I would agree. but the 196 for the 5 speed BA XR8 on the rollers before my car does seem very consistant with what I've read.

freak cars are around! latest motor mag has a ba gt pulling 242rwkw. gen iv clubbie only managed 229 and pursuit ute, which is same running gear as gt got 226. journo's didn't believe it so they dynoed it again an hour later with same result. it also pulled a 13.8 down the 1/4 which is the quickest time i've seen yet. the xr8 they tested had around 211 i think so if they had a ba xr8 on the rollers b4 hornets car putting out 196? then i reckon hornets figure is realistic. obviously a wednesday car.

having said that, dyno's are for tuning purposes, not bragging rights. the only time you can boast is at dyno comps where all cars are tested on same dyno in same cond. as in motor mag article.

Well i agree there are definstely some freak fords going around, for instance the FM and Eseries dyno day 1. My car got dyno'd when it ws completely stock! I got a better result than most of the modded sixes.

Even on LPG it was higher than some of the EA- and EB's that were modded as well not saying my result was the best thier but it was a hell of a surprise. I also beat a few v8's too.

Considering this was a group event my XR went surprisingly well for a stocker.

yeah thatsa good idea i had opened a forum about this i am going to do it to my eb turn into a street saloon racer how much for Bigger & ported throttle body Unichip + dyno tuning & cam $$$$$from there at blackwood

These are reasonable comments.... but IMO it's a matter of 'he said, she said'....

There is nothing to support the argument that the lower figures are "more realistic"... the lower figures carry just as much credit as higher rwkw figures...

For example, based on what i've seen - 103 to 108 is a good figure for a ford I6... but then, we've seen stockers do about 125... minutes later, a Gen III did 200rwkw... which would suggest the 'calibration' of the dyno was about right...

Who is to say which figure is more accurate? I see no reason to assume the lower to be 'true'....

I know this would turn into a "he said, she said" arguement.

But I still cant believe there are Ford's out there giving the figures everyone is quoting. We have GT's here pushing 340fwkw, XR8's pushing 290fwkw. I know manufacturing tolerances allow for a certain degree of plus and minus on the output figures, but come on.

Do you remember the god awful yellow VS GTS (i think it was VS). Made a fairly decent 200kw for the time. But they had a blueprint option, where the engine was stripped, hand rebuilt with components that matched the original specs for length, width and height only to get an measly 15fwkw out of the engine for about a $5000 investment.

All I'm saying here is that when people jump up and down about the figures they are getting, surely they must realise they may not be possible. I could put my 140rwkw figure in my signature for people to look at and and wow, but if they thought about it, its just not possible for my poor engine to be pushing 200+fwkw.

If I went to the same dyno on the same day as hornet, I'm guessing id get my 140 again. Wow... So I end up getting another unbelievable figure.

I cant see how you would say that my 140 figure was more believable than the 120 figure I think is most real. So either the dynos are out, or I got a magic car that dynos better on a Sunday than a Saturday and Thursday. Believe me, id love to tell everyone my EL Ghia gets 200+ at the fly, all for an exhaust change, but most of these people would more than likely go tell me to continue playing with myself.

Lol, yeah my point exactly... this discussion cant really go anywhere...

You distort the issue even further by assuming a 30% loss through the drivetrain... whilst a generally accepted assumption, it has very little merit... and is based on factory quoted specs vs 'average' chassis dyno observations.

I would not say the 140 figure is more believable than the 120 figure - i'd say they were as believable as each other. Hell, if you've a printout showing 140rwkw then to dispute this, you are either:

a) familiar with the calibration specs of that particular dyno; or
b) engaging in speculation, based on factory quoted kw specs and assumed drivetrain losses.

Yes I am assuming a % loss through the drivetrain. I think its generally accepted 30% or so is a valid figure.

How does it have little merit? Are you telling me that my auto hads different moods and decides how much power its willing to push on a day to day basis, and that the auto in my car and a mates car (both EL's) may have vastly different losses built into the unit at factory....

In answer to your questions:

a) I am not entirely familiar with the calibration specs if the particlar dyno. I would like someone to explain to me the different modes and how they work and what effects they have on the outputs. But dyno operators are very guarded about their answers to when I have asked.

b) yes I am speculating based on factory figures and drivetrain losses. refer to my answer above. I think you will agree that the assembly tolerances allow for a small plus or minus in outputs, but not a huge amount.

It has been discussed on here before that you need x amount of rwkw to move a car a certain time on the 1/4 mile. At my 140rwkw, what times would you expect me to run? And what would you expect my 1/4 mile run to be with 120rwkw?

I'm not telling anyone anything - but yes, I think this is reasonable. The viscoisity of the automatic trans fluid can be affected quite a bit by age and temperature. The viscous coupling of the torque converter is likely to be severaly affected by the properties of the fluid at any given time.

It is likely that, the day after you and your mates cars rolled out of the factory, they would behave almost identically (there's no reason why they shouldnt...).. but, we are talking about a car which is heading towards 10 years of age... i think its quite reasonable for there to be potential differences in the condition of the box, and therfore, the energy lost through heat and noise.

This is amplified by the (likely) difference in the condition of diffs and wheel bearings - all of which 'pinch' some of the power as its passed through and waste it creating noise/heat...



This point has legs. A quick punch on google finds the following formula..

Note that it's all imperial, and bases rwhp on trap speed, not ET....

RWHP = (trap speed/234)^3 x weight

So, 140 rwkw = 182rwhp
weight, assume 1800kg with driver and fuel = 3960 pounds

This gives a trap speed of 84mph or 135km/hr

Using 120rwkw = 158rwhp, you get a trap speed of 80mph or 129km/hr

To be honest, both these trap speeds seem a little low IMO, but the difference appears reasonable.

But of course doesnt consider drag, ambient temp/air density, traction etc, etc. and also worth noting that there is as many formulae for calculating hp as there is calibrations of dynos, lol.

That figure could be right. I test drove 15 EF & El falcons before i bought my el fairmont. It went so much better than the other cars i drove (better throttle response and alot more pickup when i gave it some gas). So some engines leaving the factory do put out more hp, it also helps having a low km engine i think.

Now 4.9, that is the point I was getting to in a round about way I suppose...

What is the net effect of your dyno figures on the road and 1/4 mile strip. I have seen many a person with the "but I have lots of rwkw, cos the dyno told me so, why isnt my car running better times" excuse after they picked up their time slips.

I expect a certain level from my car, which I think is a believable level, and it doesnt disappoint me. As you have described according to your formula, dyno A will give me a certain time vs dyno B's result, even though I have had the exact same mods both times. Yes, air temp, traction, drag, etc is a factor, but to a 20rwkw extent? But then the more rwkw you have will negate these external effects due to more effort produced on acceleration.

As for EL_Fairmont, you may have driven many cars and yours was better due to the simple fact is was a little newer and better looked after. I bought my car at 32,000km, its now got 130,000 on it, and I believe it has the same performance as when I bought it. Compression is good, acceleration is good, fuel consumption is good. Why? I replace ignition leads every year, spark plugs every 10,000km, oil every 5,000 to 10,000, injectors are cleaned/replaced every 12 to 18 months. Keeps my car running at its peak. You would be amazed how many seat of pant kw's are gained just by swapping leads. Even more with injectors.

Having a young car car is helps, but good maintenance will keep it like that. I've seen some shockers in my time that are turned new by new plugs, leads and cap.

What I would really like to know, if hornet and EL_Fairmont have run their car down the 1/4, what are their current best times?

so i guess arm 79 you are claiming that dyno calibration can change from car to car all dynoed on the same day. hornet quoted 200 for xr8 which you would accept as being reasonable and yet somehow between that car and his the dyno changed as his 120 odd is not believable. regarding the gt i quoted as putting out 242rw, maybe you should buy yourself a copy of may motor mag. 10 cars, 1 dyno and all on same day. a few variations.

but as i said b4 dyno's are mainly used for tuning, before and afters, and simulating driving conditions. i can't compare my figure with your figure or xrfan or hornet as all done on diff dyno's and diff days.

i do believe however that if it is a realistic figure you should be able to whack your car on any dyno and be within a percentage every time. if my 130 is correct then i would expect something around that every time, plus or minus.

i've seen cars at ford and holden show dynoed 1 year apart using diff dynoes and put out same figure. to me you could then argue that is your real figure.

end rant.

I'm not claiming that dyno calibration changes from car to car on the same day. My thoughts are that the dyno is wrong all day long.

If the dyno is being optomistic by 20% with car A, then car B will also be 20% optomistic.

If we are talking magazines here, Motor also claim that an XR6 Turbo gets 160 to 170 at the weels, by their own tests and dynos. Considering an XR8 is only 20fwkw more than, then it should show 175 to 180rwkw, not the 200 that hornet commented on. Considering thats a 14-15% difference to the to the 200 hornet quoted, then the dyno is calibrated as such and all cars on that day will display that 14 to 15% more optomistic figure. Simple maths.

Yes, dynos are there to give one off figures that demonstrate capabilities of your vehicle, and are only meaningful if you go to the same dyno all the time.

My contention, and a question that no one yet has answered is this (and we will use a BA XR8 as the example):

We have 2 XR8's. Same motors, auto, similar km, same tyres, same options and weight... Same colour even. One is dynoed where I got my EL done, and it gets a nice 180rwkw. Hornets XR8 is dynoed at the same time but on his dyno and gets an even nicer 200rwkw.

They are then taken to a track, and run side by side. Same track, temp, etc, etc and cross the line at the same time.

So, hornets XR8 driver gets out all p****d of because he should have easily won the race, hes got 20rwkw more. But my XR8 driver is wrapt as he just bet a more "powerful" XR8. So whats happened here. Either one of those dyno figures is over quoted, or one is under quoted. So that makes one right and one wrong, but which one is it. As we know in theory and mathamatics that the XR8 with 200rwkw should be quicker.

What I'm saying is that in the end, dyno figures dont mean much on paper. On the road and track they do... So when a person runs a car with a superior rwkw figure than the next guy, and doesnt do any better over the 1/4. Is his car accelerating like a car with x-rwkw and if it doesn't, what is he left to believe?

Out of interest prydey, what is your best 1/4 figure?

meh, was gunna post the chart, but not going to now. Since its mearly worthless.

dont forget talking 1/4 times brings in another uncontrollable factor - the driver. there is no way you can say that two drivers are exactly alike. on the dyno this factor becomes almost negligable.