Filed under: Sedans/Saloons, Sports/GTs, Euro, Audi
Twin turbos return to the next generation Audi S4?
There is awesomeness to the prefix "twin-turbo." It could be a Briggs & Stratton Vanguard engine (awesome in its own right) that you're talking about, but prepending any engine designation with the modifier "twin-turbo" can suck all of the air out of a room. Owners of lesser cars just nod in acknowledgment of their inferiority. Audi fans have lamented the evolution of the S4 from a twin-turbocharged V6 in the B5 version to V8 power for the two most recent iterations. Many feel that the V8 powerplant doesn't have the addictive frenetic nature of the old S4. For the next generation, Audi is returning the S4 to its roots as a more refined version of what you'll find in the Evo or the STi. The B8 S4 has reportedly been lapping the Nurburgring with a force-fed six-shooter underhood.
With the A5/S5 joining the lineup, the S4 doesn't have to worry as much about serving customers who'd rather have a GT than something more serious. Thus, an artificially-aspirated V6 displacing three liters and employing VW/Audi Group's FSI direct-injection technology and Audi's Valvelift actuation system can be parked in the S4 without fears that the hardcore nature of such a powerplant would be off-putting. Whether the external compressors are turbos or a supercharger is the subject of rumor. Also open to speculation is the horsepower output, but it'd be safe to bet that something slightly higher than the 300 HP packed into the BMW 335 can be expected. Also expect the S4 to employ Audi's Sport Differential to offer tweakable chassis attitude, as well as the obligatory styling tweaks and sumptuous cabin, too. Click the Read link below to view a couple renderings of what the next S4 might look like courtesy of Fourtitude.
[Source: Fourtitude, Rendering: Fourtitude]
Reader Comments (Page 1 of 2)
Alex 11:57AM (11/07/2007)
am i the only person who is not a fan of turbos? I would much rather a car with a smoother more linear pull from a N/A or supercharged engine.
Granted, i've never driven a B5 S4 so maybe their engine doesn't suffer from turbo lag, but the turbo cars i have driven (VW 1.8T Wolfsburg and SAAB Viggen) were very annoying.
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Rob 12:02PM (11/07/2007)
"Granted, i've never driven a B5 S4"
You needn't say more. Go drive a chipped one and THEN tell me how you really feel! :)
Johnnie 12:14PM (11/07/2007)
The B5 S4 was a 2.7 litre V6 with twin turbo's. Very different than a 1.8 or 2.0 litre 4 banger with 1 turbo.
the B5 S4 was a beast!
With that said, I do prefer more n/a engines as well. They feel more raw to me. I guess this is the reason why'd i'd rather have a 997 GT3 over a 997 Turbo.
BKadalur 12:18PM (11/07/2007)
haha, i have a 1.8t a4 and the power delivery is completely different from the b5 s4. the twin-turbo has no lag whatsoever. it's power throughout the entire powerband.
not to mention the aftermarket capabilities are through the roof with turbos compared to NA. plus, it's lighter than a higher displacement equivalent.
i've driven a B5 S4, and trust me, turbo lag doesnt exist. go drive a 335i as well. same thing, you can barely feel the lag.
416Hammy 1:16PM (11/07/2007)
I have driven a B5 S4, and compared to my N/A 350Z it was faster but the power delivery was nowhere near as smooth. Turbo lag was noticeable. The 2.0T GTI I drove was much smoother in terms of torque-delivery.
Regardless, Audi isn't likely to regress so I look forward to this being an impressive engine setup in the new S4/S5.
jgp 1:58PM (11/07/2007)
Unlike single turbos, twin turbos are usually designed with smoothness in mind. The low-pressure turbo activates with no human-detectable lag, and runs until the high-pressure turbo can kick in.
I find twinchargers (supercharger at the low end, turbo at the high end) slightly more impressive, but twin turbos are close enough.
why not the LS2LS7? 2:43PM (11/07/2007)
I own a 2000 A6 2.7T. Same engine as the B5 S4 (as spoken of here). And it's NOTHING like a 1.8T. The 2.7T is less than 50% higher displacement (2.65L) and it has two of the 1.8T turbos (KKK K03s) driving it. Because of this, it stays on boost to high revs (it rams into the 6500rpm redline, while the 1.8T starts to peter out at 5500rpm).
It most DEFINITELY has lag. It's a low-pressure turbo setup (even when chipped), so it is fine in regular operation. But taking off from a stop, you're gonna have to take efforts to get the turbos on boost. That either means revving before starting or starting at WOT to get the air through quickly.
It makes a buttload of torque and at wide rev ranges. It has a great "slingshot" feel when accelerating, performs very well even at part throttle as long as the turbos are up and spinning. And if you chip it... hold on.
Big problem was that the 2.7T has an iron block. And it's out front of the front axle. Luckily the new Audi turbos don't have iron blocks anymore.
But it'll still be heavy and expensive with all this plumbing, and with the reduced compression in a turbocharged engine, fuel efficiency isn't great anyway. Add in the AWD running gear, and this thing will never win any awards for mpg, so why go through all this?
mxrz 9:55AM (11/08/2007)
BKadalur wrote: "plus, it's lighter than a higher displacement equivalent."
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Except the 4.2L V8 that replaced it, weighs less...
mxrz 10:07AM (11/08/2007)
jgp wrote: "Unlike single turbos, twin turbos are usually designed with smoothness in mind. The low-pressure turbo activates with no human-detectable lag, and runs until the high-pressure turbo can kick in."
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Two problems:
1. The 2.7T in question here, and most certainly the next version doesn't work like that, it's a parallel twin turbo setup, one turbo for each bank of cylinders.
2. You seem to be talking about a sequential twin turbo setup, like the old school Supras and RX-7's, but that's still isn't how it works, the first turbo does not stop when the second kicks in, they both run in the higher rpm range.
EssAvant 12:33PM (11/07/2007)
I LOVE my B5 S4, and an updated version is going to be a must have for me. Plus I really like the new styling, if it looks anything like the rendering shown. Being able to squeeze 40HP just through a chip is unobtainable from a NA engine.
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TheChaz 1:09PM (11/07/2007)
All else held equal, most people would prefer a naturally aspirated engine over a turbocharged powerplant. That said, just in terms of the model line, it makes sense for Audi to better define the models. The S4 should have a V6, the S6 a V8, and the flagship S8, a V10. Now, with a V8 in the S4, and V10s in both the S6 and S8, it's all messed up.
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Tool 1:33PM (11/07/2007)
A good turbo is a wonderful thing. I owned a 1994 Rx-7 with the sequential twin turbo and it was probably the most exhilarating engine I have ever had.
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Steve_S 1:34PM (11/07/2007)
Except that S4's are around 50-55k and 335 is under 40k. Sedan to Sedan. The A4 should have an engine to compete with the TT I6 from BMW. The existing 3.2 V6 just doesn't have the muscle.
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NY Diablo 1:37PM (11/07/2007)
a 1.8T with a software upgrade (revo technik) and its a different animal !!
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HineyWipe 2:11PM (11/07/2007)
Yeah, keep BOTH hands on the wheel!
NY Diablo 3:26PM (11/07/2007)
Your not kidding there. Monster torque steer.
Michael D. 2:14PM (11/07/2007)
This is a bit disappointing and looks like a step back from Audi. I would rather see a V8 from something of this caliber, and the new design appears to have a longer hood/nose area to accomodate a V8. The new S5 coupe has a V8.
Maybe there will be a choice between a twin-turbo V6 or a naturally aspirated V8, at this point, who knows.
Perhaps the next RS4, based on the new generation may contain the V8.
It was sad to read that, Audi has been making impressive strides as of late.
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testa di cazzo 2:25PM (11/07/2007)
I think what they want to do is take the S4 back to its roots (TT V6) and make the RS4 the only V8 in the lineup (and maybe later even make it a TT V8, which would be pretty badass)...
slotownbrian 2:41PM (11/07/2007)
Well lets hope they get it a bit better this time around... the 2.7t engine was notorious for seeing turbos off, a friend of mine went through 3 sets. Yes, chipping doesn't help matters at all, but that is a sad defense that should be anticipated by engineers from the start. I sold a B6 S4 Avant 6m a year ago, but I was very happy with its engine; it was refined and the torque was eager to pull in 6th. There is no shortage of frantic cars in the world, lets hope the twin turbo setup is similar to that of BMW's.
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MikeW 2:57PM (11/07/2007)
Naturally aspirated is better (sounds like pontiac's 'wider is better')
I just drove the Audi S5 (349hp) at Audi driver's experience (for free)
http://www.audidrivingexperience.com/
3rd gear was plenty for the follow-the-leader exercise, plenty of pull from 3500-7000. The rev limiter in 3rd gear must be the close the throttle kind (holding 7000) instead of fuel cut kind. (good idea at over 90mph)
Audi still needs to move the axle under the engine. Comparing an S5 to an RS4, the front axle is moved only 2" relative to the back of the engine.
So if Audi did that, they could then increase bore spacing. 100mm for a V6 (95mm bore x 94mm stroke, 4 liters 350hp 325ft-lbs
95mm for a V8 (90mm bore x 94mm stroke, 4.8 liters 400hp, 375ft-lbs)
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