Curve shapes

[Feel]

I've got one of those questions.

After Bill posted his 485bhp plots (which seems an unusual shape), and after seeing Yermother's plots compared to some IHI cars and stock cars, I'm wondering what you can tell from the shape of the curves produced?

For instance, and purely out of interest, what makes these curves so different?

http://www.awesome-gti.co.uk/rollingroad/graph/rr.scn_09.09.06/gallagher1.jpg

http://www.awesome-gti.co.uk/rollingroad/graph/rr.scn_09.09.06/watson1.jpg

http://badger-5.com/bin/Dyno/Badger%205%20RR%20Run-small.jpg

[Mitchy]

Bills power mapping keeps on rising on his graph which shows there is maybe more to come with an increased rev limiter, its gaining power everystep of the way all up to the red line!
Bills torque is sustained torque, its not tailing off towards the red line it is being held, there is no big spike just a sustained curve.

To see how well a map is performing, look at whats under the line, bills for example is sustained and he is holding over 300lbft over a long rev range.

Bills is a perfect example of how a map should look.

Si's mapping for power, is not so sustained, its a bit jerky and its not making its power high up the rev range like bills meaning he has less usable revs to play with, its making peak power at around 5000rpm but instead of dropping off like most cars, si's power holds quite well, it doesnt drop off that much. At 6500ish rpm he is still producing 250ish whp which is good.

Now si's mapping for torque shows a huge spike at around 3500rpm which the turbo cannot sustain, it drops off quite quickly. For example he is only producing 300lbft+ over a rev range of around 1000rpm and it keeps dropping all the way to the red line!

Look at how far bills is producing 300+lbft and how far si's is producing 300+lbft

The K04 is a small turbo, even si's hybrid (Although it does give an additional 30whp over a standard K04) His exhaust manifold/Intake manifold might be stopping him from having a more sustained map as they will be nearly maxxed out if not already flow wise!

As to the map in the middle, what car is it from? Its the same, its making its peak torque and dropping off towards the red line which is normal. 99.99% of mapping will look like this. Peak power is recorded at around 6000rpm and then starts dropping towards the red line.

In summary to compare maps you need to see how long and sustained the headline figures are, take a basic figure of say 250lbft and see how long the car holds that and above that over a certain rev range.

Si's car may produce 360lbft torque, Bills car may produce 350lbft of torque, but if bill is holding 300lbft over say 5000 revs, and SI is holding his 300lbft+ over 1000 revs well its obvious bills is a lot more sustained which will show on the road by him shooting off into the distance!

[YerMother]

I'm only getting 366 ft-lbs because of the boost spike! it drops quickly because the N75 keeps opening the wastegate until it comes inline with requested boost! Its requesting 1.55BAR but it gets 1.8BAR as the turbo spools so quick and the N75 is too slow to react! I have a boost controller that should prevent this.

Middle plot is a IHI i think.

[YerMother]

Back on topic, the shape of the curves just shows how it drives and where the useable power is!

It also shows that mine is running a very aggressive map, where as the IHI and Bills, the boost is brought in in a controlled manner! Not just slam the wastegate shut! Thats why i need a custom remap really!

[ibizacupra]

its also a case of the mechanics of whats trying to spool.
you cant spool mine up like you can a k04 based unit, its too large with too much inertia.

once its spooling it continues to want to go and go, until you chicken out and impose the rev limiter. (well thats mine anyhows)

[Mitchy]

It looks like there is more to go bill as its not tailed off on that graph.

Is it not safe to rev it to 8500-9000rpm?

[Feel]

So, what we're really saying is that Sie's needs mapping - the large boost spike giving all the torque at 3,500 ("fun" is a subjective word, as is traction...) and the "flat" power curve show this. If it were mapped, would it trade off torque for more power?

The middle one - looks fine. I know the owner wants more power though.

I notice that the torque and power lines cross at the magic 5250rpm on both Awesome plots.

I read in the other thread, Bill, that your new turbo is really classed as oversized, should be on a 2.5l - hence the curve never peaking? Your puny :P motor not shifting enough volume to max out the turbo? Spooling a 1,000rpm later than the others.

Would this be a limitation of the inlet side or exhaust side (i.e can't get enough air in and the motor is choking the turbo, or is it that there's not enough exhust gas to spin the turbo faster enough?).

I should've put a k03, k03s and k04 plots up :think:

[ibizacupra]

dunno... but I am still on hydro lifters which is a concern at these high rpms.
8200rpm limiter is as far as I want to push it currently.