Dyno Mythbuster...

[MattJ]

I have touched on my despair of dyno figures and the importance most people put on the numbers at the top of the dyno sheet in a few posts over the years. I just thought I’d start a dyno Mythbusters post and pass on some of my findings over the years. This is something I have wanted to write for years as in my position of performance sales manager I have to deal with this sort of thing countless times a day. Not everyone will be happy reading this as a lot of people here and on other forums hold the dyno sheet close to the ego.

Also, I can see how some shops feel that they have to provide big numbers as the customer demands the same figure as his mate or some guy on the forum with similar mods. But in the end, it starts and finishes with the performance dyno shops.

I bought a BF Typhoon about 2 months ago, the previous owner had the car tuned with injectors and a cat mod. He was given a dyno sheet stating 315rwkw. I did not buy the car because of the stated power nor am I for a second suggesting the previous owner pulled a shifty, but when I got the car back home, and without touching a thing, it made 279rwkw on the HP-F dyno. Where the missing 35rwkw fits into the list below, I don’t know. But this is the sort of thing that can make a customer think that one shop is shit and another the kings.

No dyno reads exactly the same! HP-F have two dyno’s, they read different. A dyno is not a ruler where 30cm is always 30cm wherever it’s measured. Every dyno company and just about every shop will say theirs reads more accurate or more repeatable which is great, but the simple fact is that every dyno reads different and comparing one to another is folly. The difference between one run and the next on the same dyno is what you need to keep in mind.

There is more than one way to dyno a car! HP-F have had the privilege to be able to build and tune some of the tuffest dyno cars in the country, the dyno HP-F use to tune the big bangers is set up to make 1700+hp turn the rollers with minimal slip and when Dyno Dynamics wants there latest technology tested they come to us. Utilising this latest technology gives us no choice but to follow the rules when strapping down a car. The Dyno Dynamics dyno is calibrated to have the rear rollers stay in constant contact with the wheels all the way through the run, if they come off, the power number will be inaccurate and read higher than it should. Strapping down of the car on the dyno has a huge effect on the final reading, a car with loose straps will ride up on the front roller for most of the run and then normally just after peak power the car will sit back in onto both rollers, you can see on the graph when this happens as the power line drops, looking something like (and often confused with) faulty valve springs.

The dyno is only as good as its operator! There is quite a few other ways for the dyno to read inaccurately, the incorrect placement of the intake air temp probe is a beauty and incorrectly typing in Barometer reading will have a real effect. All these things are easy to avoid for the alert operator and easy to tamper with for the dishonest. Calibration and regular service can also help maintain constant, reliable numbers.

Different tyres will read different power! We once had a car make a lot less power then what we thought it should for the given mods, we got the car up on the hoist, searched high and low, checked compression, double checked the tune, dropped the exhaust, changed intakes, you name it we tried it. Nothing doing. One of the guys took a backward step, had a look at the car and suggested we should try different tyres. The ones on the car were brand new but what did we have to loose? We pulled a couple of wheels of Rob’s ute and bung ‘em on. The car picked up the lost power, and some… 25rwkw from a tyre change!! Tell me, how do you compare one car to another? :confused:

Each engine is different! Two cars with the same mods rarely make the same power, even in standard form most cars make different power on the dyno. Or what about auto or manual? High stall torque converters? These thing all effect the power readings. Again, how do you compare one car to another?

A tune for the dyno and a tune for the road! Simple really, a lot of times the final run on the dyno needs to be trimmed up to stop the odd ping found on the road test, big problem with XR6-Turbo’s. The main issue with this is that you pick up your car with X-power figure on the dyno graph and a few days later you dyno the car somewhere else and it reads low or, your mate expects what your makes. What about a race cam in a road car, you want to replace valve springs every 20,000 kays or do you want to flycut the pistons to fit it in?? Nothing wrong with either of these two options if your prepared to go through it, but to base you figures for a ‘cam only’ upgrade on custom shop set up’s is folly.

And Finally…

Don’t let the facts get in the way of a good story! How the car was run up on the dyno is another thing. Race fuel? Shhssh don’t tell anyone. The problem with that is that one day your going to have to repeat it and one day the car might be out of your hands and the questions will start. Disclosure of the facts is important as anything else if you want to be taken seriously and not live a life where everyone now doubts your every move. So how can you tell? Simply, you probably cant, but like life, if it is seems too good to be true, it most probably is.

Ultimately, the car makes what the car makes, its fine to have goals but the basis of these goals has to be reality. Sorry for the long post...

[ve/ss]

Nice write up.

[vz6.0]

Bra-Fkn-Vo!!!!!!!!!!!!!:goodjob:

Ive been saying this stuff for years.

Sadly, most people dont want to hear it, and every workshop owner with a dyno will tell people theirs is great, and everyone else's is poo.

Maybe now, with someone actually making sense about the subject, without the "smoke and mirrors" bullshit that pervades the rwkw phenomenon, we can finally get back to what its all about.

A tuning tool. No more, No less.

Congratulations Matt, for an honest,unbiased appraisal of what actually happens with a chassis dyno, perhaps the forumites will take some of it on board, and not pray to the golden calf that is a pair of straps, a pair of rollers, and some sophistimicated electronic doodadery.

[FPVkiller]

so true.
Very well said. :goodjob:

[macca33]

Great write up Matty and hopefully it dispels some rubbish that gets bandied about at times.

FWIW, my car has consistently dynoed on HP-Fs DD dyno to within 1-1.5rwkw of Chev's DD dyno, with both types of heads, etc. I'd say that less than 0.5% difference between the two separate machines is a fair indicator that dynos can be very accurate - if used properly, to the requisite standards.

Cheers

[STATIE]

Bit quiet today Matty?:D

[Jected]

Great write up Matt and spot on IMO.

[cards400]

Two Days In A Row And Two So True Threads (tune House Thread). The Dyno Is A Good Tool But That Is About It. Try Doing A Carby Car On A Chassie Dyno Then Run It On The Street Or Strip, I Bet Your In The Jet Master Box Pretty Quick And Playing With The Timing..lol. Well Done You Have Done A Great Thread.

[APS Fston]

Here's my Dyno...

YouTube - 1000HP BURN (http://www.youtube.com/watch?v=Y-_BJkoPKS0)

[hsv-105]

Having worked at many shops around Melbourne and even venturing beyond the border for a well publisised excursion I suppose you have seen enough inner workings of different dyno's / workshops / operators to give such a thorough opinion Matt. :goodjob:

Maybe to give everyone a better understanding of your vast experience maybe share your employment history over the last 10 - 15 years with punters so they can really appreciate the information you are sharing.

[cards400]

Here's my Dyno...

http://www.youtube.com/watch?v=Y-_BJkoPKS0

:rofl: WHAT HE SAID (DID!)

[SVNLTR]

Here's my Dyno...

http://www.youtube.com/watch?v=Y-_BJkoPKS0

Who sells them?:)

[clubbie]

Matt

That is THE best thread on this forum for ages.

Well done and thank you.

Clubbie

[Tre-Cool]

Great Post Matt.

[MADLS1]

spot on matt!!

if your car make X on the dyno & you do a mod & it makes Y after = job done :)

it had to be said & you said it perfect!!!


Juzza

[TIR33D]

So inlet temp has an effect. Should you move the sender away from the car to get a real atmosphere temp? Honestly just asking the question.

[SVNLTR]

So inlet temp has an effect. Should you move the sender away from the car to get a real atmosphere temp? Honestly just asking the question.

put the air temp sensor right in front of the entry point of the airbox,t/b

its the actual temp going into the airbox/tb that the dyno needs to see-

[Bruttas]

My ute was on the dyno at powercruise and it made 243kw=326hp,
the ute as been on 4 other diferent dynos and all within 10 kw of each other
the power cruise dyno was 30 kw shy but the graph was a good consistent
ark so im happy.
The ute as run a 12.9 on 20 inch koomos with all my shit in the back, people that know me know all abbout the crap i allways cary.
So if your not happy with the dyno chart and the car perfomes be happy,
my engine as no internal mods and a little blower to help it along.
http://www.youtube.com/watch?v=kHXnkU_JpQo&feature=rec-HM-rn

[STATIE]

Here's my Dyno...

http://www.youtube.com/watch?v=Y-_BJkoPKS0

:rofl::rofl::rofl:

Here's one of my old 330-340ish RWKW Dyno sheets from about 18 months ago.

<embed width="448" height="361" type="application/x-shockwave-flash" wmode="transparent" src="http://i189.photobucket.com/player.swf?file=http://vid189.photobucket.com/albums/z89/R8MALOO/07060210.flv">

Matt skinned some knuckles on this car a while back too.:lol:

[HYMEY]

^^^^^^^^
only real way to measure hp statie...at the track..:goodjob:

[Sid447]

Australian LS1 and Holden Forums (http://www.ls1.com.au/forum/showthread.php?t=58222)

Australian LS1 and Holden Forums (http://www.ls1.com.au/forum/showthread.php?t=88308)

[mikek73xu1]

The only accurate dyno's are the hub mounted one's.

[MattJ]

Bit quiet today Matty?:D

Nah Statie, just had a couple of dyno related issues push me over the edge :)


Having worked at many shops around Melbourne and even venturing beyond the border for a well publisised excursion I suppose you have seen enough inner workings of different dyno's / workshops / operators to give such a thorough opinion Matt. :goodjob:

Maybe to give everyone a better understanding of your vast experience maybe share your employment history over the last 10 - 15 years with punters so they can really appreciate the information you are sharing.

Thanks Mark, I dont think it really matters about where i have worked though. Needless to say I've been around the traps and am very happy doing what i am doing.


Here's my Dyno...

http://www.youtube.com/watch?v=Y-_BJkoPKS0

The dyno sheet read "Kick Arse" at the top of the page!

[Martin_D]

Nah Statie, just had a couple of dyno related issues push me over the edge :)

Few deep breaths Matt, its all good :)
How is life back in Vic treating you anyway?

[MattJ]

So inlet temp has an effect. Should you move the sender away from the car to get a real atmosphere temp? Honestly just asking the question.

Yes, Check out some of the Record Dyno numbers on some of the sheets lying around the WWW. With I.T. readings in the 200's... and some companys are still using the same dyno sheet as advertising years on. :goodjob:


Few deep breaths Matt, its all good :)
How is life back in Vic treating you anyway?

Yeah, that's about all thats required to calm back down... well, in between drinks anyway.

Vic is good, slotted back into gear like I was fitted with a triple syncro.


The only accurate dyno's are the hub mounted one's.

Trust the NZ guy to say that :) A dyno-pak dyno reads higher than the current DD, DL, ML dyno's, which also leaves interpretation issues. At least it takes the tyre issues out...

[WHLS1]

Good to see you back in print Matt. I know you have more of this sort of stuff to say so how about you get the series started.

No smoke and mirrors with Matt J ;)

[vz6.0]

The only accurate dyno's are the hub mounted one's.

And it begins.....

[Martin_D]

Those kiwi hub dynos are ok, as long as your car isnt too low or you can get beached brew :) :lol: :eek:

[BlownLS7]

excuse my ignorance, 1/how does weight affect a car? on a dyno? i would suggest its not a factor,
so in truth you need to know the weight of vehicle as well to decifer a true HP rating. if im wrong delete post ZLOL.

one thing i find frustrating is the fact that SAME dynos hand out different readings (given sae conditions),in my business 2 identical machines would give same result.even if made from different suppliers.

as well i read (oh but it was angry dyno,WTF does that mean?) is this to justify lo RWKW? of is it the case the other readings are false? and why cant the LS1 world always refer to RWKW so we can all have a starting point,some do HP/rwhp KW ,there seems to be no standard which allows some shops to pull wool over the eyes of customers,

which dyno is more accurate? is there a calibration that can be done?

can a car be tuned as good on a dyno as on the road?

so many questions

my old setup wit L98/HH122 224/230 114 cam OTR
made 400 RWKW on dynodynamics/ yet made 375 rwkw on mainline,
now the question is,which is more accurate? or can this not be answered?

car ran 11.7 113 mph 2040 kilo (can someone do a conversion and tell me which dyno came closest?


cheers paul,

PS im on a diet for t LS1 nats car should be about 2033 LOL


^^^^^^^^
only real way to measure hp statie...at the track..:goodjob:

[keen]

Well I feel much better now about loseing 70hp after your turbo rebuild...its prolly just the new tyres:goodjob::):):)

[zorro]

^^^ more importantly is how a H122 L98 & H122 LS7 made the same power??

[VSFAN]

I agree totaly with your thread Matt.:goodjob:
Working in the industrie in Perth I see the honest workshops suffer (to a degree) because off the best power graph wins syndrome.

Unfortunatly their is always going to be new shops open up and hurt the industrie with their latest and greatest performance packages that make a zillion hp, according to their mass advertising campaign. Grab a copy of our local magazine just to see how good we are in WA.

You just have to put it all aside and get on with the job with your head held high.

Thanks.

[mntlss]

Great write up matt, & i'm hangin in dere 4 da carbon fibre otr-cai lol:D

[vt2vx]

dyno results max power should be ignored they are a tool.

i've managed not to be on one for years, i have no idea on the power as long as it goes.

as far as a qtr time goes thats only one part of the tune WOT.

[wagnman]

Here here!

Take it to the track! As so many others say, there is nowhere like the 1/4 mile to see how much power your car really has!

Unfortunately for some who cant drive or are too scared to practice long enough to learn they will never know and simply have to keep on comparing willy sizes with their dyno sheets!

[Sid447]

A dragstrip,

has more variables than using a dyno.
The basic problem is not with dynos, it's with the operation of them.
Everyone believes they are doing it the same but they are not.
The problem then arises when people want to start to compare one dyno reading with another, instead of using the same dyno and same programme for correction factoring, and look for the difference.

Dynos are the best tuning tool available and are capable of showing instant changes of every parameter needed.

Will a run down a 1/4 mile show you your AFR's have gone slightly out of whack?

It's nothing to do with having a hairy chest and big balls.
The world doesn't start and end, with car abuse at a dragstrip.

Each to their own. Drag racing has it's place and it's own following, good for them. Just don't ram opinions down other peoples throats about it.

[SVNLTR]

A dragstrip,

has more variables than using a dyno.
The basic problem is not with dynos, it's with the operation of them.
Everyone believes they are doing it the same but they are not.
The problem then arises when people want to start to compare one dyno reading with another, instead of using the same dyno and same programme for correction factoring, and look for the difference.

Dynos are the best tuning tool available and are capable of showing instant changes of every parameter needed.

Will a run down a 1/4 mile show you your AFR's have gone slightly out of whack?

It's nothing to do with having a hairy chest and big balls.
The world doesn't start and end, with car abuse at a dragstrip.

Each to their own. Drag racing has it's place and it's own following, good for them. Just don't ram opinions down other peoples throats about it.

sid have a coffee mate

they are opinions and that only-

[markone2]

A dragstrip,

The world doesn't start and end, with car abuse at a dragstrip.

.

Ummmmm , : what about the abuse your driveline suffers on the dyno......there’s a damn good reason one red car made it to 550 runs without mishap to the A4 and 860 plus on the engine........

1. Dyno runs have been kept to an absolute minimum....over 4 years racing the car has had less dyno runs than I have fingers

2. Craig knows his autos :goodjob:


.

[vz6.0]

Will a run down a 1/4 mile show you your AFR's have gone slightly out of whack?


ummmmm, i have a datalogger on a 35yr old carburetted that clearly shows a difference in lambda (amongst other things) at WOT (or indeed, regular street driving), so id say YES IT WILL.

with all your fandangled laptops, obd ports and such, id say it would be a cinch to see the same data for a lsx era vehicle.

a dyno cannot accurately replicate the road conditions, it will go close, but its 90% of the job.

Maybe you can explain how accuracy is affected by an auto equipped vehicle, and the peculiarities a 5500rpm convertor might impose on the power readings, or tune in general?

[Sid447]

Here we go again!

Each to their own. As has been said. I am not a fan of either dynos or the 1/4 mile.

But using some of the logic on here, maybe it's better for every tuning shop that's worth it's salt the world over to do away with all the dynos and just have a purpose-built dragstrip outside the premises....

Lingenfelter, Katech, GM themselves, just about every manufacturer you care to mention don't really know their arse from a hole in the ground. Well I'll be!

Everyone (except some die-hards here) have known for years that the dyno is where it's best to do the initial set-up, and the racetrack is where it's at for final tweaking and tuning.

-------We learn from history that we don't learn from history----------

[QUOTE=vz6.0;1458227]ummmmm, i have a datalogger on a 35yr old carburetted that clearly shows a difference in lambda (amongst other things) at WOT (or indeed, regular street driving), so id say YES IT WILL.[QUOTE]

If you are able to closely monitor an AFR readout during a 1/4 mile run, I'd say you need to apply for the superior human being award. :)

[wagnman]

Hmmmm.....


me thinks Sid has had a bad day.

[Uncle Tone]

A dragstrip,

has more variables than using a dyno.
The basic problem is not with dynos, it's with the operation of them.
Everyone believes they are doing it the same but they are not.
The problem then arises when people want to start to compare one dyno reading with another, instead of using the same dyno and same programme for correction factoring, and look for the difference.

Dynos are the best tuning tool available and are capable of showing instant changes of every parameter needed.

Will a run down a 1/4 mile show you your AFR's have gone slightly out of whack?

It's nothing to do with having a hairy chest and big balls.
The world doesn't start and end, with car abuse at a dragstrip.

Each to their own. Drag racing has it's place and it's own following, good for them. Just don't ram opinions down other peoples throats about it.

Wholeheartedly agree 100% Sid. Well said.

Track times are for drag queens! :D

[vz6.0]

If you are able to closely monitor an AFR readout during a 1/4 mile run, I'd say you need to apply for the superior human being award. :)

thanks mate, where do i send in the application?

Although having a user set alarm, and a decent setup that doesnt look like a heart patients ecg for an af curve probably means i wont win, given that im "cheating" a bit, lol.

the dyno is a valuable tool, as is the road, so on that we agree, but given that the road is where the car is likely to be used, the dyno is only a starting point, and since its very difficult to find a nice quiet public road for WOT fine tuning, i guess the track IS INDEED more valuable to fine tune an engine after its INITIAL dyno tune

How does one simulate stop/start traffic on the dyno?

Or the true effects of a CAI?

I can go on, but i gaurantee theres not a car on the planet, that wont benefit from road tuning, including those you name dropped to bring "credibility" to your argument.

You know why this doesnt happen much?

cost....

BTW: Im not anti dyno at all, just anti bullshit "dyno as gospel"

[Ron SS]

Good post Mat. The strapping down on the dyno was covered very well by Uncle Tone in a great independant post...quite a variance for a simple change in tension in straps. This is despite many videos from sponsors on this forum showing vehicles not strapped at all. Makes you wonder!!

It interests me that GMH use a standard to SAE J1995, meaning standardised corrected power using temps of 25c, pressure 1000mb and ZERO humidity. Temp being what the air intake sees, not what the probe on the wall says.

HSV & Ford and most American cars use SAE J607, t= 15.6c, P= 1013 and also zero humidity. Dyno Dynamics tends to use the GMH std SAE J1995, whereas the Mainline dynos tend to quote to the higher readings given with SAE J607. The difference is around 3.5%, hence on a 250rwkw car, the Mainline to SAE J607 will read about 8 kw higher. This still doesn't explain why a supposed 307 kw LS2 HSV car only puts out about the same as a 270kw L98 when run on the same rear wheel dyno a few minutes apart...... obviously the 307 flywheel kw is way optimistic and is really around the 275 mark. Advertising gets in the way of fact so it seems.

As we all know, heat soak is a huge variable with VEs, hence introducing another factor to distort power, especially when dyno charts seldom show timing values for each run.

It seems to me that the shootout mode with DDs is a good way to go in trying to standardise the variables. We went to metric values in the 1960s, yet some shops annoyingly still quote HP. Shootout mode does specify strapping tension, tyre pressures and acceleration rate, hence comparisons between shops using a calibrated D/dyno should be very close. I agree with other posts though, all that matters is that your car has more power at the end of the day than before it was modified or tuned if run up in a similar fashion.

[vz6.0]

Wholeheartedly agree 100% Sid. Well said.

Track times are for drag queens! :D

what exactly is the dyno good for Tone once your cars tuned?

Unless 5 dollar trophies on a saturday morning gets you off.


Somewhere along the way, people forgot that engines are for accelerating cars, not knurled rollers for the amusement of gawking yokels. (and owners)

[Uncle Tone]

what exactly is the dyno good for Tone once your cars tuned?

Unless 5 dollar trophies on a saturday morning gets you off.

Same thing a treadmill is good for in a gym mate. Its the only time my car gets a workout! :lol:

[STATIE]

A dragstrip,

has more variables than using a dyno.
The basic problem is not with dynos, it's with the operation of them.
Everyone believes they are doing it the same but they are not.
The problem then arises when people want to start to compare one dyno reading with another, instead of using the same dyno and same programme for correction factoring, and look for the difference.

Dynos are the best tuning tool available and are capable of showing instant changes of every parameter needed.

Will a run down a 1/4 mile show you your AFR's have gone slightly out of whack?

It's nothing to do with having a hairy chest and big balls.
The world doesn't start and end, with car abuse at a dragstrip.

Each to their own. Drag racing has it's place and it's own following, good for them. Just don't ram opinions down other peoples throats about it.

I would say that the variables at the track would be identical to a dyno - basically setup, atmospherics & driver (dyno or car).
Problem is that it's near impossible to cheat at the track but pretty damn easy on a dyno, whether it be intentional or not.

How about this for a scenario.

Mario Fanginelli comes in for a tune from Ahmet Mustafa's tuning emporium - Ahmet throws a 5 minute special in it.

Need a bit more power? Adjust the ramp rate.
Mario wants more? Loosen the straps.
Still need some more? Move the IAT sensor.
Shit still not enough? Whack some 10 year old hard as a rock stockies on it (don't want to wreck those nice new 20's do we).
Bloody hell Mario still wants more? Zero out KR & dial in a few degrees of timing maybe whack some booster/better fuel in too (put it back again once off the dyno of course)

Before too long Mario drives away in a 315RWKW stocker - gets regularly chopped by Uncle Tone in a Morris Minor but hey the laminated dyno sheet looks cool down at the Souvlaki Hut being 300RW & all.

People keep saying it but some people dont listen - a dyno is a tuning tool for a tuner to see gains/losses on mods performed on the same day on the same car - not to compare against your mates Silvia's 400KW sheet from Bin Tang Motors on their Feng Shui tailshaft dyno.

It gets even worse with different brand dyno's in different states/countries with different operators running different software etc etc.
Which one is most accurate? - they probably all are in their own ways but they sure as shit aint comparable.
The closest thing to compareable is "shootout" but even with that you have different operators/versions/inputs etc.

[OOL51]

great read, agree full heartedly on no 2 dynos are the same, I've only had runs on 2 dynos and got 2 diiferent readings. as well as a higher reading as the car was run in 3rd not 4th.

[STATIE]

great read, agree full heartedly on no 2 dynos are the same, I've only had runs on 2 dynos and got 2 diiferent readings. as well as a higher reading as the car was run in 3rd not 4th.

Yeh - forgot about that one - "look how much torque you have now Mario" says Ahmet, showing him his final dyno run which was done in 3rd instead of 4th (M6).

"Fully sick Maaaaaate!" says Mario while taking the stockies of the rear & putting the 20's back on.

[SVNLTR]

I would say that the variables at the track would be identical to a dyno - basically setup, atmospherics & driver (dyno or car).
Problem is that it's near impossible to cheat at the track but pretty damn easy on a dyno, whether it be intentional or not.

How about this for a scenario.

Mario Fanginelli comes in for a tune from Ahmet Mustafa's tuning emporium - Ahmet throws a 5 minute special in it.

Need a bit more power? Adjust the ramp rate.
Mario wants more? Loosen the straps.
Still need some more? Move the IAT sensor.
Shit still not enough? Whack some 10 year old hard as a rock stockies on it (don't want to wreck those nice new 20's do we).
Bloody hell Mario still wants more? Zero out KR & dial in a few degrees of timing maybe whack some booster/better fuel in too (put it back again once off the dyno of course)

Before too long Mario drives away in a 315RWKW stocker - gets regularly chopped by Uncle Tone in a Morris Minor but hey the laminated dyno sheet looks cool down at the Souvlaki Hut being 300RW & all.

People keep saying it but some people dont listen - a dyno is a tuning tool for a tuner to see gains/losses on mods performed on the same day on the same car - not to compare against your mates Silvia's 400KW sheet from Bin Tang Motors on their Feng Shui tailshaft dyno.

It gets even worse with different brand dyno's in different states/countries with different operators running different software etc etc.
Which one is most accurate? - they probably all are in their own ways but they sure as shit aint comparable.
The closest thing to compareable is "shootout" but even with that you have different operators/versions/inputs etc.


Thats killer statie-

Thanks for the laugh-(Mustafa's)

hahaha

[Sid447]

I once started a thread on here,

It was titled something like "Dyno Graphs are Bullshit."
............It got canned.

Regardless. Used properly, dynos are an invaluable tuning tool in the tuning industry.

They aren't the be all and end all though of what is better.

However when they are used to sell products and to compare one guys peak hp figure with another, this is where it usually all falls into the "I'm better than you" mentality.

Dynos aside though, the main part of the problem is that most people still believe in the peak power myth.
The number of people that feel their goal is aiming for 40,000rwgigawatts is what it's all about and they perpetuate this mentality.

It doesn't seem to mean squat that the engine then makes piss-poor hp until it gets above 3,500rpm and you have to rev the jinglies out of it to access the power which is now all above 5,500rpm.

The whole idea of having a big capacity engine is to make use of the torque it makes available to you right from idle and at low to medium rpm.
The average 5.7 litre V8 makes more than 300lbs-ft of torque at just 1,000rpm. They make more grunt at idle than most engines do at flat chat.

Whereas your average small capacity dohc wizz-bang 4-cylinder motor that has a 7,500rpm redline would struggle to make 150lb-ft at peak torque rpm.
You HAVE to wring it's neck to get it to do anything with urgency.

Even a 3-litre straight six would be struggling to top 150lbs-ft at 1000rpm and wouldn't be anywhere near 300lbs-ft at it's torque peak either.

Yet people blindly remove this ability of these great engines and turn them into 7,000rpm screamers without a pause to consider what they've lost and what is the best part of having a thundering good large capacity engine.

One of the reasons for this could well be because of some fudged or inflated dyno figure which has psyched them out.

For people who are serious about racing off public roads that is a different matter and it is an accepted consequence. These people also realise that spinning a big pushrod V-8 to beyond 6,500rpm will need money to keep it doing so for long periods of time.
But for the street it's a moot point; each to their own.


Average hp over time that really means something (the dragstrip will show part of this, average lap times on a circuit too, or even a hillclimb).
This is what should be the concern, because it exactly this which makes the difference and will see a 300hp car beat another one of similar weight and gearing but with a higher peak hp.
It's not what it's got it's how it's using it.


The J1559 standard by the way, is a correction factor of 25c, 990mb and zero relative humidity.
Unless I missed something as J1559 is only an amendment to J1349 which is still the industry SAE standard.

Just talking of this opens up another part of the dyno myth busting. Not everyone corrects to the same standard.......
Most still use the older J607 standard, some don't even know about how to understand the correction factoring, some apply their own version of it.
It goes on and on.

it's like an SD-versus maf-sensor, or a turbo-v-supercharging debate.

People should always agree to disagree.

I personally don't have any agenda on this Forum whatsoever.
I don't care about who has the biggest, fastest, strongest, meanest, most powerful car.
For those that do, there will always be someone who has got one over on you, accept it and live with it. Because there are millions that are sure to be worse off than you.

[vt2vx]

I once started a thread on here,

It was titled something like "Dyno Graphs are Bullshit."
............It got canned.

Regardless. Used properly, dynos are an invaluable tuning tool in the tuning industry.

They aren't the be all and end all though of what is better.

However when they are used to sell products and to compare one guys peak hp figure with another, this is where it usually all falls into the "I'm better than you" mentality.

Dynos aside though, the main part of the problem is that most people still believe in the peak power myth.
The number of people that feel their goal is aiming for 40,000rwgigawatts is what it's all about and they perpetuate this mentality.

It doesn't seem to mean squat that the engine then makes piss-poor hp until it gets above 3,500rpm and you have to rev the jinglies out of it to access the power which is now all above 5,500rpm.

The whole idea of having a big capacity engine is to make use of the torque it makes available to you right from idle and at low to medium rpm.
The average 5.7 litre V8 makes more than 300lbs-ft of torque at just 1,000rpm. They make more grunt at idle than most engines do at flat chat.

Whereas your average small capacity dohc wizz-bang 4-cylinder motor that has a 7,500rpm redline would struggle to make 150lb-ft at peak torque rpm.
You HAVE to wring it's neck to get it to do anything with urgency.

Even a 3-litre straight six would be struggling to top 150lbs-ft at 1000rpm and wouldn't be anywhere near 300lbs-ft at it's torque peak either.

Yet people blindly remove this ability of these great engines and turn them into 7,000rpm screamers without a pause to consider what they've lost and what is the best part of having a thundering good large capacity engine.

One of the reasons for this could well be because of some fudged or inflated dyno figure which has psyched them out.

For people who are serious about racing off public roads that is a different matter and it is an accepted consequence. These people also realise that spinning a big pushrod V-8 to beyond 6,500rpm will need money to keep it doing so for long periods of time.
But for the street it's a moot point; each to their own.


Average hp over time that really means something (the dragstrip will show part of this, average lap times on a circuit too, or even a hillclimb).
This is what should be the concern, because it exactly this which makes the difference and will see a 300hp car beat another one of similar weight and gearing but with a higher peak hp.
It's not what it's got it's how it's using it.


The J1559 standard by the way, is a correction factor of 25c, 990mb and zero relative humidity.
Unless I missed something as J1559 is only an amendment to J1349 which is still the industry SAE standard.

Just talking of this opens up another part of the dyno myth busting. Not everyone corrects to the same standard.......
Most still use the older J607 standard, some don't even know about how to understand the correction factoring, some apply their own version of it.
It goes on and on.

it's like an SD-versus maf-sensor, or a turbo-v-supercharging debate.

People should always agree to disagree.

I personally don't have any agenda on this Forum whatsoever.
I don't care about who has the biggest, fastest, strongest, meanest, most powerful car.
For those that do, there will always be someone who has got one over on you, accept it and live with it. Because there are millions that are sure to be worse off than you.

Steve are you sure your not my clone, well said i agree 100% with those words.

mine is bigger than yours post your sheet, gee you have 20 inch rims i'd better get 25 inch. the aftermarket prey on this stuff.

[Oztrack Tuning]

Zorak the answer to your question i think is that the blowers air flow determined the peak power. But the torque of the car would have been higher below that with all else equal. 11psi in 6L vs 7psi in 7L. Plus the LS7 was only just run in and had a more conservative tune, it drove back from Sydney to Brisbane on the same day it was dyno'd

I dont believe the IAT sensor protocol for shootout mode is at all fair. It cant be made fair by sticking it in airboxes that differ in heat soak. This is a big cross in my books for shootout mode.

Matts post is spot on. People compare dynos like they are atomic clocks. You can only rely on the dyno you use all the time and even then you have to make sure everything is done consistently or you cant compare anything.

You have to appy Scientific method constantly and manage all the variable. Thats also why i would never trust a before and after unless its carefully setup to be fair , it will be likely to be very untrustworthy.

[STATIE]

That's the problem when competing workshops are involved, it is in the financial interest of one workshop to continually show bigger dyno numbers than their competitor thereby theoretically gaining more work.
You reckon you wouldn't be tempted to fudge higher numbers if it raised your bottom line by 20%?
F@#k I would.:lol:

My car goes on a dyno when I make a change that NEEDS an adjustment to the tune & the dyno it goes on you can tell to within 1 or 2 10th 's & a MPH or two what it will run at the track depending on what numbers it pulls.
That's why I would give more credence to a shop that backs up their dyno numbers with track results.

[Oztrack Tuning]

Even at the track people have to compare their own car with itself based on the weather and track at the time. My car did 11.765 one freak night in winter 2005 and it took 8 months to beat it even though the car was capable of being 0.3s faster - probably had another 20rwkw, BUT the track didnt do it justice.

Last meet i was entered in it rained - so i took it to the dyno instead! Im tuning a boat at the moment and the test of the tunes results will be how fast it can go flat out :) , we compare with whatever we can.

[vt2vx]

engine dyno

[SVNLTR]

oz what dyno have you got?

[Oztrack Tuning]

We use a dynodynamics dyno.

[vt2vx]

its already established the dyno is to get an approximate tune fine tuning is done on the road for street cars.

once a tuner have a lot of tunes saved a dyno is just for show and a bit of paper. a tuner can choose a close tune to the cars specs, load it, then run up up the dyno and then road tested to fine tune if required, back for another run to produce a bit of paper. an experienced tuner probably an hours work, most of that checking the data and logs are ok. your paying for that experience and history. basically all a fine tune to suit each cars particular characteristics. the dyno only used to produce a graph as proof of maybe what it really produces + or - 30 KW.

maybe if the customer is watching the dyno maybe played with for longer, but for no real reason.

the only tune that will take dyno time is something new, such as the ls3 and new variations of modifications if not tuned before.

It is probably worth the experinced tuners doing it for most, you can out lay for all the tools, then spend a week playing with it and still not have it right, i'd rather pay someone else to worry and do it in a short time. maybe you could eventually have it perfect, then you don't really need the tools much after that, occasional check or whatever, lot of time and money just to play around

[MattJ]

As HSV105 pointed out, I have been around. I have seen all manner of different ways dynoing a car and different dyno's. I dont really think there is a right way or a wrong way, if, and only if, you perform the dyno runs the same way every time. I have worked with people who live and breath dyno numbers, hair would be pulled out if 2kw went missing! On the flip side I have worked with other people who could not care less about chassis dyno figures, it makes what it makes is the bottom line. Either way, it does not matter as long as you realise you cant realy compare them.

The race track still has massive variables especially if the car you are racing is a street car.

Just finished a 'cam only' VXSS, the car made 280rwkw but it pulls like it makes 300!! Thats what matters.


I would say that the variables at the track would be identical to a dyno - basically setup, atmospherics & driver (dyno or car).
Problem is that it's near impossible to cheat at the track but pretty damn easy on a dyno, whether it be intentional or not.

How about this for a scenario.

Mario Fanginelli comes in for a tune from Ahmet Mustafa's tuning emporium - Ahmet throws a 5 minute special in it.

Need a bit more power? Adjust the ramp rate.
Mario wants more? Loosen the straps.
Still need some more? Move the IAT sensor.
Shit still not enough? Whack some 10 year old hard as a rock stockies on it (don't want to wreck those nice new 20's do we).
Bloody hell Mario still wants more? Zero out KR & dial in a few degrees of timing maybe whack some booster/better fuel in too (put it back again once off the dyno of course)

Before too long Mario drives away in a 315RWKW stocker - gets regularly chopped by Uncle Tone in a Morris Minor but hey the laminated dyno sheet looks cool down at the Souvlaki Hut being 300RW & all.

People keep saying it but some people dont listen - a dyno is a tuning tool for a tuner to see gains/losses on mods performed on the same day on the same car - not to compare against your mates Silvia's 400KW sheet from Bin Tang Motors on their Feng Shui tailshaft dyno.

It gets even worse with different brand dyno's in different states/countries with different operators running different software etc etc.
Which one is most accurate? - they probably all are in their own ways but they sure as shit aint comparable.
The closest thing to compareable is "shootout" but even with that you have different operators/versions/inputs etc.

Exactly. :goodjob:

[choppo]

Just finished a 'cam only' VXSS, the car made 280rwkw but it pulls like it makes 300!!
Like 300 on who's dyno? :lmao::lmao:






















Heeeheee, sorry couldn't resist :dancenana:

[vz6.0]

just throwing this out there, and not to cause shit BUT:

Instead of using shootout mode for dyno days, why not use raw data?

The protocols may be adhered to, but in my opinion, you cant vary the atmo conditions to suit yourself when racing, so why not on a dyno circle jerk day as well?

Personally speaking, i would much rather know how the car puts power down differently between a cool, high humidity day, compared to hot ,dry weather.

Correcting to fantasy land atmo conditions does not interest me in the slightest.

calling your car a 400kw animal that only makes that when run up and corrected to something that doesnt accurately reflect anything resembling real world weather is misleading at best and probably goes partway to explain the ridiculously low mph some of these cars actually run even when setup for the track.

at the end of the day, i give no fark for dyno numbers, as long as car runs better, makes more mph, and is improved from before then it was worth it.

some good discussion in here. :goodjob:

[iloveholden]

This thread is a great read and for a youngster like myself you learn a lot from people like Matt who are well experienced :goodjob:

[MattJ]

Like 300 on who's dyno? :lmao::lmao:






















Heeeheee, sorry couldn't resist :dancenana:


Hey if it feels like it makes 300rwkw it must make 300rwkw! Any way my buddy says it should make 303.45rwkw cause he once had a VL turbo with a Garrett Hybrid turbo that run's 10's on the G-tech and beat another guy down Chapel street on saturday night whose RX7 dumps the cooler through the does pipe at 80kays with out even backing off and my mate reakons that would run 8s!

[MNR-0]

It makes what it makes.

Good luck finding an honest operator who will tell you any different.

Oh, and don't believe the sticker weights Holden puts on them rego's either. Ever weighed a 1995kg Adventra? Try adding another 400kgs. They only did this to save them having to register these cars as commercials and using the cheapest poverty pack reduced weight 4x4 they could make.

Weight plays a huge part in the on-road fun factor... "how come my 300rwkw now pulls like the 260rwkw in my mates sedan"

Anyway, I'll take my NA 122mph 263rwkw over your 300+rwkw 114mph blown sled thanks - that is, if the debate is about gauging relative performance.

Still, if I owned a shop and had the money a dyno would be on my shopping list.

[DynoMark]

Hey Matty.
Keep reading and you'll figure out who this is soon enough.
I wanna help you out of your misery mate.
If you are willing to take a five minute drive from HPF we are willing to tell you everything you ever wanted to know about chassis dynos.
including why you're getting different figures from different dynos.
How they measure the power and how to make sure you are using them properly. What you can and can't do with what you've got.
Come up and see me sometime.



Cheers.
Big Fella.