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One thing i dont get is..with 4.2L and a V8, why do they only put 354hp on the S5....even G37(v6) has 330 hp, M3 has 413 hp. My guess is they dont want to create too much competition for the future Rs5...
 

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The RS4 has the same engine with 420hp. There's about a .1-.2 second difference from 0-60. It's still a very powerful V8.
 

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It's a little more complicated than just "putting on" HP. The S5 engine is a tuned Q7 V8 (IIRC). Logistically, it was Audi's best solution. The RS4 lump (420HP) is a completely different beast. The next RS4/5 should have the same 4.2 RS4 engine with FSI, which should put it around 450HP.

The S5 and M3 are not direct competitors, so no need to compare the engines. As for the G37, a big V6 is more than capable of putting out that much power. Infiniti's been messing around with that engine for a long time now...
 

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The S5 is also more fuel efficient than the RS4 version as well IIRC.
 

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I am not 100% sure if it is a good idea but my Audi dealer told me that after I make 6-7000km on my car they will be able to do something with the software of the car and make it 400hp and more...
Do you guys think its possible?
 

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As far as I know, that engine is completely incapable of putting out 400hp+ with a simple software mod. In fact, I don't think anything short of a complete rebuild will yield 400hp+ with that engine. You can get somewhat close by going all out with mods, but I don't think it can get there, especially with only software.
 

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As far as I know, that engine is completely incapable of putting out 400hp+ with a simple software mod. In fact, I don't think anything short of a complete rebuild will yield 400hp+ with that engine. You can get somewhat close by going all out with mods, but I don't think it can get there, especially with only software.
+1 You can expect a software mod to add around 10-18 HP to the gas/petrol V8, if you add a complete exhaust (with downpipes) you'll get about 10-12 (maybe 15) more with no other tuning or mods. Very doubtful that a software only mod would (or could) do 400+ HP.
 

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Dealer told me its not Audi's software.. but some other company.
Isnt the engine like the one they put in the R8 and the RS4?
 

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Dealer told me its not Audi's software.. but some other company.
Isnt the engine like the one they put in the R8 and the RS4?
No, completely different engine. There's a whole other computer in R8 and RS4 to handle the changes (specifically, the calculations needed for the increased redline) made to the lump.

Trust us, a software update WILL NOT give you 400hp from the S5's 4.2. The dealer's talking out of their @ss.
 

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No, completely different engine. There's a whole other computer in R8 and RS4 to handle the changes (specifically, the calculations needed for the increased redline) made to the lump.

Trust us, a software update WILL NOT give you 400hp from the S5's 4.2. The dealer's talking out of their @ss.
Haha :) I will write you more right after I talk to them and get more info about what they are talking about.
Thx for the info guys I will be careful with what I am doing :)
 

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One thing i dont get is..with 4.2L and a V8, why do they only put 354hp on the S5....even G37(v6) has 330 hp, M3 has 413 hp. My guess is they dont want to create too much competition for the future Rs5...
Lol if you consider the G37 even comparable, you should definitely go drive one. I test drove one like 2 weeks ago, and it's miserable. Most commonly, it is doing 0-60 in 6.0-6.2 seconds which is a full SECOND slower than the S5. Mostly because it is 3800+ lbs and only has 250 ft-lbs of torque (more similar to the A5).

The M3 is easily $10k more expensive depending on options.

-Ray
 

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Torque, flexibility and marketing...

OK so the S5 V8 puts out 354 BHP and another variant of that V8 (although quite a bit different) in the R8 and RS4 put out 420... There are a couple of things that need noting:

1) That's "peak" power... and BHP is a function of Torque and Revs, so more revs at the same torque, more BHP. The RS4 and R8 are higher-revving, so can make the BHP figure... However, put the R8 or RS4 engine and S5 engine side by side at 4,000 revs and they put out similar torque... ergo power. And this is shown in the performance figures of the RS4 and the S5... not that different.

2) So Audi have elected to put a more flexible and driveable engine with great torque characteristics across the rev range into their GT car (S5) and a higher revving, top-end torque loaded engine into their sports car (R8). That makes sense does it not?

3) The S5 is designed as a GT car, the RS5 when it arrives will be much more at the 'sports car' market and thus needs some room in the power stakes to differentiate it from the S5. In other words, if they'd put and engine with a '420' rating in the S5, they'd have to go 500+ in the S5 and that would mean large Turbos on the V8 or the V10, which would give power, but not the sports characteristics required and thus create a more powerful GT car. The RS5 will not need more than 450 BHP to be devastatingly quick if this is produced from a light engine with great response. But if the S5 had been 420bhp 'rating', would people fork out £15k more for a car which only had 20 or so more BHP?

At least that's what I think!

;)
 

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I did some searching. Between the R8 and the RS4, there isn't a lot of difference -- same 4163cc motor, bore and stroke is 84.5mm x 92.8mm. One notable difference is that the R8 runs a dry sump oiling system, whereas the RS4 uses a traditional oil pan. Visually the intake manifolds look different -- I've not seen the R8 motor up close, but it's reasonable to believe that it uses independent throttle bodies, which add response, but do not affect overall power.

Comparing to the S5, the most notable difference is that the S5 runs an 11:1 compression ratio, whereas the RS4 and R8 are running 12.5:1. Their bore and stroke are identical (84.5mm x 92.8mm) which indicates that the cylinder geometry and rod geometry are also identical, and the difference in compression is caused by a difference in piston dome shape (or head gasket thickness, which is a lot less likely). Because the high comp piston was already a production piece, it's a pretty safe assumption that the lower compression piece was produced for the purpose of marketing, as stated above, so as not to clash with either the B7 RS4 or the upcoming RS5. So in theory, I can't see anything mechanically wrong with putting RS4 pistons in your S5 to achieve a bump in compression, which typically causes a significant increase in power across the entire powerband (and ironically an increase in fuel economy). The RS4 might have additional compensation in the fuel map, so I'd probably want to run an RS4 ECU and look into fuel injector differences in conjunction with this mod, just to be safe. On the other hand, being at 11:1 puts you in a better position to upgrade to forced induction, if you so desire.

On a side note, it's also noteworthy that the 3.2L FSI in the A5 already runs 12.5:1 so that amount of static load seems to be 'normal' for mass produced Audi components.

-Ray
 

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I did some searching. Between the R8 and the RS4, there isn't a lot of difference -- same 4163cc motor, bore and stroke is 84.5mm x 92.8mm. One notable difference is that the R8 runs a dry sump oiling system, whereas the RS4 uses a traditional oil pan. Visually the intake manifolds look different -- I've not seen the R8 motor up close, but it's reasonable to believe that it uses independent throttle bodies, which add response, but do not affect overall power.

Comparing to the S5, the most notable difference is that the S5 runs an 11:1 compression ratio, whereas the RS4 and R8 are running 12.5:1. Their bore and stroke are identical (84.5mm x 92.8mm) which indicates that the cylinder geometry and rod geometry are also identical, and the difference in compression is caused by a difference in piston dome shape (or head gasket thickness, which is a lot less likely). Because the high comp piston was already a production piece, it's a pretty safe assumption that the lower compression piece was produced for the purpose of marketing, as stated above, so as not to clash with either the B7 RS4 or the upcoming RS5. So in theory, I can't see anything mechanically wrong with putting RS4 pistons in your S5 to achieve a bump in compression, which typically causes a significant increase in power across the entire powerband (and ironically an increase in fuel economy). The RS4 might have additional compensation in the fuel map, so I'd probably want to run an RS4 ECU and look into fuel injector differences in conjunction with this mod, just to be safe. On the other hand, being at 11:1 puts you in a better position to upgrade to forced induction, if you so desire.

On a side note, it's also noteworthy that the 3.2L FSI in the A5 already runs 12.5:1 so that amount of static load seems to be 'normal' for mass produced Audi components.

-Ray
'
Ray, great research and a really informative post. You make some good points about the engine's inherrent ability to handle the higher compression... maybe a good modification to think of once out of warranty... pistons or head/block skim... Must talk to APS!!

...Of course as I understand it, the negative of higher compression is the greater tendency to 'knock' and therefore the ECU must reduce the timing advance and compensate fueling, which reduces the available torque and limits the power gains.
 

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Ray, great research and a really informative post. You make some good points about the engine's inherrent ability to handle the higher compression... maybe a good modification to think of once out of warranty... pistons or head/block skim... Must talk to APS!!

...Of course as I understand it, the negative of higher compression is the greater tendency to 'knock' and therefore the ECU must reduce the timing advance and compensate fueling, which reduces the available torque and limits the power gains.
Definitely true that the stock S5 timing map may be too aggressive for 12.5:1 but that's something that could easily be tuned with a piggy back device or ECU remap. I doubt the S5 is any less sensitive to knock sensor signal as the A5, which already runs 12.5:1.

It's also worth mentioning that all factory ECU's have a degree of self-adjustment built in to compensate for differences in climate, water temperature, elevation, fuel quality, and air quality. To put it in perspective: going from 11:1 to 12.5:1 static compression ratio is about a 12% increase in air density. However, taking a drive from Lancaster, CA (~2500ft above sea level, ~560 mmHg atmospheric pressure) to San Diego, CA (~42fb above sea level, ~755 mmHg atmospheric pressure) produces a 25% increase in air density, which we know the ECU can compensate for just fine.

The icing on the cake is that the S5 manual "suggests" high octane fuel, but has fail-safe for people who decide to put shitty gas in their car. There is also varying definitions of 'high octane' across the country (91 vs 93, etc). If the ECU is this flexible, I'm pretty sure we are covered when it comes to ping prevention.

Regarding the aforementioned intake manifold difference, the RS4, like the S5, uses two different intake runners for high/low RPM (long ones optimized for velocity, short ones optimized for flow); I couldn't verify whether the R8 does, but from the pictures it looks like there wouldn't be enough room in the more compact intake plenum to have two sets of intake runners. That means the R8 is running in maximum-flow mode at all times, which accounts for the more linear torque curve (versus the RS4 which has a mini-peak ~3500 RPM). It's reasonable to believe that the RS4 and R8 use a bigger cam duration than the S5 to make the torque more effective to 8250 rpm.

In my engine building experience, 92mm is a whole lotta stroke to be taking up to 8250rpm (lots of wear on the rods due to piston speed/inertia), so I'd think it to be a good compromise to get the bump in compression from the piston dome shape but then leave the cams alone to keep the powerband street-tuned with a 7000rpm redline.

...ORRR... you could leave it stock and enjoy probably the most reliable iteration of the 4.2 FSI. =)

-Ray
 

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Lol if you consider the G37 even comparable, you should definitely go drive one. I test drove one like 2 weeks ago, and it's miserable. Most commonly, it is doing 0-60 in 6.0-6.2 seconds which is a full SECOND slower than the S5. Mostly because it is 3800+ lbs and only has 250 ft-lbs of torque (more similar to the A5).
Mind if I ask where you are coming up with these numbers? The G37 has 270 ft-lbs of torque. Also, most car mags have had the G run 0-60 between 5.2-5.4s.

http://www.caranddriver.com/reviews...rt_road_test+t-driving_impression+page-2.html

What exactly is so miserable about the car? For the price, its the best deal you can get for that kind of power, looks, and luxury...as u can see, I am a fan of Infiniti:)
 

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At risk of being off-topic...

Mind if I ask where you are coming up with these numbers? The G37 has 270 ft-lbs of torque. Also, most car mags have had the G run 0-60 between 5.2-5.4s.
I stand corrected on the torque. As for 0-60:

Motorweek (6.2s)
http://www.mpt.org/motorweek/reviews/rt2707a.shtml

Might just be an anomaly I'll admit.

What exactly is so miserable about the car? For the price, its the best deal you can get for that kind of power, looks, and luxury...as u can see, I am a fan of Infiniti:)
Ok this is my opinion, which shouldn't affect how much you love Infiniti...

I really really really wanted to like this car. But I drove it within a week of driving the A5 3.2, BMW 335i coupe, and Lexus IS350, and honestly it felt really sluggish. Bimmer aside, the Infiniti obviously has a longer and more linear powerband than the other cars. However this is not the kind of driving that seems natural in a luxury GT cruiser in my opinion. In normal day-to-day driving, it's unlikely that I would go up to redline every single time I leave a stoplight. So in terms of low to midrange power, it didn't shine.

I can't call it the best deal because the one I drove was a G37S 6MT with nav, and it was $42k. It's marginally cheaper than the competition, but not enough for me to call it the value of the century.

It does look good but part of me feels like it's trying too hard, especially when you compare it to the A5 and 335i. The A5 and 335i feel like the designer had an artistic concept and then rendered it, whereas the G37 to me feels like a committee of engineers reached into a grab bag full of sport coupe cliches and then loosely knit them together (I feel this way about a lot of cars, so don't think I'm just coming down on Infiniti). In terms of luxury, it falls somewhere between those two cars -- slightly better than the Bimmer but slightly worse than the A5. I wasn't impressed with the "washi paper" finish because it just looks like plastic.

Icing on the cake is that the three different times I've been into three different Infiniti dealers with three different people buying the car (once was myself), the service was poor. Nobody paid attention to us, probably because we're young, you basically had to pull teeth to get a test drive. The first time with my brother trying to look at a G35 coupe in 2003, he turned around and bought a more expensive GS300 Sport Design instead. Earlier this year I wanted to like the G37S but ordered an A5 (and later an S5) instead. And just last month, my friend also wanted to like the G37S but go a Lexus IS350 instead. In all of these cases we all bought more expensive cars, lol, so value isn't everything.

-Ray
 

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Hahah...actually, everything you said does make sense. And i personally know what you mean about being young and not getting any help. I still think the G37 is still a good value considering a comaparble 335i is around 50k and an A5 is around the same. But I will say there are obviously some aspects of the G37 that no live up to the 335i and the especially the A5 ( looks/interior/quality). So, I just wouldnt say the car is miserable, but just my .02 cents :)

Sorry for digressing
 

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The S5 is also more fuel efficient than the RS4 version as well IIRC.

I am not finding that at the moment, but then I have only done 2.5k miles...
 

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I am not finding that at the moment, but then I have only done 2.5k miles...
It gets a lot better. Im through 10k miles now and getting in the 19-20 mpg now compared to 16 mpg early on. Long runs can get it upto the 30mpg mark (UK gallons).
 
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