Hello Aaron_EF8. You know me and you probably know that I'm going to finish this story for you now as events have now transpired since that odd dyno result.
The car in question is a manual BA XR6 NA. As we all know these are not a hugely fast beast, basically an XT with a kit, some springs and a 3.45 diff (Single spinner in this case).
Based on the weight and 158rwkw the second dyno team concluded the car was good for a 15.0 - 15.5 second run, more on the high side. This seemed about right considering that the BA is pretty hefty and hard to get off the line.
Lets all shoot to Saturday night at Heathcote. 1/2 tank of fuel, warmish weather and decent head wind. Out of the box the car runs a 14.804 pass. Backed up a little later by a 14.800 @ 93.11mph pass. In fact it runs multiple sub 15 passes.
Given these times there is, in all probability, far more than 158rwkw lurking in the engine. My guess is closer to 175rwkw. I'd say that 7rwkw is quite easy to see in a difference between actual and a dyno figure myself, on any dyno. At around 4% of the total rwkw as a variance I'd consider that acceptabe.

Now, for another example. My car.
Also measured on the JMM dyno, producing 144rwkw. Many said that was way too optimistic, the VCT wouldnt read that well with simple exhaust and intake mods. It was impossible.
Then again, so was the 15.02 second pass I ran at Calder a few weeks later apparently.

In the end, it is really not a mojor issue. So long as it reads higher than the base run on the same dyno, prefferably same day, than the mods are shown to work. If you really want indisputable figures, the drag track will tell the tale. Time and distance are a universal standard, they dont lie.

do the DEV kits put out what there ment to or not?

theres so much f**k talk about jmm's dyno , there must be some one
on this site who's got a DEV kit , dyno chart (not from JMM) and had a run down a 1/4 mile.

Well, I do have a Dev1 on mine which means no cam, just exhaust and intake.
The Jmm dyno (before the chiptorque chip) said 144rwkw. After the chip it was 150rwkw. Thats a pretty consistant increase. On Feb 5th I'll have it on the Hallam dyno so I'll be able to see the comparison.
As for performance increase, stock the XR6 VCT auto is a 16.0 second car. After the dev 1 (no chip) it ran a 15.024@93.54mph. I'd say thats pretty consistant with 144rwkw or there abouts.

My EF Wagon has a Dev5a kit. Has seen 180RWKW on the JMM dyno, but never seen higher than mid 160's out of the JMM workshop.

yeah thats all i need to take my money some where else

Obviously the dyno will show an increase after modification, but are you sure that you first kW reading was accurate?
If a dyno is out by 10% thats huge, so your first fun was 144kW but on any other dyno that would probably only be around 130kW

Possibly, but I dont think 130rwkw would get an auto VCT anywhere near 15.02 or close to 93.5mph on the quarter. It could be 140rwkw but its not 130rwkw.
To compare, a stock EL GT runs a 15.0 1/4 with 200kw at the fly...around 145-150rwkw. It weighs around the same as a VCT.

True

In the end a dyno number is just that. Its simply a tuning tool.
For me at least the real test is the 1/4 mile. I have beaten many cars that are said to be more powerful than mine and have lost to some with less power (as far as a dyno says).
I dont put too much faith in any dyno, all I want to see is a before number, add new mods, and a higher after number. Then I'll take it to the track and get the final result.

the number given by a dyno will vary, even the latest software will have inconsistancies in it.
use a dyno only for seeing your ratio and tuning of car, leave the rest to the 1/4, as it is a real world test where there are no inconsistencies.
(ignore weather and tryes)

Try It's Performance

lol , waggin and hyena are on the ITS PERFORMANCE pay role for sure.

...But then again mark sounds like he knows his s**t

I'm talking from experience, as is Hyena.

Mark definantly knows his stuff. If I had any doubt I wouldnt have spent as much money as I did with him

I've been to three dyno shop's in sydney with various groups of people and my rwkw reading changes every time the most variance I've had is 15kw less than the last one shootout mode lie's it can be altered if the dyno operator is less than above board.
Have you seen jjm dyno it's as old as the hills it still has dials for christ sake. The guy I use around the corner from where I work seems to be the most honest dyno it's an old version of dyno dynamic doesn't have shoot out mode and admitdly it show 10kw less than what jjm claims my dev kit should have but she goes like the clappers and not much has kept up with me so I'm not too concerned about the 10kw margin.

Anyone who chooses to actively compare dyno readouts obviously lacks understanding of the purpose of a dyno.