KV6 2.5: power & torque loss?

[trikey]

Don’t forget different dyno’s can give different readings, I was speaking to a bmw owner who ran his car on two dynos a week apart, one showed 530bhp the other showed 590bhp!

[kaiser]

Originally Posted by trikey

Don’t forget different dyno’s can give different readings, I was speaking to a bmw owner who ran his car on two dynos a week apart, one showed 530bhp the other showed 590bhp!

They normally apply a correction factor to compensate for losses, in order to give you an estimated output on the crank. So if you use 0,15 or 0,2, it will make a lot of difference. Many owners will happily walk home with a curve that shows a number of ponies more!

As for testing in 5th gear, that is totally impossible in the automatic 75, unless you can hold 5th, somehow?

The tendency is to gear down immediately there is load, even a light load.
So in an auto it will give you the whole spiel, in all gears.

in a manual, you select and it stays there, until you change your mind!

[SD1too]

Originally Posted by Dorchester2

When initially Rover gave 175 bhp & 177 ft lb, from which did it come?

At the "flywheel" Arnaud, in other words it's the engine maximum output before the gearbox. When you have your car tested on a dyno, it is measured at the driving wheels so there will always be a reduction.

Dyno sessions always result in dissatisfaction so are best avoided. Just enjoy your leather seats, thick carpets and burr walnut trim and ... r e l a x!

Simon

[Dorchester2]

Originally Posted by SD1too

At the "flywheel" Arnaud, in other words it's the engine maximum output before the gearbox. When you have your car tested on a dyno, it is measured at the driving wheels so there will always be a reduction.

Dyno sessions always result in dissatisfaction so are best avoided. Just enjoy your leather seats, thick carpets and burr walnut trim and ... r e l a x!

Simon

I love your very true and positive philosophy Simon!
Unfortunately for me I'm born curious: that'll be my misfortune!
Nevertheless thanks to your crystal clear statement I understand much better where were lying my useless worries.
So no longer any complain: I'm happy, you've saved my day!

[SD1too]

Originally Posted by Dorchester2

I love your very true and positive philosophy Simon!

Thank you very much Arnaud!
(Curiosity is good though and I too have been through the dyno experience.)

Best wishes,

Simon

[Dorchester2]

BTW it wasn't a sorry experience after all (I'd asked for a remap as well, even for a rather modest - not to say mean - benefit, but I was fully conscious I had neither a diesel nor a turbo engine) .
My pride & joy was praised for her very good condition & maintenance by the pros. Likely a more gratifying exam than the MOT...
And as I'm badly suffering of perfectionism since a while I'm rewarded to see my comfy girl running at her best.
Maybe an expensive tantrum? But let's not get bored with trifles, it's only money as they say...
Hence I can enjoy even better if possible my burr walnut trim, fine leather seats and thick carpet, hey Simon?

[bl52krz]

Originally Posted by Dorchester2

BTW it wasn't a sorry experience after all (I'd asked for a remap as well, even for a rather modest - not to say mean - benefit, but I was fully conscious I had neither a diesel nor a turbo engine) .
My pride & joy was praised for her very good condition & maintenance by the pros. Likely a more gratifying exam than the MOT...
And as I'm badly suffering of perfectionism since a while I'm rewarded to see my comfy girl running at her best.
Maybe an expensive tantrum? But let's not get bored with trifles, it's only money as they say...
Hence I can enjoy even better if possible my burr walnut trim, fine leather seats and thick carpet, hey Simon?

As Simon said,dyno’s always bring dissatisfaction. If your car is performing ok, and you do not notice someone accelerating away from you in an old Yugo, don’t worry.Dyno’s are like cars.... all are different, and give different readings, especially if the operator is not conversant with how they really work. Another adage is:- if it ain’t broke, don’t try to mend it.
It is a bit like upgrades. I have always thought that increasing power by a mere 10/20 Bhp is a waste of time. Much better to have original map tweaked to whatever it is that you want. Economy.More torque in gear can be better than outright Bhp.

[Ahrle]

Originally Posted by trikey

Don’t forget different dyno’s can give different readings, I was speaking to a bmw owner who ran his car on two dynos a week apart, one showed 530bhp the other showed 590bhp!

Yep, afaik "rolling" dynos can make the wheels slip and therefore show wrong outputs. Drivetrain loss shouldn't be more than 10 or absolutely max. 15% for any 2WD vehicle.