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It seems that the Dyno that PTS use is a top of the range one and hence it must be pretty accurate.

Ross

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That made me laugh, like saying that a Maybach is top of the range so it must be pretty good? Or perhaps a better simile would be like saying the Morris Marina 1.8 TC was top of the range so must have been pretty good

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Always up for a wind-up, me

To be fair though, looking at figures, there is a question that it should be fair to investigate. I mean how can one RR calculate losses of 6% and another 20% on the same car?

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Jimbo (modded) – 278bhp & 252lbs/ft
(194bhp @ wheels = 30% losses)

Jap (modded) – 265bhp & 251lbs/ft
(196bhp @ wheels = 26% losses)

James_H (modded) – 288bhp & 254lbs/ft
(207bhp @ wheels = 28% losses)

MC_Mike (modded) – 274bhp & 262lbs/ft
(202bhp @ wheels = 26% losses)

Nigel (modded) – 302bhp & 246lbs/ft
(191bhp @ wheels = 36% losses)

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Ok looking at lightly modded coupes above PS are averaging say 28% losses which sounds too much for me.

compare the above with some other lightly modded cars taken off the Hall of Fame:

Yellafella – 265bhp & 270lbs/ft
(227bhp @ wheels = 15% losses) PTS

Solid - 266bhp & 247lbs/ft
(223bhp @ wheels = 16% losses) PTS

Steviemitch - 263bhp & 285lbs/ft
(225bhp @ wheels = 15% losses) Owen Devel

Smeg - 275bhp & 260 lbs/ft
(226bhp @ wheels = 17% losses) SRR

Gurmon - 280bhp & 280 lbs/ft
(250bhp @ wheels = 11% losses) PTS

Akeme - 284bhp & 261 lbs/ft
(233bhp @ wheels = 18% losses) PTS

Nobby - 305bhp & 285 lbs/ft
(232bhp @ wheels = 24% losses) Powerstation


Most other RR's look around 15-18% losses for our FWD cars so why are the losses most people get from Powerstation more like 25-28% Are they under-reading ATW* or over-estimating Fly?

The only thing I can see is if the peak torque figure is much different to peak power then the figures could be questioned?


*It would appear not as the ATW figs for Flea were pretty much the same at both Powerstation & Perfect Touch.


Ho hum, I know this discussion comes up every now and again and its a bit but anyway when's the next RR day down Powerstation

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First of all I'd like to congratulate flea, and T.I on his new setup I am impressed with the results 200 lb before 4000 rpm and massive power aswell

but to get back on subject transmission losses are not simply a percentage, rolling roads which calculate fly figures in this way are quite simply giving incorrect fly figures,for a FWD its simply 25 to 50 bhp ( unless your diffs completely knackered) after all your only going from gerarbox to diff to driveshaft and then to the wheels, RWD are slighty more depending on how long and heavy the prop shaft is, and 4WD loose quite a bit around 60-90 bhp as they have both the fwd gearbox a transfer box and the rwd prop shaft loses combined, am I making any sense to you guys?

So your fly figures depend on the losses measured not a percentage calculation, perfect touch use a dastek dyno as I can see from the graphs, (thankyou flea ) I know dastek have a set routine, and they actually measure the losses by costing down and measuring them as accurately as possible from what I have read and seen on numerous turbo forums, so aslong as your wheel bearings and diff are ok and your wheels are aligned correctly the fly figure should be fairly accurate, so basically the more power you have the less percentage your losses will be and the less power you have the more they will be

For those who still don’t understand…..

e.g my old colt gti was dyno'd at 134 bhp but it had 91 bhp atw, so it lost 43 bhp through the transmission which works out around 47 percent losses, so in theory if I strapped a huge turbo to it and gave it 180 atw, and then followed the percentage rule this would give it 264 bhp atf which would obviously be incorrect, were as the true atf figure would be more like 220-230 bhp.

cheers dan.

P.S I have to admit the percentage flywheel calculations go down a treat in the pub , which is basically all they are good for

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enjoy the figures for what they are.

.

how a car drives on the road , how she circulates around
a track , is far and away , for me , more satisfying.

cheers.

.

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I have always rolling roaded at PTS after any set of modifications,.. mainly to get fuelling remapped etc, but at least it gives me some confidence in saying what the efffect of each modifcation has had.

Joe

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I think it's impossible to have such massive losses on a fwd car, like I said before your only going from gearbox,viscous ,shaft then hub and direct to the drive shaft then the hub on the other,

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totally agree.........

but 480bhp sounds much better than "only" 420bhp......
and that seems to be more important for some guys (even though there is no reasonable explanation for such losses)

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Sorry to go off topic...

Just thought i would pop on to say congrats on your results Flea, you must be chuffed to bits... am i the only one who would love to hear some feedback? How much faster does it feel? whats the midrange like? any races? ....some details please... (I know its off the road at the mo, but asap)

Gotta say, Yet another coupe has come out of Torque Italia thats gone beyond what is 'known' and accepted, but when you keep moving the goalposts sometimes people get upset or confused, and question whether it is even possible.

I've been there mate , my results were said to be innacurate because those running the same turbo (withhout headwork), were some 30/40bhp down... the only reason; because it went beyond expectation. Yet recently another chap with exactly the same setup as me, got exactly 344bhp LOL.

Markus is running a smallish turbo, and has 380bhp and 340 Ftlbs IIRC, which is more the most 28RS's i know of, and has better low down driveability to boot... once again beyond expectations.

Even if your power figure, at fly or wheels, is to hard to swallow, then taking away peak power figures, you still have the best power curve that i have seen for anyone running over 400bhp at the fly on the 2litre, and better then some people running less then 400 lol.. thats the main thing.

Big peak power and a very good area under the graph, the holy grail of tuning

Try to ignore some of the negative replys and get on with enjoying your motor mate. And dont forget the feedback!

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my sentiments entirely

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Gerry Gaffney

Hi Guys,

Normally you will find on Bosch, Sun/Maha, Hofmann dyno's the test will be conducted in 4th gear, on Dyno Dynamics & Dastek Dyno's the test will normaly be conducted in 3rd.

There seems to be a huge amount of conjecture & misinformation of the subject of rolling roads, one of the biggest being that the only figure that matters is that of 'Power at the wheels' (PAW) However I strongly disagree. There is greater error on making judgements/assumptions on a PAW only basis.

Allow me to explain, the PAW on a rolling road is NOT the same PAW as transmitted to the road. The reason for this is that the rolling road in itself requires power just to be able to turn over the rollers & retarder (this power comes (or more correctly is robbed) from the power available at the wheels) This power requirement goes up in an exponential fashion with speed. Therefore the greater the roller speed at which a power measurement is made the lower the power at the wheels will be (more below) Other factors that can & DO affect the PAW is the wheel alignment, the tyre pressure, the sidewall height, the amount of strapping effort, the size & finish of the rollers, & the roller seperation (to name but a few)

I will also make another bold statement the power lost through the gearbx due to power input is less than 1/2%, the rest of the losses between flywheel & rollers, is made up of heat & noise created by the tyres, gears splashing through the oil, parasitic drag of bearings & seals (both car & dyno) & the drag caused by boundary layer windage of the rollers & retarder and this is more or less speed dependant (actually follows a 'Stribeck Curve')

http://putfile.com/pic.php?pic=5/13612560575.jpg&s=f5

So the whole agurement that power is not being transmitted & the gears are meshing on the wrong side, at worst will only make the measurement 1/2% wrong, much less than if the g/box oil temp changes by 10C or the wheel alignment is out.

I have huge amounts of real-life data on chassis dynamometers from when I first got involved in them when I was part of a team designing one for our own purposes (I was an engine builder for Toyota on WRC & SuperTouring engines) So it's not just useless drivel from the internet & salesmans blurb )

Conrad that's quite a bold statement 'some Dynos calculate transmission lossess using the coastdown method, more accurate dynos like Dyno Dynamics dont use this method' if you are genuinely interested in getting results that are truly meaningful, you need to go & try a few things (I've already tried them on the DD machine to see if any of the fabulous stories that Mr. G. spouts were even remotely true ) First mount a thermocouple in the g/box, then warm the vehicle up, do a couple of runs to get a base figure. Next drive the car hard on the dyno (like you were live mapping) & get the g/box oil temp up by around 25C. Now do another few runs, what do you get? Secondly try doing the runs in different gears? Finaly tighten your ratchet straps 2 - 3 clicks (assuming you are using the over arm ratchet pull down arrangement) then let me know if you still stand by your statement that PAW + your 'derived loss' is the only reliable number. As for no slip on the DD machine, EVERY roller dyno has slip of a certain %, some of course less then others , if you want to test this, set your dyno to 30mph, select 1st gear, at 1/4 throttle set the rpm:mph ratio (take a true independant rpm) then with the dyno controlling to 30mph (which will be xxxx rpm) start to gradually open the throttle, watch how the mph & rpm on the dyno remain constant, but your independant rpm will increase. Slip is ALWAYS present on a roller dyno, as it is ALWAYS present on the road also! Some dyno's handle it slightly better due to larger rollers, & closer roller seperation, as well as using an idler roller shaft encoder (speed pick up) to work out the slip

I have included a few screengrabs from our own dyno, to show the usefullness of the coastdown test (when used correctly) and how limiting it can be to ONLY look at the wheel power.

1) A power test conducted in 3rd to 5th gear on our own Civic Type-R

http://putfile.com/pic.php?pic=5/13611493774.jpg&s=f5

2) Zoomed in on the PAW & flywheel power

http://putfile.com/pic.php?pic=5/13611512841.jpg&s=f5

3) Zoomed in on the transmission losses on test 1 above

http://putfile.com/pic.php?pic=5/13612125068.jpg&s=f5

4) A test showing the difference g/box (& diff) oil temp makes

http://putfile.com/pic.php?pic=5/13612141620.jpg&s=f5

5) A test showing the huge affect a wrongly fitted wheel bearing can make

http://putfile.com/pic.php?pic=5/13612213418.jpg&s=f5

No Doubt this will open up a huge can of worms, but for people who are genuinely interested in credible information, they need to look much further than the marketing

Cheers,

Gerry
http://www.dastek.co.uk

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regarding your losses flea, trusting dastek i would say there accurate although 25 bhp is the lower end of what you would expect to lose on a fwd , if anything its good news it most probably means your diff, gearbox and wheel bearings are in very good condition and your wheels are also aligned correctly, it doesn’t have nothing to do with percentages tbh if you go motec and run higher boost and get 480 - 500 hp your losses could then be as low as 5 percent and still correct, like I mentioned earlier on in the thread the more power you have the less of a percentage you losses will be.

Cheers Dan.



P.S i do hope you take your fiat down to the mlr 30-130 it will muller allot of the evo's down there which will make great entertainment lol i can just see the looks on there faces now.

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Doh - forgot you were on a 28R as well! That's three of us that are near 350 on that turbo with headwork! Fingers crossed you can get over 350... maybe I should go for a cold run sometime now that it's almost winter!

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420bhp, 480bhp..............

You should be running sub 12s at the Pod next time you go, same as you should have been running mid 12s at TOTB.........we'll see.......

Jules
Gone fishing....

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im not sure it works like that...mostly down to tyre choice and how much u want to break ur gearbox

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420bhp, 480bhp..............

You should be running sub 12s at the Pod next time you go, same as you should have been running mid 12s at TOTB.........we'll see.......

Jules
Gone fishing....

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im not sure it works like that...mostly down to tyre choice and how much u want to break ur gearbox

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on the road this was proved further by us doing side by side 3rd gear tests where he would start to pull a gap.

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As you've said a side by side road test with another powerful coupe will show the difference aswell.... anyways, fleas strong point aint launches anyways!

Ross