Stored in memory bank - thanks Zuffy

 

Hi all,

Been offline for a few days after my motherboard decide to say farewell to me Sunday night. Finally dragged the old PC out of hiding until the suppliers reopen next week.

Anyway I didn't see it mentioned earlier but see that big shootout on the graph? That means the plot was run in shootout mode. I don't know exactly what that mode is really intended for but it's typically what they use at carshows etc during dyno comps. From what I know it increases the figures by at least 20%. If you take that in to account it comes back to 150kw which is exactly in line with what we'd expect.

 

I've ordered the JWT Flywheel, its 14lbs compare to stock 28lbs, bought it from the states and cost ~US$400 + shipping.
Was deciding between this and the JUN flywheel, but went for the JWT instead coz compatibility with various clutch

Im still thinking of putting in the grounding kit or not, result/comments are mixed, some said smoother but some said no diff
and suggestions?

 

ottonove - i've heard very good things about the JWT flywheel. Who are you using for the install or are you doing it yourself?

As for the grounding kit, it cost so little and it can't do any damage. In the end you have to decide if the standard earth points are sufficient. I found it improved the car around redline and idle.

Aps - good to see you back, and that point about the dyno was exactly what I was on about. I'm sure croydon knows what they are doing.

 

ottonove - i've heard very good things about the JWT flywheel. Who are you using for the install or are you doing it yourself?

I will be using the place where I used to mod my BMW, they race BMW so Im sure they know what theyre doing. at one stage they had a race prep V8 Z3, amazing car!!

As for the grounding kit, it cost so little and it can't do any damage. In the end you have to decide if the standard earth points are sufficient. I found it improved the car around redline and idle.

I already find myself hit the rev limiter more often after I install the HT, and the engine is alot smoother on the higher revs, if it improves more with the grounding kit, think I would just go and order one

Aps - good to see you back, and that point about the dyno was exactly what I was on about. I'm sure croydon knows what they are doing.

Im sure Croydon knows what theyre doing, so Im not too concern on the diff on my dyno readout compare to others

 

I wouldn't be either but if you want to compare one mod to the next on your car just remember that you need to have all runs done in shootout mode.

 

going to dyno my zed again later today
we update you guys with printout after its done
hopefully with similar gain to other ppl who hv HT

cheers

 

Hey Ottonove, How did you go with the post hi-tech dyno? What were the results?

 

still hvnt got time
been working flatout laterly....
hoping to do it first thing tomorrow morning....

 

just FYI guys we have had my car many many times already in 4th and 5th..difference each time, even on different dynos (Dynojet and DynaPack) was less than 2 hp.....

 

Can somebody who knows give us a mini expose on these dynos.
There's so much misinformation around - someone out there please elaborate -
FOR INSTANCE - hows the dyno measure
Torque
Killowatts or hp
What difference does the gearing make - ie, will the hp figures
change in proportion to the gearing ratios,

etc.

Maybe there's a site that explains.

Might try "howthingswork" meanwhile.

So far I reckon me bums been the best dyno - no bullsh*t there!
(There's some cryptic ***** for ).

FROZZLEBUM

 

I'm certainly not an expert but I'll take a shot.

Basically a dyno only measures torque (or more accurately for the chassis/rolling road dynos we generally see, tractive effort). It does this by measuring the time taken to accelerate a set resistence (in this case the rollers). From there lots of calculations are done to not only arrive at the torque output but also the power output (which is always a calculation based on torque which in turn is related to why the two curves always cross at 5252rpm). Let's just say lots of maths here.

From here we can sort of see why different dynos can produce different readings for the same vehicle. If the calibration is off on the resistence of the rollers it will effect the results. Likewise gearing multiplies torque and hence also effects the results.

Is that at all helpful for a very basic overview? How'd I do experts?

EDIT: Altered so it makes a bit more sense to people other than myself.

 

Don't wanna be a technocrat, but here's another major area of clouded info and misunderstanding -

VDC - especially relating to the yaw and G (spot) sensor.

Who knows - we see so much stuff about different size wheels,
different width tyres and so-on, and their effect or otherwise on the VDC system.

Probably should start a new thread.

Anyway, away we go.

Freezie.

 

I can't say for sure if VDC will effect it but I believe it could and so always make sure it's off.

Size of wheels, tyre width, profile, pressure, brand etc could all possibly effect the reading to some extent. Remember that we're looking at tractive effort and acceleration so anything that effects those could effect the reults.

At least that's my understanding.

 

It has always been my understanding that US Chassis dyno's apply a different weighting in there calculations when measuring Horsepower.

Croydens Shootout mode setting for there Dyno appears to be set at the US setting.

1HP = 0.7456999 KW Now ottonove's Z recorded 181.3 KW which = 243.1 HP, a reading that is what you would expect on a US roller dyno

Apps is correct when he said a dyno measures torque, the problem I have with most of the Australian Dyno Dynamic dyno's is that they dont show RPM on the bottom line, only KPH & there appears to be no allowance for wheel size.

The other problem I have (and I,m pointing the finger at no one in particular) is that nearly all of the dyno opperator's are also performance vendors & modifiers.

I have seen some dyno print outs where small mods are done logic tells me they can't be true

 

HP = TQ in foot lb's x RPM divided by 5252

Now does anyone now the math requied to calculate KW's from TQ expressed in Nm's

 

The "formula" should be the same....

ie: power = (torque X RPM)/5252

just make sure that when you do the calculations that all the units are either SI or all the units are Imperial

Whether a dyno run is done in SI units or Imperial, the torque and power curves should still cross at 5252 and you can apply a conversion factor to convert HP to kW (1HP = 0.7456999kW) or lb-ft to Nm (1lb-ft = 1.35582Nm)

 

True, I should've mentioned that. US dynos will typically read ~20% more than ours. Perhaps thats the intended purpose of the shootout mode? To compare to US results?

 

If your correct (i dont think you are) then there's something terribly wrong with Ottonove's graph printout posted on page 1 of this thread.
the crossover point is aprox 2000rpm.

 

Nathan, I agree that the graph on the first page looks funny, but nonetheless, when RPM=5252 and is substituted into the power/torque equation you end up with power equalling torque and the two graphs intersecting at this point.

BTW Nathan, how is your car coming along, and when are you racing next. I look forward to maybe seeing you on the telly.

Best of luck!