3.0 vs 3.0si vs M - help me decide

[carcar123454321]

Hi, Just wondering if someone has driven all three (3.0, 3.0si, M) and could comment on the following.

1. Power (usability, accelleration, etc.)
2. Engine maintainability and cost. (I know the N52 seems moderately bullet proof if cared for, but have no idea on S54).
3. Manual Transmission durability. (I've just seen a lot of 135i folks with gear grinding issues (e.g. "doesn't go into 2nd gear well, etc" (syncros?)...maybe that's a different trans.)

I enjoy spirited driving, have done some track days, and generally am in to performance over looks, etc. I've had a suped up Subaru, test driven many cars (but not these...finding them is as little challenging), and have a Solstice GXP for fun now.

I ignored the Z4 at first but it's intrigued me, especially the NA engine, and then when I saw the M that really intrigued me.

I love turbos but haven't had the best of luck...seems like there's always something going wrong...boost leak, ballooning IC (happened on Solstice), direct injection carbon build up, etc., etc.

I have test driven a 328i (N52) and a 135i (N55) so I have a little feel for BMW engines, etc.

Thanks.

[3002 tii]

I’ve owned both a 3.0si coupe and M coupe as well as a 135is (N55 with factory PPK)

1. 3.0si is well suited for 80% of driving needs. The ‘higher’ output N52 paired with manual gearbox are the best features you’d want from BMW prior to changing their ways if you ask me. Swap the carrier with an automatic (3.73), even better. The M has the advantage in the higher rpms - where the N52 loses steam, the S54 continues to pull hard till redline. But this difference was most noticeable for me only on track, and I rarely did high speed runs/pulls on public roads.

2. N52 hands down is way cheaper to maintain. I won’t say the S54 is less reliable however. It’s a high strung motor that requires more preventive maintenance. It’s the lack of maintenance by neglectful owners that give the engine a bad rep imo. I’d much rather deal with the N52’s leaky vcg, DISA valves and eccentric sensor over the S54 rod bearings and vanos.

I will say, from a DIY perspective however, the S54 has been around so long it’s much easier to research issues as compared to the N52.

3. Manual gearbox is same between both 3.0si and S54. Second gear grind is overblown imo. Get rid of CDV, put in good fluid, and clutch out slower (instead of banging through the gears) and you’re fine.


FYI the 3.0si is more in line with the 330i. The 328i had the lower output motor which is why everyone does the 3 stage manifold upgrade (225hp -> 255hp).

Can’t go wrong with either car, I just preferred the allure / rarity of the M (better resale and collector value) and better performance on track.

[David70]

I have an M. As far as maintenance items go, it is of course the highest. 25k mile valve adjustment, 4 wheel BMW rotors and pads sold online for about $1300 (DIY price), tires cost more, likely go through them quicker, oil change costs more, eventually need rod bearings, clutch will cost more. I don't see the durability of the transmission being a problem if it was well cared for and not abused.

[Huz-Z]

One of the biggest complaints about the SI was the factory equipped runflat tires that gave the car a bone jarring ride and caused scary tramlining. By now, any SI should have long ago tossed it’s original tires but in case you get one where the owner has replaced them with new run flats, toss em for some Pilot Sport 4s.

You should be able to get your hands on an “in nice shape” 3.0si for less $ than what an M in equivalent condition will cost.

The engine in the SI is much lighter than in the M, so the steering can be more nimble - see https://www.caranddriver.com/reviews...ake-road-test/ . But at the same time, M owners report that it’s hydraulic steering has a nicer feel than the electric unit in the SI.

First when I got my SI I took it for a spin and after passing a guy, I settled in to cruise at what I thought was 100 kph (60 mph) with the engine having plenty of grunt at that point. It was then that I remembered that the speedometer was showing me miles per hour (car imported from the US), not kilometres per hour that we have here in Canada. So at 100 mph, the SI had plenty left to give. And by the way, it can slow down to 60 mph darn quick too!

[Westersund]

If your economy allows, always go M.

[rho123]

I'll give my 2 cents but not really apples to apples comparison. I have owned a 128i and now z4 3.0si. Both have the N52 engine but the 128i had the lower output version and hydraulic steering. The N52 was very reliable and never gave me any problems. 3.0si has plenty of power for a daily driver but the EPS definitely felt too light.

[Piper1]

Originally Posted by rho123

I'll give my 2 cents but not really apples to apples comparison. I have owned a 128i and now z4 3.0si. Both have the N52 engine but the 128i had the lower output version and hydraulic steering. The N52 was very reliable and never gave me any problems. 3.0si has plenty of power for a daily driver but the EPS definitely felt too light.

It’s honestly something that I was too going to mention. My base ‘11 128 is also the lower/single stage power wise, its my salt season vehicle so it’s stock. Comparing the hydraulic steering in that to my si coupe I’d say I’d want to feel in the middle of the two for the ultimate feed back. Rpm wise though the single stage 128 in comparison to the si just flattens mid rpm even with it higher revs than the M54 it’s kind of like “oh it revs higher….and?” There’s not as much to enjoy on the top end.

Between the 3, my f/i M54 Z4 gets more smiles than my stock coupe and 128 even with lower red line of the M54, boosted its all smiles through the full revs as how the M was compared to the si. I’d be interested to hear a n/a comparison on a si with a tune from Severn in comparison to stock.

But regarding the eps negativity I think is over hyped. If it’s something you’re hell bent on both here and the uk based z4 forum there are how tos in converting both the M54 and N52 to hydraulic so there’s an option if that’s a deciding factor.

[rho123]

Originally Posted by Piper1

It’s honestly something that I was too going to mention. My base ‘11 128 is also the lower/single stage power wise, its my salt season vehicle so it’s stock. Comparing the hydraulic steering in that to my si coupe I’d say I’d want to feel in the middle of the two for the ultimate feed back. Rpm wise though the single stage 128 in comparison to the si just flattens mid rpm even with it higher revs than the M54 it’s kind of like “oh it revs higher….and?” There’s not as much to enjoy on the top end.

Between the 3, my f/i M54 Z4 gets more smiles than my stock coupe and 128 even with lower red line of the M54, boosted its all smiles through the full revs as how the M was compared to the si. I’d be interested to hear a n/a comparison on a si with a tune from Severn in comparison to stock.

But regarding the eps negativity I think is over hyped. If it’s something you’re hell bent on both here and the uk based z4 forum there are how tos in converting both the M54 and N52 to hydraulic so there’s an option if that’s a deciding factor.

Sure, EPS is not a deal breaker but just wanted to point out the difference in feel.

[pungo]

Having extensive experience with both the 3.0si and ///M, for a daily driver, the 3.0si is a great choice, for a weekend warrior and or track use, the ///M. The 3.0i is a fine engine, though the ///M just has more going for it as the sum are greater than the parts. There's not much engine performance upgrades for the 3.0si, BMW already did a good job with it out of the box. There are a ton upgrades for the ///M from the M3 world. Word of warning, if you don't plan on getting the M, don't drive one since the connected hydraulic steering feel alone and LSD is worth the price of admission.

Since it sounds like you're concerned with maintenance costs, the ///M is probably not the right car for you

[Huz-Z]

Been driving my EPS equipped SI since 2009 and once I ditched the run flats, I’ve not regretted getting the car.

[wdb]

I had both at the same time. The 3.0si is a much friendlier daily driver, and it has its own unique virtues when things get twisty. That lightweight N52 really makes it nimble. EPS is a minor minus, no LSD is a bit bigger minus. If I had kept the si it would have gotten one. It’s absolutely wonderful for touring. A manual si is exceedingly rare but worth the search.

I kept the M longer. It really only has one function; to go. Hard. Now. Right now. It doesn’t like trundling around. It likes to use fuel. It likes to use tires. It’s much more immersive. There’s a rawness underneath that never lets you forget it’s there. It makes glorious noise.

Both are memorable.

[deemo319]

I was considering an M Roadster and 3.0si and wound up with a 3.0si. A couple of reasons were there weren’t many M Roadsters available when I ready, and a 3.0si popped up 5 miles from me.

My long due diligence at the time was that the 3.0si was the gem in the lineup. A better package than the 3.0i and without the specialized maintenance of the S54-powered M Roadster that at the time would have been a serious challenge/problem for me.

I got a 3.0si but it was the worst color imaginable which was Jet Black but it was a 6-speed manual, one-owner and had the Dream Red interior with the very desirable M Sport seats.

Eight years later I still have it and after doing pretty much every preventative maintenance that we could it’s been a great car. And since I despise black cars I got a set of E92 M3 219 M wheels, a color change, one-off custom top, and custom interior as well.

Once a year I think about getting a supercharger from ESS but at that point my thinking is just get a faster car. I still think that I will get an E85 M Roadster someday as it was the last analog BMW.

[Huz-Z]

I didn’t think that the N52 engine could withstand a horsepower boost because it’s a magnesium block.

But hey, there is the supercharger on the ESS site:

https://esstuning.com/ess-n52-n52n-g...-system-gen-3/

[Piper1]

Originally Posted by Huz-Z

I didn’t think that the N52 engine could withstand a horsepower boost because it’s a magnesium block.

But hey, there is the supercharger on the ESS site:

https://esstuning.com/ess-n52-n52n-g...-system-gen-3/

Shhhhhh it’s exactly the same as “we don’t talk about Bruno” (thanks to my kiddo ). It’s been out there, but haven’t seen too much out there in years/miles of running like you do for the M54/S54. Josh at Severn might have bit more insight too as it’s something I’ve been kicking around my brain to do to the coupe one day too.

Last I looked too ess pulled their kits for the M54 from the site.

Edit: damn now I’ve got the song stuck in my head

[86Zed]

Originally Posted by wdb

I had both at the same time.

I kept the M longer. It really only has one function; to go. Hard. Now. Right now. It doesn’t like trundling around. It likes to use fuel. It likes to use tires. It’s much more immersive. There’s a rawness underneath that never lets you forget it’s there. It makes glorious noise.

Both are memorable.

Very well put. As an M owner I still want to find a 3.0si to experience for an extended period of time.

[belcom]

Originally Posted by 86Zed

Very well put. As an M owner I still want to find a 3.0si to experience for an extended period of time.

As a 3.0si roadster and Z4M Coupe owner I can tell you that after driving both throughout the last 2.5 years I always want more performance out of the 3.0si. I think it would be much better with headers, tune, perhaps a more free flowing and slightly louder exhaust and an LSD. Brakes are fine and actually share the same brake pads as Z4M (only Si) and front rotors are same size almost as non-comp e46 m3. Si also has quite a few suspension options to choose from. Si is a great car and much more civil overall than the M. But M just does everything better out of the box.

[cbpip]

On the Si , change out the oem suspension to a more suited one, LSD with at least the same gearing as the M (3.73) , motor/trans mounts, adjustable rear camber arms . You'll have a very competitive car and capable of keeping up with most others and still have a comfortable dependable ride.

[Huz-Z]

The thing about an SI is that you don’t have to drive aggressively to enjoy the turbine smooth power delivery and torque of that big 3 litre straight six.

[Sergio19]

N52 (and N62 by extension) are my favorite BMW engines. Naturally aspirated, light weight, valve-tronic for great economy and port injected.

[3002 tii]

Originally Posted by belcom

As a 3.0si roadster and Z4M Coupe owner I can tell you that after driving both throughout the last 2.5 years I always want more performance out of the 3.0si. I think it would be much better with headers, tune, perhaps a more free flowing and slightly louder exhaust and an LSD. Brakes are fine and actually share the same brake pads as Z4M (only Si) and front rotors are same as non-comp e46 m3. Si also has quite a few suspension options to choose from. Si is a great car and much more civil overall than the M. But M just does everything better out of the box.

The statement about brakes isn’t correct. 3.0si brakes are same as e46 330i. The Z4 M brakes are the same as the M3 ZCP which use 348mm front rotors.

[wdb]

Originally Posted by 3002 tii

The statement about brakes isn’t correct. 3.0si brakes are same as e46 330i. The Z4 M brakes are the same as the M3 ZCP which use 348mm front rotors.

That's my understanding too, I think. The Z4M got the M3 CSL brakes and steering rack.

[belcom]

Originally Posted by 3002 tii

The statement about brakes isn’t correct. 3.0si brakes are same as e46 330i. The Z4 M brakes are the same as the M3 ZCP which use 348mm front rotors.

Meant to say "same/similar size". 325x25mm (330i/Z4 3.0si) vs non-comp M3 @ 325x28mm which are thicker. But now I wonder, are the rotor hat offsets the same...? Could one put the thicker 325mm m3 rotor on the Si with a different brembo caliper for example? hmm

Cool fact by the way... you can get 330i/z4 si front rotors from SHW Performance which are perforated and pin drive style just like Z4M/M3 CSL

m3 zcp though? 345mm or 348mm? Don't think I've seen a 348mm disc.