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2.5Si or 3.0Si

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Mr Tidy
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2.5Si or 3.0Si

Post by Mr Tidy » Tue Nov 28, 2023 10:35 pm

coldel wrote: Tue Nov 28, 2023 10:36 am I had an E86 3.0si with 60k miles on it and then bought an E85 3.0si with 115k miles on it and to be honest you are hard pressed to notice the difference in terms of engine delivery.
I missed this earlier but I'd agree based on my experience.

My first E86 had done 54K when I got it and my second had done 91K when I sold it and I really didn't notice any difference in how they performed.

As far as economy is concerned over the 7,000 miles I did in my 325i compared to the 16,000 I've done in my 330i there has been less than 1 mpg difference. And my E86s were both within 1 mpg of them, despite getting driven a bit more enthusiastically! (I'm one of those sad people who keeps an Excel spreadsheet). :roll:
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coldel
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2.5Si or 3.0Si

Post by coldel » Wed Nov 29, 2023 10:58 am

It really depends on the suspension done OP, if you post the car up we can help a lot more :D

If they have thrown springs onto OEM shocks then it could cause problems, depends on the spring rate and condition of the OEM shocks. If they have gone the full matched coilover route, it would depend on the type of coilovers you have there as they come in different specs and models.

Generally I have found that springs on OEM springs create a harder ride (as they tend to lower the car) and will increase wear and tear. I put some on a previous car and the front top mounts failed twice in the space of 18 months. Cause of coincidence, who knows.

But generally I wouldnt be paying extra for a car because the current owner is pointing as some aftermarket springs, in answer to your original question.
Currently BMW Z4 E85 3.0si
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2.5Si or 3.0Si

Post by Abbas » Wed Nov 29, 2023 12:06 pm

As others have said, I wouldn't focus on mileage too much and instead look at service history, maintenance work done, and just overall ownership. I know when I was looking for my E86, there was some with very low mileage at dealerships and charging ALOT, so you'd expect them to be pristine but the MOT history was salty as f and so was the service history. Sometimes having a high number of previous owners isn't always a bad thing either, as one way you can look at it is that every owner bought it for a bit, spared no expense, babied it and then sold it on. Rather than one owner who didn't really care all that much and kept it for 15 years.

This video may also help as he compares the 2.5 and 3.0 > https://www.youtube.com/watch?v=Lh5noZ6HBGE
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2.5Si or 3.0Si

Post by coldel » Wed Nov 29, 2023 12:15 pm

Note that video is not comparing the SI versions which are significantly different. :thumbsup:
Currently BMW Z4 E85 3.0si
Previously
BMW Z4 E86 3.0si
Vauxhall VX220 Turbo
Toyota Celica ST205 GT4
Nissan R33 Skyline GTST
Vauxhall VX220 NA
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True-Blue
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2.5Si or 3.0Si

Post by True-Blue » Wed Nov 29, 2023 12:22 pm

I’ve owned both, 3.0Si all day long… :thumbsup:
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2.5Si or 3.0Si

Post by pvr » Wed Nov 29, 2023 12:26 pm

True-Blue wrote: Wed Nov 29, 2023 12:22 pm I’ve owned both, 3.0Si all day long… :thumbsup:
Very much so. The weekend loaners I had when they came out, was the 2.5 litre engine and it fell very sluggish compared to the 3.0
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2.5Si or 3.0Si

Post by Abbas » Wed Nov 29, 2023 12:34 pm

coldel wrote: Wed Nov 29, 2023 12:15 pm Note that video is not comparing the SI versions which are significantly different. :thumbsup:
Ah yes, fair point!

Overall, if both are within budget, and reasonably clean, and sensible things like fuel economy etc aren't a deciding factor. Only one way to go ;)
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2.5Si or 3.0Si

Post by True-Blue » Wed Nov 29, 2023 12:39 pm

pvr wrote: Wed Nov 29, 2023 12:26 pm
True-Blue wrote: Wed Nov 29, 2023 12:22 pm I’ve owned both, 3.0Si all day long… :thumbsup:
Very much so. The weekend loaners I had when they came out, was the 2.5 litre engine and it fell very sluggish compared to the 3.0
The 2.5Si feels a bit like an S2000 engine that doesn’t rev as high and isn’t as manic at the top end. It’s a very smooth experience, much better than the 2.5 non-Si, but lacks torque. You’ll probably be eaten alive by something like a Fiat 500 Abarth :|


The 3.0Si would be my choice for sensible real world performance at a palatable price, the additional power is noticeable :D


Condition and service history/maintenance over mileage OP.
Alpina Roadster S Lux no. 204 (1 of 15 uk cars in Alpina Blue)

Previous Z4’s :E89 30i, E89 20i, E85 3.0Si (X4) E85 3.0i, E86 3.0 Si, E85 2.5si, E85 2.5i

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2.5Si or 3.0Si

Post by sars » Wed Nov 29, 2023 9:55 pm

Funny I found the 2.5Si more zingy than the 3.0Si, shorter stroke etcetera
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2.5Si or 3.0Si

Post by True-Blue » Wed Nov 29, 2023 10:08 pm

sars wrote: Wed Nov 29, 2023 9:55 pm Funny I found the 2.5Si more zingy than the 3.0Si, shorter stroke etcetera
What do you mean by ‘Zingy’

The shorter stroke does make the 2.5Si more ‘sewing machine’ revy like the Honda, but the 3.0Si is a significantly quicker car
Alpina Roadster S Lux no. 204 (1 of 15 uk cars in Alpina Blue)

Previous Z4’s :E89 30i, E89 20i, E85 3.0Si (X4) E85 3.0i, E86 3.0 Si, E85 2.5si, E85 2.5i

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2.5Si or 3.0Si

Post by sars » Wed Nov 29, 2023 10:41 pm

Sewing machine, really, are you twelve years old :D how can you describe a 215 bhp six cylinder engine as a sewing machine :poke:

and my meaning of zingy, an engine that revs freely. Also the difference in performance between the 2.5Si and 3.0Si is similar to the difference between the 3.0Si and the Z4M, and many 3.0Si owners on here have argued that that was enough. IMHO all the six cylinder models offer lively performance and the OP won't be disappointed with any of them.
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2.5Si or 3.0Si

Post by True-Blue » Thu Nov 30, 2023 12:26 am

sars wrote: Wed Nov 29, 2023 10:41 pm Sewing machine, really, are you twelve years old :D how can you describe a 215 bhp six cylinder engine as a sewing machine :poke:

and my meaning of zingy, an engine that revs freely. Also the difference in performance between the 2.5Si and 3.0Si is similar to the difference between the 3.0Si and the Z4M, and many 3.0Si owners on here have argued that that was enough. IMHO all the six cylinder models offer lively performance and the OP won't be disappointed with any of them.
‘Sewing machine smooth’ revs freely… like a sewing machine… it’s not a slur! I’m not saying it’s got the power of a sewing machine FFS :rofl:

There’s a marked difference between the 2.5Si and 3.0Si
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Previous Z4’s :E89 30i, E89 20i, E85 3.0Si (X4) E85 3.0i, E86 3.0 Si, E85 2.5si, E85 2.5i

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2.5Si or 3.0Si

Post by Mr Tidy » Thu Nov 30, 2023 1:08 am

sars wrote: Wed Nov 29, 2023 9:55 pm Funny I found the 2.5Si more zingy than the 3.0Si, shorter stroke etcetera
Admittedly I've only had both in a 3 Series but despite the longer stroke I've found the 3 litre far more "zingy" than the 2.5 because the 2.5 took some time to get back up to speed and didn't rev any higher!

2.5 made a claimed 215PS at 6,500rpm, 3 litre was 258PS at 6,600rpm. But the torque was way better for the 3 litre with 300Nm at 2,500rpm rather than 250Nm at 2,750rpm for the 2.5. And as they were both very high-geared 70mph in 6th was around 2,500rpm so my 2.5 just felt a bit gutless. Accelerating in that from 60 often meant dropping down a gear or two but my 330i just goes.

Claimed outputs for facelift Z4s were 218PS at 6,500rpm for the 2.5Si and 265PS at 6,600 rpm for the 3.0Si with torque at 250Nm @2,750rpm for the 2.5Si and 315Nm@2,750rpm for the 3.0Si, but they are also lower geared than my E9*s.

Put simply I'd just get a 3 litre!
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2.5Si or 3.0Si

Post by deltasierra » Thu Nov 30, 2023 9:45 am

There is a big difference in torque 180 v 230ft/lbs that’s to be expected with a short stroke engine, in the real world on the road you have to change down a lot more because under 3000rpm it’s not quick. Change down and use the revs and it’s quick enough but there are going to be hot hatches that are quicker, wether you have a 2.5 or 3.0, to be sure of putting them down you need a Z4M. So decide where your price point is, today a decent 2.5si is going to be £5k+, a 3.0si £7k or a Z4M £15k.

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2.5Si or 3.0Si

Post by coldel » Thu Nov 30, 2023 3:00 pm

So buy a 3.0si, enjoy the extra performance, make sure its in great condition, and enjoy the fact you didn't get sucked into focusing on mileage when you are wringing all that extra power out the N52 :thumbsup:
Currently BMW Z4 E85 3.0si
Previously
BMW Z4 E86 3.0si
Vauxhall VX220 Turbo
Toyota Celica ST205 GT4
Nissan R33 Skyline GTST
Vauxhall VX220 NA
Nissan 350z

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