POOR DYNO RESULT 16v

[yr51ocw]

^ ignore my other post, i can see in the pics that its rasp.

How much do they charge for a set of runs?

[sexy_gt]

Originally Posted by Gareth_R

lol they take the wheel figure and apply transmission losses to get the fly figure

this one does not show graph or give details for wheel power. 1st thing i asked was what the wheel power. i was told "this doesnt give wheel figures. its about 20% less"...

i can only tell you what ive been told

[sexy_gt]

Originally Posted by yr51ocw

^ ignore my other post, i can see in the pics that its rasp.

How much do they charge for a set of runs?

£45 inc vat.

[Gareth_R]

sorry added some more info afterwards,

a dyno works by measuring the power at the wheels - they just havent given it to you

[sexy_gt]

Originally Posted by Gareth_R

lol they take the wheel figure and apply transmission losses to get the fly figure

so they've got a wheel figure, either applied a standard 20% loss or used the overrun to calculate a 20% loss (sounds like they've just called it 20%). Then taken the wheel figure, divided by 80, times by 100, theres your 114 bhp

different places will apply a different figure, some will do a proper calculation on the overrun, iirc Northampton Motorsport showed mine as an 18bhp loss, cant remember how they calculated it.

So if you went somewhere else you could get a higher or lower figure depending on how the transmission losses are worked out (although this wont be the only factor obviously)

explination appreciated

[Mochachino]

Originally Posted by Gareth_R

lol they take the wheel figure and apply transmission losses to get the fly figure

so they've got a wheel figure, either applied a standard 20% loss or used the overrun to calculate a 20% loss (sounds like they've just called it 20%). Then taken the wheel figure, divided by 80, times by 100, theres your 114 bhp

different places will apply a different figure, some will do a proper calculation on the overrun, iirc Northampton Motorsport showed mine as an 18bhp loss, cant remember how they calculated it.

So if you went somewhere else you could get a higher or lower figure depending on how the transmission losses are worked out (although this wont be the only factor obviously)

Dont they work out the fly power from after hitting the limit or peak power they let the car de-accelarate and its the rate it de-accelarates they do some maths and work out the flywheel bhp or something?

[ryanmt]

Yeah they use the drag on the rollers

[titchster]

Yup, like they've said dude, rollers measure wheel hp (think about where it's measuring from), and then use maths (usually calculating a 15-20% loss for FWD) to give flywheel power.

The only way to get an accurate flywheel reading is on an engine dyno.



Either way, the car proves itself to be fast, so whether it's making less peak power than others or not, it's obviously not a great hindrance.

[AndySAXOp]

Nms dyno cala the tranny lose on the down run!

Also by the look of it they use a dd type dyno, which is pre cala the tranny lose not on the down run.

It also depends how it calibrated, the dd type us logd cells to do it, where as nmp use weights, a load cell has to be calibrated itself that could be incorrect from the start.

I been on two same dynos at two different companys, and my torque was the same my bhp had increase 6 bhp, but first time was when the engine had done 500 miles secone it had done 2000 miles so think the increase was due to the engine opening up more.

Wouldnt say it was to bad, and if the engine get a lot of track days and 100k could be starting to wear now.

The peak rpm is low for standard vts normally 6.6k,

I wouldnt worry to much if it still drives well then just drive it.

[axsaxoman]

std vts should give max power at around 6700-6800 ,so the rpm must not have been calibrated correctly ,as for actual power ,if as already siad they just add 20% and do not do a run down to get transmission losses ,then maybe theres your reason ,also how hot was the dyno bay .
if air temp AT t/body was up in the high 40,s then theres another 3-5% loss at least ..
normal figure i would expect is around 95 'wheels ,but there again what gear oil + are you sure your box is goood ,so many possibilites for these readings , maybe even a bit of wheelspin at highe rpm and that would acount for max power being shown at wrong rpm

[sexy_gt]

very interesting replies.

i do remember the operator doing a calibration run.

coldnt give you a temperature figure but it was cold in the workshop watching

as for wheelspin i had the 888's on. very loud on the rollers.

the gearox has only covered 2,000 miles since new bearings and quaife fitment. i did have an issue with the box but it turned out to be the clutch not releasing properly.

does the box need more miles to run in? its seen 600 track miles and 1,400 road.

[Gareth_R]

i would expect a box to be running well after 2k miles

the power band between peak torque and peak bhp is quite narrow as well, i had peak torque at 5500 and peak power at 7k and have been told that 1500 rev is a good range from peak torque to bhp

as for why you're getting those results, maybe its the LSD (just throwing the idea in) and its behaving differently on the rollers, but the gains you'll get from having the LSD will far outweigh the losses on a piece of paper

if it drives well, i wouldnt worry too much

[saxo_ron]

I had my saxo on the rollers with a diff fitted and it made no difference to figures.

I normally wouldnt worry about rr figures at all as they all vary, but did you say similar vts' on the same rollers make 130-135bhp?

But truthfully probably nothing to worry about, the width or pressure of tyres could have effected the result

[sexy_gt]

^^ a local with vts btb exhaust and manifold makes 130 every time. he has no atb and similar milage.

[jzink]

Mine was remapped and rolling road tested at chip wizards, he is very good spent 5hts doing mine including knife edge on throttle butterfly valve for free! The best £350 I Spey on my car, especially as mine is the harder to remap 3pin Ecu that very few people can map! Cams mak a huge difference s standard a vts should be 120bhp at flyso if less with mods is probably under reading! I know mine is quick as easily out drags stripped 172 clio cups on long straights at Bedford and 182 clio as well! Don't read to much intonit mate and don't worry! Rake it to another rollers before mods and see if different before mods

[sexy_gt]

going to stick to my local mate.

(not doing bedford on the 6th nov?)

[jonathon5]

what fuel did you have in it ?

[sexy_gt]

regular unleaded.

[AndySAXOp]

Originally Posted by jonathon5

what fuel did you have in it ?

Not really going to make a difference, the high octane fuel is better but really wouldnt make much of a difference.

[Gareth_R]

Vts engines are able to adjust ignition timing according to what fuel you use, would make a minor difference, nothin major