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Author old dyno result
craig_s
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Registered: 5th Mar 06
Location: Birmingham Drives: mk4 astra gsi
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15th Sep 07 at 19:49   View User's Profile U2U Member Reply With Quote
just wanted peoples opinions really.this graph was done when the engine was burning oil.it will now be a freshly built 20xe with 262 cams.how much more do people think it will make and do you think the old figures were good??
Nic Barnes
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Registered: 5th Apr 04
Location: nowhere near ginger people
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15th Sep 07 at 19:49   View User's Profile U2U Member Reply With Quote
go on steve, comment away
Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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15th Sep 07 at 19:50   View Garage View User's Profile U2U Member Reply With Quote
yeah seems good
craig_s
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Registered: 5th Mar 06
Location: Birmingham Drives: mk4 astra gsi
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15th Sep 07 at 19:51   View User's Profile U2U Member Reply With Quote
i was just reading some one else thread and thought i would post this and see what people think.and what people think it will make next time i get it tested.
Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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15th Sep 07 at 19:51   View Garage View User's Profile U2U Member Reply With Quote
no that seems all cool, was gooing to take me leon to aldon automotive, but they were a bit unhelpful when i rang them
craig_s
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Registered: 5th Mar 06
Location: Birmingham Drives: mk4 astra gsi
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15th Sep 07 at 19:53   View User's Profile U2U Member Reply With Quote
never delt with them myself the bloke who had the car before me had this done.and i just wanted to see if people think its accurate.do you think im losing a lot through my gear box?
phil_sutton
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Registered: 8th Sep 07
Location: Nottingham
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15th Sep 07 at 19:55   View User's Profile U2U Member Reply With Quote
30% is a tad over kill, I normally use 15%. Would rathr under quote on power than over.
Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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15th Sep 07 at 19:56   View Garage View User's Profile U2U Member Reply With Quote
all depends on the gear its tested in, 30% might be correct for the gear and drag curve

[Edited on 15-09-2007 by Steve]
craig_s
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Registered: 5th Mar 06
Location: Birmingham Drives: mk4 astra gsi
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15th Sep 07 at 19:58   View User's Profile U2U Member Reply With Quote
so im not losing too much then?and how much do you recon it will make with a fully rebuilt 20xe bottom end and 262 degree cams?

[Edited on 15-09-2007 by sri power]
Nic Barnes
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15th Sep 07 at 19:59   View User's Profile U2U Member Reply With Quote
they normally only have 2 cams dont they?
craig_s
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Registered: 5th Mar 06
Location: Birmingham Drives: mk4 astra gsi
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15th Sep 07 at 20:01   View User's Profile U2U Member Reply With Quote
edited just for you
Dave A
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15th Sep 07 at 20:14   View User's Profile U2U Member Reply With Quote
exactly why coastdown is such an innacurate way of calculating losses through transmission.

put it this way, car goes on a dyno and makes 100 bhp, losses during coastdown are calculated at 15%, all seems well.

car goes away and gets a turbo fitted, now makes 300 bhp. same transmission loss calc is used as before, 15%. all seems fine? not really.

in the first test where it made 100 bhp and lost 15% it lost 15 bhp through transmission and tyres etc. in the second test it has now lost 45bhp through the same gearbox and tyres.

hence why modern dynos dont use percentages or coastdowns in their estimated flywheel calcs. I have seen a coastdown dyno add 20 bhp to a flywheel figure due to a sticky brake caliper
phil_sutton
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15th Sep 07 at 20:29   View User's Profile U2U Member Reply With Quote
our coast down was adding about 130bhp loses to a z20let. Flywheel figuers are just bullshit figures anyway, I always go by wbhp that way I know whats getting down to the road.
craig_s
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15th Sep 07 at 20:30   View User's Profile U2U Member Reply With Quote
i get what you mean now dave.how does your measure transmission losses then?
Dave A
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15th Sep 07 at 20:38   View User's Profile U2U Member Reply With Quote
there are clever little wizard gnomes that live in the pc that work it out. In al honesty, I dont 100% understand how exactly it does work out the fly figures, and especially how it gets them so accurate. All I know is what Dyno Dynamics tell us which is that years of testing and experience in their labs is what make the dyno so accurate at estimating fly figures. The dyno asks you waht type of car you are running, i.e 4 cyl 6 cyl, 8 cyl, fwd, rwd, turbo, porsche, what type of car it is such as the make, model and engine type....


I totally agree about using wheel figures, thats how its done in the usa and australia. when mapping we always use wheel graphs.
craig_s
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15th Sep 07 at 20:46   View User's Profile U2U Member Reply With Quote
what do you recon it will produce now?with a fully rebuilt 20xe bottom end and 262 cams?
Dave A
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15th Sep 07 at 20:47   View User's Profile U2U Member Reply With Quote
155 bhp. cams wont do anything power wise without verniers and mapping.
craig_s
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15th Sep 07 at 20:49   View User's Profile U2U Member Reply With Quote
yeh the bloke said they are ok to run without verniers but im going to get some and get them dialled in properly
Dave A
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15th Sep 07 at 20:50   View User's Profile U2U Member Reply With Quote
Steve
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Registered: 30th Mar 02
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15th Sep 07 at 22:19   View Garage View User's Profile U2U Member Reply With Quote
decent rolling roads, will calculate whats called a drag curve to make the flywheel hp accurate, im assuming yours does this dave, it may not necessarily plot the drag curve on the printout, some do some dont, but the drag curve takes into account wheel friction, brake friction etc etc and proportionatly alters the flywheel hp accordingly.

i assume the rr that arent so accurate dont have this

you can make out the drag curve here



this means the drag coefficient can alter, some rr's just say lets give it 15% drag losses and its just set as that, which is where the innacuracies start to come into things
Dave A
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15th Sep 07 at 22:23   View User's Profile U2U Member Reply With Quote
drag curve/coasdown dynos will be a thing of the past within the next 5 years.
Steve
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15th Sep 07 at 22:24   View Garage View User's Profile U2U Member Reply With Quote
it also mean it doesnt matter which gear you test in, although higher gears are preffered to get a decent length graph, some rr's always test in 4th regardless because there loss figures are fixed
Dave A
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16th Sep 07 at 21:46   View User's Profile U2U Member Reply With Quote
you should all listen to steve when he types stuff about dynos. He has years of experience of typing stuff about them that he read elsewhere on the net. and everyone knows that the internet is all true.
Steve
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16th Sep 07 at 21:51   View Garage View User's Profile U2U Member Reply With Quote
i didnt learn anything about dynos off the net dave, unlike yourself
Nic Barnes
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16th Sep 07 at 21:52   View User's Profile U2U Member Reply With Quote
quote:
Originally posted by Steve
i didnt learn anything about dynos off the net dave, unlike yourself


where did you learn it steve? do you have your own dyno at home?

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