BiTDI

[AudiInNZ]

Hi,
I currently drive a BMW 535d and love the twin turbo engine in it. I am ordering an A6 Avant BiTDI and wonder about the lag I read about in some reviews.

Can anyone comment how the engine/transmission compare with the 535d I am familiar with?

Thanks

[jbanfie]

Hi,

I can't comment on the difference between a 535d and the BiTurbo Audi as I've never driven the 535d, but here are some thoughts on the Audi BiTurbo:

The lag is more down to the Auto transmission than the engine. At modest revs the small turbo is delivering half boost as seen on my laptimer display, and the pick up is terrific.

What is bad is the kick down which really takes the sting out of an overtaking manoeuvre, mine has kicked down from 2nd to 1st and that was a big surprise.

There's a couple of things here, firstly when not in 'sports', briefly pulling back on the gear leaver shifts you straight to sports mode, which generally kicks the gears down one or even two, but you will still get a kick down if you plant your foot, and maybe the best thing is not to do that.

Second if you pull on the manual paddles, it goes into manual control, but I think I've still had a kick down occur when planting the foot.

Third if you put the gear leaver over to the manual position and then either use it or the paddles, you actually get control, although it does upshift when you hit the limiter, which is nice.

I'm not convinced the engine and gearbox mappings have been thought through that well, as there is so much torque there is no need to kick down and the kick down takes so long, any advantage of the lower gear is probably lost, especially when it has to change up again when the revs reach the limit. Kicking down to first is a bit of a joke!

I kind of wonder if VCDS can be used to change the kick down behaviour, and I need to experiment more to trully establish the behaviour patterns in each mode/gear etc etc. That for me is the biggest problem, you never quite know what is going to happen, and that removes the confidence for the overtake!

That said, when you do go to manual control, and shift down so the revs are mid range or so, it goes like stink, with no noticeable turbo lag at all, because they are spinning well by that point anyway.

I'd be interested to hear other people opinions on this, and indeed some views on the 535d, which I only rejected because it's rear wheel drive

[AudiInNZ]

Thanks, that is interesting. Like you, I am looking at the A6 because of 4 wheel drive.

The BMW 535d doesn't seem to have any issue engine vs transmission. The two work together perfectly. I just leave it in D and never really notice what exactly is going on, even at kickdown.

Disappointing that the same isn't true with the Audi. Like you say, it does sound like something that could be fixed by a software improvement...

Thanks for the detailed feedback.

[jbanfie]

Maybe I'm overly critical of the behaviour as this is my first proper automatic car, it will be interesting to hear your opinions when you get the Audi having then owned both!

[robbyg]

I have driven both cars this year (530d SE and 535D Msport both 8 speed). The BMW actually has the same gbox (ZF) as the A6 bi tdi but mapped differently. Google ZF 8 speed and find out all sorts.

I agree with john above bitdi is abit slushy in the lower gears and does sometimes kick down when it really didnt need to, that certainly contributes to a feeling of lag. To be fair i leave mine in D nearly all the time and its fine. If i want to do a fast overtake i usually drop a couple of gears manually first with the paddles. Its abit slower off a standing start than the BMW and than a Stronic audi gearbox as it allows more slippage. Once you are on the move it makes lovely crisp changes, same as the bmw and better than the audi S tronic. I havent yet tried building torque against the footbrake in a launch control style in case i break something, i tried it in an A5 3.0tdi stronic courtesty car last week - christ it jumped from 0-40 in what felt like a second.

Putting it into manual gives you total control (unlike some other makes). I have tested the true turbo lag at various engine speeds, there is upto a second gap between flooring the pedal and receiving full torque, but this is no different than any other modern turbo diesel engines. If you go from no throttle to lots there will always be turbo lag, if you go from part throttle to lots it is negligible. Best thign about the bitdi is it give huge torque from about 1200rpm.

I posted various videos on youtube a few weeks back, these show how it works in normal driving, serach for a6 bi tdi, my user name on there is robbybobbyg or similar.

[AudiInNZ]

Thanks for your comments, very interesting.

I will let you all know how I find my new car. First of course they need to build it....

At this stage I have a delivery date of end of Jan 2013. I think I ended up with a spec not a lot different from RobbyG. Boy, the options add up quickly. I would have loved the B&O upgrade but at $15,000 NZ$ ($US 12,000) it is insane.

A previous car was an E46 M3 with the 1st gen SMG transmission. That was a great car but the SMG was useless as an auto. The only way to drive smoothly was with the paddles. In auto, it was like "Is this a joke? Has it had a major system failure? No, that is how it is supposed to be...".

Since then I have driven various cars with the dual clutch transmissions and they have been great.

Anyway, back to the A6. I will check out the videos on YouTube. Need to do something while I wait :-)

[DBLincoln]

Hi Guys

I slot straight in here..................I have had 2 BWM 535d' SE & still currently have a 2009 M Sport. The latest was remapped and also had a tuning box fitted to it. 342 bhp and 720 nm, really quick and for some reason each time we increased the power output the fuel consumption went down as well.............overall 8 mpg better off. Performance was incredible and the only thing that let it down were the brakes when being pushed (which I did often).

I have just taken delivery of an A7 biturbo and although early days I have to say how much I like the car over the BMW. I have added 20” Alloys, Air Suspension, the Sport Differential and dynamic steering along with upgrade to Bose (the surround sound is amazing if you source 5.1 DVD’s). I have also added soft close doors and the active headlights.

So early days and yes I can see the performance differences. I went to an Audi Driving day at Silverstone Race Track and got to understand a lot of the cars features. I overcome the ‘lag’ by using the ‘paddles’ but really it was not that was intruding in the first place.

I have spoken to a ‘specialist’ remapping firm, as apposed as out of the box remapping and they have already played with the engine. They are saying 385 bhp and 760 nm, but what they have also found is that the ‘lag’ has disappeared and mid-range grunt is superb. I am going to resist temptation until 3000 miles on the clock.

So driving the Audi in comparison to the BWM; the Audi is in a league of its own. Much better balanced and one thing that I have really noticed is the fact that it appears slower until you look at the Speed and has caught me out a couple of times when I simply did not know I was going that fast and roundabouts loom up fast………………….honest officer!

Across country it covers the ground quickly, the sports diff does make a big difference and cornering is no drama. I am simply amazed at just how quick and smooth they are. Not as good on fuel as the BMW buy about 8 miles per gallon, but early days and if I am honest is same as the BMW was before the tuning.

Couple of nags………….CD and DVD’s do not copy to the Juxbox (hard drive in the car) something to do with copyright. The other bug is that you need a sim card in the car to get Audi Connect and Google Earth Maps but cannot run an iPhone at the same time. I am told this is an Apple problem. So it either Google Maps and no phone or via versa. Works fien with an android!!

Exhaust sound is to die for………..

Will update when I have had the remap done.

Best wishes

DBLincoln

[jbanfie]

DBLincoln welcome and thanks for that detailed description, very interesting that you ended up virtually with the same options as myself - just don't get a towbar fitted by PF Jones as they don't understand Air Suspension well enough, unless you live near wiltshire where you can get it fixed for free!

Do you have details of your remapping firm, I would be interested in hearing more about that

Also, I take it you have the Head Up Display, and I would recommend getting the laptimer enabled which is a quick job with VCDS (gives you boost gauge, oil temp and a timer!), if you are ever near Somerset I can sort that for you.

Cheers

Jon

[robbyg]

thanks DB, nice to hear another viewpoint. Pleased you are enjoying your car too.

i am trying to convince myself there is no need to re-map this car. i have had my previous 3 cars done. no need no need no need no need (head rocking backwards and forwards........)

let me know how you get on.

[DBLincoln]

Hi Robby

I have tried tuning boxes and remapping and both! Found (out of the box) remapping alone did not give the fuel savings that fitting the box does. Bespoke remapping done by a specialist, as opposed to someone who simply send the map away to get it modified, has produced far better results both performance as well as economy.................perhaps a half way house if simply the box that can then be taken off for servicing/warranty work ect.

I have a motorhome, van and other cars............and all run boxes not so much for increase performance but the fuel saving........7 mpg better in the motorhome.

Have a look at this article: Audi 3.0 BiTDI Biturbo Diesel Engine Boosted by B&B to 390 HP - autoevolution

Mine will not be so extreme, but first I might just try the box .....................and later the remap.

I liked what Jon said in fitting the VCDS and think I will explore this.

Just enjoying the car at present.

Kind regards

David
A7, BiTdi S Line
Air Suspension, Sports Diff, Dynamic Steering, 20” Alloys, Adaptive LED Headlights, Bose 5.1 Surround Sound, Insulating & Privacy Glass, Adaptive Cruise (leap of faith), Ambient Lighting, 4 zone heating, Heated Front & Rear Seats, Power Door Closure, Park Assist.