Stick with 640i or swap to 550i?

[carbon83]

Hello everyone,

Some advice please.

I have a 2017 640i Gran Coupe, 47k miles. A nice spec, looks good (in my opinion) and drives well. It has a rock solid BMW warranty on it too since I purchased it through BMW (and am very confident of the BMW Approved Used warranty having had £6k of warranty work done on a previous BMW and £2k on this one!).
Not sure if this is true or not but I am not a fan of the fake engine noise as I think it has that active sound thing? Unless that was in the diesel only?

Anyway, an opportunity has come about where i can swap (+£1k) my 640i for a F10 LCI 2014 550i, 39k miles. I have done quite a bit of reading and it seems the main consensus is to stay away from this engine in the 550i, even if some improvements were made in the TU engine.

So my question is would you swap? The garage where the 550i is (it's not listed online yet so I cannot share the link) will give a warranty, extendable if I want, but of course will not be as good as the BMW extended warranty.

Thank you

[parabolica]

It's a healthy step-up in performance, but although the F10 is a handsome enough car, I'd prefer the looks of the 6er myself (ex-640i coupe owner speaking). If the 550i wasn't available, would you still be looking to change your car? Better the devil you know and all that, but given the two I personally would stick with the 6 series, unless you really want to scratch the V8 itch.

[bmwmike]

From what I've read I wouldn't touch a n63 engine myself. Check the warranty terms carefully as they often have limits which would be far below a set of injectors or a timing chain would cost to do.

F10 M5 with the S63TU is a more reliable bet as far as I'm aware..

Happy to be corrected and reliable is a relative term especially where BMW v8 engines are concerned!

[Touring442]

The N63 is....erm....'troubled'. In the US where they are more common they have been a disaster resulting in BMW buying back cars, upgrading the warranty, goodwill repairs etc. The problem is the heat from the central turbos cooking everything - stem seals, chain guides and ingenious turbo coolant pipes with plastic(!) Y pieces.

The 40i engine is a cracking thing and one of BMW's best.

[Court_S]

The B58 in the 40i series cars is punchy and pretty reliable other than a few minor bits like the coolant cap.

BMW V8’s don’t have a particularly great reputation for reliability, so I’d be wary as others have said.

[carbon83]

Thank you everyone.

It seems like I should stick with the 640i. Just to clarify that it is the N55 engine in my 640i.

Thank you.

[steve_n]

I've owned an F11 535i for a few months now, having spent the last five years in a C63 S204 6.2 Estate.

If you haven't tuned the engine at all then this is what you should do. As standard it feels a bit limp. OK I had a mighty engine to compare it to but my N55 now feels swift enough to enjoy.

I'd recommend a metal charge pipe (they break on standard boost), MHD tuning package and their WiFi adapter, plus a bigger intercooler. That'll still be within the limits of other things like fuelling so isn't that expensive overall. I've also got a sports cat coming as that'll unleash the last stage on the MHD remaps.

After those upgrades it feels a lot more big chested like a V8, lots of torque in the mid range. Sound is a subjective thing but I'm just as happy with a six as an eight.

[Stephen-733s2]

steve_n said:

I've owned an F11 535i for a few months now, having spent the last five years in a C63 S204 6.2 Estate.

If you haven't tuned the engine at all then this is what you should do. As standard it feels a bit limp. OK I had a mighty engine to compare it to but my N55 now feels swift enough to enjoy.

I'd recommend a metal charge pipe (they break on standard boost), MHD tuning package and their WiFi adapter, plus a bigger intercooler. That'll still be within the limits of other things like fuelling so isn't that expensive overall. I've also got a sports cat coming as that'll unleash the last stage on the MHD remaps.

After those upgrades it feels a lot more big chested like a V8, lots of torque in the mid range. Sound is a subjective thing but I'm just as happy with a six as an eight.

Surely that would void the BMW warranty which the original poster seems very keen on?

[steve_n]

Yep, guess you can't do that then. I'm willing to bet a fair amount more than £2,000 has been spent on the warranty though.

[carbon83]

Thanks both. Yes indeed, I do not wish to interfere with the engine or mapping (or anything else) to preserve the BMW warranty.

Thank you.