Flea as im sure you know, BHP is a calculation of Torque and RPM

We are looking at peak BHP figures, why you have different results I dont know.

The fact is that Chassis dyno's measure WBHP then any other calculation are taken from that.

Yes dave does say he does not operate a dyno but im sure he has a better idea of how they work than most, on his site he explains how they work!!

Not to mention that he builds engines for people and then they get mapped on dyno's obviously he knows what his engines can do and he seem to be getting consistent results from most dyno's apart from powerstations, so i think he is more qualified than you or i to say powerstaions dyno is out or not


TBH i cant see why you are trying to defend there dyno, you cant honestly beleive that you are hetting 24% trans losses??

Maybe they are puting up the trans losses to compensate for how inacurate its measuring WBHP? i dont know but one thing i do know is there dyno has been known to read low on WBHP and High on trans losses


Are you telling me that everyone else's dyno are wrong?

I dont think thats the case

Clearly not that at all mine made 250wbhp but i have another graph from when it made 335bhp again and only lost 30bhp so you tell me how any wbhp calculations can even be significantly correct when theres a differencr of that?

the bloke from powerstation stated on the day that the wbhp is insignificant so dont take much notice of it because of reasons he explained but i personally can not remember.

i was there when he told you luke but also cannot totally remember. Something to do with drag and wheel pinch, and ignore wheel power alltogether on that dyno it is the fly figure which is correct

/\ +1, heard that also, from someone

Sorry luke but of course he say that, his dyno seems to be tottaly inacurate.

And TBH all of this is of minmal importance, the reason why i said people should quote WBHP is simply because there is less chance of the operator manipulating the results with inflated trans losses

Again though its not that important what the peak HP is, is the car running well?? thats important

and if you want to measure your gains people should use one dyno from standard to modified and that way you can see whats done what

the problem is people put to much stock in these pub figures but if people are going to quote them at least use the most accuarte way possible and in this case that is WBHP the problem is people that have used powerstations dyno will always have low figures as there dyno seems to be inacurate

the only more accurate way would be to put all the cars on one dyno that is accurate but this sort of problem will always show itself when you compare dynos as well as results

All in all its not that important as long as your happy and from what you have said luke you are.

drag and how the rollers pinche the tyres awkwardly thats it

Nope micheal Jackson sang Black OR White turboj

wow what have i started well i think we need to do another rolling road day at another rollers,that will be well interesting,imagine the thread lol

this is why dynos need to be calibrated, presuming the dyno is calibrated then is should be accurate the problem is that this dyno is giving results quite different from other dyno's that have been calibrated, you could allow for a bit but this dyno seems to be right at one extreme

agreed, not PT or powerstation, maybe SSR and maybe they can do a deal on a sunday if lots of people turn up for power runs alone?

A dyno can measure torque and extrapolate BHP according to rpm or it can measure workrate i.e. horsepower, and extrapolate torque from that. Torque is a measurable turning force, horspepower is the rate at which the torque is applied.



I don't have different results? Since when did peak bhp figures occur at the same rpm, that would be very remarkable! At Dastek I made peak BHP at 5803rpm (for reasons stated in this thread) and at Powerstation peak was at 7535rpm. How can you possibly compare transmission losses with 1700rpm difference? Transmission losses are not uniform, they increase with rpm so obviously they are going to be greater. Indeed, transmission losses change significantly between gears, that is low gears have lower transmission losses than higher gears. You have to compare at the same rpm point as I did, ergo at 5800rpm there is a 61whp difference between the dynos.



Dave understands in layman terms how dynos work, but how can he possibly know the difference in engineering between them. That would be like saying all otto engines work exactly the same, yes they do in principle, but the unique engineering differences can create enormous differences.



I favour neither the Dastek or MAHA dyno, I don't need to?? I use both as you know, so if I get high wheel power from one and low from the other what do I care. As long as they are consistent between runs and the flywheel figures are close enough then that's the idea. What I won't do is simply dismiss a dyno out of hand without any knowledge of how they work on an engineering or software level.

Wheel horspower is too low, no idea why, but must mean flywheel power is wrong and using this internet formula these are the correct results.

That is frankly absurd especially when the flywheel figures correlate more accurately between dynos than the wheel figures, that alone should tell you something. Just because you don't know how something works doesn't make it wrong.

indeed my only issue is which i have just stated in my tuning thread "guess my new BHP" near the end of it (page 6) soo if you would like to give your experience on that would be interesting

To be totally honest Flea, i dont care if you trust what the powerstation dyno is saying and i getting bored going over the same points

These dyno's both measure BHP at the wheels then they work out flywheel figures from that

lets ignore trans losses or which dyno is better at working out flywheel BHP, its not important

What matters is the figure that all these calculations are made from, thats WBHP, hence why i say people should quote WBHP as frankly flywheel BHP is to reliant on other calculations that tend to be different from tuner to tuner and are open to debate


If you want flywheel BHP then take the engine out of the car and put it on an engine dyno its the only way to be accurate, any other flywheel BHP figures are simply estimated


I dont have anything against powerstation or the dyno they are using but there is no way that anyone can argue that 24% trans losses are normal so somethings not right as other people have confirmed, not just people without a clue but Dave, from puma race engines, who is one of the most respected engine builders in this country, an despite him explaining how a dyno works on his website in laymens terms, who do you think reads his site? i can assure that its mostly people with limited knowledge

You dont get a reputation like he has by not knowing what your doing, nor would you be able to get the results he gets, so lets not question his abilities as he more than likely knows more than either of us


If you think that 24% trans losses are correct then you are saying that First of all Dave is wrong and you would be disagreeing with VW and Bosch them self, i dont think companys like that get this sort of thing wrong TBH

So Flea Beleive what you like, i will beleive what i think is correct, which funnely enough seems to be the same as most of the tuning seen in europe and car manufacturers


Most people with tuned cars will beleive the biggest number and thats what they will tell everyone, the only people that will know the difference will be people in the know so who cares?

I sure as hell dont, i simply suggested that people all quote there power figures at the wheels or using the same formula, that way we can have a more uniform idea of what power these cars are producing

I personally dont know a lot,if anything about dyno's
and how they calculate the bhp,wbhp and torque

I just went to powerstation to get my fuelling checked and to see if my hard pipe kit improved spool up

TBH im not fussed my car only done 271wbhp and i think no one else is

As long as it's running well im happy

Ben

Benny, your 100% right and this is how people should look at it

If you read the thread you will know why the flywheel calculation is most relevant in this instance

1. They correlate significantly more than the wheel power

2. The dyno designers themselves (and operators) have determined that the flywheel power is best used.

My Dastek coupe is not faster than my Powerstation coupe I can assure you, it's exactly the same despite 40whp+ difference

Oringinaly i was told by the first place i went to for rolling road that the Wbhp was the figure to look at... so i thought great, i had 249 wbhp with 265 fly wheel bhp!! this was a single roller rolling road, thinkit was a dyno jet??
since going to the rolling road at power station sat i now believe that fly wheel figure is most relevant as since last rolling road (about 5 months ago), i've only changed injector size, And my Flywheel bhp was 267, VERY similar to last time, YET my Wbhp was only 180ish???

Therefore i reckon if ya gonna compare rolling roads then only compare Fly bhp!!

Also while i'm here.. quick question to those in the know??

If you had 2 identical cars but 1 was running slighty rich and the other slightly lean which would make most power??

I'm guessing the slightly lean one??

Nick

In general most engines are happy with lambda 1. A slightly richer mixture results in better torque around lambda 0.9. A slightly leaner mixture results in better fuel economy which occurs around lambda 1.1.

Now let’s talk about WOT:
Remember an engine is an air pump you can always add more fuel but air is valuable and limited. Air and fuel are not perfectly mixed so slightly more fuel should be added to allow for as much oxygen in the air as possible to be used for combustion. Slightly richer allows for a faster flame speed, any more fuel than this is used to keep combustion temperatures under control (mainly turbo applications). Richer mixtures allow more spark lead (less advance to reach MBT at the right time), and cooler exhaust temperatures thus producing more torque safely.

A lean mixture actually burns cooler (yes it does) and more complete but its slower and it’s this slowness that causes cylinder temperatures to rise risking detonation.

So in summary:
Power = rich mixtures.
Clean and efficient = lean mixtures.

11.1-11.7 is what I would be aiming for in a turbo application.

There must be something wrong here or I have been told wrong.

When I was at my first RR session, the guy after me had a drop in power at high rpm ( I think it was from 6000 rpm). The guy who owned the RR said it its due to rich mixture. He used a chip from a German company (not Novitec) and was told not to use it. Too much fuel can damage the engine.

At the second RR me and my friend Alx went to check his car and tune the new FPR. After the first run we were told that we needed to take away some fuel, the fuelling was to rich. So after the next run we got +10 HP. We change the FPR a little bit more and after the third run we had managed to gain 20 HP. So from 300 HP to 320 HP.

So for me it is the opposite.
Less fuel = More HP

Is this wrong?

i'm thinking this.... as the first rollers i went on (very lean), i made my max bhp at 5300, where run was stopped??
also peak torque 263ft lb was made really early at 4000 revs! This was using 440injectors with 2.5 bar fpr!

Same chip at powerstation i got got a tiny bit less torque and it didn't peak untill 5500 revs??
Fly power was pretty much the same but i didn't get this untill 6500 revs... both my peaks were tiny bit less and much later in power range1
I'm thinking i was VERY rich as was using 630 injectors with 3 bar fpr, (didn't actually check AFR tho)!!

I think on the first rollers if he'd have gone to 6500 revs i would have made MORE power as i've got C&B fast road cams?!?

so from my results i'd say Leaner = more power (but dangerous)!!

Nick

Nick, when we are talking about powerstations dyno i suspect that the dyno has not been calibrated and it reads low WBHP, if powerstation used a normal trans loss calculation they would always get low flywheel figures so what it looks like they have done is push up the trans loss calculation to an un realistic figure to compensate for how low the WBHP is reading

This is not fact just what i suspect is happening, you need to remember that people would stop going there if anyone that put there car on it seemed to loose 40bhp everytime, as unfortunatly people chase BHP figures and nothing else


Look at it this way, all rolling roads measure WBHP and in an ideal world they would all be accurate and read exactly the same, unfortunatly that impossible but most read with 5-10% of each other they then add a trans loss on that and take a educated guess as to what the flywheel BHP is

Like this

dyno 1, read 10 WBHP + 15% trans loss = 11.5 flywheel bhp
dyno 2, read 9 WBHP + 28% trans loss = 11.5 flywheel bhp

these are justfigures i picked out of the air but powerstations seems to be like dyno 2, unfortunatly thats not what nearly every dyno in the country does

Unless my lecture notes are wrong


Surly he must mean too rich you just don't run lean at these rpms.

We were on engine dyno cell the other month mapping Vauxhall 2.2 N/A engine. Alpha/n mapping to a target of 0.92 for that particular fuel. I ask why 0.92 how do you get that number is it a guess? No for power you map to peak torque. To do this we go to a cell and hold the rpm/tps and watch the torque reading on the dyno. We are trying to get the highest reading but must be quick as heat soak occurs, it's like trying to find the top on a falling slope. After a few goes adjusting the AFR I found that it was making most power at 0.92 and that’s how you achieve lambda target.

Powerstation have a MAHA LPS3000 which is fully calibrated. It is actually one of the most popular dynos in the UK and Europe and indeed the most expensive at over £100,000. All MAHA dynos work the same as Powerstation, there is no "pushing up" the transmission losses. I believe Ross (h2ypr) on here used a MAHA dyno in Scotland, same results.

As Nick has stated, if we consider flywheel power then that is the important measurement and will ensure we can correlate everything much more closely. As I have said above Tricky but you obviously missed it, if the dyno designers and operators say we should consider the flywheel power then that's all there is to it.

Flea, i will consider flywheel BHP when its measured at the fly, in other words an engine dyno, other wise its estimated

For everyone else, if we follow the manufacturers advice and also that of the dyno operators then we can't go too far wrong with flywheel power.

Interesting findings here...

Some of the varying results are even found on the same machines at different RRs.

I have not read it all but right at the bottom its says to stick with WBHP and you wont go to far wrong

It also says that outright power figures should be taken with a pinch of salt


and the difference between the highest and lowest was 13.4 bhp

Actually they called the 13.4 difference shocking, on at 74bhp car that's a difference of 17%. On a 300bhp car that could be as much as 50 wheel horspower, hardly possible to compare is it?

I meant too. Missed a letter

When I RR my car I got AFR 12-12.5.

OK - for a start, I'm not taking sides in this discussion, but it IS interesting enough to carry on

So - here's a situation that needs some explanation

20 October 2008 at Powerstation

271 at the wheels @ 6410rpm - max test rpm, 7135 / 130.6mph
351 at the fly
equals 80bhp transmission loss

31 January 2009 at Powerstation

287 at the wheels @ 6830rpm - max test rpm, 7000 / 129.3 mph
388 at the fly
equals 101bhp transmission loss

interestingly, torque was almost identical 330 in October and 333 in January

so - the way that Powerstation measure transmission losses is via the coastdown method - i.e dip the clutch at peak revs, then the rollers measure resistance as the revs die away. We know this is better than a simple guess at transmission losses, as there's actually some measuring going on.

However, other than sorting a couple of boost leaks, my car was in exactly the same condition - same tyres, same pressure. The ambient was 6 degrees colder on the January run and barometric pressure was very slightly higher.

So - how did my transmission suddenly lose me 20bhp?

my guess (for what its worth) is that the drag measurement is partly calculated as well, rather than just a pure measurement