I would smell brakes on a long run though wouldn't I?? I have been suggested to change the fuel filter and check the brakes so will see where it goes from here....I might have to borrow that old boost gauge Dave and get the garage doing my water pump to wire it up.
At least then I can see if the boost is correct. Rich said he couldn't get a very good vacuum line on it so that might have been an issue?
The binding brakes wouldnt hold it back but it would affect the readings, the rolling road takes 2 readings the first is the power run where the car revs through the range and the second being on the run down where the rollers measure the drag in the transmission, tyres, bearings etc etc. This loss is then used along with the figure from the first measurement to work out the wheel power figure. If there is any additional drag through the transmission (such as soft tyres, binding brakes, thick diff/gearbox oils) it increases the losses through the transmission and reduces the wheel power figure.Originally Posted by ANDY black s13
to explain why its not a percentage read this: http://www.dynamometer-info.co.uk/po...ywheel-BHP.htm
or more importantly this part of the link:
Below is a copy of an email that I just replied to...
Basically its NOT ever a percentage! Or close to one and it never can be.
Because if I were to take for e.g. 2 stock old GSXR Suzuki race rep 750 bikes, both would give me say 100rear wheel HP in 3rd 4th and maybe 2 less in 5th and 6th.
The two less are simply aerodynamic losses on the wheel and tyre due to the 170mph wheel speeds...
Now, add 50bhp of nitrous to the 2nd bike.
Dyno it and it makes almost 50 BHP extra! There are NO EXTRA losses other than one or two hp, in thrust bearings and gear faces etc.
Now, add another 2nd 50 BHP of nitrous to the 2nd bike in the form of another stage - now it makes 100 BHP more.
If it were a percentage then the second kit would show a smaller power increase! But it doesn't of course.
I have done this sort of thing so many times and always with the same result.
Once the motor has overcome the frictional losses that are simply speed related, nothing else seems to change much.
Now the manufacturer claimed 112 BHP at the motor, so 100bhp represents 12hp losses. Or about 12 "percent" if you prefer!
But the second bike with the extra power has only 5 or 6 percent losses now! if you were expressing it as a percentage!
Now take the "touring" version of the same bike engine with its smaller carbs, low compression, smaller valves, softer cams etc.
Manufacturers engine claims are now 70bhp. But on the dyno we see only 58 or so...
So its losing almost the same 12bhp.. But now its a whopping 17.4 percent transmission losses! But its the SAME transmission...
So if it really WAS a percentage fitting the same nitrous systems to this bike would give LESS power!
But guess what! 100 extra total would be seen again... No 17.xx percent loss....
Which of course is correct because it uses the same transmission and wheel and tyre..
If you measure the power required to "push" the transmission/wheel as far as the clutch at the same road speeds in the same gear it will say the same thing (12bhp). The losses on both bikes will be identical 12hp (at max - speed not power dependant) required to overcome the rolling resistance of the parts, tyre, chain, oil etc.
This loss isn't a constant but increases and changes with speed and gear ratio.
There is also a small element of this that increases with torque, but at least on bikes transmissions this is pretty small...
Hope your head doesn't explode!
id guess you should be able to smell the brakes, it depends how badly they were binding (if at all) if you take the car a run feel the wheels after stopping, if the brakes are binding you may feel more heat on the affected wheel when compared to the rest
Brakes not binding as there is never excess heat, pads and discs are good and coasting down to a stop there is no grabbing or friction. I have adjusted my actuator to suit the map better today and i'm changing the fuel filter....then its going to charlie for another run.
Dyno's all read different and rollers more so due to so many variables and thats before you get into thge programming.
Also, dont be fooled by manufacturer figures, a clio 182 is doing well if it sees 170 for instance, you cant just 'fit K&N, add 10bhp, add chip = 30bhp'
Fair enough that dyno may read under in comparison to others, but rather than get eggy, just percentage it off JCs previous comparison, then your friends in the pub may like you more
Its nothing to do with projected figures from volvo.....this engine is used by volvo and ford over a 16 year or so life span and is renound for holding very very good figures. Someone measured a stock 850 t5 with about 4k on it and it measured 230bhp.....5 more than actually projected.
Stock cars on VPCUK have seen around 230bhp also with over 150k miles.
I am not fussed at my figure if I had a stock car as they all lose power with age etc....but there is no way my car can be this quick and see those figures. It kept up with a mates e36 m3 evo earlier today without problem....
Due to the fact I am running double standard boost with fueling to match. All the volvo lot say I should be seeing much greater figures. I have let a few mates drive it today and they are all stunned at how fast it is. If the car was unhealthy I would know and I would accept the lower figure but the fact it runs so well and can keep up with cars in the power bracket I should have leads me to be annoyed at the figure.
I would say that surely that's all that counts then? But I know how disappointing it is to not see the figure you were hoping for especially after putting the time and efforts in with the mods. Maybe try it on another dyno?
I take it this was a typo and you meant 'fly' in both of those cases, because if not, then without sunding like an arse, that's bollocks
As Ben said, dyno figures are sort of crap on their own - their best application is to use as a before/after comparison between chunks of tuning.
Different Dynos read differntly.
I had my car on 2 different dynos just over a week apart and it was nearly 10% different.
There are 2 things that Dyno figures are good for-comparison on your car, between mods done, and bragging down the pub. Using fly figures is even worse, as it's an extrapolated value, as big_mac says - the fact that people quote them down to decimal places is just silly tbh.
Last edited by Si; 19-03-2012 at 06:50.
I didn't think the results from that day were that bad at all... well for my car at least.
My '94 S14 (with 170k on clock) with a FMIC and an exhaust system and everything else standard measured 235bhp, which in my eyes was way more than I was expecting.
Dont worry dude. ignore the paper.
my car made poor numbers on a Dyno (287) with a PE1420 turbo, everyone was shocked & laughing at me.
it feels like 350 anyday of the week, drives perfect, runs perfect, responds instantly, no lag, eats M3s for lunch. but thats not what the dyno says.
feels quicker than my mates dyno proven (389hp) s14a with 2871r
Why does everyone get bothered about flywheel figures?
Oh yes, that's right - so they can brag.
I am personally much more impressed by wheel figures. Aside from being much easier to reliably measure, it's the figure that actually matters as that's the one propelling you down the road.
I'll never forget a GTI-R owner getting really excited about supposedly getting 300+ bhp at the flywheel - shame the wheel figure was only 175bhp.
I've seen flywheel figures on my car vary by 30+bhp at different dynos, but the wheel figures have always been within 5-10bhp of each other. I also remember going to one rolling road, getting on the rollers, and when they put my reg no in for the run it called up a previous run from a few years beforehand. Their saw the result and said 'Oh I'm sure you'll get more than that today', and sure enough, my flywheel figure was higher. Shame that the wheel figure was actually slightly lower, and I had made absolutely no changes whatsoever so couldn't possibly suddenly have more.
That's another good point - I'd rather have a power curve that looked like Ayers Rock and topped out 50 bhp lower than a curve that looks like a skyscraper.
Last edited by Keith_C; 19-03-2012 at 09:28.
banter. What Bens trying to get Brody to do is stop winging like the man whore he is and GIVE IT MORE POWERZ
We are men there for we brag!
Sounds like everyone was down about 10%.
Whenever someone puts their car on the dyno and doesn't get the results they want its always the dyno or the operator that's wrong. Never the car.
We haven't even seen the graphs, it might be making good torque in the low to mid rpm range and then tailing right off at the top end (he's already said its rich at the top end). It would still feel quick on the road if that was the case, but not be making good peak power...
What was it at the wheels?
If all the cars were < x% on what they expected you could assume the dyno readings are conservative. If it was only yours or a select few, then don't dismiss it - go and get tested elsewhere to confirm then diagnose. If your satisfied with your cars on-the-road performance though it's really a non-issue.
Last edited by s13silvia; 19-03-2012 at 10:48.
183 at the wheels apparently..if I remember correctly....if I get a chance I will post the graphs......torque figure peaks at somewherein the 5-6k region.....power doesn't tail off, if anything its strongest at top end as thats what the map is designed to do.
It won't handle much more power anyway due to it being front wheel drive....
Going to do 2 visits to SRR...one after I return from France and one after decat and exhaust system.
Posting Permissions
Reply With Quote
