RS5 versus S5 Power plots - what you've been waiting for!!

[Ianhp1]

OK Guys... this is what you've all been waiting for! ...and I must say, I'm changing my view of the RS5 now. The headline figures may seem a little 'mediocre', but when you see the power graphs, and compare to the S5, you can get a real impression of what this car will be like (well you can if you drive an S5!!). I'll comment on this later.

I got the data from the Audi published plot for the RS5 and from a dyno plot of my S5... then did all the conversion to common units and plotted together.

Just look at that Torque curve!! that is some serious valve/cam timing work to get that power up at those revs and not have a complete lemon at normal driving revs. I'm blown away by this!

Here's the plot:

[Ianhp1]

The S5 has very 'linear' power, it kicks you in the back st 2,500 rpm and hauls you effortlessly to 5,000 rpm... after that, it's a little un-dramatic... it accelerates well and shows plenty of power, but there's no extra drama as the revs rise... it just pulls. shift up near the red line and you get the same punch... and again right through the 'box to very illegal speeds. It's downfall really is that the 'box has quite 'long' ratios, so a good blast in second, shift to third and after a second or so, you're breaking the limit....and all the way up to 90, where you shift to 4th... and it's here on upwards that the engine and 'box gets 'sweet' and the car shows just how rapid it is... which is not ideal for UK roads... (but superb for the autobahn).

Looking at these plots, the RS5 will behave very similarly when 'pootling' around at normal speeds... although slightly lower powered than the S5 I don't think anyone will notice much difference, and certainly will have no cause for concern over a 'lack' of power. Like the 3.0TDi, the in-gear acceleration for the first 3-4 seconds will be marginally quicker in the S5, but a shift of a cog or two and BANG... 100 extra BHP on tap. and the RS5 will, unfortunately leave the S5 standing... the S-tronic 'box will help here too, making the shift for you when you hit the loud pedal. Given the torque available at those revs, this car is going to be INSANE!!

...Finally, the S-tronic 'box will help the car make the most of it's power at all speeds, by having the extra ratios and enabling the car to really use the revs, and not be 'caught-between gears' as happens with the S5 - especially around 40-50mph - so I really do see an 'every-day-driver' that has a second persona that lives at 5,000rpm+ - it's going to be an absolute screamer, with the fun of a Honda V-tec and the comfort of the S5 V8... and I think a decisive victor over the S5 and M3 with relative comfort.

[gruffle]

+1

I agree - these better resolution graphs give a much clearer idea of how the RS5 will perform, that torque curve always looked very flat, indeeed it is.

Two dabs on the paddles and byebye
foot off gas and box will slip back into auto and smoooth

very good indeed


...but still not a turbo and still considerably short of an XFR

[Spinner]

Posted yesterday on the RS5 brochure thread ...

Originally Posted by Spinner

Need to study that dyno chart, looks to me like the RS engine holds onto it's torque throughout the rev range far better than the S5.

I'm of the a very similar opinion Ian. When I first saw the chart I was seriously impressed and was intending to do the comparison myself.

The way the torque is held by this engine is a serious advancement over the S5 V8 and will no doubt make it a far greater car than most would have believed.

Still not for me but a very worthy engine and along with IMO a very competitive price for Audi. On reflection I would think the press and majority of those in the market for the RS will be estatic with this sort of on-tap power.

Originally Posted by Ianhp1

but a shift of a cog or two and BANG... 100 extra BHP on tap

I might be wrong but doesn't the S-Tronic box have the next gear selected? so to drop it 2 ratio's wont happen that quickly especially if it's already preselected a higher gear as the next option and something that's always despite being faster when used in a linear manner puts me off these autos. E.g. when in 4th and pre-selection is 5th, then have to unselect 5th and change to 3rd before selecting it, which dependant on ECU preselection it could then choose 4th or 2nd as the next gear, if 4th it has to then unselects 4th and selects 2nd before changing. Could be embarrassing in this senerio but you'd certainly have fun making up for it once you got the right gear

[Ianhp1]

Spinner... you ever wondered what that RS5 engine would be like with a VF engineering supercharger?

[Spinner]

Yep I have Ian.... I would think the word is INSANE! That is if the S-Tronic box could handle the torque which I have my doubts.

However there is the extra £35-40k needed to get the fully spec'd RS and then a definate £20k on top for the blower, it's just not worth it

[Ianhp1]

Originally Posted by Spinner

Yep I have Ian.... I would think the word is INSANE! That is if the S-Tronic box could handle the torque which I have my doubts.

However there is the extra £35-40k needed to get the fully spec'd RS and then a definate £20k on top for the blower, it's just not worth it

...it would be nice to know which RS parts can be applied to the S... a bit like the S4 and RS 4... add RS pistons and cams to and S4... and you are mostly there... so will RS5 cams etc be able to be fitted to the S?? ... Only APS will find out!!

[Spinner]

Yep, I wouldn't be surprised if Ed wasn't already thinking about that offering, especially if a decent blower is unrealistically priced.

[Spinner]

Saying that perhaps I missed your point. RS parts and blower, now there's a thought

[C99]

I am surprised, that someone is surprised by torque characteristic.

What you have been waiting for?
There is the same 4,2 litre volume, with sport camshafts and probably higher compresion ratio, so this was really predictible result.

It hasn't changed through the years, not even with electronic control unit and direct injection...

That is reason why I would prefer 3.0TFSI.

[Spinner]

Hmm correct me if I'm wrong C99 but based on the dyno reports of a RS4 (see attached example) I'd suggest the reason for the excitement is that it shows the standard RS5 torque characteristic is more consistant than the RS4 and through the most useable part of the rev range, whilst addtionally producing approx 50-60nm more. Also this was a direct comparison to the S5 where the characteristics of the S5 torque is from the above dyne report clearly different.



Surely you can see this is a big improvement over the engine it is effectively replacing?

Now whether or not it makes these figures in real life is a differnet matter all together.

[Ianhp1]

Originally Posted by C99

I am surprised, that someone is surprised by torque characteristic.

What you have been waiting for?
There is the same 4,2 litre volume, with sport camshafts and probably higher compresion ratio, so this was really predictible result.

It hasn't changed through the years, not even with electronic control unit and direct injection...

That is reason why I would prefer 3.0TFSI.

No, it's not the predictable result... The predictable result would be a peaky but narrow-ish torque curve... a bit like the current RS4... but with some bloody clever engineering, it has similar torque/power characteristics to the S5 and then holds that torque as the power rises in the higher rev band... the flat-topped torque curve itself looks more akin to a turbo car... albeit without the bottom-end (2,000rpm) torque.

That is a clever piece of engineering and a real step up from the RS4, which as you say, showed all the characteristics one would expect from higher compression and cams.

I expect that they've worked heavily on the variable cam timing and the variable intake geometry to get this... POSSIBLY moved to a flat-plane crank, as this would be the logical upgrade to get this sort of performance... but I think Audi would be shouting about it if they'd done that. (unlike when they secretly put flat-plane cranks in the A4 DTM cars and got disqualified!) - anyone seen the firing-order for the RS5... that should tell us!

[SDS5]

[quote=C99;110764]I am surprised, that someone is surprised by torque characteristic.

What you have been waiting for?
There is the same 4,2 litre volume, with sport camshafts and probably higher compresion ratio, so this was really predictible result.

It hasn't changed through the years, not even with electronic control unit and direct injection...

I agree, but I did expect a small <10% increase due to variable valve lift.

However with a NA engine its the intake manifold length that basically affects where the peak torque appears in the speed range (variable valve timing and valve lift help too). Even with variable intake tuning its a compromise to match for maximum torque over the wide speed range of this RS5 Engine, and it is clearly optimized at the high RPMS to keep the power curve rising all the way up to the redline, which is very good.

With the DSG gearbox and software controlling the optimum shift point the power/torque characteristic should really be transparent to the driver

But... then again, this is an RS car... a true drivers car, so why is it an automatic anyway?

Would have been nice to see a V8 turbo - anyone remember the RS6 4.2V V8 Turbo 450bhp? (flat torque basically from 2000 - 5000 rpm - it ate transmissions for breakfast).

[Graham]

Originally Posted by Spinner

Posted yesterday on the RS5 brochure thread ...



I might be wrong but doesn't the S-Tronic box have the next gear selected? )

Probably, when your in 'D' but probably not when your in Manual mode.

I know my S5 Tip is an Auto box but it performs very different in the two modes ( just as you would want it to ). If your in a 'spirited' driving mood you select the Tip mode and it does nothing till you tell it to with the paddles. It's my guess that the RS5 will be a similar concept.

[HAWKiS5]

Originally Posted by Graham

Probably, when your in 'D' but probably not when your in Manual mode.

I know my S5 Tip is an Auto box but it performs very different in the two modes ( just as you would want it to ). If your in a 'spirited' driving mood you select the Tip mode and it does nothing till you tell it to with the paddles. It's my guess that the RS5 will be a similar concept.

Even in manual mode (either by putting the shift lever to the passenger side or by using the paddles) the S-tronic box has its own "will" when pressing the pedal to the floor..... pity bnut true.......let's wait for the manual!

[Spinner]

Originally Posted by HAWKiS5

Even in manual mode (either by putting the shift lever to the passenger side or by using the paddles) the S-tronic box has its own "will" when pressing the pedal to the floor..... pity bnut true.......let's wait for the manual!

This is what I was lead to believe. Perhaps Audi will have a different version or at least updated software for complete control when shifted into manual mode on the RS.

[BkS5]

wow ill keep my S5. i do 95% of my driving between 2k and 4k RPM. there is no way i can justify an RS5.

[martininwillerby]

Just hope that the new s tronic gearbox for the rs5 is better than the one they put in the a5's.
The new one is geared up to take around the 750Nm. The other one can take about 550Nm.

Martin

[HAWKiS5]

Originally Posted by martininwillerby

Just hope that the new s tronic gearbox for the rs5 is better than the one they put in the a5's.
The new one is geared up to take around the 750Nm. The other one can take about 550Nm.

Martin

The "old" 6-speed S-tronic was able to handle 350Nm max, the "new" 7=speed S-tronic (like in the S5) can handle 550Nm, but where did you find that there is also a 750Nm version? I assume the RS5 just gets the same version as the S5, since it has "only" 440 Nm of torque and since it is NA, it will normally not get above the 550 Nm limit (only when somebody decided to supercharge it).

[martininwillerby]

I'd read about the 750Nm version somewhere. But after reading what you said about the rs5's torque then I guess they will be using the lower end one.
Or to put it another way "the not so good one"
IMO it's too soft for a sports car gearbox.
The original DSG/ s tronic now that was a sports gear box.

[martininwillerby]

I'd read about it here...

http://pictureposter.audiworld.com/s...2767228&page=2

martin

[gruffle]

Originally Posted by martininwillerby

I'd read about the 750Nm version somewhere. But after reading what you said about the rs5's torque then I guess they will be using the lower end one.
Or to put it another way "the not so good one"
IMO it's too soft for a sports car gearbox.
The original DSG/ s tronic now that was a sports gear box.

nope - don't follow that one Martin.

A gearbox changes gears - the S-Tronic does that very quick indeed - it's only a bit of software that says when and this is customsied for each engine. The RS5 will have its own exclusive mapping no doubt.

[martininwillerby]

My Audi A4 had the new s tronic with mapping to mate it to the 2.0t engine. Infactvit ended up having about five different versions, but still none of them worked.
As I said earlier it's was too soft for a sports car unlike the six speed version.
Just hope they make the software more of a sports car than a touring.

Martin

[gruffle]

I vote for a "Learn" mode
-teach it the way you want it then

[SupraBlur]

Originally Posted by Ianhp1

OK Guys... this is what you've all been waiting for! ...and I must say, I'm changing my view of the RS5 now. The headline figures may seem a little 'mediocre', but when you see the power graphs, and compare to the S5, you can get a real impression of what this car will be like (well you can if you drive an S5!!).

Isn't that kind of like someone saying he's tough because he can beat up his little sister? Let's see some dyno comparisons with cars that are actually fast.....

[15DGR V6]

Looking at that dyno plot, you can see that if the S5 had the torque curve of the RS5, it'd be making about 400 bhp at 7,000 RPM. I wonder if the RS5 cams are compatible with the S5 engine. I'm sure that Schrick could develop a set that would work well. I'd be pretty happy with a 400 bhp NA S5 if the RS5 doesn't come stateside.

[SupraBlur]

I've actually given a lot of thought to trying to use the RS4 head / valvetrain config on the "low-revving" motor.

In theory it should produce the same curvature to the torque delivery as the RS version... The only thing that can physically prevent that is lack of ignition or lack of air flow. If it were mainly ignition, you'd see bigger gains from software remaps, so I'm led to believe that Audi has intentionally restricted the air flow (combination of manifold, valve, cam, and port design).

Only reason I can see why they would do this is that the S5/Q7 version of the motor can't handle sustained heavy load at 7k RPM the way the RS version can due to excessive rotational inertia. This is just an educated guess, but it seems valid, and anyone who has built engines would agree that taking a 92mm stroke V8 up to 7k rpm is a feat in itself let alone asking the engine to produce power at that RPM without causing the rods to warp.

The RS version's lighter bottom end would help to relieve this problem, so for now my hypothesis is that you can likely bolt on the RS top-end components and implement the RS ecu map, but you might risk dangerously stressing the bottom end.

[SDS5]

I agree, plus there are issues with oil cooling and distribution, piston ring chatter and not to mention that the RS4 high revving V8 has two ECU.

With 350Hp spread linearly over 7krpm this is about 50hp/1000rpm - if you really want a few more HP, why not just rev the Engine a bit closer to the red-line?

I don't personally, but then I rarely find a place where I can develop full power - this car is so fast and powerful

[SupraBlur]

I agree, plus there are issues with oil cooling and distribution, piston ring chatter and not to mention that the RS4 high revving V8 has two ECU.

Well, I would be willing to venture that the rings are the same in both engines, and that the ECU and oil cooling is relatively cheap/easy to address compared to swapping the shortblock.

With 350Hp spread linearly over 7krpm this is about 50hp/1000rpm - if you really want a few more HP, why not just rev the Engine a bit closer to the red-line?

Per the dyno graph, the engine starts running out of flow at 4000 rpm, so increasing the engine speed becomes a diminishing return after that, as evidenced by the horsepower curve compared to the RS curve. The whole purpose of this curiousity was to solve the flow bottleneck to have 50 extra hp at 7k rpm, not just a couple of extra ponies.

I don't personally, but then I rarely find a place where I can develop full power - this car is so fast and powerful

I think the gearhead mentality is less out of necessity and more about the challenge. When I was into Benzes, one of the big accomplishments was dropping an E55 (n/a) motor into a C43 and running it on C43 electronics. It was way more straightforward than you'd think.

The S5 and RS4/5 motors have a lot more in common than the C43 and E55 motors, and I'm willing to wager that the RS motor is a potential source of bolt-on upgrades for the S5, much like how Carrera S guys like to use GT3 throttle bodies. For now it's just pondering, and there's a lot of risk involved, but I have a feeling that there might be something cool at the end of all the curiousity.

[15DGR V6]

It'd be nice to see a tuner get involved in seeing what is possible with the parts swaps. I'd be willing to give up low end torque for an additional 50 hp at 7,000 RPM.

I don't think there would be an issue with the engine internals making this sort of power since you're not increasing the revs of the engine, just the amount of torque the engine is making at those revs.

Looking at the torque curves, I'm pretty sure it would require a cam specific tune to optimize the air-fuel ratios with the large differences in torque in the lower and higher RPM's.

These changes would probably make the car a bit slower at in gear acceleration from a given speed, but you'd end up with an overall faster car. You'd have to adjust your driving style to match the new power curve.