My day out comparing chassis dyno's....

[boXXer]

thanks very much mate Steve is a gem!

[Toby]

so we talking wheels or f/wheels figures as dont rollers give wheels figures and a gestamate of f/wheel

 

That was one million gigawatts at the wheels mate

[boXXer]

shiiiiiit! enough to power the flux capacitor!

[Toby]

shiiiiiit! enough to power the flux capacitor!

 

Enough to warp the time continuem

[w p e]

that aint answerd me question properly is peters wheels or flywheel? come on someone out there must know

[boXXer]

shiiiiiit! enough to power the flux capacitor!

 

Enough to warp the time continuem

 

PMSL! just make sure this baby hits 88mph!

[w p e]

??????????????? WELL

[Toby]

that aint answerd me question properly is peters wheels or flywheel? come on someone out there must know

 

Sorry mate. Line above the graph is wheels.

 

When he lets off the transmission loss is supposedly represented by how much it goes under the line at ther bottom of the graph, so he adds that on for "his" flywheel figure.

 

The graph is in KWs, Multiply by 1.36 (ish) for HP.

[w p e]

supposedly. the word i was waiting for as it seems each RR operator as there own interpretation of how it works but not many can explain it in laymans

[Guest MK1gaz]

So Toby , did Peter use the biro and slide rule on your sheet and write the magic number on it or have you applied your own maths to get to 190+ bhp . If so then it don't count as only he can fathom out the workings of the proper oldskool "earthquake graphs" from his machine . It's great at Sanspeed , if you've never been then shame on you cos you get a real sense of nostalgia over there . A proper oldskool engine tuner with no fancy gadgets , bodies sitting in the boot to get traction , Mk2 Escort B.D.A. rally car in the background and he still gets the same numbers as most of the modern rollers

[Toby]

supposedly. the word i was waiting for as it seems each RR operator as there own interpretation of how it works but not many can explain it in laymans

 

It has to be an interpretation as they ALL can only measure wheel HP.

 

I was told recently of one that even bolts onto the hubs, supposedly for accuracy's sake.

 

As the majority are stating though, the figures don't matter apart from in the pub, unless you're talking about PERFORMANCE figures.

 

Moral of the thread - Stick with one road, look for improvements of the graph shape / height, keep your charts.

[Guest MK1gaz]

My mates Skyline has been on Abbey motorsports Hub dyno . Bhp at the hubs !!!!!!! WTF , when will you race anything with your wheels missing !!!!!!!

[Cookie]

Top read

 

well done to all behind this test, good work

[Toby]

My mates Skyline has been on Abbey motorsports Hub dyno . Bhp at the hubs !!!!!!! WTF , when will you race anything with your wheels missing !!!!!!!

 

 

Yeah, and dyno's, I mean, who'd race anyone with their whole car missing!!

[boXXer]

christ! 10 pages of crap now!

[chris@torque of the devil]

adding to the crap, peak dyno figures are all about how big ya willie is

 

my dyno just reads a couple of inches less than others

[Retromotorsport]

adding to the crap, peak dyno figures are all about how big ya willie is

 

my dyno just reads a couple of inches less than others

 

Chris, on the average mans scale... i would have said millimeter, not inches ..

 

and as for the size thing, even that equates to dynos.. its not the size, its what you do with it

 

As for how accurate a Dyno is .. surely we need to compare them to a Horse pulling a weight out of a mine shaft ... ahhh but what horse do we use ???? that is the question.

[w p e]

so is mike[boxxer] compering his 187ish.hp @ f/wheel to RR figures whith read at the wheels? coz as its a gess to f/wheel figures then chris"s dyno done a pretty good gess. any read out could be 5hp out either way proved when standing at TOTD watching . each time the sensor wire moved the hp reading changed at one point to approx50hp more just by a temppreture reading change. as were peters dont read temppreture . so is it safe to say to chris leave the air temp sensor out of the system and his dyno will the same as the others

[boXXer]

no idea. i was mostly comparing my flywheel figure that i got on HT's dyno, to the closest set of rollers i could find, and iv'e done exactly that.

[boXXer]

so is mike[boxxer] compering his 187ish.hp @ f/wheel to RR figures whith read at the wheels? coz as its a gess to f/wheel figures then chris"s dyno done a pretty good gess. any read out could be 5hp out either way proved when standing at TOTD watching . each time the sensor wire moved the hp reading changed at one point to approx50hp more just by a temppreture reading change. as were peters dont read temppreture . so is it safe to say to chris leave the air temp sensor out of the system and his dyno will the same as the others

 

i dont think that would work, as the 2 different rollers calculate power in different ways i believe. Im sure sanspeed/T 'n' R use coast down figures to "guess" the flywheel power, and the dyno dynamics work in a different way or something. chris will be able to explain.

[w p e]

so this has proved what ive said all along that dyno/R-roads all tell lies there just a gestamate and should only be used to set the engine up to its best /driverability fueling and timing and forget the hp figures coz its torque thats the power any. probley why mine never went to any rollers when it was alive accept once many many years ago[apollo racing] he fooked it up for £50 and i put it right at the side of the road after it broke down on the way home. think ill stick to my trained ear for now

[boXXer]

basically, yeah. Unless youve had your engine on a dyno, than any RR is a guess! Only way to find out properly is take it out and do that.

 

that wasnt the point of this whole thread though. The thread was about MY engine, in MY car, and who's rollers read closest to MY actual flywheel figure. no-one else's.

[chris@torque of the devil]

engine dyno's and chassis dyno's are great to optimise fuelling boost, cam timing and ignition, chassis dyno's score highly on seeing before and ater results from changing these parameters when the engine is IN THE CAR(where it ends up!), also a tuning session on my dyno is £90 per hour (plus vat) and usually takes 1-1.5 hrs depending on the car, that (i think) is a lot less then an engine dyno set up session and takes into account the inner wing being close to the trumpets, exhausts that bend all over the place to clear the axle, radiated heat in the engine bay, fuel temperature and so on.............factors not usually when present on the engine dyno, my dyno corrects for relative humidity, barometric pressure and inlet temperatures, if other dyno's are not inputting this information how can anyone assume they are correct?

 

The dyno dynamics dyno's do not guestimate the transmission losses on overun, transmission losses should be measured when the engine is under power not when the clutch is pushed down after the power pull like other dyno's.

 

the figures that dyno dynamics come up with are more true to life in my opinion, they tested many many different engines using an engine dyno first then with transmissions attached to it and axles/props etc and measured the the torque at each step of the way to give the closest power/torque figures they could to "flywheel" figures.

 

 

page 79 of jan 2008 issue of performance ford details how dyno dynamics collated this information.

[boXXer]

 

so do you HONESTLY think my car could have lost 13hp since i put the engine in my car about 8 weeks ago, and by adding a single box competition exhaust system and 3pc manifold (which they use on the dyno i believe).

 

Think i need some NOS to boost it up.

[bortaf]

My mates Skyline has been on Abbey motorsports Hub dyno . Bhp at the hubs !!!!!!! WTF , when will you race anything with your wheels missing !!!!!!!

 

The reason they use a hud dyno is to illiminate power loss through the tyres if you overpump the tyres you'll get less roll down losses and more if you run with flatish tyres, or so i was told last time a went to a RR