BMW Z4 sDrive 35i Tuning help - 400hp?

[nathannjay]

Hey guys, this is my first post on here so please let me know if there's anything I need to do differently

I'll be buying an sDrive35i at some point in the near future to replace the current E85 roadster! The current E85 has been great fun but I'm ready for something a bit quicker / exciting. I intend on (hopefully) one day taking the newer 35i from the stock 306hp to closer to 400hp with aftermarket mods such as the JB4 PnP for the N54 engine.

One thing I'm unsure about is what sort of mileage car would this be unsuitable for? I've read some horror stories of owners modding their higher mileage 35i Z4s and blowing turbos among other problems :O

I'm budgeting for the initial purchase of the 35i but if you guys think I should avoid a higher mileage example then I'd need to spend more. It'd be great to hear if any of you guys have done similar and if you have any advice for a soon to be new E89 owner!

Thanks

Nathan

[Z4M-2006]

RE 92 is your man on this..

I wouldnt be happy just relying on the map to jump you 100bhp...

[Maniac]

I wouldn't take it to 400hp without looking at suspension too.

[35i-Nut]

you will need catless downpipes and Front mount intercooler to get 400hp otherwise your looking at about 360bhp

Look at the MHD tuning platform , Evolve have also tuned a few on here

I would defo look at suspension mods too , the 35i is a handful as it is in stock form

[Maniac]

Then add in an LSD

[nathannjay]

Thanks for the replies guys, yeah I did think those mods would be needed. I'm seeing some higher mileage 35i's on autotrader at the moment at the 70-80K range - what are your thoughts on this? What issues should i be looking for at these sort of miles? Do you guys have any horror stories for your own E89 Zeds?

thanks!

Nathan

[Z4M-2006]

The N54 is a strong unit..

Just the ancillaries bolted out it are a bit crap..

Fuel pumps
Injectors
Turbo's
Water pump
Vanos solenoids
Cam ledge bearings..

They can be troublesome, and when the boost gets wound up you naturally stress the components more

[Johnbmwz4]

Thanks for the replies guys, yeah I did think those mods would be needed. I'm seeing some higher mileage 35i's on autotrader at the moment at the 70-80K range - what are your thoughts on this? What issues should i be looking for at these sort of miles? Do you guys have any horror stories for your own E89 Zeds?

thanks!

Nathan

My 3.5i has 85k n the clock and is fantastic, no oil usage at all and pulls like a train. I wouldn't be put off with high mileage cars if they have been looked after

[Rockford]

My 35i is running Evolve remap and conservatively we stopped at 360bhp as I have a DCT gearbox. As 35i-nut says you need DPs and intercooler but 400bhp is certainly achievable.

My car now has 93k on the clock, runs perfectly and no signs of any trouble at all. Evolve had no hesitation in mapping the car, N54 itself is strong, just the bits around it that aren't (and could break on a stock low milage model).

[KERMIT1970]

I would do your home work on this one. My standard 35is with 340bhp was a handful on the edge sometimes, I had ecotune wanting to map mine but to be honest I think the chassis & brakes couldn't take much more without looking at suspension & brakes.

[Rob s]

Thanks for the replies guys, yeah I did think those mods would be needed. I'm seeing some higher mileage 35i's on autotrader at the moment at the 70-80K range - what are your thoughts on this? What issues should i be looking for at these sort of miles? Do you guys have any horror stories for your own E89 Zeds?

thanks!

Nathan

I dont know exactly what is available for the Zed but i had my 1 series at 400bhp with a 200cell sports cat, the JB4 and BMS intake (also had some m3 suspension bits). Im not sure how the standard IC performs but you might no need to upgrade unless you plan on prolonged hard driving/track work.
Other things to consider
1) tyres - stickier tyres could increase performance without the need to increase power as much.
2) Exhaust - with the downpipe changed the car will get louder add a sports exhaust and it could be very loud especially on cold start. How loud do you want it to be?
3) Turbos will need changing at some point on all turbo cars. Increasing the power will most likely increase the wear even if its only marginally so the more mileage the car has the sooner they will need changing.

[R.E92]

I've been using a custom MHD map for the last two years at 18PSI, tapering down to 14PSI. I've not been on a dyno but virtual dyno suggests between 410 and 420bhp which is in the correct ballpark for the boost and timing. I don't really car much for the headline power figure, just the way the car drives.

The engine is completely stock aside from the ECU tune, there's absolutely no issues reaching 400bhp without other mods.

The DCT can handle any power stock turbos can throw at it. The only stories of problems with DCTs on tuned cars are purely a result of bad tuners or people using the JB4 unit.

Personally I don't find traction an issue with the Z4. I'm using 9.5J width rears with some Michelin Pilot Super Sports and even in -2C temps and wet roads I can put down a reasonable amount of power, in 10C+ and dry conditions the car hooks up brilliantly. I wouldn't expect any more traction on a 2WD car.
Don't go expecting grip from the standard run-flat tyres or any non-performance all-season tyres. Expect to pay £150-£200 per corner for some proper tyres.

An LSD would be a nice upgrade but it's not as essential as most would have you believe. The current record holders for drag strip times in the N54 world are not using an LSD. For track use it would be a great mod but for people like me who just stick to the road I don't feel any inclination to make the change.

So far I've not had any reliability issues related to the tune. The car has had all the usual N54 failures, most of which before it was tuned, but none can be attributed to the increased power. The stock engine block is still having its limits tested above 900bhp and the DCT is being used on cars with 650-700bhp. Turbos will wear faster but that's a fact of life when you tune any turbo vehicle.
If you want to run more power then it's prudent to change the oil more often and put a fresh set of spark plugs in every 20k miles.

[Rockford]

Interesting and encouraging about DCT and output figures, thanks for posting.

I think the majority of negative feedback r.e. DCT tuning is as a result of piggy backs as you say. There is undoubtedly people complaining of slippage and premature failure but all running piggies.

Sticky tyres are worthwhile - on a warm day with Continental Sport Contact 6's I have no traction issues what so ever. On a cold damp winters day then it can slide a little on full throttle but not uncontrollable and just need to be a little progressive.

[Z4_35i]

We run ESS stage 2 for almost all of our 4.5 years of 35i ownership, no issues, awesome drive and performance, Eibachs helped, but still a lot of wheel spin in the wet

[Z4Rick]

I am the last person to ask about this since my experiance is limited. However, I have had some experiance with a massively over powered car and would urge anyone considering this type of mod to be dam sure your driving skills are up to the car's abilities. I have an over-enthusiastic friend, ( who is stupidly wealthy from the sale of his internet business), who, on a whim really, bought a pre-built Factory Five Cobra kit car with a Marcos Mantis supercharged 5.0L Coyote Modular V8 (500+HP and 460 ft pounds of torque). The car weighed 2200 pounds. He could not de-tune it enough to make himself comfortable and wrecked it in the first week of ownership. I had a chance to drive it - and passed. Dam thing scared me half to death. A 420 hp E89 is roughly a 7/1 HP/Weight ratio - "The Kraken", (my friends name for the Cobra) was about half that. He is the most experianced driver I know and has owned many high-HP cars in his 20 years of racing. He fixed it up and sold it as a dragster - not the track car he hoped. I asked him not long ago about the car...."Worst decision I ever made - I mean, REALLY, what the hell was I thinking?" He bought an Ariel Atom with the proceeds.... (His Daily Driver is a Ford GT - he pays $14,000 a year for insurance!!)

Having said all that, I just suggest you need to be honest with yourself. I am still learning the E89 35I after 7 months and will likely never consider mapping, but suspect 400+ HP makes that car a handful for most any driver I know. Just sayin......