M3 vs B8 S4

[AutoEnthusiast]

Just to clarify a couple of things I have seen which are either incorrect or wrong in general with the discussion about supercharging, and in specific to the S4 after some research:

- 7,200 RPM is not fast for a roots type supercharger
- The engine and supercharger are not spinning at the same RPM anyway so the above comment is moot
- At engine redline, the TVS supercharger (which is a roots style, but not like a roots in many ways) spins at 18,000 RPMs, so you were off by over 100%
- The supercharger has an internal bypass valve, which recirculates the already boosted air back into the screws again, so by using the bypass, there is indeed less stress on the supercharger in the stock tune , since it is not having to compress as much air with the bypass opened.
- The bypass is a way to mitigate the amount of boost, not a protection method that keeps the supercharger from blowing up
- The TVS R1320 on the S4 is warrantied and rated to 18,800 RPM's steady use with burtst to 21,000 RPMs, so Audi's implementation is well within tolerances, even if the bypass valve was a saftey blowoff type valve - which it is not.
- While the TVS R1320 is rated at 21PSI, even the tuners have not been able to eek more than just under 13PSI out of it, likely due to it operating out of the efficiency area mentioned by jdgamble.
- The engine never sees 21 PSI of boost (as previously mentioned) not at 5K not at all ever. It maxes at about 11-12PSI at 5K, and grandually builds after this to redline. Reference, the tuner's own graph:



Just thought it would be good to clear up any misinformation, since some of you appear to be arguing over false information.

[jdgamble]

Originally Posted by AutoEnthusiast

Just to clarify a couple of things I have seen which are either incorrect or wrong in general with the discussion about supercharging, and in specific to the S4 after some research:

- 7,200 RPM is not fast for a roots type supercharger
- The engine and supercharger are not spinning at the same RPM anyway so the above comment is moot
- At engine redline, the TVS supercharger (which is a roots style, but not like a roots in many ways) spins at 18,000 RPMs, so you were off by over 100%
- The supercharger has an internal bypass valve, which recirculates the already boosted air back into the screws again, so by using the bypass, there is indeed less stress on the supercharger in the stock tune , since it is not having to compress as much air with the bypass opened.
- The bypass is a way to mitigate the amount of boost, not a protection method that keeps the supercharger from blowing up
- The TVS R1320 on the S4 is warrantied and rated to 18,800 RPM's steady use with burtst to 21,000 RPMs, so Audi's implementation is well within tolerances, even if the bypass valve was a saftey blowoff type valve - which it is not.
- While the TVS R1320 is rated at 21PSI, even the tuners have not been able to eek more than just under 13PSI out of it, likely due to it operating out of the efficiency area mentioned by jdgamble.
- The engine never sees 21 PSI of boost (as previously mentioned) not at 5K not at all ever. It maxes at about 11-12PSI at 5K, and grandually builds after this to redline. Reference, the tuner's own graph:



Just thought it would be good to clear up any misinformation, since some of you appear to be arguing over false information.

Just to clarify, I never meant to imply that the supercharger was running at 7200 RPM, only the engine... that would mean a 1:1 pulley ratio, which is obviously not the case. I just figured they geared the SC to operate efficiently in the desired "engine" RPM range. I maintain that the higher the RPM, the less efficient a Root-type design. I did a little reading on my favorite factual website, Wikipedia, and the page on Roots-type supercharger supports everything I said and your chart (check it out MERC). There is a diminishing returns situation with Roots blowers (and any positive displacement pump for that matter), and temperature can become an issue.

You must be one of those technical types to register just for this post!

[ihyln]

Originally Posted by MERCSUk153

1. $13k doesn't grow on trees or my Daddy doesn't buy me the car.
2. It it called winter. Snow 5 months of the year. AWD>RWD in snow.
3. Wife also drives the car in winter.
4. S4 better daily driver, and M3 better track car IMO.
5. I will be getting a used 997 turbo or GT-R as track car in about 2years so putting M3 idea aside for now so I can budget for this and $13k is a good start.
6. Interior of S4 is warmer and less clinical IMO.
7. In other countries the M3 is 30% more than an S4. For some that may not be a lot of money but for others it is money that could be used for another nice car rather than another avg. car or for investments.

1. Agree. $13k is still a substantial sum
2. Here in the tri state area I've been driving RWD cars for a good 10 years. The AWD argument really doesn't fit as well because a dedicated set of winters is better than AWD with crappy all seasons (I know we will both agree on this) but in harsher climates AWD does make sense.
3. I'd never let my wife/SO drive but that's just me
4. Subjective
5. I thought about this route but having to worry about another car + insurance made less financial sense than the $13k price gap you were bringing up.
6. Subjective. I personally do not like Audi interiors.
7. No car is an investment. Unless it's a classic.

[AutoEnthusiast]

Originally Posted by jdgamble

Just to clarify, I never meant to imply that the supercharger was running at 7200 RPM, only the engine... that would mean a 1:1 pulley ratio, which is obviously not the case. I just figured they geared the SC to operate efficiently in the desired "engine" RPM range. I maintain that the higher the RPM, the less efficient a Root-type design. I did a little reading on my favorite factual website, Wikipedia, and the page on Roots-type supercharger supports everything I said and your chart (check it out MERC). There is a diminishing returns situation with Roots blowers (and any positive displacement pump for that matter), and temperature can become an issue.

You must be one of those technical types to register just for this post!

You got me I like the techie details and have owned various American, Japanese and German cars for decades, I love the newest tech and understanding (as best I can) how it works. I didn't immediately register during the heated debate as I needed to do a little more research.

As to the effciency, yes and no, this is a slightly new animal, trypical roots have a 60 degree twisted screws, these have 160 degrees of twist in the screws, as a result they have sweet spots where the efficiency rises, peaks and drops. There are lots of maps of this on the Eaton site (maker of this particular supercharger).

Here's the one pertinent to the one on this car, the colors show increasing efficieny as they darken, with the scale also reflecting supercharger RPM's and the pressure ratio:



It looks to me like there could be a couple of reasons this one doesn't push the kind of pressure it's rated at, but these are guesses:

- They wanted more torque/power/grunt down low, so they have this spinning faster down low, which puts it out of efficiency ranges near redline as a result of getting into the meat of the boost down low

- The displacement of this unit is not well matched to the engine's ability to take in larger volumes of air as the engine spins faster while the unit's efficiency starts to drop


While I also have not data to back it up, it does stand to reason that putting more boost and therefore more fuel into the engine over what was there stock, as well as advancing of the timing by the tuning company will certainly put more stress on the engine and components - if this will that result in any sort of measurable drop in reliability remains to be seen.

[Radiation Joe]

Originally Posted by MaxL

Having said that, I'd probably take S4 over M3, if I had another car for track. Well, in that case I'd actually take Audi Allroad over any of those, but Audi was "smart" enough to discontinue it.

One of my faves. I've been tempted to pick one up several times. Very expensive to maintain, but lives up to it's name.

[BlancM3]

The S4 as i have seen with many of my friends has poor reliability. The resale value is just the worst where I live as well.. However the new rs5 seems to be interesting..

[Advskier]

Originally Posted by MERCSUk153

Argument 2 doesn't really make sense as you are comparing winter tires to all season on the AWD. I am comparing AWD winter tires and RWD winter tires. Just because it is AWD doesn't mean you can bypass winter tires. I am not saying that RWD and winter tires aren't good just not as good obviously as AWD with winters. I don't need my wife calling me and telling me she is in the ditch. The S4 is her car as I mentioned I am setting her up for the 997 turbo bomb in about 2 years. shhhh! LOL
I wasn't saying invest in a vehicle silly. I was just saying that I would take the $13k and invest it so I can use some of the profits (hopefully) for the 997 turbo and with some budgeting this will work out.

You still ranting about the S4 over the M3, now because of price and wanting a 997?
Why not save even more money and buy a Suzuki 4wd??? It will stand as much of a chance as your S4 (in overall performance) of beating the M3 in any real comparison.
Are you planning on coming back in 2 years when you get your hypothetical 997 to tell us about how much better it is as a DD then the M3?

[brava09]

Originally Posted by Advskier

You still ranting about the S4 over the M3, now because of price and wanting a 997?
Why not save even more money and buy a Suzuki 4wd??? It will stand as much of a chance as your S4 (in overall performance) of beating the M3 in any real comparison.
Are you planning on coming back in 2 years when you get your hypothetical 997 to tell us about how much better it is as a DD then the M3?

+1

He said the S4 is his wife car in fact...troll....probably he doesn't have driving license as yet

[brava09]

Originally Posted by MERCSUk153

I don't need my wife calling me and telling me she is in the ditch. The S4 is her car as I mentioned I am setting her up for the 997 turbo bomb in about 2 years. shhhh! LOL
I wasn't saying invest in a vehicle silly. I was just saying that I would take the $13k and invest it so I can use some of the profits (hopefully) for the 997 turbo and with some budgeting this will work out.

Troll....you say your wife is driving the S4, I could bet it's your dad's S4 in fact


Yeah, you take the $13k your dad saved when buying the S4 instead of the M3, and you're gonna be so successful and buy a 997 turbo from your $13k investment return...give me a break.

[graider]

you remind me of footie.

anyway, I see three different kind of trolls on this forum and mostly coming from audi/porsche (same company).

1. uneducated audi trolls who would put anything audi above bmw.
2. educated audi trolls who like to bring up that they presently/past own an m3 so they can express why audi is better based on their experiences.
3. crazy trolls who would just call everybody fanboys as soon as they praise the m3. ridiculous because after all this is a bmw forum and people praise the m3 because they think it is the best car for them.

Originally Posted by Radiation Joe

Oh well. Not much we can do about the juvenile fanboys.

I've been on the Audi boards and a couple of M3 boards for about 5 years. The Audi boards are typically more civil and I find the Audi folks seem to have a much better sense of humor.

I'm still on the M3 boards because that's what I'm driving, but the fanboys are really annoying. What's even more annoying is that most of them don't even drive an M3. Then there are the dorks that do drive M3s but think they're some sort of status symbol. If you equate your self worth to what you drive, you may be a candidate for therapy.

I never try to convince others that my car is better. I always strive to emulate my hero.

[Advskier]

Originally Posted by graider

you remind me of footie.

anyway, I see three different kind of trolls on this forum and mostly coming from audi/porsche (same company).

1. uneducated audi trolls who would put anything audi above bmw.
2. educated audi trolls who like to bring up that they presently/past own an m3 so they can express why audi is better based on their experiences.
3. crazy trolls who would just call everybody fanboys as soon as they praise the m3. ridiculous because after all this is a bmw forum and people praise the m3 because they think it is the best car for them.

+1,000,000

[kmac1980]

I have to say, living in Toronto which has some nasty winter and having driven AWD and RWD comparably equipped cars:

AWD as a safety feature is highly over-rated. Most accidents and mishaps in the snow have everything to do with cars not being able to stop in time. Thankfully, all vehicles are equipped with All Wheel Braking systems, so with a good pair of snow tires, a RWD car will be fine in the snow. Many people here in SUVs think they are immune to winter driving conditions and end up rear-ending someone.

I have to say I have full confidence driving my RWD M3 with dunlop wintersport 3D tires in any kind of conditions we get here in Toronto.

Bear in mind this comment is applicable to city driving, not rally-crossing! Also, that this is purely a comment on AWD being a big safety feature in bad weather. I quite like the B8 s4 and might consider it for my next car once the M3 lease is up!

[radiantm3]

Originally Posted by MERCSUk153

The problem with you fanboys is that you only read where I say the S4 IMO is a better daily driver but don't read where I said the M3 is a better track car or that I would have bought the M3 if I lived in warmer weather place.
Show me where I have compared the S4 to M3 in performance area.
I am not the only one who thinks a higher torque cars like the 335i and S4 are better daily drivers than a higher revving lower torque car such as the M3. I have not ever mentioned in this thread that the S4 or a 335i would ever beat a M3 on a track or cornering performance. I unlike you are not so stuck up to think my car is supreme in all areas even thought it isn't. If you think your M3 is the best in all areas than I got one word for you FANBOY.
Seriously why don't you just pay more attention to reading than skiing.

I could have sworn the M3 and 335i have similar peak torque numbers. And from what I've read, the M3 maintains peak torque over a much broader rev range than the N54. The N54 just happens to start a bit earlier. I'm sure someone will correct me if I'm wrong.

Edit:

Here's the data I remember seeing:
http://www.m3post.com/forums/showthread.php?t=419634

[Advskier]

Originally Posted by MERCSUk153

The problem with you fanboys is that you only read where I say the S4 IMO is a better daily driver but don't read where I said the M3 is a better track car or that I would have bought the M3 if I lived in warmer weather place.
Show me where I have compared the S4 to M3 in performance area.
I am not the only one who thinks a higher torque cars like the 335i and S4 are better daily drivers than a higher revving lower torque car such as the M3. I have not ever mentioned in this thread that the S4 or a 335i would ever beat a M3 on a track or cornering performance. I unlike you are not so stuck up to think my car is supreme in all areas even thought it isn't. If you think your M3 is the best in all areas than I got one word for you FANBOY.
Seriously why don't you just pay more attention to reading than skiing.

And here comes the "fanboy" remarks.

Contrary to what people like you would have everyone believe, just because the M3 can snack on cars like S4's on a race track, they are not a track car. They are BMW's top of the line 4 passenger 3 series sedan/coupe. It is a street car. As to your idiotic torque argument, do a little reading because any informed enthusiast already knows about the M3 winning torque arguments all over THIS site, as well as in every publication. BMW does not market the M3 to be only better than anything on a track, since only the smallest percentage of them end up on a track. It very simply, is the best all around performance sedan you can buy in it's price range.
Argue all you want, but I trust every major car publication and TV review more than your ignorant opinion.

Now the one area you might have an advantage on all of us here. Please tell us how by saving $13K and purchasing an inferior car, you can turn it into a 997 Turbo in 2 years. Assuming your wife gives you permission Does she pick out your cloths for you as well?
You might not know jack about cars, but you must be a rocket scientist when it comes to investing.

[jdgamble]

Originally Posted by MERCSUk153

The problem with you fanboys is that you only read where I say the S4 IMO is a better daily driver but don't read where I said the M3 is a better track car or that I would have bought the M3 if I lived in warmer weather place.
Show me where I have compared the S4 to M3 in performance area.
I am not the only one who thinks a higher torque cars like the 335i and S4 are better daily drivers than a higher revving lower torque car such as the M3. I have not ever mentioned in this thread that the S4 or a 335i would ever beat a M3 on a track or cornering performance. I unlike you are not so stuck up to think my car is supreme in all areas even thought it isn't. If you think your M3 is the best in all areas than I got one word for you FANBOY.
Seriously why don't you just pay more attention to reading than skiing.

I have a 335 loaner right now, which is just EVER SO slightly slower than an S4, and I was driving with the girl last night and got on it, and she didn't even react until we got to about 80. Then she said "ok that's enough." In the M3, she freaks out midway through 1st gear. I asked her if it felt fast, and she said "Yeah, but nothing like your car." Funny... amazing how the "lower-torque" car is so much faster than those higher torque cars!

Originally Posted by MERCSUk153

Funny thing you chose to respond to that reply as obviously you know it applies to you hence you respond.
It really is amazing that you fanboys think that anyone who happen to have both the M3 and S4 and say that both cars are great in different areas will still think that that M3 owner is still a troll because they god forbid said anything positive about another car.
I mean the owners of both the M3 and S4 can't be more informed than you who most likely never even have driven the new S4.

You gotta get on that multi-quote feature... especially when so many people are directing comments at you.

PS - I don't think anyone is really picking on the S4... They're picking on YOU. It's because you are an easy target. I can't believe you are still even on this post. I think we're up to about 8 posts suggesting that you pull your head out of your ass. You're embarrassing yourself.

[jdgamble]

Wow... Make that 10. In the time I wrote my post, 2 more direct (and negative) responses to MERCSUk. I think it's time for a new screen name little guy!

[graider]

Originally Posted by MERCSUk153

Funny thing you chose to respond to that reply as obviously you know it applies to you hence you respond.
It really is amazing that you fanboys think that anyone who happen to have both the M3 and S4 and say that both cars are great in different areas will still think that that M3 owner is still a troll because they god forbid said anything positive about another car.
I mean the owners of both the M3 and S4 can't be more informed than you who most likely never even have driven the new S4.

think what you want, but i found it funny some guys want to act hero and start calling everyone who prefer the m3 a fanboys. i can't stand BS like that so I have to respond. sound like you try to justify your puchase more than anything.

nobody here disagree that both are great in different area, but the point here is for most people, the m3 is the better car / more special car and they would choose it over the s4. myself included. is that somehow wrong? if you don't believe me, go back and read all my posts.

i say it again. if money is not an issue, i would buy the m3 over the s4 everyday. don't care if it is faster than the m3 in straight line or how much faster it is with a chip. the same can be said for a 335i.

[Advskier]

It's funny, how to the average Audi owning troll who visits an M3 site, every M3 owner is a fanboy.
And it's equally funny, how they all say the M3 is a better car, except where it counts.

Isn't there a good Audi forum?

[brava09]

Originally Posted by MERCSUk153

No I am not a rocket scientist in investing but obviously you aren't a rocket scientist in reading and comprehension. Only someone like you would think when someone says investing the $13k and budgeting for a 997 turbo would think that turning $13k investment into a 997. It called a small headstart genius. As I do have a well paying job that I can set aside a BUDGET. If you still don't understand this concept than go ask daddy.
With the M3 torque if you look at the graph smart guy you can see that the 335i torque starts much earlier than your car and if you add the JB3 onto it then you can see how it is a better dd. It will get up and go much sooner than your M3 and you don't have to wait for the torque or rev your engine to get it. This has been discussed many times on e90post. Some of you M3 boys just don't get it or don't want to get it. It will get up and go much sooner than your M3. If you like to take your girlfriends butt dyno as evidence that your M3 is faster than you go right ahead because I am sure that is much more accurate.

Troll.

Get lost.

[ihyln]

I've seen the light. the S4 is clearly better than both the M3 and the 335i. So does anyone want a mint condition E90 M3?

[brava09]

Originally Posted by ihyln

I've seen the light. the S4 is clearly better than both the M3 and the 335i. So does anyone want a mint condition E90 M3?

Thanks to Mersuck

[Advskier]

Originally Posted by MERCSUk153

No I am not a rocket scientist in investing but obviously you aren't a rocket scientist in reading and comprehension. Only someone like you would think when someone says investing the $13k and budgeting for a 997 turbo would think that turning $13k investment into a 997. It called a small headstart genius. As I do have a well paying job that I can set aside a BUDGET. If you still don't understand this concept than go ask daddy.
With the M3 torque if you look at the graph smart guy you can see that the 335i torque starts much earlier than your car and if you add the JB3 onto it then you can see how it is a better dd. It will get up and go much sooner than your M3 and you don't have to wait for the torque or rev your engine to get it. This has been discussed many times on e90post. Some of you M3 boys just don't get it or don't want to get it. It will get up and go much sooner than your M3. If you like to take your girlfriends butt dyno as evidence that your M3 is faster than you go right ahead because I am sure that is much more accurate.

With DCT my M3 can be at any RPM I choose in the blink of an eye.

But you are absolutely correct. The S4 is a vastly better DD than my M3. I can hardly stand to get in the thing, and every time I see an S4 or 335 I can barely control my envy. When I see an S4 or 335 I run in fear, because for all I know it might be "modded".
I even went so far as to ask several S4 and 335 owners if they would do a direct trade, but they were all to smart to take me up on it. Even if I offered to throw in some cash.
I guess I'm stuck with this POS for now. But eventually I hope to trade up for an S4, and maybe (like you) tell everyone how I am saving for a 997 Turbo, which is a real car.