Z4M - 380bhp from a chip, filter & exhaust?

[mmm-five]

I'd guess the actual figure is less than 350bhp, assuming it's being run on fresh super unleaded on a kosher dyno (I've had 290-340bhp from my 3.8 M5 over the years, and I know how to strap a car down or how to use different 'correction factors' to make it raise/lower the result). Did the tuner do a live mapping, adjusting the fuel map specifically for your car over a number of hours, and did they do this again when they put the 'intake' on, and again when the exaust was fitted, or did they simply put a 'superchip' in?

The intake will give you 1-2bhp (but I'm being nice so we'll say 5bhp), the exhaust (if it's just the rear pipes and you having put racing cats on) will give you about 5bhp, and the remap might give you 10bhp - so we'll say a total of 20bhp for a final figure of 363bhp.

However, it's not that simple - most power claims by mods are not cumulative.

And don't forget, that this is all assuming the car had the factory 343bhp to begin with - I've known S54 engines to be tested on engine dynos (i.e. not through the wheels) with figures from 330bhp to 350bhp. So you may have 343bhp after the mods, or you may have 360bhp.

There's only one thing I'm certain of, and that's that you won't get 380bhp unless you've slipped in some new cams, crank, valves, etc. and reprogrammed/removed the VANOS.

Personally I'd pay LESS for a modified car than for a standard one, as I'd assume it'd been driven harder, and would not know the quality of the work gone into it, nor whether BMW would honor any powertrain warranty claims - after all if you do have 380bhp (with a corresponding increase in torque) then you may have similar problems to the owners with chipped 335/535Ds where BMW have refused their claims for damaged transmissions as they're putting more power through them than they're designed for.

 

[Beedub]

i would say about 350! anythink more than that is poo, i dont think ive seen a 380+bhp s54 engine that hasnt had 6k+ spent on it! simple as that.

 

[Mr Whippy]

350bhp for me.

That K&N filter, of all the mods, is the killer one for me.

A remap might give 5bhp or so, on this racey engine. The exhaust maybe 10bhp too, tops. But then lets imagine the engine might only make 330bhp as standard... 340-355bhp is more realistic.


BUT, that K&N will probably COST a great deal of any power gained.

The ram air benefit is lost, which will add up at speed, and under static conditions it will be a nice 'hot air' intake system.


I've seen on cars with similar quality ram-air intake systems (OEM), intake temps remain about 0-1degC above ambient, from 0deC to 25degC conditions in the UK.
Ones that have been logged with K&N cones (even with the old ram feed pointing at it), remain around 20degC above ambient even after 5 mins of driving steadily, so 5-10degC ambient and 25-30degC intake.

Doing some quick maths, 273+5 / 273 + 25 = 93% air mass change ~ 93% of 350bhp ~ 326bhp... or 25bhp loss. That is a huge potential loss. Even if it allows 10bhp more at high rpm due to flow, it could so easily cost that + more due to being a hot air intake!
I'd love to do a logging session on the Z4M for ambient air temps K&N vs OEM...


Honestly, whoever sells ANYTHING like that in this day and age, is a bad tuner. And then that leads me to worry about what they actually did for the remap too, and the rest of the claims

Before/after @ wheels independent dyno is what I'd want as proof, and I'd want one for each change too, so I could see the cumulative effects.


Bad tuning imho... you need to offer impartial advice, and be open to your customer base and customers. If your work doesn't stand up to scrutiny, then you are not doing your job well imho...



Since this thread is about the car in the classifieds, it'll be a nice car, it just needs reverting imho. I don't get tuners who do such shitty jobs, because not all customers ARE clued up on things, so I don't blame the owner. The tuner should act more honestly imho. ESS, Dinan and the like get my respect because they don't bullshit.
All those that do bullshit simply make me think they are liars, and I have good reason to believe ESS and Dinan because they DO show their proof! That is why I will always recommend them, but none of the others, simply because their lack of proof means they have something to hide, or simply don't know!

Dave

 

[Darren M]

Who is the poster who selected <340bhp - you pessimist.








(he says while hoping user info isn't logged with the vote )

Justification, is : often modified cars don't quite work as well as they should, power can be lost more easily than gained. So I take a risk and say <340bhp . I am semi-joking though and hope I'm wrong and it does indeed have more

I don't think you can accumulate the power either. If a remap does give 15bhp and cone 5bhp, that doesn't necessarily mean a total of 20bhp increase, you may for example just get a 5bhp somewhere else in the range which is below peak power anyway.

 

[AlanJ]

Good tuning is a dynamic process which ensures all parts work in unison to mutual and maximum benefit. There are not many bolt on parts that in my experience (and it is limited in this field) that have any significant and noticeable individual effect. I would defy any competent driver to identify a 5bhp gain across the engines rev range - professional drivers’ maybe but how many are there out there in this forum of mere mortals.

We can perhaps achieve sharper throttle response, cleaner burning engines etc with minor modifications and nice sounds from a throaty exhaust (watch You Tube - its not about increased speed but the sound) – but tell you insurance company that on a Z4 you have altered filtration, exhaust or engine mapping and get ready with your cheque book. Many high performance vehicles are certainly not taken to the limit (or anywhere near) their performance capability because us mortal drivers (that’s about 99.99999% of us, ME INCLUDED) do not have the driving ability to explore their full potential. From my professional work in the UK I have some stunning photographs of those that thought they could and failed often at the expense of innocent others.

The only people who benefit from wild exaggerations of performance improvement or engine enhancement are those that sell the bits – they laugh all the way to the bank! RANT OVER

NOISE AND EXHAUSTS I REST MY CASE..... http://www.z4-forum.com/forum/viewtopic.php?f=23&t=16112

 

[adjenkins]

I am getting my Z4M car remapped on saturday by a local tuner. Claiming around 18bhp increase. To be honest I'm not all that bothered about the actual HP increase but more in how the car feels after the remap. I have used this dealer before with great results. He has done plenty of M3's and believes the remap will give a noticeable improvement when driving. It is a custom remap setup on a dyno.

Was planning on changing the Zed recently but for the money couldn't find anything better or more fun. Going to throw a few £'s at the car to put me off changing for a couple more years until perhaps prices of sdrive35is lower.
BMW dealer going to attempt the cruise retrofit on Friday as well.

 

[mmm-five]

I am getting my Z4M car remapped on saturday by a local tuner. Claiming around 18bhp increase. To be honest I'm not all that bothered about the actual HP increase but more in how the car feels after the remap. I have used this dealer before with great results. He has done plenty of M3's and believes the remap will give a noticeable improvement when driving. It is a custom remap setup on a dyno.

Making a remap 'noticeable' is one of the easiest 'tricks' in the trade. You simply make sure there a sharp peak where there wasn't one and even if the actual power at that point is lower, the owner will feel it as a sudden rush of power and think they've got more.

It's a similar feeling you get when your on half throttle and you feel the different VANOS profiles coming on at 2000, 4000, etc.

They can reduce the fueling slightly on the rise to 4000 and then feed it back in at the changeover point so instead of feeling a rise from 200bhp to 210bhp, you get 190bhp to 210bhp (not those figures, but simply examples).

Unless you get a dyno print of the the before after runs (not forgetting that the car has an adaptive mode anyway) you won't know where they've added power, and I'd guess that 18bhp they're claiming is not at your peak, so you won't suddenly get 360bhp (unless they've fitted a CSL engine while you weren't looking) at 7900rpm, but you might get an 18bhp rise at a point where the fuelling is not particularly good - say 3000rpm.

And please note, that most of these remaps will not come with any warranty on consequential loss - if the chip breaks you might be covered for that cost, but good luck if you're engine grenades and BMW find you have had your car remapped (and walk away if they claim they're undetectable).

 

[EdButler]

350bhp for me too, agree with mmm-fives comments about tuner 'tricks' and optimistic estimates.

The only circumstance id ever get an NA car remapped is where its strapped down to a dyno, lambda in the pipes, and it doesnt come off until its done start to finish with the Tq/Hp/Lambda comparisons.

 

[AlanJ]

So how much does your insurance company charge you when you tell them you have had a re-map....? Oh....you do tell them don't you

 

[pvr]

It was undetectable remember

 

[adjenkins]

So how much does your insurance company charge you when you tell them you have had a re-map....? Oh....you do tell them don't you

:lol: I did actually inform them & got an email confirming. No cost. With a remap on a prior car I informed them as well although I guess many (most) don't. Car just out of warranty so less of a concern. I guess all I'm looking for is a "feeling" of more power / acceleration. As long as the remap is done well and doesn't adversely impact the engine I think it is worth a few hundred pounds.