turbotrev

Anyone used a hub dyno on here?

Im guessing they are typically more reliable/accurate compared to regular rolling roads due to the fact power is measured at the wheels and there's no chance of wheelspin etc?

Cheers Paul

Mark Shead

The ones I have seen and used read higher at the hubs so you can't add Rr losses to hub losses.
To really compare you need to run your car on both and then you know the hp on both rather than guessing.

Mark

turbotrev

Good point.

Why do you think they would read higher?

Cheers Paul

turbotrev

I feel like all your doing lately is answering my questions! Lol!
Thanks though!

Cheers Paul

Rob_DOHC

iTrader: (4)

I think it depends what you want to do really. They are a pain in the cock for power runs as it takes quite a long time to load and unload cars. However once loaded they are probably better for tuning as (like you say) no pissing about with straps or wheel spin/keeping large sticky tyres cool etc.

They are also (or can be at least) very compact so you can roll them out the way and use the space for other things when not tuning.

If space and money was no object I would personally buy a chassis dyno as I believe them to be more representative of real world conditions (as much as can be anyway) and combined with a super dyno cell (like MSD) they are a superb tool, loading and unloading is also nice and fast for dyno days. A good cell is where its at really.

Horses for courses, but for me if you spend most of your time tuning and not doing dyno runs, and want repeatable and safe tool for the job a good hub dyno would be hard to beat. If you spend your time doing both and have the space a dyno dynamics chassis dyno is the respected name.

Both are as inaccurate as the operator.

Rob,

Mark Shead

All diff makes of dyno read diff I have found so if you want to compare apples to apples buy from tesco

Mark

turbotrev

I'm not keen on apples....

Cheers Paul

Fast Guy

Probably because you've removed rolling resistance associated with the tyres.

turbotrev

I thought that but surely the hub dyno's have some kind of resistance setting to give an accurate figure?

Cheers Paul

XRT_si

iTrader: (2)

Interestingly, I know Devil Developments recently built a Focus RS which dyno'd on their Dyno Dynamics rolling road at 766hp. This was obviously calculated at the flywheel.

People called bullshit etc... as always, so it was taken to an independent and well respected hub dyno down at Torque Developments. There it made 692bhp at the hubs, which meant it was about right on the Dyno Dynamics.

That shut everyone up as people tend not to question hub dyno figures. It was only done to compare really.

stevieturbo

Why do Dynojet read higher, why does any dyno read higher or lower ?

And higher or lower than what exactly ?

If they are repeatable, consistent etc...that's all that matters.

stevieturbo

So will engine dyno's read higher because they've removed resistance from all drivetrain components ?

It's Czech Mate

Blimey, back in the day this would have been a violent 20 page mega thread how times change

Rob_DOHC

iTrader: (4)

They will try to guess friction, rolling and of transmission etc but friction is really difficult to accurately model so they most likely have a generic correction factor which won't be the same for all vehicles and will not be the same for all brands of hub dyno, just like with chassis dynos, they all read fairly differently but give you a ball park figure.

turbotrev

Good info xrt Si.

So in reality there's probably not much difference in either with respect to that.

Cheers Paul

XRT_si

iTrader: (2)

Yeah, I think it shows certain dynos CAN be considered just as accurate. It's not quite as black and white as that, as the Devil Developments' dyno is known for being 'accurate', but that's not enough to please some people! I've seen a car that made 700bhp at AmD's dyno struggle to make 550bhp on the Devil's dyno.

I think the key thing to remember is that a well run dyno, with an operator who knows what he's doing, is the most important thing for consistency. Figures are figures, but it's nice to know similar results can be accomplished across different dynos.

Rob_DOHC

iTrader: (4)

Surrey rolling road is supposedly very accurate, what ever that means. He is at least independent and not trying to lower power figures to get business.

The fewer guesses the more accurate the results will likely be. A hub dyno giving hub BHP WILL be more accurate than a DD giving estimated crank bhp. In the same way that an engine dyno will give a more accurate crank bhp figure than either.


Anything which isn't being measured at the load will be an estimate. Ie, accurate Hub HP using Hub, crank HP with engine dyno and wheel hp with chassis dyno. From this point of view I would argue that wheel HP meant more than Hub HP.

turbotrev

Funnily enough Rob I gave surrey rr a ring a few weeks back about a power run for my car (2wd saff) and he didn't wanna know.
Even though I ran my RS turbo there a few years ago he said he don't like to run older fords as they are just trouble.

He has a dyno dynamics rr

Cheers Paul

Mark Shead

Try Eurospec in Guildford they have a Dyno Dynamics RR and wont have a problem running it.

Mark

turbotrev

Guildford ain't far from me at all, nice one.

I did in the end went to Dynotech Hayes Engineering, in Eirth, Kent.
Problem was my car broke traction as it came on boost and spun the wheels every run.
Not 100% sure but think it was due to the super soft compound rear tyres I have fitted??
Small bits of tyre were flying everywhere!

Hence my hub dyno question

Cheers Paul

Mark Shead

Strapping it down is the most important thing, I have run 809hp on Rods with little trouble,
With the semi slicks like toyo once they start to spin you have little chance of getting them to grip again.
I have also done 1053hp on a 4wd car at Eurospec with no problems either.

Mark

turbotrev

They said if it was 4x4 it wouldn't be a problem.
They tried strapping it down harder but with no luck.
I read somewhere that when the soft semi slicks get hot and start slipping it's game over on a rr??

I will be fitting new wheels with 'normal' road tyres in January hopefully so would like to try again with them fitted.

They said this had never happened before with even with big hp supras and skylines....

Cheers Paul

Fast Guy

They should do because you're measuring direct at the crankshaft and you don't have any of the drivetrain losses otherwise your engine dyno would read the same as the hub dyno meaning you had a drive train with no associated losses which I'm sure at the moment is not possible.

stevieturbo

And you can be sure the initial units they're measuring in aren't HP etc.

On any system there will be many maths channels at work to give the final numbers you see. Which means type of dyno used should be completely irrelevant.

but the all read different anyway, so it's no big deal. Use them as they are supposed to be used. As a tuning tool, nothing more. Stop all the pub HP bullshit.

Rod-Tarry

It can be done Trev. Went the day before to experiment. Let tyres down then strapped as hard as possible then pumped the tyres back up to 40+psi, it worked. Would have been some Power loss doing that but 809bhp was recorded this is a 803bhp run during the testing. It had made 838 on an Engine Dyno 3 years before.

Rob_DOHC

iTrader: (4)

How do you strap big power stuff down Mark? I did a 600bhp skyline recently and let the car climb the front roller, ie left 3/4" of slack in the straps and used the brake bar to drag the back end down as it moved forward. That worked well and we had no wheel spin, every dyno I see who just strap RWD cars down with out the slack seem to just break traction as they come on boost.

However doing similar things on a FWD, especially if the tracking is out can be a night mare.

Rob,

Rob_DOHC

iTrader: (4)

Thats really weird mate, in the past he has always been helpful but I usually rent the dyno rather than take cars for power runs... I haven't been to him for a long time and use another place instead for convenience.

turbotrev

He seemed just really anti-ford on the phone so just hung up on him!

Where do you work Rob? Or run cars?

Cheers Paul

turbotrev

What tyres and compound was them power runs on Rod out of interest?

If I can work it out I can try and put a my vid up or pics of the graph

Cheers Paul

Rob_DOHC

iTrader: (4)

I usually do the dyno stuff at Austec racing in Crawley as I just hire the dyno for half a day and they leave me to it. I don't know what they would be like if you just turned up for a power run. It a dyno dynamics and whilst its not the newest of models it is in a really nice Maha dyno cell with proper extraction rather than being just a dyno sat in the middle of a workshop.

turbotrev

I know guy that works there (or used to), Glenn Sone?

Didn't know theirs was a dyno dynamics rr to be honest

Cheers Paul

dojj

iTrader: (3)

the correct answer is "you get more bragging rights down the pub (regardless of if the operator has still guesstimated the flywheel figures, let alone the power before you take into account all the parasitic losses from the likes of the alternators and power steering pumps and if it was a hot day or the guy had forgotten to remove the probe from his cup of tea etc) because it's the next big thing inni't bruv"

Rob_DOHC

iTrader: (4)

Don't know who Glenn is sorry mate. They used to have a Maha dyno which was replaced with a DD. Sadly they got a lot of bad rep as the bloke who used to do lots of their tuning just fudged results to make power. As soon as a company does that they are doomed in my eyes. When we use the dyno we use the DD default weather station corrections (thats what its for after all ) with the understanding that the car makes what ever power it makes and I will not under any circumstances fudge results to make a customer car look better down the pub lol.

I ran my girlfriends not very old Honda Civic type S on the dyno a while back and got results which fitted the car perfectly (ie standard) so have no qualms over accuracy... or at least no doubts over ball park accuracy in as much as any other DD out there would give similar results.

scoooby slayer

iTrader: (4)

I did abit of research into this a few years ago with my own cars, comparing Dyno runs and real world recorded performance times

I came to the conclusion that a hub Dyno figure to get an approximate crank figure add 15 hp per hub connected to the Dyno, so add 30 hp for fwd or rwd, and 60 hp for AWD just as a guide

Jay,

iTrader: (4)

Charlie at Surrey 're has had a few cossie piss oil every where ECT and ended up costing a fortune in clean ups when the owners say the cars are perfect and as mentioned he's a independent so don't want the hassle these days

stevieturbo

3 year old thread bump ?

scoooby slayer

iTrader: (4)

I didn't take any notice of the date just saw it searching and replied

Rsmat

iTrader: (2)

Didn't know the toyo semi slicks are bad to gain traction again if they light up on the dyno ..I've got my escort in at the moment for mapping and it's on toyo R888's .

stevieturbo

Depends on the dyno.

Some have shit rollers that nothing grips on, others have rollers that are quite aggressive and need harder tyres to grip, as soft tyres get eaten up. There are just lots of variables.

Rsmat

iTrader: (2)

dyno dynamics it's being mapped on ..don't fancy my new R888's being eaten .