Anyone know much about Dynos?
Discussion
Hello!Untrue, does depend on how good their set up is, air temps, cooling fans, etc etc and where readings are taken from, lot of rr's measure at the wheel and then the operator does a rough guestimate for an atf figure.
We put the spyder on the RR at motoscope, http://www.motoscope.co.uk/ who have a dastek 4x4 RR which calibrates readings taking into account air temp & humidity etc. On a rather warm day it came out at 510bhp at the flywheel.
But I'm sure there's folk who know plenty more will be able to give an indepth answer!
blot said:
Hello!Untrue, does depend on how good their set up is, air temps, cooling fans, etc etc and where readings are taken from, lot of rr's measure at the wheel and then the operator does a rough guestimate for an atf figure.
We put the spyder on the RR at motoscope, http://www.motoscope.co.uk/ who have a dastek 4x4 RR which calibrates readings taking into account air temp & humidity etc. On a rather warm day it came out at 510bhp at the flywheel.
But I'm sure there's folk who know plenty more will be able to give an indepth answer!
How's the car?! Crap weather today unfortunately ay?
This Dyno thing doesn't seem an exact science and seems a little complicated too.
Ok explain what 510bhp at the flywheel means to a novice like me, as all I know if your car should be 520 BHP at the wheels or the flywheel I have no idea?
Hi,
The first thing to remember is that power is not measurable, it is the calculated result of the torque and engine speed.
Any form of chassis dyno, whether it be a rolling road or hub mounted version can only measure the torque at the point of contact (at the wheels or at the hubs), which is then used to calculate the power at the wheels or hubs.
Some rolling roads have a function that estimates the transmission losses and then adds that to the measured figure to provide a flywheel figure. The rolling road manufacturers do not like to admit it is an estimate by the way
.
We use the Rototest hub mounted chassis dyno which is probably about the best available
Some
The first thing to remember is that power is not measurable, it is the calculated result of the torque and engine speed.
Any form of chassis dyno, whether it be a rolling road or hub mounted version can only measure the torque at the point of contact (at the wheels or at the hubs), which is then used to calculate the power at the wheels or hubs.
Some rolling roads have a function that estimates the transmission losses and then adds that to the measured figure to provide a flywheel figure. The rolling road manufacturers do not like to admit it is an estimate by the way
.We use the Rototest hub mounted chassis dyno which is probably about the best available
Some
Lovely day up here again, been scraping flies off from yesterday's run out
Ok, 2 figures you generally get quoted from RR's, at the fly wheel (engine bhp) which should be around 520bhp for mine (so 10bhp out from quoted factory figure), at the wheels figure shows what is getting laid down on to the tarmac as it were.
At the wheels figure was 400bhp, this due to transmission losses and the car being 4x4 (which if I remember correctly normally sees 20-25% loss??)
Ok, 2 figures you generally get quoted from RR's, at the fly wheel (engine bhp) which should be around 520bhp for mine (so 10bhp out from quoted factory figure), at the wheels figure shows what is getting laid down on to the tarmac as it were.
At the wheels figure was 400bhp, this due to transmission losses and the car being 4x4 (which if I remember correctly normally sees 20-25% loss??)
Ok I think I'm getting there.
I have been looking at dyno sheets ready for when I get mine done but I am never sure which figure I am looking at, I seem to remember them just saying max power = xxx
Do RR's sheets tend to be at the flywheel figure?
TDIPLC - do you have experience of whether Lambo's hit the Manufacturers figures?
I have been looking at dyno sheets ready for when I get mine done but I am never sure which figure I am looking at, I seem to remember them just saying max power = xxx
Do RR's sheets tend to be at the flywheel figure?
TDIPLC - do you have experience of whether Lambo's hit the Manufacturers figures?
All quoted manufacturers figures are at the flywheel.
You can't measure this unless you take the engine out and bolt it to a dynomometer.
The best you can do is a rolling road or hub dyno, measure the torque there and calculate the power and then do a coast down to get an approximation of the driveline losses and add them back in to give you an approx flywheel figure.
Unless you specify otherwise most dyno sheets are the calculated flywheel figure.
As has been said hub dynos tend to be more accurate because they remove some variables like tyre slipage and variance due to tyre pressures.
Miyagi, I thought you had already had your car chipped and dyno'd?
You can't measure this unless you take the engine out and bolt it to a dynomometer.
The best you can do is a rolling road or hub dyno, measure the torque there and calculate the power and then do a coast down to get an approximation of the driveline losses and add them back in to give you an approx flywheel figure.
Unless you specify otherwise most dyno sheets are the calculated flywheel figure.
As has been said hub dynos tend to be more accurate because they remove some variables like tyre slipage and variance due to tyre pressures.
Miyagi, I thought you had already had your car chipped and dyno'd?
bertie said:
All quoted manufacturers figures are at the flywheel.
You can't measure this unless you take the engine out and bolt it to a dynomometer.
The best you can do is a rolling road or hub dyno, measure the torque there and calculate the power and then do a coast down to get an approximation of the driveline losses and add them back in to give you an approx flywheel figure.
Unless you specify otherwise most dyno sheets are the calculated flywheel figure.
As has been said hub dynos tend to be more accurate because they remove some variables like tyre slipage and variance due to tyre pressures.
Miyagi, I thought you had already had your car chipped and dyno'd?
Yep correct Bertie. However since then I have had exhaust upgrade and I plan to do intake afterwards.You can't measure this unless you take the engine out and bolt it to a dynomometer.
The best you can do is a rolling road or hub dyno, measure the torque there and calculate the power and then do a coast down to get an approximation of the driveline losses and add them back in to give you an approx flywheel figure.
Unless you specify otherwise most dyno sheets are the calculated flywheel figure.
As has been said hub dynos tend to be more accurate because they remove some variables like tyre slipage and variance due to tyre pressures.
Miyagi, I thought you had already had your car chipped and dyno'd?
So I want to know what gains I'm really getting for my money, you know?
Edited by Miyagi on Saturday 6th October 21:13
Miyagi said:
Yep correct Bertie. However since then I have had exhaust upgrade and I plan to do intake afterwards.
So I want to know what gains I'm really getting for my money, you know?
Rolling road dynos vary massively so you need to do a before and after on the same dyno to really know.So I want to know what gains I'm really getting for my money, you know?
Do you have before and afters for the ECU chip?
I'd be interested to see them.
bertie said:
Miyagi said:
Yep correct Bertie. However since then I have had exhaust upgrade and I plan to do intake afterwards.
So I want to know what gains I'm really getting for my money, you know?
Rolling road dynos vary massively so you need to do a before and after on the same dyno to really know.So I want to know what gains I'm really getting for my money, you know?
Do you have before and afters for the ECU chip?
I'd be interested to see them.
I didn't even do before and after with my exhaust. It's just dificult fitting it in around work.
But I'm not going to make that mistake again.
What reg is your car again Bertie?
Dyno figures only have any relevance if they are done by an operator who has nothing to gain from tweaking the results, and testing has been carried out on the same machine with the same ambient conditions.
It is notoriously common for tuning companys to tweak the results to justify why they charged £3K for an exhaust, or £2K for an (alledgely) modified ECU.
Even if a 911 Turbo is strapped to a dyno straight after a Gallardo, the 4WD transmission systems are different enough that the results won't actually mean anything. So comparing different cars isn't foolproof either.
The only way you can ever be satisfied that a mod has worked is to have your car independently tested, on the same dyno, before and after fitting. Ideally on the same day. It should come as no surprise to discover that the number of companys who will agree to this method of doing business can be counted on the fingers of one hand.
Absolute numbers are not important, a gain is still a gain, a loss is still a loss. Whether a dyno initially shows 500 or only 450bhp before mod, doesn't really matter. So long as there is an improvement afterwards is all that matters. And make sure the torque curve doesn't suffer as a result. There's little point (on a road car) to stacking the power closer to the redline at the expence of bottom end grunt. You'll just have to thrash the knackers of it, which is not really worth paying for.
Many upgrade specialists rely on "emotional tuning". That is, if it sounds like it's making more power then it MUST be making more power. They then just have to supply the customer with information that is consistent with this. Easiest £3K they ever made.
I dare say that you could spend around £10K on various intake and exhaust mods and never know if they've made even a scrap of difference. They may even have made things worse.
Alternatively, you could spend this money in shedding weight (which is much easier to quantify) and get some definite benefits. Ideally concentrating on unsprung weight first.
A stock G weighs around 1600kgs wet and makes about 510bhp at the crank. A 5% weight loss will have much the same effect as a 5% power gain. So getting rid of just 80kgs will have the same effect as a 25bhp gain.
So what could you spend your money on? Well, a set of carbonfibre seats will save around 50kgs straightaway and you're more than half way there. You could have the G converted to rear drive only, which would save another 50kgs, but alot of the driveability would also be lost and no one is quite sure how the electronics will behave (unless you've heard different).
Or just go everywhere with a half empty tank of fuel. I know it sounds ridiculous but this is the sort of gain we're talking about.
I'd go for c/f seats, get someone to make up a c/f engine cover (has anyone else felt how light the SL's is?) and fix the poiler in the UP position. I'd then work out how to fit the carbon brakes from the '06 RS4. Should still be within budget and you'll have the added benefit of knowing that you haven't just lined someone's pocket and got back something worse (but louder) than you started with.
IMHO. Obviously.
It is notoriously common for tuning companys to tweak the results to justify why they charged £3K for an exhaust, or £2K for an (alledgely) modified ECU.
Even if a 911 Turbo is strapped to a dyno straight after a Gallardo, the 4WD transmission systems are different enough that the results won't actually mean anything. So comparing different cars isn't foolproof either.
The only way you can ever be satisfied that a mod has worked is to have your car independently tested, on the same dyno, before and after fitting. Ideally on the same day. It should come as no surprise to discover that the number of companys who will agree to this method of doing business can be counted on the fingers of one hand.
Absolute numbers are not important, a gain is still a gain, a loss is still a loss. Whether a dyno initially shows 500 or only 450bhp before mod, doesn't really matter. So long as there is an improvement afterwards is all that matters. And make sure the torque curve doesn't suffer as a result. There's little point (on a road car) to stacking the power closer to the redline at the expence of bottom end grunt. You'll just have to thrash the knackers of it, which is not really worth paying for.
Many upgrade specialists rely on "emotional tuning". That is, if it sounds like it's making more power then it MUST be making more power. They then just have to supply the customer with information that is consistent with this. Easiest £3K they ever made.
I dare say that you could spend around £10K on various intake and exhaust mods and never know if they've made even a scrap of difference. They may even have made things worse.
Alternatively, you could spend this money in shedding weight (which is much easier to quantify) and get some definite benefits. Ideally concentrating on unsprung weight first.
A stock G weighs around 1600kgs wet and makes about 510bhp at the crank. A 5% weight loss will have much the same effect as a 5% power gain. So getting rid of just 80kgs will have the same effect as a 25bhp gain.
So what could you spend your money on? Well, a set of carbonfibre seats will save around 50kgs straightaway and you're more than half way there. You could have the G converted to rear drive only, which would save another 50kgs, but alot of the driveability would also be lost and no one is quite sure how the electronics will behave (unless you've heard different).
Or just go everywhere with a half empty tank of fuel. I know it sounds ridiculous but this is the sort of gain we're talking about.
I'd go for c/f seats, get someone to make up a c/f engine cover (has anyone else felt how light the SL's is?) and fix the poiler in the UP position. I'd then work out how to fit the carbon brakes from the '06 RS4. Should still be within budget and you'll have the added benefit of knowing that you haven't just lined someone's pocket and got back something worse (but louder) than you started with.
IMHO. Obviously.
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