Engine 850: B5234TR/2.3/20v/T5R: Dyno Run 850R 1996 with RICA

[s70t5chris]

Originally Posted by s60ben

Hi Guys , as you know in Europe we quote BHP at the flywheel (ie the power coming out of the engine) rather than the power measured at the road wheels. Obviously the latter will always be a lower figure due to power being lost through the gearbox,tyres etc.But which is the best and most reliable figure to quote? In the US the guys often use wheel horse power figures. The reason being ..(1) this is the actual power being put through to the tarmac and (2) loses through the engine do not need to measured or calculated or guessed!
OK this looks at first glance of being the better option , but if you look further you realise that flywheel figure is the only reliable figure....
The main problem with wheel horsepower (whp) is the tyres. Firstly the tyre is squashed at 2 points on the rollers not one (as it would be on the road) so the drag is increased . For every rotation of the wheel the rubber is squashed throughout its entire circumference not once but twice! Also consider the gear you are in ; if you do a run in third gear and then again in forth gear ,the 'length of rubber' that gets compressed in third gear will be less than in forth. -So you will get more WHP in third than forth.
Taking this further you will also get more WHP with narrower tyres (assuming no slip) higher tyre pressures, a smaller diameter tyre , a later MCS (with its lower gearing) ,etc etc.
From this you can now see that quoting WHP is pretty meaningless due to so many things that will effect the measured output.
This is why we need to MEASURE the losses and add this figure to the WHP figure to get a true indication of the engines power.Using a figure and just adding it to the WHP is laughable. At a rolling road event a while ago I spoke to another Mini tuner who said he just measures ast the wheels and adds 20-25% !
OK, the measuring is quite straightforward and just involves (after reaching beyond peak power) knocking the car into neutral and letting it coast down. At this point the the inertia and weight of the rollers are driving the wheels and gearbox,- not the other way round. This shows as a 'negative' horsepower .eg at 5000 on coastdown it may measure 'minus 20bhp'. This 20bhp will be added to the WHP at 5000rpm to give the 'flywheel BHP ' at that engine speed. This 'minus' bhp is measured and then added on to the WHP at all engine speeds from peak revs down to maybe 3000rpm ,at which point the RR operator gets bored and applys the footbrake.
Now because we have measured the ACTUAL losses it makes no difference to the FLYWHEEL BHP what gear/tyres/tyre pressures you used as the losses however big or small are added accordingly.
As an example lets take a stock Cooper S with 16" wheels 50psi tyre pressures,
and run it up in third gear on the rollers. Lets say the WHP came out at 160bhp.
We then take the same car put 19" wheels on it with 15psi in the tyres and run it up again in forth gear. This time the WHP comes out at 130bhp!
From this its clear the WHP although necessary to measure is not the 'final figure to be quoted'.
What we now need to do now is apply the run down losses we measured on each of the two runs;-
On the first run (16" tyres pumped to 50psi, third gear...) the losses measured 10bhp.So 160 WHP + 10bhp losses=170 bhp @ flywheel.
On the second run (19" tyres 15psi tyre pressure, forth gear...) the losses measured 40bhp.
So 130WHP + 40bhp losses=...........wait for it........170bhp.!

Thanks for that Ben. It explains what I already knew, but hopefully will help others to understand why WHP is all a bunch of BS. Unfortunately people will only believe what they want to believe.

[jonnyv]

Well done, Ben. As usual totally on the ball. Just felt we needed to see the graph...as it just didn't read right! Not for a Rica!

[s60ben]

Originally Posted by s70t5chris

Thanks for that Ben. It explains what I already knew, but hopefully will help others to understand why WHP is all a bunch of BS. Unfortunately people will only believe what they want to believe.

Nay probs Chris

Really unfortunate is that some people will only believe what comes out of the mouth of HLM Tuning ...

It may appear to smell of roses - but we all know what they grow roses in don't we...

[960kg]

Originally Posted by s60ben

Nay probs Chris

Really unfortunate is that some people will only believe what comes out of the mouth of HLM Tuning ...

It may appear to smell of roses - but we all know what they grow roses in don't we...

The thing is Ben you believed what came out of someone elses mouth whatever it may of been to learn about these type of things. I am not for one joining the gang that say it is true or untrue.
If you read all the post correctly you will see that members such as Frankie are only trying to help the OP, it does seem for what motor he is driving and the specification of it that something is amiss with the figures given by the dyno he visited.
It was others that started off this "we know better than you attitude" and nobody actually "pi**ed on his chips" Is the OP happy? he gave no indication that he was either way but did start to think that maybe something was wrong.

I have been into cars and tuning since 1966 and practically lived at Brands Hatch as it was just up the road from where i lived, ok, i know a lot about tuning N/A motors and turbos are relatively new to me how they work but above all there is one thing that stands out of all these 46yrs amonst the tuners and the hot saloon car owners and that is each thinks his sh*te don`t stink and will go on to tell others especially on forums such as this one. It is all so "clicky" on here but the S/V40 site is much more friendly and helpful towards peoples problems and when one comes to the VPC it is friendlier still and if any member has a problem they rally round and are there to help without this pettiness about who know`s more than you do attitude. It is the way it is done and it does leave a rather nasty taste in one`s mouth.

You should be ashamed due to the status of your membership and also those that agree with your posts.

[outnumbered]

i was under the impression that all this site was friendly and helpfull not just one specific section.people are entitled to post what they feel is in the good interest of forum members, if i agree that the post is helpfull then i will thank that person if its not then i will not post there are enough trolls as it is . as to the dyno there is something wrong and if it had been mapped by Rica its not doing what it says on the tin.the i no better than you attitude that's a fact of life i appluad there bull**** that is if it is so. if the information is correct then its fine by me as for others that is entirely up to them and you.
what i do not agree with in your post is the us and them attitude on how helpfull each section is.
mike

[s60ben]

Originally Posted by 960kg

The thing is Ben you believed what came out of someone elses mouth whatever it may of been to learn about these type of things.

Difference is, I'm prepared to listen, but more importantly to learn - and to do my own research.

Originally Posted by 960kg

I am not for one joining the gang that say it is true or untrue.
If you read all the post correctly you will see that members such as Frankie are only trying to help the OP, it does seem for what motor he is driving and the specification of it that something is amiss with the figures given by the dyno he visited.

I didn't say anything other than Frankie was wrong, and then attempted to provide simple understandable guidance.

He even said he had similar figures from his own car on a Maha dyno... but chooses to believe the "Random Number Generator" at HLM, despite the fact we've proven that the MAHA dynos are accurate and repeatable at a number of different locations on different days.

I should also point out that the figures given by the OP's dyno chart are "uncorrected".

Originally Posted by 960kg

It was others that started off this "we know better than you attitude" and nobody actually "pi**ed on his chips" Is the OP happy? he gave no indication that he was either way but did start to think that maybe something was wrong.

FWIW - The only reason the OP thought there may have been something wrong, was due to the bull being banded about with the Dyno figures spouted, by someone who clearly has no knowledge.

Originally Posted by 960kg

I have been into cars and tuning since 1966 and practically lived at Brands Hatch as it was just up the road from where i lived, ok, i know a lot about tuning N/A motors and turbos are relatively new to me how they work but above all there is one thing that stands out of all these 46yrs amonst the tuners and the hot saloon car owners and that is each thinks his sh*te don`t stink and will go on to tell others especially on forums such as this one. It is all so "clicky" on here but the S/V40 site is much more friendly and helpful towards peoples problems and when one comes to the VPC it is friendlier still and if any member has a problem they rally round and are there to help without this pettiness about who know`s more than you do attitude. It is the way it is done and it does leave a rather nasty taste in one`s mouth.

You should be ashamed due to the status of your membership and also those that agree with your posts.

I'm not ashamed as to the "Status of my membership" - Unlike some, I don't live my life by how many thanks there are, nor what the silly post figures or what the silly membership indicator says, nor do I "post whore" to get there.

I gotta love the "it's all so clicky on here" comments - I've never found that, but what I do find is a large number of people with their heads stuck up their a$$es. I'm pleased you like the S40 site, I personally prefer to read generally technical posts, without the BS stuff, like "what you up to today" or "I've just had cornflakes for my breakfast". I also prefer the sites where you can put a topic in the wrong section, and not receive a warning for it.

Each to their own, and I fully appreciate that those of younger years like different sites to those of advanced years. What I do find amusing, is those that choose to post whilst adding nothing to the discussion, but that decide they can be critical of others who are adding information to the discussion, without adding any of their own, ie. purely a typical old mans moaning. I've noticed the older the member, the more they appear to regress and prefer kindergarten sites.

Maybe I should have been less friendly to the OP, after all I've seen him locally a number of times, exchanged PM's tonight, and he'll now know who it is when we see each other

My point, is that the OP has come to say XYZ, and then someone jumps up and down saying it's not making adequate power - based on their mistaken understanding of the Dyno graph, and Dyno's in general <and let's not mention physics>.

I'm actually attempting to show the OP that there's potentially absolutely nothing wrong with the power he's creating, and to inform and educate the main person saying there's a problem...

If you have a problem with that - tough - enjoy your s40 site.

[960kg]

......and so the crap goes on....

You don`t have to prove yourself to me, as you have commented in a different kinda` way i was tuning cars when you was probably in your Father`s ball bag!

[Axionknight]

Take it to the PM's if you have a personal grievence, or better yet, act like adults and let it lay..... Thread has been hijacked enough.

[Jardon]

Thanks Ben. OP that looks normal to me - what Rica claim and reality are different. It won't get near 304 or whatever they quote. 260-280 and ~400nm is ball park "correct".

[winsox]

I never thought posting my results would start such a war in words !!



Oh well ....hope everyones carmed down a little !!

:-)