Nick_Cat

iTrader: (5)

I've just had my my97 catalunya on the dyno. As far as a I am aware it is standard. It made the following figures (see below). Now, while I am happy with the bhp figure I am confused by the torque which seems very low. Also the bhp and torque curves don't cross at 5250 rpm like I thought they should.

Unfortunately the master of the dyno was away and another (trained) operator did the job.
Also they said the boost and oxygen figure were fine - can ne1 confirm this.

Thanks in advance
Nick

bhp / FtLb
http://i16.photobucket.com/albums/b4...bhp_torque.jpg

bhp / bar
http://i16.photobucket.com/albums/b4...07/bhp_bar.jpg

bhp / lambda
http://i16.photobucket.com/albums/b4...bhp_lambda.jpg

TonyFlow

Hmmm - it is physically impossible for the figures to not cross over at 5250, as Power (bhp) is a figure calculated from torque (lb/ft), and the calculation makes the figures cross at 5250. Are you sure it is not power at fly and power at wheels?

Nick_Cat

iTrader: (5)

It could be I suppose, but I asked where the power was taken from and they said at the flywheel. The right axis of the graph has FtLb as a title.

TonyFlow

It does look to be torque, but it is impossible for the the figures to not cross at 5252.
Horsepower is a measurement made from
(Torque * RPM) / 5252 - hence the impossibilty of the figures not crossing - a dyno measure torque and then calculates the power!

TonyFlow

Assuming you are making peak power @ 5.6krpms, then torque is 203lb/ft (at the same point), so way over what the figure is, meaning it cannot be torque!

Should also add, that a dyno run is usually done in 4th gear IIRC!

Nick_Cat

iTrader: (5)

Thanks - that's what I thought. I questioned the torque and they said that it could have been 'scaled' wrong. It didn't occur to me at the time to point out that the curves should cross at 5252. They're going to bring it up with the operator when he returns.
Nick

ex-webby

The main thing here guys is that the scale for both BHP and TORQUE is not the same on the graph..... that would certainly allow for the fact that BHP and TORQUE would never cross at 5250 on the graph that you show.

Unless the scale is the same on the printout, you will be unable to compare apples with apples.

Regards,
Shaun.

Nick_Cat

iTrader: (5)

So I should disregard the torque figure altogether?

Nick_Cat

iTrader: (5)

Can ne1 comment on the boost and lamda readings.
It is a tdo4 turbo.
cheers
Nick

TonyFlow

Doh - didnt even look at the scale! Still say that it is not a valid torque figure though!

Jay m A

iTrader: (2)

Can't see whats wrong with it

0.9 bar peak, torque is about 170 peak, holds quite well at the top, hence the 217 HP

BlueSimon

FYI, you left your reg plate number in - you might want to scrub it

TonyFlow

Jay, IIRC, BHP = (lb/ft * RPM)/5252, therefore, lb/ft = (BHP * 5252)/RPM, so at the BHP peak of 217 @ 5600 rpms, we can assume:

lb/ft = (217 * 5252)/5600 therefore lb/ft at 5600rpms must equal 203.515.

Perhaps my maths is flawed, but from memory they are the calculations for power/torque!

Nick_Cat

iTrader: (5)

Thanks for pointing that out!


I didn't know the calculation but it didn't seem right to me that it could make 217bhp with a torque figure of c.170 lb/ft, if the two are related. Also as the boost was ok and holding up to 5000 rpm.
Cheers
Nick

mightyyid

Remember that is slightly incorrect. The car was on a dyno thus it was measuring the power at the wheels, and making an assessment of what the power is at the flywheel, as it cannot measure the frictional losses etc that happen. So ultimately, it's down to the programmers of the dyno to assess this. That's why engines figures are done with the engine out of the car, as its accurate at the flywheel. A dyno is only as good as the calculations that have gone into it...

vindaloo

...erm... I still think something is wrong with it. It's more like BHP @ fly & torque @ the wheels. You can approximate 160 lbft for the torque and re-scale it from the BHP scale. It still doesn't cross @ 5252.

J.

Nick_Cat

iTrader: (5)

Now have the correct print out showing bhp and torque. Have posted it under the thread requesting power graphs:
http://bbs.scoobynet.co.uk/showthrea...t=power+graphs

Nick