MADsteveCOS

Congratulations Nyk,

Good to see you got such a positive result, and an awesome top speed. As has already been said in this thread, the car just looks 'right', and now has the power (and plenty of it) to match.

I can sleep at night now that I know my old engine has achieved something quite spectular.

Credit to Mark for an awesome build, and Nyk for the bowling-ball cajones for getting it up to 180.

Chip

iTrader: (3)

Dyno dynamics rolling roads often struggle to get a RPM feed from an autronic ECU, as a result normally they have to calibrate the RPM feed against roller speed using the tacho in the car for a reference.

If they do this, the BHP figure will be exactly the same regardless of what error is involved in the RPM feed, but it can alter the torque figure accordingly, so that may be an issue here.
It will NOT effect the peak BHP though.


Nyk, can you quote us as exactly as possible please, the two peak BHP RPM points, as this will let us know if the rpm calibration on the dyno dynamics was out at all.

CossieRich

iTrader: (1)

Mike,

Fair point but Mark has explained that in his little paragraph under the graph.

Chip

iTrader: (3)

Rich, it may also been be down to rpm calibration on the rollers for the capri.

If when they set the rollers at 4000rpm on the tacho, its actually doing 4100rpm, all the torque figures will be out by 2.5% too low.

It wont effect the BHP at all though (well other than moving it 2.5% higher up the rev range so it may read peak at 6150rpm instead of 6000rpm) in terms of the figures but the actual BHP figures recorded will not be effected AT ALL.

Zetec_mk4_XR3i

awesome awesome car! love it mate!

Martin-Hadland

iTrader: (2)

They could have used an injector pulse for an rpm reading..

Chip

iTrader: (3)

Thats not very reliable unfortunately, when we put the astra on a dyno dynamics on SM4, they tried:
Coil
Injector
RPM output of ecu


And the dynodynamics wasnt happy with any of them, so they had to use the roller speed method.


As Ive mentioned though, it does NOT effect peak BHP at all even if the roller speed calibration is wrong, but it can make torque under read (or over read depending on which way out it is)

Martin-Hadland

iTrader: (2)

You keep harping on about that but is anyone disputing it? It would obviously nice to have the rpm accurate for any comparison purposes though.

Chip

iTrader: (3)

Martin, was just making sure it was very clear so that people didnt need to ask the question in the first place, saves a few pages of to'ing and thro'ing, lol

ECU Monitor Enthusiast

iTrader: (1)

Chip,
Not having a go at you personally and maybe I am being dumb as to the exact point you are trying to make there but as you know I sometimes look at mathematics from a reverse angle due to the way I program software when using non high level languages.

But I think what you are saying is wrong ! LOL

(I have deliberately worded the following simply and expanded explanations so everyone can attempt to understand it)

Excluding RPM.....Torque is the ONLY variable you can measure on any dyno/RR. (as opposed to BHP)
This does not depend on RPM except when the torque curve is plotted on the graph as this is then shown relative to RPM.

When the dyno/RR does a power run, these torque values are stored with an RPM reference.

BHP can only be calculated from torque and RPM from the following calculation...

BHP = TORQUE x RPM / 5252

Now the way I understand things, if you measure RPM wrong then both BHP and TORQUE will be shifted up or down the graph by the same amount in their relative ratio's.

For example using fictional figures....

An engine produces a peak torque of 400lb/ft @ 6000 rpm.
Thus 400 (lb/ft) x 6000 (rpm) / 5252 = 456.9 BHP

Now if the RPM over reads by 200 rpm....
Thus 400 (lb/ft) x 6200 (rpm) / 5252 = 472.2 BHP

Going the other was and undereading by 200 rpm...
Thus 400 (lb/ft0 x 5800 (rpm) / 5252 = 441.7 BHP


So my conclusion is that during an incorrectly read RPM graph PEAK TORQUE will always be correct even though its in the wrong place on the
graph relative to RPM.
BHP will be wrong as the RPM ratio changes based on the RPM value.

Thus your comment that peak BHP will be correct for an incorrect RPM reading is not right !!!!

BHP will ONLY ever be correct if the RPM is absolutely correct !

I await your comments

Christian and Beccy

iTrader: (14)

We try VERY hard to get a proper RPM reading from the car, as opposed to using Roller Speed. We have various adaptors to help with this.

Only then can you prove that the car didn't wheelspin.

CossieRich

iTrader: (1)

Blimey,

Simon has written something i actually understand. dont know if its correct but i get the jist

Mike Rainbird

iTrader: (3)

Chip

iTrader: (3)

I look at mathmatics from every angle mate, Ive programmed in high and low level languages though, and I can assure you that 1 + 1 is always 10 in all of them underneath, sometimes it is just presented differently to the end user


You are mistaken, what ive said is correct.

Yes the TORQUE at the ROLLERS and the RPM at the ROLLERS (not the engine)

From this, an accurate curve of torque vs rollerspeed is plotted in the software.

That then needs to be translated to engine torque, to do this you need to know the relative speed of the engine compared to the rollers.


Totally incorrect, you have it all backwards.

What you would actually get for your 400lb/ft @ 6000rpm which is registering as 6200rpm due to a slightly incorrect RPM calibration is that instead of being 400lbft, it would be incorrectly scaled and would come out as 387lbft

Which is EXACTLY the same BHP as it should be, 456.9, but now registered at 6200 rpm


So as I said all along, the BHP will be EXACTLY correct values, but shown at a slightly different RPM to where it should be, and the torque will under or over read.

Hope you can see the mistake you have made there, if not then let me know and I will go into more details for you

Incorrect

Incorrect

Nope, Im right, you are wrong

Nope, BHP will be correct as its calculated from:
Roller Torque * Roller Rpm / 5252

And I await yours now Ive hopefully explained it to you enough for the penny to drop my good friend

Chip

iTrader: (3)

I believe you have the mental capacity to understand what Im saying if you just read it through a few times and take it in small steps Mike, so rather than just take Simon's word for it, try and work it out yourself from the points Ive raised, and you will (imho) be inteligent enough to come up with exactly the same conclusion as me, as it is of course the only correct one, its not a matter for opinion, merely fact or not fact, and what I have said is fact, and what Simon has said is not fact.

Try it again Mike, you can suss it

And if you cant, give me a ring and i'll talk you through it in even smaller steps

ECU Monitor Enthusiast

iTrader: (1)

Chip,

Instead of just dismissing my comments and saying "INCORRECT" please say why !!!

I would appreciate you editing your above post and copy and paste it into another post

Of course the graph will be 100% correct in relation to the rollers but we want to know what the engine is doing !
If we are not measuring the engine RPM correctly, any readings given in a graph will be wrong ... FACT !!!
Except the peak torque value which will be in the wrong RPM place.

The graph only shows one RPM scale... How do you know how to correct the reading if we are not measuring it directly !!!!

If you agree that the following calculation is correct then all your reasoning is wrong...

BHP = TORQUE x RPM / 5252

Torque is a measurement independant of RPM !
BHP is always calculated from TORQUE and RPM.
It dosent take much brains to see that if TORQUE or RPM is wrong then BHP will be wrong !!

In fact you said I am wrong above in one place then quote the same calculation to me

sbd16v

im interested in this but please move it ALL into another thread

jb fletch

iTrader: (1)

Chip, Simon !!

I love you guys !!

jb

Chip

iTrader: (3)

Agreed, can a mod seperate this out please and put it in GD as its own topic?

ECU Monitor Enthusiast

iTrader: (1)

I just want it made clear I have nothing but respect for Chip and also this in no way is a diss to MAD.
Its just a nerd fight LOL

I love you too Fletch

lead_foot

iTrader: (1)

Won't there be a direct correlation between Engine RPM and Roller RPM ?

Chip

iTrader: (3)

Simon, Id have thought you'd know me better than to think I would make a mistake about something as pure mathmatics as a rolling road, lol

PM me your number and I'll give you a ring, easier to explain on the phone than pages and pages of typing, then once you understand how it works, I'll go back and type it all up properly when I get the chance.

ECU Monitor Enthusiast

iTrader: (1)

Maybe, not guaranteed. - How do you really know what the difference is if you dont measure both !

Also, dont forget wheel spin !!

Chip

iTrader: (3)

Providing wheel spin is controlled, without which you will NEVER get a meaningful reading on ANY rolling road, yes its even more direct than a correlation, its quite simply a multiplication factor for each gear.

Chip

iTrader: (3)

Because what you have typed isnt how it works.

I'll just address the key issue here mate, it will all become clear to you im sure, failing that, pick up the phone, its so much easier to teach people when its a dialogue rather than just typing it out.

The torque and the RPM will BOTH be wrong, one will be out by a positive percentage, the other will be out by a negative percentage, and the two will then be multipled together.

As a very extreme but simple example, lets assume we have 100lbft of torque at 5252rpm at the wheels from our engine, and of course hence 100bhp at the wheels too.

Now we're going to get the rpm VERY wrong just to demonstrate what happens.

Lets get it wrong by 50%, just for arguments sake?

Ok, so now we are seeing 2626rpm instead of 5252, and of course, that means we we do the calculation to get from roller torque to engine torque, this will also be out by the same amount, but in the opposite direction, so the torque we will see will be 200lbft instead of 100lbft.

So what we will see in our example, is 200lbft @ 2626 when its really 100lbft @ 5252, as BOTH will be out by the same factor (one halves, the other doubles)

Tell me please simon, what BHP will we see if we do the maths on 200lbft@2626 and can you tell me what % discrepancy there is from the 100bhp we were expecting?


Indeed I have, you ase using the right equation, you are just using it wrongly

mad russell

Nice one MAD/Nick

Russ

Mark Shead

For those who missed it
This RR was done with the Ignition pick up as you can clearly see it listed with the If Ftl this means it was run with The Ignition pick up,
So no fudgingof the graph can happen and you can see the temp and baro also.

Mark

b16nyk

Hi Mike
Thanks for the kind words,appreciate it

Chip
Max torque on the engine dyno was at 4400rpm
Peak hp was 500.1 at 6560rpm and 500.2 at 6840rpm

CossieRich

iTrader: (1)

Nice Mark,

point made i do beleive

Rab

What kind of Rear Axle are you running?? Cheers!!

davi

Well done nyk, really good result you must be well chuffed. Do you think there's anymore in it?

Cheers Terry.

b16nyk

Axle is standard 2.8 with uprated shafts and a tightened up stock diff

Terry,to be honest I don't think It'll go much faster.
saying that,there was a slight headwind,we were down .2 bar due to a split diaphragm in the dump valve and I was struggling to get 5th gear so maybe a touch more mph if everything came together
We might be closely matched on top speed but 10s quarters are well beyond my reach!

davi

What diff ratio are you running? 3.44? I reckon 10s are possible, have you ran it up the 1/4 yet?

b16nyk

Yup,3.44 gears
The problem being 1245kg verses, I guess, under 1000kg for your car
Car used to run 12.20s at over 117mph on only 330bhp on AO48s with the previous engine.
Puddy spent ages looking for a hidden nitrous lines that were never there!!

CossieRich

iTrader: (1)

so an 11 sec 1/4 mile is on the cards yes Nic?

DangerousBryan

may have too much power now,so may actually run a slower time but with a higher terminal?

pig

stunning car this,cracking job on it by all involved.i was at brunters on monday when it ran the 180,fuck me this things goes like fuck and sounds the tits.nick you have big bollocks m8 as it was wet as fuck there with puddles all over the place.

costina

iTrader: (1)

Nuff said

Nothing beats a cossie powered old skool ford

Paul