700 hp club

[FaisalJ]

Nice

I bet 700PS shifts!!!

I actually wanted to come back to this...

Tadass910, not sure what your fuel enquiry is? If you actually use 700 bhp instead of 560 bhp to shift your 2 tonne car, and it's very seductive, believe me, then basic physics states you will need more energy/fuel. There's no free energy, so nothing for nothing. The tuning companies suggest you might get more efficient combustion with their remapps, so if you cruise at the same speed or accelerate at the same rate, i.e. use the same power, then if they are right you should be using less fuel and so doing more mpg - small margins though, I suspect. You will definitely be able to burn more fuel and therefore accelerate quicker and travel faster, which is the chief objective. Trust me, you have to hold on to the steering wheel tighter, so you don't loose your grasp; its the first time driving all sorts of high performance cars that I'd ever really noticed that!

I've often wondered about this...

So an engine typically has a thermal efficiency of something like 25%, and the other 75% is wasted (mainly as heat).

So a turbo takes some of the otherwise wasted energy and feeds it back into the system, to do more work--> making the engine for thermally efficient.

So then, if you increase the turbo's effect (more boost), then do you not increase the efficiency more?

On the other hand, you're feeding more fuel in. So can fuel efficiency go down even as thermal efficiency goes up?

Any mechanical or chemical engineers about? Not fake ones like me...

[Markp]

It is theoretically possible to improve both thermal and volumetric efficiency by fiddling with boost / maps which might in turn improve fuel consumption at same speed (when compared to before and after re-map). But any improvements in efficiency are tiny and the main aim is to push more fuel / air in to get more power, and if you use that extra grunt you will be averaging fewer mpg.

[RS6chris!]

Aye...700bhp is fun....

But can't hel but feel it's until your doing (Licence losing) speeds is when you enjoy it most??

[brab]

They managed to code out the 4-cyl modus and that was a pita for me since i felt like "the car changed gear" and exhaust pop (Milltek Non res cat back) each time the 8 went in. This option can not be healty for the engine due to many reasons.

It's funny that some people have those symptoms, I haven't noticed the 4/8 switch ever and I did already 15,000km with the car...not a single glitch...

[MikeFish]

They managed to code out the 4-cyl modus and that was a pita for me since i felt like "the car changed gear" and exhaust pop (Milltek Non res cat back) each time the 8 went in. This option can not be healty for the engine due to many reasons.

It's funny that some people have those symptoms, I haven't noticed the 4/8 switch ever and I did already 15,000km with the car...not a single glitch...

Is your car remapped or have a tuning box? I think this seems to be an issue with tuning boxes rather than proper remapped cars.

[brab]

Is your car remapped or have a tuning box? I think this seems to be an issue with tuning boxes rather than proper remapped cars.

Mine is completely stock, but as far as I understood jipettersen his was also until 4-cyl disable...

[MikeFish]

I read that as he had problems with the COD due to tuning box then ended up having to do a proper ECU tune to code it out so ended up having a proper remap. He already had a milltek on it and has been talking a lot about tuning boxes (MTM I think). But you're right he doesn't specifically state he has a tuning box so could have been standard other than exhaust.

[Tadass910]

Picked up my 2017 Perf today after two days in dyno for disable 4-cyl modus and remap .
They managed to code out the 4-cyl modus and that was a pita for me since i felt like "the car changed gear" and exhaust pop (Milltek Non res cat back) each time the 8 went in. This option can not be healty for the engine due to many reasons.

Since they had to "break into" the ECU to do this, it was no turning back for warranty and the car was ready to be tuned.
Stock was 604 PS /745 nm, so thats pretty close to promised ( car has only 2000 km / 1500 miles).
The most aggressive map they tried was measured to 720 PS / 920 nm. This map is perfect for 100+ oct but thats not an option where i live. The engine management had to much correction on ignition times when 98 oct was used and it became a little to hot on exhaust temp so they decided to take it a little bit down.
The map i use deliver 700 PS / 880 nm and the car feels different i can promise. The trottle response is

Maybe i buy the MyGenious from Dimsport to be able to switch maps myself.

ABT said that 4 cycl modus is not affected with their unit box:

"because of our advanced development of our engine upgrades and the usage of our AEC control unit, our upgrade is working in a different way than other tunings.

When driving with little throttle, our engine upgrade is not giving extra power.
The extra power is need when driving with more throttle up to full throttle. So under circumstances when all cylinders are working.
As we consider, that you don´t need more power, when driving slow and with small throttle only.
But you want to have better acceleration when overtaking or just want to have fun.
So it makes sense that you then have the increase in power.

Therefore we are not influencing the management of shutting down cylinders or not, as this is outside of our range of performance.

With other tunings that might be a problem, as you constantly have the extra power. No matter how much throttle you are driving."

P.s maybe ABT unit box works differently than mtm that's why one of mtm users had problems with 4 cyl module

[jipettersen]

My car (2017 Perf) has been stock except for Milltek cat back non reso up to last week when i took a ECU tune and disable of 4-cyl modus.

Reason i did this was i felt that the 4-cyl was a pita for me. Didn't noticed anything when the car did the swap from 8 to 4 but the other way. Normally i go in "Auto" and "D". Cruising steady at a speed around 50 -70 miles. On flat road this normally trigger the 4 cyl modus. So far so good. But at a slight move on the trottle or the road goes uphill all 8 kick in. That switch was felt in the car by me like a small jerking. Also heard in the exhaust note that "something" was happening. Obviously when you are more brutal or floor it you cannot feel / separate this switch.
Maybe its my driving pattern? Or this is oversized in my head ? Anyway this was discussed with Audi stating this was "normal" and not possible to disable.

So then i talked to my local MTM dealer. Together they tried 3 or 4 maps (no tunebox) but the 4 cyl kill was done without help from MTM.

If none of you have this or feel that this bothers then fine and stay happy

PS! Audi claim this save fuel an emissions. But so far i see that its the opposite.

[Tadass910]

My car (2017 Perf) has been stock except for Milltek cat back non reso up to last week when i took a ECU tune and disable of 4-cyl modus.

Reason i did this was i felt that the 4-cyl was a pita for me. Didn't noticed anything when the car did the swap from 8 to 4 but the other way. Normally i go in "Auto" and "D". Cruising steady at a speed around 50 -70 miles. On flat road this normally trigger the 4 cyl modus. So far so good. But at a slight move on the trottle or the road goes uphill all 8 kick in. That switch was felt in the car by me like a small jerking. Also heard in the exhaust note that "something" was happening. Obviously when you are more brutal or floor it you cannot feel / separate this switch.
Maybe its my driving pattern? Or this is oversized in my head ? Anyway this was discussed with Audi stating this was "normal" and not possible to disable.

So then i talked to my local MTM dealer. Together they tried 3 or 4 maps (no tunebox) but the 4 cyl kill was done without help from MTM.

If none of you have this or feel that this bothers then fine and stay happy

PS! Audi claim this save fuel an emissions. But so far i see that its the opposite.

Strange, my car stock only Miltek non resonated catback installed and I don't feel anything, maybe if I put tune box then it will change, we will see...