Rolling Road on 24/11/2007

[mrdeli]

I guess if we were to take audi figures as correct we could get a 'mean' of drivetrain losses. 414bhp with 20% loss should, as you say, show around 331 at wheels. With that being the case - why are people so annoyed at getting dyno results in and around this figure? Is there any hard data suggesting what drivetrain losses the RS4 B7 should be suffering? - surely with modern manufacturing (and cars of similar ages/ mileages) - losses should be within a percent or so of each other?

[VARSITY]

A good RR operator will input the car type, trans, engine, temps etc etc and the computer will give a very good indication of what it should be. Do understand though these RR are engineering grade measuring eqt and as such if set up badly will cullate badly and your result will show this. It needs a skilled and knowledgable operator/engineer who understands the car and the trade they represent.

I stand by what I said so many times, it is highly unlikely that any RS4 sold in this country that was produced after Aug 2006 will have the advertised power. And almost certainl that it will have between 360 and 380bhp, unless of course it has been mapped and then I would doubt it wll reach the 414bhp.

This also counts for any RS4 running the new 'V80' software.

[mrdeli]

Why were the pre August 2006 cars more powerful?

[S4TAN]

I am going back in two weeks time, my mapped car running V-power only managed 323 bhp!

If this was @ the wheels, IMO it's not far short, 331BHP @the wheels = 414bhp claimed.

If you read the Thorney MS RR day thread you'll find that it was actually 261hp measured @wheels, and 323 calculated @crank ...

That said, no-one present at the day thought this was right, and that the RR calibration was out when Jason was on (or the rollers were misaligned)

[mrdeli]

If i get 323, I'll be a very disppointed chap!

[GrahamS4]

Why were the pre August 2006 cars more powerful?

Yes, what is the reason for this?

[simple1]

I thought the claimed loss was 16% on this car, the test that one of the motoring mags did in the summer was using that figure. will see if I can find the scan of the article again.

[simple1]

Here

[simple1]

Sorry the quality is rubbish, but what it says in the losers section is Audi RS4, 2006, quoted horsepower 414, power at wheels 345, loss 68 bhp = 16.5%. The article gsays the car which suffered the least loss was an M5 which lost 7%. Test results are published at WWW.rri.SE and if you want a readable copy PM me with an email address, as I had to reduce the size to post it.

[GrahamS4]

None of those figures seem likely from my ex pereince of RWD and AWD cars on dynos. Unless the latest technology has advanced so much the transmissions are so much more efficient. I recall the results gnerally being questioned at the time though as unbelievable for the most part.

So did you get near 345BHP at the wheels at DMS Simon?

If so what shoot out mode was it in (SHOOT_xx at the bottom of your plot)?

[tartan_rob]

Guys, guys. There is no need to get hung up about figures? It is not a good talking point down the pub! A bit like, I can bench press 100kg's - with one hand.....

What is much more important is how the car feels and if it feels quick. THE ONLY way find out definitively if the engine has the correct power is by removing it, setting it up on a test bed and attach it to a dyno.

Otherwise, drive it and enjoy it, get it fixed or hand it back.

[audijohn]

This is interesting, a 335i smoking some !!!!!!!!!!!!!
http://www.dpccars.com/car-videos/06-25 ... udi-S8.htm

[mrdeli]

'This is interesting, a 335i smoking some !!!!!!!!!!!!! '

That's way way off topic !!!!!!!!!!!!!!!!!

I'll be hoping for around 350hp at wheels then - maybe a little hopeful, but we'll see tom.

[GrahamS4]

Guys, guys. There is no need to get hung up about figures? It is not a good talking point down the pub! A bit like, I can bench press 100kg's - with one hand.....

I don't think that is really the point.

Perhaps more the B5 section, but many of us spend a lot of time and money (I am sure I don't need to preach to you here) about making the car perform better. This means increasing BHP and torque.

I am a way off B7 RS4 affordability yet, but if these cars are really sub 400BHP, I want to know and so do those owners who have them currently I would have thought.

A healthy discussion on if they are down, why they are down or why they measure down but really aren't is not anything to do with pub talk.

I persoanlly think dyno operators "those are pub numbers" is an easy excuse for not explaining or not using their equipment correctly.

[S4TAN]

If 16.5% is the calculated drivetrain/transmission loss for a B7 RS4 does anyone know the accepted loss figure for a B5 S4/RS4? Just interested to know (and I'm sure a few B7 owners would have owned a B5 previously)

e.g. At the recent RR day I got 314 measured@wheels, 406 calculated@crank - which equates to around 22.6% loss. Is the higher transmission loss for the B5 due to old-technology or just old/worn parts? (7 yr old car)