?, it takes more effort to accelerate the back wheel quickly, than if you were to build up speed slowly. You are still turning the same wheel, just as you are turning the same transmission, only quicker.
As i understand it, thats how a dyno measures power, how long it takes to turn the drum of the dyno. A dyno actually only measures torque, which is then equated into horsepower. Its something to do with that formula Power= work done in a given time, sounds a bit too much like algebra to me though, and i hated school!
I think the reason it's important,(if it is important at all) is that there are a lot of people quoting flywheel power figures, when the car hasnt been anywhere near an engine dyno, would be nice to know how they arrived at the figures they get.
Also, its important to understand why, and where we lose power, so that we can do something about it, would be nice to get an extra 20/30 bhp, just by messing about with the transmision somehow
Cheers, Dave