Downside to 3.0si vs 3.0i?

[gmushial]

I'm coming from 170hp 2.5, so going to the 3.0i would be a step up... but people keep saying: get the 3.0si - it's a freebie, it's a no brainer... which, yes, if the extra 40 hp is free, then why not... but I'm wondering: the extra hp comes from the three stage intake manifold, and remapping the software... it seems that a more complex manifold might be a minor maintenance negative - but with the DISA already there, one has to wonder if it is really a significant increase in complexity... for those with 3.0si's... what have been the maintenance issues? Or are they really the same, other than maybe the initial upfront cost difference - but buying used clearly one doesn't have that... ??

[psycleridr]

I have an '08 3.0si and have to say that the car has been relatively maintenance free. Like all owners I have changed the top motor and other than that just fluids. It's been a fun car and even better once I got rid of the RFT's.
I have never driven the 3.0 so can't offer any comparison. Either way I don't think you will be disappointed coming from your model.

[BimmerBreaker]

The 3.0si uses the N52 and the 3.0i the M54, just FWIW... they are quite different engines as well (as different as M50 vs M54 maybe)

The N52 has shown to be less troublesome than the M54 when it comes to the DISA type stuff. The three stage manifold is a further evolution of the DISA, further improving performance and reliability. If you look you can find reports of N52's having Valvetronic or VANOS issues, but these are not reported very often and most were reported under warranty with not much being reported after the cars have been out of warranty.

Plus, going from your M52TU to an M54 is not really a change, you are basically going from the small M54 to the big one. The N52 will be something new. Go test drive one, talk to some people who own them at car meets or something (they powered a lot of BMW 28i and 30i suffix cars from 06-some time later). We have one in my family and we love it. You won't trust forum-goer's experience as much as you would a living breathing person I imagine...

Oh yeah, if you get a roadster, plan on replacing the top motor. That is IMO the biggest drawbacks with the Z4's - the top mechanisms are just plain awful. You were spoiled coming from a Z3, what with the convertible tops that seal out water... Z4's don't do that. They are actually designed to let water ingress into the top stowage area where there are drains that are designed to ...drain. But there are two stupid things about this - one, the drains themslevs are pretty tiny so they are very easy to get clogged up and secondly they actually stored the top motor in this area. So what happens is the drains clog and then this area fills with water, submerging the top pump, which causes it to rust out and fail. Replacing it requires removing the entire softtop (some people have reported being able to do it without removing it - I did this job on my own Z4 a few years back and couldn't figure out a way to do it without removing the top... but maybe there is a way). Theory goes we can prevent the problem from happening again by drilling larger holes and sealing the casing around the top motor in silicone. But reading the many stories of people having to do that job twice does not inspire confidence in me that doing those things actually prevents it from failing again...

[gmushial]

The 3.0si uses the N52 and the 3.0i the M54, just FWIW... they are quite different engines as well (as different as M50 vs M54 maybe)

The N52 has shown to be less troublesome than the M54 when it comes to the DISA type stuff. The three stage manifold is a further evolution of the DISA, further improving performance and reliability. If you look you can find reports of N52's having Valvetronic or VANOS issues, but these are not reported very often and most were reported under warranty with not much being reported after the cars have been out of warranty.

Plus, going from your M52TU to an M54 is not really a change, you are basically going from the small M54 to the big one. The N52 will be something new. Go test drive one, talk to some people who own them at car meets or something (they powered a lot of BMW 28i and 30i suffix cars from 06-some time later). We have one in my family and we love it. You won't trust forum-goer's experience as much as you would a living breathing person I imagine...

Oh yeah, if you get a roadster, plan on replacing the top motor. That is IMO the biggest drawbacks with the Z4's - the top mechanisms are just plain awful. You were spoiled coming from a Z3, what with the convertible tops that seal out water... Z4's don't do that. They are actually designed to let water ingress into the top stowage area where there are drains that are designed to ...drain. But there are two stupid things about this - one, the drains themslevs are pretty tiny so they are very easy to get clogged up and secondly they actually stored the top motor in this area. So what happens is the drains clog and then this area fills with water, submerging the top pump, which causes it to rust out and fail. Replacing it requires removing the entire softtop (some people have reported being able to do it without removing it - I did this job on my own Z4 a few years back and couldn't figure out a way to do it without removing the top... but maybe there is a way). Theory goes we can prevent the problem from happening again by drilling larger holes and sealing the casing around the top motor in silicone. But reading the many stories of people having to do that job twice does not inspire confidence in me that doing those things actually prevents it from failing again...

Excellent post - thank you :-) That's exactly what I needed to hear/read. .... didn't the Z4 come with a mechanical top and the electric top was an option? If so: is it possible to just disconnect the motor, and revert it to mechanical? ... but equally, from what you've said: then the 3.0si is the correct choice. Again: many thanks.

[BimmerBreaker]

The Z4's did come with a manual top but most of the cars in the US - the vast majority - are electric power tops. The power top came included with most accessory packages so even if you could find a unicorn manual top, it'd be lacking other features you want (although, most those features are easy to add in with coding)

As far as reverting the power tops to manual. Don't really think so... I mean, at least not in the way you are thinking with a Z3. I say again... regarding the tops, you are spoiled when it comes to the Z3. The correct sequence to transition from Z3 ownership to Z4 ownership would be Z3 roadster then Z3 coupe then Z4 coupe then Z4 roadster. You have made a fatal error by going from roadster to roadster. We'll see you back in the Z3 world soon enough

[gmushial]

The Z4's did come with a manual top but most of the cars in the US - the vast majority - are electric power tops. The power top came included with most accessory packages so even if you could find a unicorn manual top, it'd be lacking other features you want (although, most those features are easy to add in with coding)

As far as reverting the power tops to manual. Don't really think so... I mean, at least not in the way you are thinking with a Z3. I say again... regarding the tops, you are spoiled when it comes to the Z3. The correct sequence to transition from Z3 ownership to Z4 ownership would be Z3 roadster then Z3 coupe then Z4 coupe then Z4 roadster. You have made a fatal error by going from roadster to roadster. We'll see you back in the Z3 world soon enough

Yet again: thanks... though why do you think I'll be back in Z3 land... what am I missing? [I'm concerned in that you've owned both, and my impression is that you've gotten rid of the 4's] ... w/re mechanical top on Z4 - I remember seeing a youtube vid a guy doing the up/down with one: looked about like the Z3 mechanical one [remember: we're talking '06-'08 - not the stupid folding hardtop]... but if one just disconnects the drive motor from the electric one, and probably remove any pieces/parts that might get in the way: wouldn't one be able to one arm reach, pull it up, or pull/push it back down??

[BimmerBreaker]

The Z4 tops do not have an easy bypass like the Z3's. Z3's you rotate the handle and it becomes a manual top. Z4's are electric all the way (and have many more failure points as a result). They electrically disconnect from the windshield frame, retract, then fold down and locks into its lowered position (compared to Z3's that the top sort of just "sits" there). When Z4 tops break you need to fix them, if Z3 tops break you can just turn them into manual tops by rotating the T-handle...

The top was actually one of the reasons I sold mine. Loved the car overall but the top was a headache. A Z4 3.0si coupe and Z3 M roadster would be a perfect garage

[psycleridr]

The Z4 tops do not have an easy bypass like the Z3's. Z3's you rotate the handle and it becomes a manual top. Z4's are electric all the way (and have many more failure points as a result). They electrically disconnect from the windshield frame, retract, then fold down and locks into its lowered position (compared to Z3's that the top sort of just "sits" there). When Z4 tops break you need to fix them, if Z3 tops break you can just turn them into manual tops by rotating the T-handle...

The top was actually one of the reasons I sold mine. Loved the car overall but the top was a headache. A Z4 3.0si coupe and Z3 M roadster would be a perfect garage

I don't think that is entirely true. You could leave the bypass lever on manual for the top and as long as you are not having electrical problems with the lock/unlock function it would then be semi manual?
Basically when my top motor failed this is what I did and theoretically I could have left it like that as the button still would release and lock the top into place even though it would not retract or lift the top back into position. However, I will say I don't know if this would cause codes to be thrown over time.

[gmushial]

I don't think that is entirely true. You could leave the bypass lever on manual for the top and as long as you are not having electrical problems with the lock/unlock function it would then be semi manual?
Basically when my top motor failed this is what I did and theoretically I could have left it like that as the button still would release and lock the top into place even though it would not retract or lift the top back into position. However, I will say I don't know if this would cause codes to be thrown over time.

So there is some provision to disconnect the motor from the top [bypass lever]?? - and when this is the situation, one just reaches back and lifts the top, or conversely, guides it rearward and downward?? ... I just have this image of pulling to the side of the road, planning of dropping the top; and have the motor die in the middle of the process... not being able to disconnect the failed motor from top, and have to continue down the road with a 8' high sail standing upright :-( and of course in the middle of a 3 week road trip, 2200 mi from home etc etc... it's all these weird failures which is part of my interest to move beyond the Z3... but it almost sounds that owning a bmw is to have to deal with such - independent of model. ... ie, life is full of decisions: boring Toyota, but drive it 500k miles uneventfully; or an interesting car, but with a crisis filled existence.

[psycleridr]

There is a bypass in the trunk which releases the hydraulic pressure from the motor allowing you to manually move it up and down. Then you can still use button on console to latch/unlatch the roof to the windshield.
I don't really know if you can completely disconnect the motor and still make it work manually but I'm sure there is a way.
However, the latch the locks and unlocks the roof to the windshield must work electronically. There is also a manual mechanism for this but requires removing a piece and using an Allen wrench which is a PIA, and not something you want to deal with unless you have to

[psycleridr]

Our owners manual has the instructions for getting the top up and down manually. If the owner has it you can look through it for directions. If not you can find one online.

Edit: I added pdf manual. Go to page 27-28 https://cloud.tapatalk.com/s/592b6293...4_roadster.zip

[gmushial]

Our owners manual has the instructions for getting the top up and down manually. If the owner has it you can look through it for directions. If not you can find one online.

Edit: I added pdf manual. Go to page 27-28 https://cloud.tapatalk.com/s/592b6293...4_roadster.zip

Thank you for uploading the manual... I down loaded it and read it: yes, in a pinch, one can move it up and down... no more fear of having it stuck inbetween on the side of the road :-) ... I think at this point I'm leaning toward the Z4... I'll keep doing my homework, also test drive some locally then they come up... but probably next winter when prices bottom, will pull the trigger and do it... but it sounds like a '07 or '08 3.0si ragtop will be the choice. Thanks again. :-)

[psycleridr]

Your welcome. It's a great car and even though mine is low mileage at 24k miles (and sometimes but not always garaged) it still has been a relatively problem free car after 9 years if ownership

[gmushial]

Your welcome. It's a great car and even though mine is low mileage at 24k miles (and sometimes but not always garaged) it still has been a relatively problem free car after 9 years if ownership

I've enjoyed the Z3, but the ongoing this breaks, that breaks, has been frustrating... if there was no Z4, then I'd probably just go with anther Z3, knowing what I'm in for... but I'm hoping that BMW leaned from their mistakes/stupidities on the 3 and did it better on the 4... so I'm willing to give a try... though I don't know how you've done so few miles... I have trouble not wanting to drive here, drive there etc... have driven the Z across country multiple times; maybe a dozen times from Redding to KS; something like a couple dozen times to the desert sw, where the standard trip is 2500 to 4000 miles... or to the Oregon coast, where a 1000 mi trip is a nobrainer. ... I think as I posted at the top: 205k miles came pretty quickly and easily.

[pbpbpb]

I'm a new Z4 owner ( '03 2.5 133k ) and I just removed the pump/motor combo entirely after pulling the top. I still use the electric latches, and the top itself gets moved manually. For the little money I have in this car, it doesn't really bother me too much.

[dbarton62]

Look for a manual top car.
I rarely put the top up on mine and it takes all of 10 seconds to do so.

[gmushial]

I'm a new Z4 owner ( '03 2.5 133k ) and I just removed the pump/motor combo entirely after pulling the top. I still use the electric latches, and the top itself gets moved manually. For the little money I have in this car, it doesn't really bother me too much.

Sounds like an interesting option/workaround... though I think I'd wait for the motor to die, then do such. But glad to hear that such is an option. Thanks for the post.

- - - Updated - - -

Look for a manual top car.
I rarely put the top up on mine and it takes all of 10 seconds to do so.

In the '06-'08 series, was that even an option? ... but maybe I'll get lucky and find the right color, engine, mileage combo, and it'll have a manual top... thanks.

[dbarton62]

Sounds like an interesting option/workaround... though I think I'd wait for the motor to die, then do such. But glad to hear that such is an option. Thanks for the post.

- - - Updated - - -



In the '06-'08 series, was that even an option? ... but maybe I'll get lucky and find the right color, engine, mileage combo, and it'll have a manual top... thanks.

Ah yes.......not sure on the facelift models

[wdb]

A Z4 3.0si coupe and Z3 M roadster would be a perfect garage

I'm halfway there! To be honest I'd probably go with a Z4M roadster over the Z3M; the Z4 was designed from the start for the power, unlike the Z3 which was designed for a 1.9L four.

But what I really want for my roadster is a Lotus Elan.

[gmushial]

I'm halfway there! To be honest I'd probably go with a Z4M roadster over the Z3M; the Z4 was designed from the start for the power, unlike the Z3 which was designed for a 1.9L four.

But what I really want for my roadster is a Lotus Elan.

As someone else here has already done: a Z4 for touring; and an Elise for fun in the corners [which will almost be coming full circle: had a JPS Europa many many moons ago].

[BimmerBreaker]

I'm halfway there! To be honest I'd probably go with a Z4M roadster over the Z3M; the Z4 was designed from the start for the power, unlike the Z3 which was designed for a 1.9L four.

But what I really want for my roadster is a Lotus Elan.

Variety is the spice of life and in my opinion the engine that best compliments the refined character of the Z4 is the 3.0si - smooth, linear, predictable power in a very comfortable yet sporty and practical package - a great daily driver. The Z4M is a bit more numb and refined than the Z3M, it is definitely more capable but I've always found Z3's more fun and engaging to drive. Personal preference of course - but that's why I'd have the Z3M as the "fun " car and the Z4 coupe as a fun but comfortable daily driver

My garage will very soon consist of an S54 Z3 M coupe, S52 Z3 M roadster and a Z4 3.0si coupe. Just need the Z4...

[montaillou]

Just so you don't get the wrong impression, OP, the top motor isn't something that breaks every two years. My z4 is an '03 and I finally ran into top problems last year (though I think my problem is not the motor but the switch, just haven't gotten 'round to it yet).

If I didn't have the roadster, I'd have the coupe. Personal preference, I prefer the z4 lines over the z3. For my slice of variety, I just buy more cars which explains why I'm up to 2 cars a truck and a motorcycle.