My car, as below, has one of these, and I find I have to work it a bit hard, it doesn't have the kind of low-down torque that gives the kind of effortless motoring I prefer. Tuning options seem to be pretty limited AFAICS, and BMW seem to have deliberately dialled down its power in comparison to the N52B30 which is generally regarded as excellent. I am looking to go to E89 35i unless some options emerge. Views?
Is the N52B25 engine a bit of a dud?
- Thread starter Storini
- Start date
theres only so much you can do with a 2.5 litre naturally aspirated engine! though that said, 174bhp is less than 70bhp per litre, when it could be 80 or even 90.
but for low down torque and effortless motoring, sounds like you need a turbo. the 35i will be a rocketship compared to what you're used to - with a remap it'll make twice the power that an N52B25 does.
but for low down torque and effortless motoring, sounds like you need a turbo. the 35i will be a rocketship compared to what you're used to - with a remap it'll make twice the power that an N52B25 does.
A quantum remap will get you a bit more of a kick low down in the rev range and makes the engine feel noticeably punchier from 2.5k rpm , still a bit slow to pick up from stand still but the power comes in earlier and if you keep it spinning its actually a decent little engine..that said if you want the lazy effortless torque then turbo is the only way to go really, I actually prefer trying to wring the things neck when i want a bit of fun, adds a bit of fun to the equation for me 
:driving:
:driving:comes in three different flavours i can see
N52B25
130 kW (174 bhp) Applications:[17][18]
2006-2008 E85 Z4 2.5i
150 kW (201 bhp) Applications:
2009-2011 E89 Z4 sDrive23i
160 kW (215 bhp) Applications:
2005-2008 E85 Z4 2.5si
https://en.wikipedia.org/wiki/BMW_N52#N52B25
certainly the lowest powered is a bit wheezy, 215bhp in the 2.5si isnt so bad.
Though, still sounds like the OP would be way better off with a N20B20 engine, with a turbocharger...
https://en.wikipedia.org/wiki/BMW_N20#N20B20
N52B25
130 kW (174 bhp) Applications:[17][18]
2006-2008 E85 Z4 2.5i
150 kW (201 bhp) Applications:
2009-2011 E89 Z4 sDrive23i
160 kW (215 bhp) Applications:
2005-2008 E85 Z4 2.5si
https://en.wikipedia.org/wiki/BMW_N52#N52B25
certainly the lowest powered is a bit wheezy, 215bhp in the 2.5si isnt so bad.
Though, still sounds like the OP would be way better off with a N20B20 engine, with a turbocharger...
https://en.wikipedia.org/wiki/BMW_N20#N20B20
Any idea why the e89 n52 is slightly lower on power than the e85 n52?
Another thing to consider is the servicing of the car.
Is it decent parts and oil that's used? Tyres in good condition and at the correct tyre pressure?
All these things could cause poor performance.
Have you had a chance to drive another car that has the same engine to compare them?
It may well be that it's not what you need and will prefer the pantomime horse e89.
Is it decent parts and oil that's used? Tyres in good condition and at the correct tyre pressure?
All these things could cause poor performance.
Have you had a chance to drive another car that has the same engine to compare them?
It may well be that it's not what you need and will prefer the pantomime horse e89.
If you have the N52 2.5 engine, i believe there are some small changes (manifold?) you can make (taking parts from the 2.5SI) to get the 218 BHP delivered in the si cars.
The 218 doesn't feel lightyears apart from the 3.0si's 265.
The 218 doesn't feel lightyears apart from the 3.0si's 265.
Storini said:
As above, there is. Your Z4 has a fair bit more torque for it's weight than the X3. Sounds like you needed to buy the auto, or a turbo as above.
FWIW, I drove a friends X3 3ltr auto a couple of hundred miles last and found it pretty gutless to be honest. It had to kick down to accelerate up the slightest incline on the motorway. Better not mention the ride either.
only just clocked on the OP has a facelift 2.5i which is probably a little wheezy compared to the si 
Storini said:
Sadly I think it may be, but the 2.5i in the facelift isn't a detuned 3.0Si, it's actually a detuned 2.5Si because both the 2.5s are 2.5 litres - the 3.0Si is a 3 litre.
I think it was intended as an entry level 6 cylinder to replace the pre-facelift 2.2i becuase it barely makes any more power than that. Also from what I have read on here there is no simple or cheap way to get it up to 2.5Si power output.
A few years ago I bought an E91 325i with the same engine as the 2.5Si Z4 and found that underwhelming, but the extra weight and stupidly long gearing probably didn't help. In 6th it was only revving at 2,500rpm at 70 and if I got baulked by slower traffic on A-Roads or Motorways it struggled to get back up to speed, so I usually dropped it down to 4th! Anyway it only lasted a year before I replaced it with a 330i with the N52B30 which works much better.
But it worked much better still in my E86s as well as sounding much better than in the 3 Series!
I can understand the appeal of an E89 35i/35is but I think you'd notice a huge difference if you drove an E85 3.0Si, or even an E89 30i as either would give you another 80+ bhp.
Or you could think about an Alpina or MR. :lol:
Ah, well, let me bring up the other gotcha. WTF is the 6-speed manual gearbox so effing notchy? You would have thought after God-knows-how-many years they would have figured that one out. The cold weather doesn't help, but still.
And there's that wierd suction/vacuum thing with the clutch that tries to stop you stalling the car.
Yes @Mr Tidy, Alpina is fab but really rare.
So DCT for me I think...
And there's that wierd suction/vacuum thing with the clutch that tries to stop you stalling the car.
Yes @Mr Tidy, Alpina is fab but really rare.
So DCT for me I think...
Agreed on the gearbox, very agriculturalStorini said:
you'd have thought German engineers with a century of experience could do better than that