Atacama Yellow 35is build thread

[B21]

So if you want to know in detail what spending over £7k on bigger turbos, bigger exhaust system, bigger inlets, outlets, bigger intercooler, better ignition syste and better LPFP gives you then its about 150 BHP more than a stock 35is and 180nm torque..or put it another way £500 gets you the first 60 BHP and the next 90 BHP costs £6k+..you can all now leave..

For those that stayed..

So my tame tuner Richard aka carabuser on certain forums has with me iterated slowly through 6 revisions of tune..we are now at 20.5 PSI boost on 99 RON fuel, running very sweetly.

Took the car to the dyno guys today (Met with Nanu there)..and we did three sets of runs on V4 (As its called) of Richard's tune..with stock airbox and filter, with a Pipercross foam filter and with the airbox lid off..ie fresh air into the inlets..

The dyno results are on the graph shown, and for reference included the old MHD V10 stage 2+ maps with its best figure (lid off).

So its a 500 bhp 700nm torque engine now (there's is a liitle more tweaking to be done, but we are really as far as this is going to go..that is reliably, forever and with absolutely fabulous driving ability..

The price of discovery is usually high..no regrets..but I think tuning wise, subject to fine details we are done..

Enjoy..

https://youtu.be/o88ldXzhpe4

[Pondrew]

you can all now leave..

I left!
Carry on..............

[B21]

you can all now leave..

I left!
Carry on..............

I realise that the executive summary would be useful to those whose time is precious

[sars]

Executive Summary, He's spent £6k getting a little more Nm of torque at a higher and broader RPM range over the £500 on the MHD 2, though I bet that's quite a noticeable improvement in acceleration, overtaking and drivability, shame it's not a manual.

I wonder if it would have been cheaper to drop a B58 in there and a remap

[B21]

Executive Summary, He's spent £6k getting a little more Nm of torque at a higher and broader RPM range over the £500 on the MHD 2, though I bet that's quite a noticeable improvement in acceleration, overtaking and drivability, shame it's not a manual.

I wonder if it would have been cheaper to drop a B58 in there and a remap

Hi SARS…yes the B58 is a pretty marked improvement on the N54..unlike the N55…

There has been discussion on the more technical forums about it but the electronic integration aspects of it effectively preclude it…assuming you could get the physical bits to line up…

So sadly I’ll just have to limp on…

If BMW had made a G29 in yellow them history may have been different..

I’m trying to get the dyno guys to put the MHD v10 graphs on the same page as the TTE500 runs….

I have to say that the TTE500s have changed the character of the car somewhat as you can see it now wants to rev on..I did make it shift at 6750 before as it was pointless letting it rev…I’ll move it to 7k now..

It’s about st the limit of adhesion now..in 4th even with 275 sports contact 7 and Quaife lsd we are getting that yaw yaw feeling as you boot it as it tries to contain things..

Guess I could have spent the money on landscaping…

A manual box would have long given up..or at least the clutch..

It revs way to fast for manual changes…

As an aside the aftermarket exhaust system was quite boomy and resonant around 2k and the new turbos have softened that out a bit..

[Nanu]

As said previously, met up at the Performance Centre and like many, the technical stuff was beyond my limited comprehension.

For those that wanted an executive summary, that's easy, on a rolling road booted from standing to 145mph+ it sounded fantastic

Also agree a G29 in Atacama yellow would look good

[ronk]

Also agree a G29 in Atacama yellow would look good

What about a wrap if a particular colour is vital? Is a wrap expensive?
We do have a respected fella on the forum so perhaps he could give us the heads up?

[B21]

For those interested in how tuning is done …the car is put into manual 3rd gear and rolling at less than 2,000 rpm..it’s then booted at full throttle to the shift point, after the shift the run finishes..the MHD data logging strips out the before and after and gives a window with upto 80 variables that are recorded which then can be analysed after …

Afterwards the logs can be viewed within MHD or a custom viewer in this case Spoolstreet..

I’m showing todays logging which is the 8 th iteration of tune..the strategy to be safe and slowly increment variables to see how the engine responds…every engine is unique albeit with some common traits ..eg on the N54 normally cylinders 5 and 6 are more problematic as the gas flow to them is poorer and the back of the engine is hotter..

I’ve used the reader bar to show some data values…

You can’t graph all variables at one time as the scales get compressed and there’s too much clutter.

So there are several to show different attributes..

I todays run on a different road and I can see the rpm line is not as smooth previous ones as the car was riding less smoothly..

We can see on one chart rpm, called for boost pressure and actual boost pressure..this is a good graph as the real boost pressure is pretty closely tracking the called for once we are underway….at the beginning we have the lag effect of what’s called for and what’s available falls short.

We have a graph showing high pressure fuel flow ..this is a mechanical pump with no speed control ..the good news is we above 1,500 psi all the time we need it..running low could result in melted pistons…

We have a graph showing ignition deviation per cylinder from the planned timing...corrections are common and there’s a trade off between not enough power and too many corrections..note the odd rogue one..

Another graph shows waste gate duty cycle ..100% is waste gate fully closed ..this should only occur when initial boost production…a good rule of thumb is to be at 50% ish when going full chat..showing your turbos are working too hard..

The air intake temperature graph is a function of how good your intercooler is, how hard your turbos are working and how cool the air coming into the intakes are..

In this case we have excellent control…bearing in mind this is in F and we can get upto 300c air temps leaving the turbos if it’s all going bad..

Enjoy..

[B21]

Got a set of 437Ms in the usual diamond cut version with minor cosmetic damage on one wheel for a good price…

Checked for bends n cracks then refurbished..

Ignored the masses with their recommendations..went with Graphite …rather pleased..nice set of 235/35 19 and 275/30 19 Conti Sports Contact 7s…went with 235 to lighten the steering a little and lower the nose..

Looks great in the sun n shade …will have to see how they look on the Yellow Peril in due course..once the other tyres have worn down…

[Silverstar]

I am sure graphite will look great with yellow!

[Miyli]

It's great that you got the updated turbos, good power
went to sell mine and got a small engine g29 instead

[B21]

It's great that you got the updated turbos, good power
went to sell mine and got a small engine g29 instead

Yes a B58 engine has more potential…but I just don’t like the looks of the G29..so that’s a no for me..

Here are the integrated graphs for stock, best of MHD V10 and the TTE500 turbos do far..

[Nanu]

The Graphite should look great with the yellow, less harsh than the straight black IMHO

[B21]

The Graphite should look great with the yellow, less harsh than the straight black IMHO

Yes I’m thinking it’s the solution…

[sars]

Those graphite wheels are just lush