Torque & horsepower 3.0si vs. S54

[djlogan33]

I have owned a S52-engine Z3 M Coupe and a S54-engine M Coupe.
The power band was much stronger at all RPMs with the S54-engine compared to the S52-engine.

I really liked the Z4 Coupes when they came out and I sold my S54-engine Z3 M Coupe.

I read a lot of good things about the 3.0si-engine in the new Z4.

Before I ordered my new Z4 Coupe, I drove the Z4 Coupe 3.0si and the Z4 M Coupe.
I did not feel that much difference in the power band of the two cars at lower RPMs.
Because the Z4 Coupe was an extra $14K, I decided to buy the Z4 Coupe 3.0si.
I was very happy with my decision.

In July, someone on a cell phone, did not stop soon enough and ran into the back of my Z4 Coupe 3.0si.

While it was being repaired, I started looking around for another Z4 Coupe 3.0si.
A friend of mine found a real good deal on a Z4 M Coupe, the same year as my Z4 Coupe 3.0si, with ½ the miles, still under
BMW warranty at a real good price, so I bought it.

Now I am trying to sell the Z4 Coupe 3.0si.
I have the pleasure of driving both of them back to back all the time.

They both still feel the same up to about 4500 RPMs
The Z4 Coupe 3.0si after 4500 RPMs stats going flat.
The difference is the Z4 M Coupe continues to pull strong up to 7000 RPMs.

I decided to prove what I was feeling, so I searched for DYNO graphs of each, at the rear wheels.

I entered the torque figures together and horsepower figures together into an Excel graph.

The graph on both shows the same thing I feel:
• The torque & horsepower is about the same up to 4500 RPMs
• The M Coupe, with the S54 engine torque & horsepower continues to grow well after 4500 RPMs.

See graph below and both cars under the graph.
Oh...did I mention the Z4 Coupe 3.0si is FOR SALE?

[ZStig]

tweed. classy. hahahaha


good info though. just poking fun

[GP20]

I think you're forgetting about gearing.

3.0Si coupe manual -3.46
3.0Si roadster manual - 3.23
///M - 3.62
(I'm omitting the 3.0Si automatic gearing ratios. Why? Because automatic.)

The M and 3.0Si could have the same engine, making the same horsepower and torque, and the M would still be quicker because of the more aggressive gearing ratio. You must've had a tough time selling your 3.0Si that you had to make this thread.

And I think your pictures served as an exhibit that even though the M-coupe and 3.0Si coupe share similar lines, the M just looks so much better and so much more aggressive. Personally, having owned 4 Z4's, I'd pay $5k more for the M just because of the styling, brakes, and hydraulic steering alone even if it had the same N52 engine making 255HP as the 3.0Si. The hydraulic steering being the biggest difference maker. The electric steering in the E85/86 is downright pathetic and terrible.

[vachss]

Originally Posted by GP20

I think you're forgetting about gearing.

3.0Si coupe manual -3.46
3.0Si roadster manual - 3.23
///M - 3.62

and I think you're forgetting about tire diameter - 25" for the 3.0si and 26" for the M - handily balancing out the 3.46 vs. 3.62 gearing. Engine rpm at a given speed/gear is the same for the M and the si coupe.

All the other advantages of the M are certainly there (my favorite would be the limited slip diff), but there isn't really any gearing advantage.

[djlogan33]

Originally Posted by GP20

I think you're forgetting about gearing.

3.0Si coupe manual -3.46
3.0Si roadster manual - 3.23
///M - 3.62
(I'm omitting the 3.0Si automatic gearing ratios. Why? Because automatic.)

The M and 3.0Si could have the same engine, making the same horsepower and torque, and the M would still be quicker because of the more aggressive gearing ratio. You must've had a tough time selling your 3.0Si that you had to make this thread.

And I think your pictures served as an exhibit that even though the M-coupe and 3.0Si coupe share similar lines, the M just looks so much better and so much more aggressive. Personally, having owned 4 Z4's, I'd pay $5k more for the M just because of the styling, brakes, and hydraulic steering alone even if it had the same N52 engine making 255HP as the 3.0Si. The hydraulic steering being the biggest difference maker. The electric steering in the E85/86 is downright pathetic and terrible.

================================================
When I had my S54 Z3 M Coupe, I replaced the stock 3.15-diff with a 3.73-diff.
This was an 18% difference and it could really tell the difference.

The difference between the 3.46-diff in the 3.0si and the 3.62-diff in the M Coupe is only a 4% difference and can not be felt.

Also, gearing difference when comparing the dyno results of each engine, has even less impact.

The point I was making was the upgraded 3.0 engine (215 HP) to the 3.0si engine (255 HP) with not only double-VANOS,
but only Valvetronic (continuously variable valve lift control), has the same torque and horsepower numbers as the S54-///M engine up to about 4500-RPMs,
but above 4500 RPMs, the high-reving S54-engine continues to pull up to 7000 RPMs, while the 3.0si engine starts to fad...

BTW, the 3.0si Roadster & 3.0si Coupe have the same 3.46 Final Drive Ratio.

Also, the new sticker price on my Z4 M Coupe was $58K.
The new sticker price on my Z4 Coupe 3.0si was only $42K ($16K-38% less).
I didn't think then and I don't think now the M Coupe was/is 38% better than the Z4 Coupe 3.0si.

But…even though I had to fly to Florida to buy the M Coupe, I got it for a really good deal.

Oh…did I mention that my Z4 Coupe 3.0si is FOR SALE?
http://www.zpost.com/forums/showthread.php?t=564284

[WestCDA]

Originally Posted by djlogan33

BTW, the 3.0si Roadster & 3.0si Coupe have the same 3.46 Final Drive Ratio.

According the 2006 BMW Z4 Catalog (UK version), the 3.0si Roadster has a 3.23 rear end, and the 3.0si Coupe has 3.46. Could have been different for the Euro cars, but RealOEM shows two different part numbers for the roadster/coupe differential assembly on the US cars as well.

Fuel mileage estimates in that same catalog are shown as slightly worse for the coupes, but they have a slightly better 80-120 (kph) acceleration time. 0-100 kph (roughly 0-62 mph) time is shown as the same for both.

[djlogan33]

Originally Posted by WestCDA

According the 2006 BMW Z4 Catalog (UK version), the 3.0si Roadster has a 3.23 rear end, and the 3.0si Coupe has 3.46. Could have been different for the Euro cars, but RealOEM shows two different part numbers for the roadster/coupe differential assembly on the US cars as well.

Fuel mileage estimates in that same catalog are shown as slightly worse for the coupes, but they have a slightly better 80-120 (kph) acceleration time. 0-100 kph (roughly 0-62 mph) time is shown as the same for both.

================================================
U may B right...

I have two different sale brochures for the Z4 3.0si Roadster & Coupe.
Neither one shows the “Final Drive Ratio” like my Z4 M Coupe sales brochure.

BMW Gear Ratios
The Chart below shows E36 E46 E90 E91 E92 E93 E85 E86 E83 E82 E88 transmission gear ratios. It only shows cars that were available in the US.

Note: Data may not be 100% accurate. Please let me know if you see any errors
Model Platform Type Transmission 1 2 3 4 5 6 reverse final drive redline
Z4 3.0si E86 coupe manual 4.35 2.5 1.66 1.23 1.00 0.85 3.93 3.46 7000
Z4 M3.2 E86 coupe manual 4.35 2.5 1.66 1.23 1.00 0.85 3.93 3.62 8000
\

Nevertheless, the low-end torque in my Z4 Coupe 3.0si feels and is shown to be the same up to 4000-4500-RPMs and my Z4 ///M Coupe continues to pull all the way up to about 7000-RPMs.

I really like the silky smooth and quiet, civilized, low-end torque and maintenance-free 3.0si engine…and…
I really like the silky smooth, noisy, un-civilized, low-end and top-end torque of my ///M Coupe…

When I had my first S54-engine in my 2001 Z3 M Coupe, BMW had lots of problems with the S54 engine.
As a result, I was given a 100K-mile warranty on the engine. I sold it while it was still under warranty.

The S54 was plagued with rod bearing failures in early production. BMW attempted to blame vehicle owners for the failures early on but eventually started replacing rod bearings, oil pumps, and whole engines under warranty. This fault was attributed to a problem with the connecting rod bottom-end bearing shells that were supplied to BMW by a third party that did not meet BMW's specifications. This problem was fully corrected by BMW on engines produced after 06/2003.

The S54 engine is really a racing-engine and does not have self adjusting values, which have to be maintained regularly.

Hmmm, should I keep the 3.0si and sell the S54…or should I keep the S54 and keep the 3.0si…?

[pokeybritches]

Sell your M coupe to me, and keep the 3.0si.

[djlogan33]

Originally Posted by pokeybritches

Sell your M coupe to me, and keep the 3.0si.

==============================================
Both are FOR SALE at the right prices...

[BTM]

Having driven both cars I concur that the 3.0si does feel very strong. It's lighter, and the N52 is no slouch. However, I stop short of comparing dissimilar dyno charts in order to prove this. Unless they were done on the same day, on the same dyno, the margin of error is just too large. I'm not saying that I don't expect a similar outcome in this case, but just that it isn't really beneficial to compare data that doesn't have the same "base."

[djlogan33]

Originally Posted by BTM

Having driven both cars I concur that the 3.0si does feel very strong. It's lighter, and the N52 is no slouch. However, I stop short of comparing dissimilar dyno charts in order to prove this. Unless they were done on the same day, on the same dyno, the margin of error is just too large. I'm not saying that I don't expect a similar outcome in this case, but just that it isn't really beneficial to compare data that doesn't have the same "base."

==============================================
The torque & horsepower numbers/graphs are real close to what I felt when I decided to buy the 3.0si, instead of the M Coupe, back in 2007 and what I have felt multiple times in the last couple of weeks by driving both.

Driving within the speed limit around town and even on the local expressways, they both feel close to the same.

But…when I attend my local Driver Schools @ Mid-Ohio Sports Car Course and able to drive 100-130mph and I am able to keep the M-Coupe’s RPMs between 5000-7500 RPMs, that is when I will feel the M-Coupe’s extra high-end torque/horsepower that the 3.0si would not have…

Oh...did I mention my Z4 Coupe 3.0si is FOR SALE?

[mfanatic325]

I know about the power and torque similarities/differences, but when I test drove both cars, same model years, around same mileage, both 6-speed manuals, and actually both were TiAg on black leather; I definitely was blown away by the ///M variant over the SI and chose the M in the end for a bit more money. I have absolutely no regrets The overall package that the M provides over the SI is worth every penny, especially if one can be found for a decent deal, in whichever color and/or combo you prefer, and if mileage is relatively low, etc.

After some modifications, my car now is not shabby at all, even when compared to a supercharged Z4M (ESS VT2-500) ^_^

[djlogan33]

Originally Posted by mfanatic325

I know about the power and torque similarities/differences, but when I test drove both cars, same model years, around same mileage, both 6-speed manuals, and actually both were TiAg on black leather; I definitely was blown away by the ///M variant over the SI and chose the M in the end for a bit more money. I have absolutely no regrets The overall package that the M provides over the SI is worth every penny, especially if one can be found for a decent deal, in whichever color and/or combo you prefer, and if mileage is relatively low, etc.

After some modifications, my car now is not shabby at all, even when compared to a supercharged Z4M (ESS VT2-500) ^_^

==============================================
I assume, with all the high performance upgrades, you must do a lot of Driver Schools, right?
Did you notice a difference after installing the "OEM Strut Bar"?

[BTM]

Does anyone know of a 3.0si coupe for sale? Preferably black...

[wdupdog]

^

[psygnosis]

Originally Posted by GP20

I'd pay $5k more for the M just because of the styling,.

Styling? You mean the front and rear bumpers?




And those sexy sexy dual exhausts

[djlogan33]

Originally Posted by BTM

Does anyone know of a 3.0si coupe for sale? Preferably black...

==========================
Hmmm...I think I do...

WTF...I'm goin' 2 keep da 3.0si and sell the wimpy, overpriced over hyped ///M…

[djlogan33]

Originally Posted by psygnosis

Styling? You mean the front and rear bumpers?




And those sexy sexy dual exhausts

=================================================
I really like the hood better on da ///M...

[BTM]

Originally Posted by psygnosis

Styling? You mean the front and rear bumpers?




And those sexy sexy dual exhausts

Don't forget the hood, ////////////////////Badges and steering wheel!!

[3002 tii]

Originally Posted by psygnosis

Styling? You mean the front and rear bumpers?




And those sexy sexy dual exhausts

Don't forget the hood which has a crease...

I have no problem admitting I wish I had bought the M coupe. Dealer said it could be mine for 8k more but being new to BMW's and coming from a 1.8T, I thought 255hp n/a sounded good enough as is.

Since then the addition of the Quaife, stickier tires and better pads/fluid have kept me satisfied on the track, all while ironically getting better mileage than my daily driver =)

[psygnosis]

Originally Posted by BTM

Don't forget the hood, ////////////////////Badges and steering wheel!!

How could I forget the hood and that nice think chunky wheel, forgive me

And you can never have enough ///M badges, how many does the car have? 11?

edit: I like 30mpg, I don't need an M, I like 30mpg, I don't need an M, I like 30mpg, I don't need an M........

[BTM]

Mine came with 4 or 5 but that wasn't enough, I stepped my game up to like 35