"In this entry, we hit the dyno and the S85-EVO gets tuned. We can finally answer our initial hypotheses on whether high duration camshafts make power, and if so - how much. I go in depth on the numbers and compare with various benchmarks."
- Matt 

Understanding dynos. 

Since the start of this Series, I've had conversations with various owners of S85s regarding the Sxx-EVO program. I sought to gauge reactions and questions to create the right content.

These conversations were evidently focused on dyno numbers, yet the overall misunderstandings on what dyno numbers actually mean was striking. I've lost count on the claims of factory freaks and unicorn'esque 500whp with bolt ons. 

To set the stage, an introduction to dynamometers is required.

Fundamentally, dynos are devices engineered to measure torque relative to rotational speed. In our use case, they are used as a tuning tool: we're looking for a before/after comparaison in a controlled environment to optimize engine management parameters.  

Chassis dyno types.

Most common to the automotive aftermarket are the chassis dynos, often referred to as "rolling roads". There are 2x primary sub types: inertia and load based. Dynojet is the common brand for inertia, while MustangDyne is the common brand for load based. 

Dynojet. 

The inertia type is straight forward: engine torque is derived from the car's ability to move the rollers to speed. Speed is converted to RPM and the graph is plotted.

Operators will use the gear closest to 1:1 ratio to eliminate the transmission's torque multiplication benefits. In an S85 SMG3, this would be 6th gear with a 1.00 ratio. 

As there are no operator inputs, DynoJets tend to provide the most accurate comparative tool between dyno when numbers are corrected. 

Dynojets will tend to read the highest across chassis dynos with an approximate 15% drivetrain loss for front engine, rear wheel drive and manual transmission cars. 

MustangDyne. 

Load based dynos offer additional flexibility as they can account for variations in load to simulate various driving conditions.

The MustangDyne's load cell adjusts load per gear. Consequently, the gearing's torque multiplication is nullified. The gear selected will solely influence the length of the run. If you're interested to learn more, MustangDyne has a 431 page manual here.

In short, they're not good for marketing: MustangDynes will read lower by 5 to 10% compared to Dynojets, and a total drivetrain loss of approximately 20%.

This is the dyno we selected for the development of tuning maps for the Sxx-EVO program. My choice was driven by operator experience and dyno accessibility. 

Notes on correction factors. 

Understanding correction factors is critical to properly assess dyno charts. 

Correction factors are determined by the Society of Automotive Engineers (SAE) using standardized weather parameters such as pressure, temperature and humidity to provide comparable figures for accurate comparaisons. 

In North America, we use SAE and STD correction factors. These standards will be selected by the dyno operators.

The increase in power will vary from to 2 to 3% from SAE to STD corrected numbers. Marketing savvy operators know numbers sell: DynoJets and STD correction factors are the steroid placebos of the dyno world. 

	SAE	STD
Pressure	29.60 InHg (100.2 kPa)	29.92 InHg (103.3 kPa)
Temperature	77°F (25°C)	60 F (15.5°C)
Humidity	36%	0.00%

As an example, the dashboard below showcases a Weather Correction Factor of 0.962. It is automatically provided by the dyno's weather station using sensors to continuously update the coefficient. The below 1.00 factor indicates our uncorrected numbers would read higher than average.

The uncorrected numbers were useful to demonstrate the MSS65's ability to adapt to colder temperatures. With the +/- 10C ambient temperatures, we experienced a +/- 5% power increase.

All of our dyno charts posted in this entry show weather corrected numbers using SAE standards.

For reference, DynoJet charts will indicate the correction factor on the top right of the chart while MustangDyne charts will indicate WCF next to Power and Torque numbers. 

Notes on crank power. 

In MustangDyne's chassis dynamometer software, engine crank power is a calculated value.

The overall gearing between the engine and the dyno's rolls has been calculated and used to scale the measured torque from a dynamometer roll shaft value to an engine crankshaft value. No correction factor are applied to account for drivetrain losses.

The formula used is: EngineTorque = ((DynoShaft Torque * DynoShaft RPM) / EngineRPM)

Notes on stock baseline. 

I have never dyno'ed my S85 in stock trim, neither have any other stock S85 been on this dyno. As such, the stock numbers provided in the table summaries will be a calculated figure from drivetrain losses.  

Nonetheless, upon scouring forums and social media, you'll find approximate drivetrain losses per dyno type will line up with theoretically calculated numbers. As an example, this thread offers realistic Dynojet numbers showcasing differences in correction factors for what is otherwise an original M5. 

Stock M5s will dyno +/- 400whp on a MustangDyne and +/- 430WHP on a dynojet with SAE weather corrected numbers.

Notes on FBO baseline. 

To set the baseline to a tuned S85, we used InnovAuto's 1 series drift car fitted with an S85B50.  

Their V10 is considered Full Bolt-On (FBO): it is equipped with catless headers and exhaust system. The orignal plenum was without any filters for optimal performance (not reliability). 

It uses the MSS65 DME in stand alone mode tuned for 91 octane pump fuel. It was performance tuned on the dyno with a hard rev limiter set at 8,500 RPM.  

Most importantly. this car had been tuned on the same dyno with the same operator - providing a reliable comparative baseline to evaluate performance gains.

This upgrade package provides on average a 10 to 12% power increase over stock, translating to +/- 50whp over stock on most dynos. 

The relatively flat torque curve has a slight dip in the mid range that leads into peak torque of 340wtq at 6,100 RPM. The original S85's camshaft durations run of out of breath by 8,000 RPM with a 450whp peak horsepower. There is no additional horsepower gain beyond.

Still, increasing the rev limiter to 8,500 is useful to benefit from gearing advantages and additional power under the curve.

Hypothesis 001: Can the MSS65 manage the high duration camshafts on its own?

S85-EVO baseline. 

Message boards of yesteryears have sporadic threads with comments about camshafts where claims are made that they do not provide any gains on the S65 and S85. 

To test this hypothesis, I uploaded an AlphaN tune with stock ignition timing tables and original 8,250 RPM rev limiter. The car was driven to allow adaptations to settle. As a reminder, AlphaN is an engine mapping protocol and does not provide power on its own. For detailed understanding, read the entry "Alpha V10".

S85-EVO untuned chart. 

The chart below shows our best run with the AlphaN mapping with standard parameters.

Peak torque of 345 wtq was achieved at 5,750 RPM and immediately dipped and trended downwards unevenly. The torque dip between 3,500 to 4,500 of a standard S85 was accentuated along with the torque ramp up. 

The rough torque curve generated an uneven power curve that cut off at the soft rev limiter of 7,900, approximately 300 RPM before fuel cut off.  It managed a respectable 448whp. 

This is more than likely where previous attempts at fitting cams to an S85 ended.  

Results 001: No.

The chart below compares the untuned S85-EVO with the tuned FBO S85. This comparaison was made to highlights the challenge of tuning ignition timing for high duration camshafts. 

It did not yield meaningful gains - and lost a significant amount of mid range torque. 

The MSS65 cannot adapt to new duration parameters on cams as the entire valve timing is mechanically different.

Instead, it will adjust valve timing based on knock, combustion quality, intake temperatures and other factors in an attempt to manage the high duration camshafts within the original parameters.

This chart is our short answer: no, cams did not provide gains.

Hypothesis 002: Can the MSS65 be tuned for high duration camshafts?

Addressing misinformation. 

Prior to diving into the tuning, I will address various comments I have read online about MSS65 and MSS60 VANOS timing tables being encrypted, undiscovered or simply unavailable. 

I cannot comment on where that idea comes from. My observation is they tend to come from individuals without significant experience with these engines. 

Ultimately, this is misinformation.

A good tuner will have those tables decoded and labeled to understand and adjust each parameters in relation to one another. As an example, here is my M3 V8 and its MSS60 being tuned for its S65-EVO program.  

Theoretical tuning. 

Prior to the dyno session, we developed a base map for the S85-EVO using the technical data provided by Schrick on valve lift and duration versus the original camshafts. 

Tuning for high duration camshaft is focused on valve overlap: the moment when the intake and exhaust valves are opened simultaneously. In a nutshell, we are looking to optimize airflow coming into the combustion chamber and the scavenging effects for exhaust gases to exit the chamber post combustion.

The higher duration camshafts give us the potential to maximize those parameters for high RPM use, unlocking top end power. To make use of the higher durations, we increased rev limiter to 8,500 RPM - the usual rev limiter for conventional off the shelf maps.

Results 002: Yes.

Preliminary tuning gains. 

Prior to the first runs, we proceed with warming up the car to its operating temperatures and begun testing for partial throttle complete runs. This allowed us to adjust timing parameters before going wide open throttle.

The gains over the original map were staggering: 493.8 whp at 8,130 RPM and 362.7 wtq at 5878 RPM. 

Most importantly, the torque curve was smoothened out making for a steadily increasing horsepower curve. 

A keen eye will notice a unique feature of the power curve: the rate of horsepower increase didn't falter as we hit the soft rev limiter at 8,150 RPM. This was far different to original cams that peak at 7,800. 

We concluded more power could be found higher up in the rev range.

Hypothesis 003: Will we continue making power at higher revs?

Notes on soft rev limiters.

The MSS60/65 DMEs integrate soft revolution limiters that pull ignition 200 to 300 RPM prior to complete fuel cut off. The soft limiter's purpose is to protect the internals from abrupt, rapid changes at high revolutions.

This is visualized on the charts with the steep downward slopes on the horsepower and torque curves. While we increased rev limiter was increased to 8,500 - horsepower peaked at 8,150 at the soft rev limiter.

To better understand the soft limiter and fuel cut off dynamic, I've uploaded the video below upon testing for 8,800 RPM.

Close to the mid way point between 8 and 9, you can hear the DME pulling power and letting it rev to 8,800, making it appear as if we are revving to 9,000 - we were not. 

Results 003: Yes. 

Our next test was to evaluate whether the high duration camshafts would continue making power at higher revs. We increased the fuel cut off from 8,500 to 8,800 RPM. This would allow us to test fo ran effective 8,500 RPM soft rev limiter. 

The increased of revs correlated to a steady increase in power: we crossed the 500whp mark with weather corrected numbers, hitting 522whp uncorrected.

500whp on a DynoJet is an extremely strong S85 with high likelihood of fudged correction standards. 500whp weather corrected on a MustangDyno is unheard of.  

Per MustangDyne's calculations, this resulted in a crank horsepower figure of 627 hp.

Sustained rate of increases. 

Previously, we gained +/- 30whp from 7,000 to 8000 RPM with a 3whp per 100 revs. This time around, the extra 300 revs provided us with +/- 8 whp for a rate of 2.67whp per 100 revs. 

The very slight decrease is due to the heat building up into the S85's cooling system after 2 hours of intermittent full throttle runs.

Our tests indicate a strong likelihood more power could be achieved by revving higher. We chose not to for reliability purposes. This is where our testing ended on this round of dyno tuning.

The charts below compare the final S85-EVO tuned run versus our S85-EVO baseline with the original engine map on AlphaN protocols. 

Notes on higher revs & reliability.

The variables to sustain higher revs are many: the block's alloy, bore treatment, block design, rotating assembly weight & balancing, fasteners strength, oil rating and circulation, cooling system, etc.

As rule of thumb, the leading variable to evaluate an engine's capacity for higher rev limits is its piston speed. The formula is driven by stroke length and RPM as determined by rev limiters. 

From the numbers below, it can confidently be stated the S65/S85 have the underpinnings to sustain the slightly increased revs. It would be prudent to tighten maintenance intervals on oil changes, spark plugs and other engine consumables.

Engines	Piston Speed (m/s)	Redline
S85B50	20.60	8250
S62B49	20.80	7000
S85B50-EVO	22.00	8800
S85B58	23.50	8500
S54B32	24.30	8000

As piston speed increases, inertia increases exponentially. Inertia is driven mostly by piston weight and stroke length. 

The S65/85 use lightweight aluminum cast piston that weighs 488 grams traveling over a 75.2mm stroke. 

As a comparaison, the smaller diameter S54 pistons are 485 grams and travel over a 91mm stroke - ouch. 

Final charts. 

For clarity's sake, you'll find the final charts below. All of them use weather corrected numbers (SAE) and 91 octane fuel. 

S85-EVO.

S85-EVO tuned v untuned.

S85-EVO v FBO. 

Table comparaison. 

The table below compares horsepower and torque differences in 500 RPM increments over 5000 RPM taken directly from the MustangDyne's software.  

There is a torque dip resulting in a maximum loss of 22 whp at 4,500 RPM. In the real world this matters little, I will explain why in the next entries discussing gearing. 

From 5,400 RPM to 7,200 RPM, the gains build into a steady +/- 35whp. On the top end, the torque gains stretch to 30whp, resulting in a 50whp increase by redline. 

This particular FBO car revs to 8,500 RPM hard limiter. This is unusual: tuning for FBO will usually have a max fuel cut off at 8,500 RPM with a soft rev limiter around 8,200 RPM. 

	FBO		EVO		Delta
RPM	tq	hp	tq	hp	tq	hp
3500	300	198	301	200	1	2
4000	310	234	288	218	-22	-16
4500	309	263	283	241	-26	-22
5000	309	293	319	302	10	9
5500	324	337	358	373	34	36
6000	338	384	364	414	26	30
6500	338	417	359	444	21	27
7000	326	432	351	467	25	35
7500	314	447	342	486	28	39
8000	297	450	327	498	30	48
8500	277	448	318	500	41	52

Hypothesis 004: Can high duration camshafts match a 5.8 stroker's peak power?

At the onset of the development of the Sxx-EVO programs, I sought to evaluate whether we could achieve naturally aspirated power levels previously exclusively achievable with strokers [...] for 1/4 of the price. 

First order of business was to ascertain what the actual power level of S85 stroker is. Unfortunately, very few owners have published dynos.

The only published dyno I could find was from Michael G on M5board, a long term owner with 5.8 by RDSport in California. He's one of the few, if not the only member of this forum to have posted his dyno results.

"Folks can talk about this and that stroker, but the until you run the numbers it’s all BS."
Michael G. / Reference

RDSport's 5.8.

To achieve the 5.8 liter capacity, forged rods are machined for an 8mm increase in stroke from 75mm to 83mm and the original Alusil block is bored from 92 to 94mm.

Lightweight forged pistons retaining the original 12.0 compression are fitted to counteract the increased inertia.  Lastly, a completely new crankshaft is machined to a larger radius for the increase stroke sweep. 

Michaels car was equipped with Eventuri intakes, OE+ carbon plenums, underdrive crank pulley and long tube headers. Overall, the engine modifications are similar to my S85-EVO. 

The numbers*.

The RDSport 5.8 stroker was tuned on EuropeanAutoSource's (EAS) dyno in California. EAS' dynojet is known across BMW communities to provide optimistic results. A leading factor is likely to their use of the STD correction factor.

The stroker achieved 544whp at 8,090 RPM and peak torque of 372wtq at 5,200 RPM on what I assume is California's 91 octane pump fuel. 

The stroker shows its strength in the flatness of the torque curve. It nearly fully eliminates the torque dip on stock 5.0s and expands the torque curve with peak torque achieved 700 RPM less than the FBO and S85-EVO stock displacement figures. 

Results 004: Yes. 

If we correct the stroker's numbers for SAE using the mean value of 2.5%, we obtain a corrected peak power of 530whp and the MustangDyno equivalent of 499whp.

For all intents and purposes, the S85-EVO has peak horsepower numbers of a 5.8 stroker.

The stroker has its benefits: the flatter torque peaks approximately 1,000 RPM earlier, making for a stronger mid range in day to day driving. I will make the case for the S85-EVO being much more fun to rev, relentlessly making power all the way to the redline unlike any other S85 upgrade package. 

Furthermore, the stroker's mid-range advantage will be short lived. The S85-EVO's higher rev limiters enables final drive gearing changes to 3.91 (SMG3) and 4.10 (6spd) that will enhance torque multiplication without losing top speed. This will be documented in future entries.

The S85-EVO in perspective. 

I've gathered the data we've compiled to tell various stories that put the S85-EVO in perspective.  

Gains per stages. 

The table below compares the various tuning stages of the S85.