125i - one of BMW's best engines?

[SonicHedgeHog]

Bit of a dumb title to the thread but never mind. Following on my other thread, does anyone have a 125i? If I'm honest a 135i might be overkill (nothing wrong with overkill), and the 3 litre NA straight six might be more like the kind of thing I'm after. Is it a (very) good engine or has it been reined in so as not to step on the toes of the 135i?

[cheadle hulme]

I guess you're looking at coupes? The x30 engine is generally considered the step down from the x35. They have 265bhp whereas the x25 engine has 214bhp IIRC.

The 130 is a peach, but doesn't come in coupe flavour.

[andyscole]

I have been told that the only difference between the 125i (3 litre)engine and the x30i engine is a remap. So you can get to nearly 280bhp from your 125i so i think it's a great engine/car combination. Marginally down on power to the 135i but lighter, better economy and na.....

[andyscole]

I'm not 100% on the current 125i lump, but in the recent past, detuned versions of BMW's 3.0 lump in the e9x had more differences than merely an ECU map. To quote wiki, the detuned versions of the N52 omitted "the variable resonance system, dual plenum intake runner system, and the variable back pressure muffler."
[/quote]

I agree that normally the engines have a few internal differences but have my car booked in with Will at p torque this thursday. I was saying 20bhp extra was impressive for an na and he then told me about the 125i. He said that it wasn't well known but had done it to a customer's 125i. impressive as as you said a 130i is preferable to a 135i...

[abarber]

Well, make sure you get before and after dyno runs to see what your money has bought you.

In the states, plenty of folks have tried chipping the 328i, which is the 330i N52 engine without the variable intake manifold, etc, and not got great results.

At least one chap has done the full conversion, including hardware which worked. Check e90post.

[andyscole]

abarber said:

Well, make sure you get before and after dyno runs to see what your money has bought you.

In the states, plenty of folks have tried chipping the 328i, which is the 330i N52 engine without the variable intake manifold, etc, and not got great results.

At least one chap has done the full conversion, including hardware which worked. Check e90post.

Had the remap done and the gain are very very impressive, so unsure why the in the states they struggle. Got 25.6 more horses and 20 more torques!!!

[andyscole]

anonymous said:

[redacted]

My car is the 330i so it's 280bhp and 241lb now and had before/after rolling road. When i was talking to him he mentioned the 125i engine power gains not that i've got one. I tell you what though, auto's sap the power more than i thought....

[MKIVALEX96]

I'm no expert, but I've seen that essentially the engines in UK 125i's (and possibly elsewhere?) have the same hardware as 130i's, whereas in the US they don't have the same valves.
I've read of people and companies mapping 125i's in the UK to 130i figures (280 ish bhp and 260 ish lbft)

[stemplar41]

• you're

[Earthdweller]

stemplar41 said:

*you're

The grammar Police are 18 months late

Top lurking by the way

[Mr Tidy]

Random resurrection, but then the N52 is still a great engine over a decade later!

[Court_S]

Yup….that’s one hell of a thread resurrection,

Had my other half’s 125i remapped and it made a massive difference to the car.